Influence of Stone Processing Waste on Mechanical,Durability,and Ecological Performance of Hybrid Fiber-Reinforced Engineered Cementitious Composite

Abstract

The current study is focused on the characteristics of sustainable engineered cementitious composites (ECCs) with the inclusion of various types of fibers (PVA, PET, and MSE) in hybridization, silica sand (SS), river sand (RS), and stone processing waste (SPW). SPW is termed as hazardous material because of the presence of finer particles and inorganic substances which contribute to leaching problems, and cause adverse effects on aquatic life and human health. The objective of this study was to introduce new kind of cost-effective, sustainable, and greener ECC to encourage its use in diversified applications. The characteristics of different ECC mixtures were assessed by observing the slump flow, compressive, tensile, flexural, ultrasonic pulse velocity, air permeability, electrical resistivity (ER), sorptivity, ecological behavior, and cost analysis. Experimental results revealed that the combination of micro-fibers enhanced the overall performance of ECC with reduction in the matrix cost. The addition of SPW in place of aggregates enhanced the flowability, strength, and durability characteristics, and contributed to reducing the carbon dioxide emissions. This study confirms that the combined use of PVA, PET, and MSE fibers with SPW inclusion is a promising alternative over the fully PVA blended ECC with SS.

Keywords

advanced concrete materials polyester electrical resistivity high-performance concrete self-consolidating concrete sustainability durability of concrete

The brittle nature of cement-based products produces cracking problems, leading to deterioration of the service life of structures in the long run. In the last few decades, great efforts have been made by using steel reinforcement, fibers, supplementary cementitious materials (SCMs), and so forth, to counteract these drawbacks ( 1 – 4 ).

One such excellent cement-based composite, engineered cementitious composite (ECC), came to the picture in the current era to overcome the problems associated with conventional concrete ( 5 , 6 ). ECC is a novel class of fiber-reinforced cement composite (FRCC) which relies on micro and fracture mechanics theory and features ductility under tensile loading ( 7 , 8 ). The pseudo strain hardening with numerous tiny cracks (<100 µm), high toughness, tensile ductility (1%–8%), and energy absorption (approx. ≤ to 30 KJ/m²), are the excellent characteristics of ECC matrix which make it distinct from other kinds of FRCC ( 9 , 10 ).

The constituents used in the mix design of ECC are similar to FRCCs, but the abovementioned characteristics are attained by using 2% of polyvinyl alcohol (PVA) fiber and micro silica sand (SS) which helps to attain slip hardening behavior. However, coarse aggregates are eliminated in the mix design of ECC because they affect the ductile performance ( 6 – 8 ). A large quantity of aggregate is used in conventional concrete for economic reasons. The aggregate types, size, quantity, and some other physical parameters strongly influence the performance of cementitious products. The larger size aggregates affect the aggregate cement–paste interfacial bonding and distribution of fibers (by fiber balling), which contributes to the poor mechanical and durability performance of concrete ( 11 , 12 ). To attain the ductile nature of the ECC matrix, the micro-size constituents (SS, fly ash) need to be used in huge quantity.

In the last few years, several researchers have used polyethylene (PE) and PVA fiber to reinforce the ECC. The hydrophobically natured high-modulus PE fiber does not sustain any chemical bond with the cement matrix; however, it exhibits frictional bonding, which significantly enhances the complementary energy of fiber bridging ( 13 – 15 ). PE is also known as ultra-high-molecular-weight polyethylene (UHMWPE) as it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu ( 16 ). Moreover, the cost of PE fiber is higher than PVA fiber ( 7 ).

On the other hand, the hydrophilic nature of PVA fibers helps in sustaining a strong bond chemically with the cement matrix, which restricts the multiple cracking behavior and straining in the post-cracking zone through fibers’ rupture rather than pull out under loading conditions ( 17 ). To lessen the chemical bonding between fiber and cement paste a thin layer of oil coating (1.2%) was applied on the PVA fiber, which contributed to better strength and strain parameters than unoiled PVA fiber ( 18 , 19 ). The process of oil coating increased the cost of PVA fibers, which tends to limit the utilization of ECC matrix in large-scale construction activities, despite its unique fracture performance. The addition of high-cost fibers, finer-size aggregates (micro SS), and a higher amount of cement increases the overall cost of ECC. In recent years, the fibers have been blended in hybridization with the inclusion of various types of SCMs to decrease the cost of the ECC matrix.

The introduction of low and high-modulus fibers in hybridizations such as PVA and steel, polypropylene (PP) and PVA, and PE and steel resulted in better shear strength, deflection capacity, energy absorption capacity, impact resistance, tensile strength, and fiber bridging capability (13 –15, 20 –25). Recently, notable research works have been conducted on cement-based products with the dispersion of several types of fibers such as steel, basalt, nylon, glass, textile, carbon, bagasse, PP, polyester (PET), PE, PVA, and so forth, to improve the behavior of the cement matrix. The nature and percentage of fibers affect various properties of the cement-based matrix. Thus, the performance of cement-based products varies from parameter to parameter (different effects on various properties) as a result of the combination of fibers. The published literature reported that the most widely used SS in ECC has very little effect in reducing the shrinkage and creep ( 26 , 27 ). Also, the type and size of sand significantly affects the matrix properties K_m (fracture toughness of the mortar matrix) and J_tip (crack tip toughness). The pseudo strain hardening characteristics and composite ductile performance of ECC strongly rely on the abovementioned matrix properties (K_m and J_tip) ( 26 , 27 ). Therefore, the careful customization and proportioning of materials is required to attain the unique characteristics of ECC.

The current paper presents the careful evaluation of low-cost, sustainable, and greener ECC with the inclusion of various types of fibers in hybridization and stone processing waste (SPW). In the present investigation low-cost PET and micro steel (MSE) fibers were combined with PVA fibers in a matrix to decrease the cost of ECC. Locally found fine river sand (RS) instead of SS, and SPW as alternate substitution of both types of sand were utilized to solve the problem of high cost and waste disposal. Hybridization of polymeric and non-polymeric fibers and utilization of waste products was mainly employed to decrease the cost and adverse impact on the environment, and improve the fiber–matrix interactions.

PET fibers used in the current investigation were derived from virgin polyester and graded as low-modulus class. The introduction of PET fiber into cement mixtures revealed better mechanical and durability performance than conventional approaches ( 28 , 29 ). PET fiber sustained a very good bond with cement matrix because of its distinctive (neither hydrophobic nor hydrophilic) characteristics ( 28 ). The addition of PET fiber in concrete with high volume of fly ash (HVFA) increased the abrasion resistance ( 29 ).

Dimensional stone products are the main components of the construction industry used for ornamental purposes. The quality, type, mineralogical composition, and durability parameters of stone products rely on the category and nature of the existing materials ( 30 , 31 ). The demand for stone products is fulfilled from rocks, and there is an amount of waste accumulated during processing of these products. Generally, two types of waste are produced: (a) solid stone waste, and (b) slurry stone waste. Dressing operations result in solid waste, whereas cutting, sawing, and finishing processes leave slurry stone waste as residue ( 32 , 33 ). Disposal of stone waste covers hectares of land resources, and the finer-size particles create problems for adjoining areas in relation to living standards, land fertility, and environmental ecosystems ( 34 ). Very limited investigations are available on the utilization of SPW in the construction of ECC matrix ( 35 ). In the past, the notable research has been conducted on cement mortar, concrete, and FRCCs with the utilization of stone waste (SW) which revealed the improvement in mechanical and durability parameters as a result of its filling effect ( 36 , 37 ).

The aim of the current investigation is to reveal the effect of various types of fibers in hybridization with the inclusion of SS, RS, and SPW (dried stone slurry powder) on slump flow, compressive, tensile, flexural, ultrasonic pulse velocity, air permeability, electrical resistivity (ER), and sorptivity characteristics, and ecological and cost analysis. The outcomes and suggestions from the current study will contribute in the application of ECC matrix in large-scale construction activities by launching cost-effective, sustainable, and greener cement-based material with the inclusion of fibers in hybridization and SPW as an alternative substitution for aggregates, and RS instead of SS.

Experimental Program

Selection of Materials

The mixtures of cementitious composite comprised with 43 grade ordinary Portland cement (OPC), blast furnace slag (BFS), SS, RS, and SPW. The chemical composition of the utilized cementitious materials (OPC and BFS) as per energy dispersive X-ray spectroscopy analysis is presented in Table 1. The aim of using locally available RS in place of SS was to save energy and reduce the overall cost of the ECC matrix. SPW was utilized as partial substitution of SS and RS at the level of 50% for each type of fine aggregate. In the current study, the maximum size for SS, RS, and SPW was 175 µm, 600 µm, and 90 µm, respectively. The incorporation of SPW can resolve its disposal issue and contribute in sustainable construction.

Table 1.

Chemical Composition of Ordinary Portland Cement (OPC) and Blast Furnace Slag (BFS)

Compound	OPC (%)	BFS (%)
Calcium oxide	61.56	34.26
Silicon dioxide	21.92	40.42
Magnesium oxide	5.37	4.11
Aluminum oxide	7.18	17.61
Sodium oxide	1.55	0.42
Sulfur trioxide	1.27	1.85
Potassium oxide	1.15	1.34

The fibers selected to reinforce the ECC mixtures were PVA, PET, and MSE, as shown in Figure 1. The information related to the fiber properties is presented in Table 2. Polycarboxylic ether-based super plasticizer and water were added to form the fresh ECC mixture.

Table 2.

Information Related to the Properties of Fibers

Specifications	PET	PVA	MSE
Tensile strength (MPa)	480	1600	2000
Length (mm)	12	12	13
Diameter (mm)	0.025–0.035	0.04	0.20
Aspect ratio (L/D)	400	300	65
Elongation (%)	30	7	NA
Young’s modulus (GPa)	NA	42.8	NA
Electrical conductivity	Low	Low	High
Density (g/cm³)	1.31	1.3	NA

Note: MSE= microsteel; PET = polyester; PVA = polyvinyl alcohol; L/D = Length/Diameter; NA = Not available.

Figure 1.

Pictorial view of used fibers: (a) polyester (PET), (b) microsteel (MSE), and (c) polyvinyl alcohol (PVA).

Mix Proportions

In the current experimental approach a total of 12 ECC mixtures were designed in two different groups to judge the influence of various types of fibers, aggregates (SS and RS) on the performance of the ECC. Group-I represents the SS-containing mixtures with different fibers in hybridization, and Group-II represents the RS-containing mixtures with different fibers in hybridization. The proportions and designation of the various ECC mixtures are presented in Table 3.

Table 3.

Engineered Cementitious Composite Mixture Designation and Proportions

Mix Id	OPC	BFS	SS	RS	SPW	PVA (%)	PET (%)	MSE (%)	w/b	SP (%)
(Group-I)	1	1.2	0.8	0	0	2	0	0	0.27	0.45
SS1
SS2	1	1.2	0.8	0	0	1.5	0.5	0	0.27	0.45
SS3	1	1.2	0.8	0	0	1.0	0.5	0.5	0.27	0.45
SS_SPW1	1	1.2	0.4	0	0.4	2	0	0	0.27	0.45
SS_SPW2	1	1.2	0.4	0	0.4	1.5	0.5	0	0.27	0.45
SS_SPW3	1	1.2	0.4	0	0.4	1.0	0.5	0.5	0.27	0.45
(Group-II)	1	1.2	0	0.8	0	2	0	0	0.27	0.45
RS1
RS2	1	1.2	0	0.8	0	1.5	0.5	0	0.27	0.45
RS3	1	1.2	0	0.8	0	1.0	0.5	0.5	0.27	0.45
RS_SPW1	1	1.2	0	0.4	0.4	2	0	0	0.27	0.45
RS_SPW2	1	1.2	0	0.4	0.4	1.5	0.5	0	0.27	0.45
RS_SPW3	1	1.2	0	0.4	0.4	1.0	0.5	0.5	0.27	0.45

OPC = Ordinary portland cement; BFS = Blast furnace slag; SS = Silica sand; RS = River sand; SPW = Stone processing waste; PVA = Polyvinyl alcohol; PET = Polyester; MSE = Microsteel.

Mixing and Specimen Casting

The process of ECC production was done using an electric mortar mixer. To obtain the correct composite mixture, first all the powdered constituents were poured into the mixer and rotated for 2 to 3 min. Afterwards, 75% quantity of total calculated water and admixture were added into the dry constituents and the mixer was operated for an additional 3 min. The remaining quantities of water and admixture were poured into the mixer and rotated again for two more minutes to obtain a consistent mixture. A measured amount of fiber filaments was deliberately spread into the drum during the rotation of the mixer, and the mixer turned until the fibers were evenly distributed. Thereafter, a fresh mixture of hybrid engineered cementitious composite (HECC) was collected and tested for slump flow deformation and flow time (T₅₀). For hardened parameters testing the uniform mixture was poured into moulds of cubes, prisms, plates, and dog bone-shaped specimens of dimensions 70.6 mm × 70.6 mm × 70.6 mm (for compressive strength and ER), 500 mm × 100 mm × 100 mm (for flexural response and ultrasonic pulse velocity [UPV]), 250 mm × 250 mm × 75 mm (for air permeability and sorptivity), and 310 mm × 100 mm × 20 mm (for tensile characteristics) and stored in the laboratory for next 24 h at room temperature. All the prepared specimens were taken out from moulds after 1 day and immersed in water tank for required age of curing.

Test Methodologies

Fresh State Properties

To check the impact of fiber hybridization, SS, RS, and SPW on the rheological performance of ECC, the slump flow test was carried out on fresh mixture without any obstacle as per ASTM C1611 ( 38 ) specifications. From this testing two different aspects—slump flow range and time to spread for 500 mm (T₅₀)—were recorded. These aspects indicate the horizontal flow diameter by recording the slump flow deformability, and viscosity of the fresh mixture by recording the flowtime for ECC to reach the determined flow distance.

Compressive Strength

To analyze the impact of fiber hybridization, SS, RS, and SPW on compression behavior, the cubic samples were tested in a compression testing machine after 7 day and 28 day water curing as per the recommendations of BIS:516-1959 ( 39 ) and BS-EN-12390-3 ( 40 ).

Tensile Response

Dog bone-shaped samples were removed from the water tank after 7 days and 28 days to analyze the impact of fiber hybridization, SS, RS, and SPW on tensile characteristics and were tested at loading rate of 0.2 mm/min. The tensile response was measured on maintained 80 mm gauge length as per the recommendations of Yu et al. ( 25 ) The block diagram of the dog bone-shaped specimen is shown in Figure 2. The deformation on defined gauge length of specimens was recorded by using a universal testing machine and displacement transducers. The test setup used for recording the tensile response is shown in Figure 3.

Figure 2.

Block diagram of dog bone-shaped specimen.

Figure 3.

Test setup for recording tensile response.

Four-Point Bending Test

To record the load deflection response of ECC matrices the prism-shaped samples were removed from the water tank after 28 days and checked as per the recommendations of BIS:516-1959 ( 39 ) and BS-EN-12390-5 ( 41 ) part 5.

Ultrasonic Pulse Velocity

To examine the effect of fiber hybridization, SS, RS, and SPW on quality of ECC matrix the non-destructive UPV test was conducted on prismatic specimens after 28 days of water curing by using Pundit’s apparatus as per the recommendations of BIS:13311 ( 42 ) and ASTM C597-16 ( 43 ).

Electrical Resistivity

The examination of ER refers to the movement and diffusion of ions through the matrix and indicates the corrosion potential of cement-based products. It is a non-destructive technique and can be used as a durability indicator of cementitious composite. ER was recorded on cubic specimens via a two-point method after 1, 3, 5, 7, 14, 21 and 28 days of water curing. The ER (ρ) of the cubic specimens was calculated by the following equation:

ρ = R \frac{A}{L} k Ω - cm

(1)

where A=Cross-sectional area of the cubic specimen (cm²)

L = Height of the cubes

R = Resistance of the specimen ( $k Ω$ ).

The recommended values of ER related to corrosion risk (CR) and chloride ion penetration (CIP) are presented in Table 4.

Table 4.

Correlation Between Electrical Resistivity (ER), Chloride Ion Penetration (CIP), and Corrosion Risk (CR) (44, 45)

ER (kΩ-cm)	CIP	ER (kΩ-cm)	CR
<12	High	<5	Very high
12–21	Moderate	5–10	High
21–37	Low	10–20	Low to moderate
37–254	Very low	>20	Negligible
>254	Negligible

Air Permeability and Sorptivity (Water Absorption)

Air permeability and sorptivity (water absorption) are affected by the ionic structure of pores present in cement-based products and are related to the durability performance of the matrix. To judge the impact of various constituents on the durability parameters (air permeability and sorptivity) of the ECC matrix, the plate specimens were tested as per the recommendations of the Autoclam permeability operating system ( 46 ). The Autoclam apparatus fabricated by Queen’s University, Belfast (United Kingdom) can be used for recording the air permeability, water permeability, and sorptivity (water absorption) in the laboratory or on site. The assembled setup of the permeability system on plate specimens to conduct the air permeability and sorptivity test is shown in Figure 4. To record the air permeability, the 500 mbar pressure inside the Autoclam body and decay in pressure was monitored with time. The line of natural logarithm of recorded pressure against time was plotted by regression, and the slope of the regressed line between 5th minute and 15th minute was reported as the air permeability index (API) in units of Ln (mbar)/min.

Figure 4.

Assembled set up of Autoclam apparatus.

Moreover, to record the sorptivity (water absorption) on the same specimens the volume of water entering the ECC matrix specimen was recorded every minute for the next 15 min with a maintained nominal pressure of 20 mbar. The amount of water ingress against square root of time was plotted, and slope of this graph revealed the values of sorptivity index in units of m³ × 10⁻⁷/min^1/2.

Results and Discussion

Visual Inspection

The hardened surface of the ECC matrix specimens was found to be smooth and well finished and no significant change was observed due to the use of various types of fibers in hybridization. The utilization of SPW as substitution of SS and RS provided better finishing and a well sound surface.

Self-Consolidated (Workability) Performance of ECC

The workability performance of fresh ECC mixtures was assessed based on slump flow deformation (mm) and time (T₅₀, sec) required for the slump flow to first reach the outer edge of a 500 mm diameter circle. The observed values of slump flow, T₅₀ and relationship between both are shown in Figure 5, a and b .

Figure 5.

(a) Self-consolidated performance of mixtures containing silica sand (SS) (Group-I) and (b) self-consolidated performance of mixtures containing river sand (RS) (Group-II).

From Figure 5, a and b , it can be seen that the slump flow of mixtures including fibers of polymeric nature was less than that of the hybrid mixture of metallic and non-metallic fibers blended mixtures. The slump flow of SS3, RS3, SS_SPW3, and RS_SPW3 mixtures was higher by 5.54%, 8.30%, 3.72% and 3.94%, respectively, as compared with SS1, RS1 SS_SPW1 and RS_SPW1 mixtures. The differences in slump flow values were attributed to the high surface area and water absorption capacity of polymeric fibers in the early stage as compared with non-polymeric fibers. The blend of polymeric nature (PVA + PET) fibers showed no significant changes in slump deformation. Moreover, the slump flow of SS-containing (Group-I) mixtures was observed to be higher by 9.55 to 13.61% as compared with RS-containing (Group-II) mixtures. Previous research has revealed that the presence of SW powder in cement-based products reduced the flowability of the matrix due to its higher specific surface area ( 31 ). Therefore, in the present investigation the amount of high range water reducer admixture (HRWRA) was adjusted to achieve the desired flowability. The fixed amount of adjusted HRWRA also showed an enhancement in flowability as compared with their counterpart mixtures.

The relationship between slump flow deformation and T₅₀ showed that the time to flow reduced with the rise in the slump flow values; this was because of better flowability properties. The values of slump flow deformation and T₅₀ range from 638 to 780 mm and 1.98 to 3.19 s for all mixtures in this study. Finally, based on the self-consolidated properties it was concluded that all fresh ECC mixtures had the self-compacting property even when prepared with polymeric fibers, non-polymeric fibers, SS, RS, or SPW.

Compressive Strength

Impact of Fiber Hybridization

The observed compression behavior showed that the combination of PVA and PET fiber reduced the compressive strength, whereas the blend of PVA, PET, and MSE fiber improved the compressive strength. The low and high modulus of PET and MSE fiber was responsible for strength reduction and enhancement, respectively. The enhancement and reduction in compressive strength resulting from the hybridization of fibers was found to be marginal, as reported by other researchers also ( 29 , 47 ).

HECC Containing SS (Group-I)

The compressive strength results of HECC containing SS and SPW as alternative substitution for SS at different curing ages is shown in Figure 6a. It can be seen from Figure 6a that the utilization of SPW as a replacement for SS enhanced the compressive strength of various mixtures at different curing ages. The compressive strength of SS_SPW1, SS_SPW2, and SS_SPW3 mixtures was higher by 3.21%;6.34%, 1.50%;4.61% and 2.99%;7.91% as compared to their counterparts after 7 days;28 days of water curing, respectively. The enhancement in compressive strength was attributed to the micro pore-filling effect of SPW, which fills the micro voids and produces a denser microstructure. Similar findings were reported by Almeida et al. ( 32 ) and Singh et al. ( 33 , 34 ), who reported that the enhancement in compressive strength was owing to the filling effect of SPW.

Figure 6.

(a) Compressive strength of mixtures containing silica sand (SS) (Group-I) and (b) compressive strength of mixtures containing river sand (RS) (Group-II).

HECC Containing RS (Group-II)

The compressive strength results of HECC containing RS and SPW as alternative substitution for RS are illustrated in Figure 6b. After 28 days of water curing the compressive strength of fully RS-included mixtures was observed to be higher than fully SS-included mixtures. The better compressive strength in fully RS blended mixture was observed, and may be due to higher aggregate size than SS which provided toughness to the matrix, resulting into strength enhancement. It can be seen from Figure 6b that the utilization of SPW as alternate substitution for RS enhanced the compressive strength of various mixtures at different curing ages. The compressive strength of RS_SPW1, RS_SPW2, and RS_SPW3 mixtures were higher by 6.04%;7.73%, 5.27%;8.20% and 5.94%;8.95% as compared to their counterparts after 7 days;28 days water curing, respectively.

On the basis of the compressive strength results it has been found that the re-utilizing of SPW is a good alternative for fine aggregate replacement in ECC. The micro-size particle of SPW contributes to making a denser microstructure of HECC, which results in compressive strength increment. The enhancement in compressive strength with SPW inclusion was observed for all three fiber combination groups selected in present study. The observed compressive strength values showed that the addition of SPW as RS substitution was more effective than SS substitution. Better compressive strength was found in RS_SPW3 mixtures than all the other mixtures explored in this study.

Tensile Strength

Impact of Fiber Hybridization

The hybridization of fibers strongly influenced the tensile strength of various HECC mixtures. The combination of PVA and PET fiber decreased the tensile strength by up to 20.13% as compared to fully PVA blended mixtures. Moreover, the blend of PVA, PET, and MSE fiber improved the tensile strength up to 7.32% as compared to fully PVA blended mixtures. Numerous research investigations have revealed that the dispersion of low-modulus fiber in ECC is responsible for strength reduction, whereas the usage of high-modulus fibers in cementitious mixtures contributes to strength improvements ( 18 , 19 ). Therefore, in the present investigation the reduction and enhancement in tensile strength was observed due to low and high-modulus nature of PET and MSE fiber, respectively, as compared with PVA fiber.

HECC Containing SS (Group-I)

The tensile strength results of HECC (with different fiber combinations) containing SS and SPW as an alternate substitution of SS at different curing ages are illustrated in Figure 7a. It can be seen from Figure 7a that the utilization of SPW as substitution for SS enhanced the tensile strength of various ECC matrices at different curing ages. The tensile strength of SS_SPW1, SS_SPW2, and SS_SPW3 mixtures was higher by 4.21%;3.08%, 6.36%;13.01%, and 3.71%;3.70% as compared with their counterparts after 7 days;28 days of water curing, respectively. The finer particles of SPW reduced the porosity at the transition zone around the fibers and contributed to making a denser matrix, which results in strength enhancement.

Figure 7.

(a) Tensile strength of mixtures containing silica sand (SS) (Group-I) and (b) tensile strength of mixtures containing river sand (RS) (Group-II).

HECC Containing RS (Group-II)

The tensile strength results of HECC containing RS and SPW as alternate substitution of RS are illustrated in Figure 7b. After 28 days of water immersion the tensile strength of fully RS-containing mixture was observed to be higher than fully SS-containing mixture. The better tensile strength was found in fully RS-containing mixture as a result of higher particle size than SS, which provides matrix toughness and results in strength enhancement. It can be seen from Figure 7b that the utilization of SPW as alternate substitution of RS enhanced the tensile strength of ECC mixtures at different curing ages. The tensile strength of RS_SPW1, RS_SPW2, and RS_SPW3 mixtures was higher by 13.26%;10.74%, 11.13%;9.60% and 10.56%;9.09% as compared to their counterparts after 7 days;28 days of water curing, respectively.

On the basis of the tensile strength results it was found that the utilization of SPW is a good alternate for fine aggregate replacement in HECC. The micro-size particles of SPW contribute to making a denser microstructure of HECC, which results in tensile strength increment. The enhancement in tensile strength with SPW inclusion was observed for all three fiber combination groups in the present study. Therefore, the tensile strength results have shown that the utilization of SPW has no adverse effect on the fiber hybridization. It was concluded from the tensile strength values that the utilization of SPW as RS substitution was more effective than SS substitution. The maximum tensile strength was found in RS_SPW3 matrix. Tensile strength enhancement in SPW-included mixtures was observed due to finer particle size of SPW. SPW in ECC acts as a gel when mixed with the self-consolidated ECC mixture; that is, it contributes to reducing the porosity at the transition zone around the fibers, which results in strength enhancement.

Tensile Strain

Impact of Fiber Hybridization

The tensile strain capacity of ECC depends on the types and quantity of the constituents used, and tailoring of the process, which makes ECC differ from other kinds of cement-based products. Numerous research investigations have reported that the quantity, type, nature, length, and shape of the fibers strongly influence the tensile strain capacity of ECC mixtures ( 5 , 18 , 47 ). Similarly, in the present investigation the combination of fibers in various groups affects the tensile strain characteristics of ECC. The hybridization of PVA and PET fiber enhanced the tensile strain capacity up to 8.77% as compared with fully PVA blended mixtures. Furthermore, the blend of PVA, PET, and MSE fibers (in the SS_SPW3 mixture) decreased the tensile strain up to 21.09% as compared with the fully PVA blended mixtures (SS1 mixture). Previous studies reported that the introduction of low-modulus fiber into the cement matrix enhanced the energy absorption capacity, which contributes to improved ductility, (19, 21) whereas the presence of MSE fibers improved the strength parameters and bridging stress ( 19 , 47 ). PVA and PET fibers both are polymeric in nature; however, the mechanical properties of both fibers are different. The PVA fibers created a strong chemical bond with the cement matrix due to its hydrophilic nature, which results into fibers ruptured rather than pull out ( 17 ). On the other hand, the distinctive nature (neither hydrophilic nor hydrophobic) of PET fiber used in this investigation was able to create a very good bond between the cement matrix and fiber surface ( 28 ) Therefore, low modulus, distinctive nature and some other unique characteristics of PET fiber are responsible for the tensile strain capacity enhancement in SS2, RS2, SS_SPW2 and RS_SPW2 mixtures as compared to other mixtures.

HECC Containing SS (Group-I)

The tensile strain results of HECC (with different fiber combinations) containing SS and SPW as alternate substitution of SS at different curing ages are illustrated in Figure 8a. It can be seen from Figure 8a that the inclusion of SPW as alternate substitution of SS enhanced the tensile strain capacity of various matrices at different curing ages. The tensile strain capacity of SS_SPW1, SS_SPW2, and SS_SPW3 mixtures was higher by 9.07%;15.51%, 8.67%;12.19% and 10.22%;16.49%, respectively, as compared with their counterparts after 7 days;28 days of water curing.

Figure 8.

(a) Tensile strain capacity of mixtures containing silica sand (SS) (Group-I) and (b) tensile strain capacity of mixtures containing river sand (RS) (Group-II).

The finer particles of SPW, after reaching at the micro voids present in the transition zone around the fibers, may have improved the interfacial properties between fiber and matrix, resulting in tensile strain capacity enhancement.

HECC Containing RS (Group-II)

The tensile strain capacity of HECC containing RS and SPW as alternate substitution of RS at different curing ages is illustrated in Figure 8b. The tensile strain capacity of fully SS blended mixtures was observed to be higher than fully RS-containing mixture. The higher particle size of RS increased the matrix toughness which delayed the crack initiation, resulting in tensile strain reduction as compared with fully SS blended mixtures. It can be seen from Figure 8b that the utilization of SPW as alternate substitution of RS improved the tensile strain of various matrices at different curing ages. The tensile strain values of RS_SPW1, RS_SPW2, and RS_SPW3 mixtures were higher by 16.2%;18.28%, 15.12%;17.13%, and 12.65%;13.91% as compared with their counterparts after 7 days;28 days of water curing. The failure and cracking pattern of the tested dog bone specimens are shown in Figure 9.

Figure 9.

Failure and cracking pattern of tested dog bone specimens.

The observed tensile strain capacity results showed that hybridization of fibers as well as SPW inclusion in the ECC matrix contribute to enhancing the novel parameters (tensile strain capacity) of ECC. The hybridization of fiber and inclusion of SPW is a suitable option to decrease the cost of ECC and for utilization of SW.

Flexural Response

Impact of Fiber Hybridization

The load deflection response of various matrices was recorded to analyse the flexural response. Figure 10, a and b , depicted the load deflection response of various HECC mixtures after 28 days of water immersion. It can be seen from Figure 10, a and b , that the blend of polymeric fibers (75% PVA + 25% PET) reduced the flexural strength, whereas the mid span deflection was increased. The hybridization of PVA and PET fiber decreased the flexural strength up to 10.39%, whereas the mid span deflection was increased up to 35.34% as compared with the fully PVA blended mixtures. Moreover, with the blend of polymeric and non-polymeric fibers (PVA + PET + MSE fiber) the opposite flexural response was observed as compared with polymeric fibers hybridization. The hybridization of PVA, PET, and MSE fiber enhanced the flexural strength up to 3.72%, and decreased the mid span deflection up to 17.35% as compared with fully PVA blended mixtures. The observed flexural response from the fiber hybridization revealed that the introduction of low-modulus polymeric fiber contributed to enhancing the energy absorption capacity, whereas the high-modulus non-polymeric fiber takes more stresses during fiber bridging.

Figure 10.

(a) Load deflection response of mixtures containing silica sand (SS) (Group-I) and (b) load deflection behavior of mixtures containing river sand (RS) (Group-II).

HECC Containing SS (Group-I)

The flexural response of HECC mixtures (with different fiber combinations) containing SS and SPW as alternate substitution of SS is depicted in Figure 10a. It can be seen from Figure 10a that the inclusion of SPW as alternate substitution of SS improved the flexural response of various mixtures. The flexural strength of SS_SPW1, SS_SPW2, and SS_SPW3 mixtures was higher by 4.63%, 5.72%, and 3.18%, and the mid span deflection was higher by 25.75%, 14.04%, and 16.27%, respectively, as compared to their counterpart mixtures after 28 days of water curing. The inclusion of SPW in ECC mixtures contributed to improving the interfacial properties between fiber and matrix, resulting in improvement of the load deflection behavior of the HECC mixtures.

HECC Containing RS (Group-II)

The flexural response of HECC containing RS and SPW as alternate substitution of RS is illustrated in Figure 10b.

The flexural strength of fully RS-containing mixtures was observed to be better than fully SS-containing mixtures. The higher particle size of RS increased the matrix toughness, which contributed to enhancing the load-carrying capacity as compared with fully SS blended mixtures. It can be seen from Figure 10b that the utilization of SPW as alternate substitution of RS enhanced the flexural response of various mixtures at different curing ages. The flexural strength values of RS_SPW1, RS_SPW2, and RS_SPW3 mixtures were higher by 5.56%, 4.67%, and 3.97%, and the mid span deflection values were higher by 29.03%, 19.27%, and 18.06%, respectively, as compared with their counterparts after 28 days of water curing. The microcracking behavior and failure pattern of the tested prism specimens are illustrated in Figure 11.

Figure 11.

Microcracking behavior and failure pattern of tested prism specimens.

The analyzed flexural responses of various mixtures showed that the hybridization of polymeric, non-polymeric fibers, and SPW utilization in ECC matrix improved the load deflection behavior of hybrid ECC and contributed to making cost-effective and green ECC by using low-cost fibers and waste products.

Electrical Resistivity

Impact of Fiber Hybridization

The variation in ER due to inclusion of different types of fibers, SS, RS, and SPW is shown in Figure 12, a and b . It can be seen from Figure 12, a and b , that the blend of polymeric fibers (75% PVA + 25% PET) improved the ER performance of various ECC matrix groups. The hybridization of PVA and PET fiber improved the ER performance of SS2 and RS2 mixtures by 12.75% and 10.04%, respectively, as compared with SS1 and RS 1 mixtures after 28 days of water curing. The nature of both the fibers (PVA and PET) is the same, whereas their interactions are different with ECC matrix; as a result of this variations in ER values were observed. The presence of the hydrophilic PVA fiber increased the percentage of pores at the transition zone around the fibers ( 48 , 49 ), leading to easy movement of ions through the whole matrix structure; that is, directly related to resistivity, permeation, and corrosion. However, the PET fiber used in the study was distinctive in nature (neither hydrophilic nor hydrophobic) and specially designed for cement-based products, able to sustain a very good bond with cement paste and reduce the micro pores present at the transition zone around the fibers. Moreover, the blend of polymeric and non-polymeric fibers (PVA + PET + MSE fiber) shows opposite ER performance as compared with the hybridization of polymeric fibers. The hybridization of PVA, PET, and MSE fiber decreased the ER of SS3 and RS3 mixtures by 5.76% and 11.64% as compared with SS1 and RS1 mixtures, respectively, after 28 days of water curing. The conductive nature of the MSE fibers allows the easy flow of current ions through whole matrix structure, which results in ER reduction in the MSE fiber-reinforced ECC ( 50 ).

Figure 12.

(a) Electrical resistivity (ER) behavior of mixtures containing silica sand (SS) (Group-I) and (b) ER behavior of mixtures containing river sand (RS) (Group-II).

HECC Containing SS (Group-I)

The ER performance of HECC mixtures (with different fiber combinations) containing SS and SPW as alternate substitution of SS is shown in Figure 12a. It can be seen from Figure 12a that the inclusion of SPW as an alternate substitution of SS improved the ER performance of the ECC matrix with various fiber combination groups. The ER of SS_SPW1, SS_SPW2, and SS_SPW3 mixtures was higher by 12.61%;8.91%;12.14%, 14.72;11.20%;6.93%, and 10.12%;7.85%;9.60%, respectively, as compared with their counterparts after 7 days;21 days;28 days of water curing, respectively.

The finer-size particles of SPW help to fill the voids present around the fibers, which results in densification of the whole matrix structure. It is postulated that the compact nature of the SPW–ECC mixtures restricted the movement of ions through the whole structure, which contributed to the improvement in ER.

HECC Containing RS (Group-II)

The ER performance of HECC mixtures containing RS and SPW as alternate substitution of RS is illustrated in Figure 12b. The ER of SS-containing (Group-I) mixtures was observed to be higher than that of RS-containing (Group-II) mixtures, which may be due to SS-containing mixtures were less porous as compared with RS. It can be seen from Figure 12b that the utilization of SPW as alternate substitution of RS improved the ER performance of various matrices at different curing ages. The ER performances of RS_SPW1, RS_SPW2, and RS_SPW3 mixtures were higher by 17.61%;11.81%;15.98%, 16.19%;17.84%; 14.93%, and 9.09%;14.02%;10.85% as compared with their counterparts after 7 days;21 days;28 days water curing, respectively. The density state of the ECC samples prepared with SPW contributed to reducing the porosity and blocking the pore connectivity, which contributed to the ER enhancement. The recommended values of ER from Table 4 show that the risk of corrosion and penetration of chloride ions was negligible/very low in all selected mixtures.

Air Permeability

Impact of Fiber Hybridization

The porosity, permeation, and the presence of different types of materials strongly influenced the durability aspects of the cement matrix. Figure 13, a and b , illustrate the API of HECC mixtures after 28 days of water immersion. It can be seen from Figure 13, a and b , that the blend of polymeric fibers (75% PVA + 25% PET) reduced the API of SS2 and RS2 mixtures by 10.49% and 9.18% as compared with SS1 and RS1 mixtures, respectively, after 28 days of water curing. The API values revealed that the inclusion of polymeric fibers in combination reduced the percentage of micro pores present in fully PVA blended (SS1 and RS1) mixtures. The reduction in pore percentage in the matrix helps to restrict the movement of ions and subsequently improves the permeability performance. Additionally, the blend of polymeric and non-polymeric fibers (PVA + PET + MSE fiber) also improved the API performance as compared with the polymeric fiber hybrid mixture and fully PVA blended mixture. The blend of PVA, PET, and MSE fiber reduced the API up to 23.45%, 24.49% and 13.55%, 14.84% as compared with SS1, RS1 and SS_SPW1, RS_SPW1 mixtures, respectively. The metallic (MSE) fibers sustain a perfect bond with cement-based products and also show sticking behavior between them. The perfect bonding and packaging of particles with MSE fiber reduced the percentage of pores and helped to impair the movement of ions through the matrix ( 51 , 52 ). Therefore, the hybridization of polymeric and non-polymeric fibers in HECC mixtures enhanced the API characteristic and also helped to reduce the overall cost.

Figure 13.

(a) Air permeability index (API) of engineered cementitious composite (ECC) mixtures containing silica salt (SS) (Group-I) and (b) API of ECC mixtures containing river salt (RS) (Group-II).

HECC Containing SS (Group-I)

The API performance of HECC mixtures (with different fiber combinations) containing SS and SPW as alternate substitution of SS is depicted in Figure 13a.

It can be seen from Figure 13a that the inclusion of SPW as alternate substitution of SS improved the API performance of the ECC matrix with various fiber combination groups. The air permeability of SS_SPW1, SS_SPW2, and SS_SPW3 mixtures reduced by 27.16%, 24.82%, and 17.74%, respectively, as compared with their counterparts after 28 days of water curing.

HECC Containing RS (Group-II)

The API performance of HECC mixtures containing RS and SPW as alternate substitution of RS is illustrated in Figure 13b. The air permeability performance of SS-containing (Group-I) mixtures was observed to be better than RS-containing (Group-II) mixtures, which may be because of the reduced porosity of the SS mixture which helps in blocking the pore connectivity. It can be seen from Figure 13b that the utilization of SPW as alternate substitution of RS improved the API performance of various mixtures. The air permeability of RS_SPW1, RS_SPW2, and RS_SPW3 mixtures was reduced by 34.69%, 33.14%, and 26.35%, respectively, as compared with their counterparts after 28 days of water curing.

Sorptivity (Water Absorption)

Impact of Fiber Hybridization

The sorptivity (water absorption) of any cement matrix depends on the whole matrix structure, the interaction of fibers in the matrix, the presence of vivid solid contents (various supplementary cementitious products), and so forth. All these factors play crucial role in the water absorption performance of any cementitious matrix. The water absorption performance of various mixtures was analyzed through assessing the sorptivity index using the Autoclam system. Figure 14, a and b , illustrate the sorptivity index of various HECC mixes after 28 days of water curing. It can be seen from Figure 14, a and b , that the blend of polymeric fibers (75% PVA + 25% PET) reduced the sorptivity index of SS2 and RS2 mixtures by 8.61% and 7.62% as compared with SS1 and RS1 mixtures, respectively, after 28 days of water curing. The large number of hydroxyl (OH) groups present in PVA fiber makes its nature hydrophilic, which limits the water barrier properties of PVA-based products. The introduction of PVA fiber into the ECC matrix enhanced the porosity at the transition zone around the fibers ( 48 , 49 ). All these PVA fiber parameters increased the chances of water absorption in fully PVA blended mixtures as compared with the other mixtures used in this study. However, the nature of PET fiber is hydrophobic, and shows a water-repellent performance ( 28 , 53 ). Therefore, because of the differences in the properties of fibers and the interaction characteristics of different fibers with the matrix, variations in the sorptivity index were observed.

Figure 14.

(a) Sorptivity of engineered cementitious composite (ECC) mixtures containing silica sand (SS) (Group-I) and (b) sorptivity of ECC mixtures containing river sand (RS) (Group-II).

Further, the blend of polymeric and non-polymeric fibers (PVA + PET + MSE fiber) also improved the sorptivity performance as compared with the fully PVA blended mixture. The blend of PVA, PET, and MSE fiber reduced the sorptivity index up to 7.65%, 4.70% and 4.09%, 3.51% as compared with SS1, RS1 and SS_SPW1, RS_SPW1 mixtures, respectively.

HECC Containing SS (Group-I)

The sorptivity performance of HECC mixtures (with different fiber combinations) containing SS and SPW as alternate substitution of SS is shown in Figure 14a. It can be seen from Figure 14a that the utilization of SPW as an alternate substitution of SS reduced the sorptivity index of the ECC matrix with various fiber combination groups. The sorptivity index of SS_SPW1, SS_SPW2, and SS_SPW3 mixtures was reduced by 35.64%, 34.29%, and 33.16%, respectively, as compared with their counterpart mixtures after 28 days of water curing.

The reduction a/reduction after 28 days of curing in various parameters of phase-I HECC mixtures as compared with SS1 mix proportion is given in Table 5. The finer-size particles of SPW help to fill the micro voids present in the ECC matrix structure and contribute to blocking the pore connectivity. Therefore, all these parameters reduced the chances of water flowing through matrix, thus lesser the sorptivity index.

Table 5.

Percentage Enhancement/Reduction in Various Parameters of Phase-I HECC Mixtures as Compared with SS1

Mix id	CS	TS	TSR	FS	MD	ER	API	ST
SS1	—	—	—	—	—	—	—	—
SS2	−0.80	−20.13	8.77	−10.39	35.34	12.75	−10.49	−8.61
SS3	−0.24	0.81	−20.81	3.72	−10.48	−5.76	−23.45	−7.65
SS_SPW1	6.34	3.08	15.51	4.63	25.75	12.13	−27.16	−35.64
SS_SPW2	4.61	13.01	12.19	5.72	14.04	20.57	−32.71	−39.95
SS_SPW3	7.91	3.70	16.49	3.18	16.26	3.29	−37.03	−38.27

Note: CS = Compressive strength; TS = Tensile strength; TSR = Tensile strain capacity; FS = Flexural strength; MD = Mid span deflection capacity; ER = Electrical resistivity; API = Air permeability index; ST = Sorptivity index.

HECC Containing RS (Group-II)

The water absorption performance of HECC mixtures containing RS and SPW as alternate substitution of RS is illustrated in Figure 14b. The sorptivity performance of SS-containing (Group-I) mixtures was observed to be better than that of RS-containing (Group-II) mixtures; this may be because of the smaller pore structure of SS which helps to impair the pore connectivity.

It can be seen from Figure 14b that the utilization of SPW with RS reduced the sorptivity index of various mixtures. The sorptivity index values of RS_SPW1, RS_SPW2, and RS_SPW3 mixtures were reduced by 36.09%, 34.70%, and 35.29%, respectively, as compared with their counterparts after 28 days of water curing. The percentage enhancement/reduction of curing in various parameters of phase-II HECC mixtures after 28 days as compared with the RS1 mix proportion is given in Table 6.

Table 6.

Percentage Enhancement/Reduction in Various Parameters of Phase-II HECC Mixtures as Compared with RS1

Mix id	CS	TS	TSR	FS	MD	ER	API	ST
RS1	NA	NA	NA	NA	NA	NA	NA	NA
RS2	−1.59	−12.23	6.66	−9.18	25.99	10.04	−9.18	−7.62
RS3	1.13	5.45	−18.06	3.34	−9.67	−11.64	−24.49	−4.70
RS_SPW1	7.73	10.74	18.27	5.56	29.03	15.98	−34.69	−36.09
RS_SPW2	8.20	9.60	17.13	4.67	19.27	26.48	−39.28	−39.68
RS_SPW3	8.95	9.09	13.91	3.97	18.06	−2.05	−44.38	−38.34

Ultrasonic Pulse Velocity

The UPV test results of various mixtures are summarized in Figure 15, which shows that the quality of all mixtures was excellent as per BIS:13311 ( 42 ) specifications. The pulse velocity increased with the usage of polymeric and non-polymeric (PVA, PET, and MSE) fibers in hybridization, whereas no significant change was observed with the usage of only polymeric fibers in hybridization.

Figure 15.

Ultrasonic pulse velocity of various mixtures.

The UPV of SS-containing (Group-I) mixtures was observed to be higher as compared with that of RS-containing (Group-II) mixtures. Moreover, the utilization of SPW in HECC mixtures (with the use of different types of fibers) increased the pulse velocity; this may be attributed to the filling effect of SPW. The UPV results of HECC mixtures indicated that the hybridization of polymeric and non-polymeric fibers and addition of SPW enhanced the compactness of the matrix by filling the micro voids. Finally, based on the UPV values, it was concluded that all the ECC mixtures demonstrate excellent quality and consistency of samples when prepared with polymeric fibers, non-polymeric fibers, SS, RS, or SPW.

Environmental Impact Assessment and Cost Analysis

The sustainability and environmental impact of cementitious matrices rely on the consumption of energy, carbon dioxide emissions and waste released during the construction practice. In this study, the sustainability of HECC matrices was evaluated on the basis of carbon dioxide (CO₂) emissions. The statistics for each constituent of ECC matrices related to carbon dioxide (CO₂) emissions were collected from the existing literature as represented in Table 7. In the literature, the variations in the values for ecological parameters existed for various components of the ECC, depending on the age of the data, transportation, country, machinery, boundary conditions, and many other factors. The true values of environmental impact should be evaluated based on the whole life cycle analysis for the specific type of material. SPW is a by-product of the stone industry, and it is used as in the received form to prepare the HECC mixture; therefore, the values of carbon dioxide emission were not considered. Limited data were available on PET fiber sustainability, therefore CO₂ emissions data for virgin recycled polyethylene terephthalate fiber were used in this study. The polyethylene terephthalate fiber is a low-cost polymer belonging to the polyester group that has been widely used in plastic-based products ( 54 ). The values of carbon dioxide emission from all designated HECC matrices are illustrated in Figure 16.

Table 7.

Carbon Dioxide Emission Values for Various Constituents

Constituent	CO₂ emission (kg/ton)
OPC	870^a
SS	23.28^a
RS	5.1^b
BFS	26.5^c
SPW	NA
PVA	1710^a
PET	810^d
MSE	2150^e
SP	600^b
Water	0.8^b

^aData obtained from Choi et al. ( 55 ).

Data obtained from Sharma and Khan ( 56 ).

Data obtained from Yang et al. ( 57 ).

Data obtained from Yu et al. ( 54 ).

Data obtained from Mastali et al. ( 58 ).

Note: OPC = Ordinary portland cement; BFS = Blast furnace slag; SS = Silica sand; RS = River sand; SPW = Stone processing waste; PVA = Polyvinyl alcohol; PET = Polyester; MSE = Microsteel; SP = Superplasticizer; NA = not available.

Figure 16.

Carbon dioxide emission in various hybrid engineered cementitious composite mixtures.

It can be seen from Figure 16 that the CO₂ emissions value in the SS1 mixture was maximum (572.72 kg/m³), whereas the value for the RS_SPW2 mixture was the minimum (558.12 kg/m³). The utilization of SPW and fiber hybridization in the HECC matrix exhibited reduction in CO₂ emissions. ECC mixtures made with locally available RS released less CO₂ emissions as compared with SS blended mixtures. The RS_SPW2 matrix released 7.90% less CO₂ emissions as compared with typical ECC (M45) ( 6 ).

The cost of different ECC mixtures was computed by using industrialized and market price of the constituents. It can be seen from Figure 17 that the incorporation of SPW, RS, and fiber hybridization reduced the cost of the ECC matrix. The cost for the SS1 mixture was maximum, and that for the RS_SPW3 mixture was minimum. The hybridization of PVA and PET (at level 75% + 25%) reduced the cost of ECC matrix by 20.31%. Moreover, the blend of polymeric and non-polymeric fibers (50% PVA + 25% PET + 25% MSE) reduced the cost of the ECC matrix by 41.53%. Eventually, based on the ecological performance and cost analysis, it was concluded that incorporation of SPW, RS, polymeric, and non-polymeric fibers in hybridization contributes to reducing the carbon dioxide emission and overall cost of the ECC matrix.

Figure 17.

Cost analysis of various engineered cementitious composite mixtures.

Performance Indices

The performance indices (PI) of all the designed ECC matrices are presented in Figure 18, a and b . The PI method helps in finding the optimal content of SPW, RS, SS, PVA, PET, and MSE to produce the most suitable HECC matrix as per the required parameters criteria.

Figure 18.

(a) Performance indices of engineered cementitious composite (ECC) mixtures containing silica sand (SS) (Group-I), and (b) performance indices of ECC mixtures containing river sand (RS) (Group-II).

The PI values less than or greater than 5.0 show the inferior or superior performance as compared with fully SS1 and RS1 mixtures. Moreover, in case of API, sorptivity, cost, and ecological aspects, values lower than 5.0 show better/desirable performance. It can be seen from Group-I mixtures (Figure 18a) that SS_SPW2 is the most preferable mixture for tensile strain, ER, deflection, sorptivity and ecological aspects, whereas, for strength parameters, API, and cost, mixture SS_SPW3 should be preferred.

On the other hand, from the Group-II mixtures (Figure 18b) the RS_SPW2 mixture is the most preferable for tensile strain, ER, deflection, sorptivity and ecological aspects, and for strength parameters, API, and cost, mixture RS_SPW3 should be preferred.

Conclusions

The present investigation attempts to develop low-cost and sustainable ECC with the inclusion of various types of fiber (PVA, PET, MSE) in hybridization, commonly available fine RS in place of SS and SPW at different percentages. PVA, PET and MSE fibers were used in this study. The impact of various constituents on ECC mixtures was analyzed through the slump flow, flow time (T₅₀) compression, tensile, flexural response, ER, UPV, API, sorptivity, PI, and environmental impact assessment. Based on the analysis of experimental observations, the following prominent conclusions have been drawn:

The combination of polymeric fibers depicted not much significant changes in slump flow deformation, whereas the blend of polymeric and non-polymeric fibers enhanced the slump flow up to 8.30% as compared with fully PVA blended mixtures.

The strength (compression, flexural, and tensile) parameters of the ECC matrix decreased, and tensile strain capacity and mid span deflection improved with the blend of polymeric fibers (PVA and PET). The introduction of low-modulus PET fiber in the ECC matrix contributed to enhancing the energy absorption capacity.

The combined introduction of polymeric and non-polymeric fibers (PVA, PET, and MSE) into the ECC matrix exhibited opposite behavior than polymeric fiber hybridization on strength and strain parameters. The introduction of high-modulus MSE fiber sustained a strong bond with cement matrix and enhanced the load-carrying capacity of ECC matrix.

ER of the ECC matrix increased with the use of distinctive nature PET fiber, whereas with the blend of MSE fiber a reduction in ER was observed because of its conductive nature.

The blend of polymeric and MSE fibers reduced the air permeability and sorptivity in the ECC matrix as compared with fully PVA blended mixtures. The inclusion of PET fiber in the ECC matrix contributed to reducing the porosity at the interface between fiber and cement paste, which resulted in impaired flow of ions in the matrix. Thus, the addition of PET fiber enhanced the durability parameters of the ECC. The MSE fibers sustain a perfect bond with the cement matrix, contributing to a state of densify at the fiber–matrix interface.

The utilization of SPW as alternate substitution of SS and RS enhanced the strength, strain, and durability parameters of the ECC matrix. The finer-size particles of SPW help to fill the micro voids present around the fibers, resulting in densification of the whole matrix structure. It is postulated that the denser nature of SPW–ECC mixtures restrict the movement of ions through whole structure of the matrix, and as a result improvement was recorded.

The addition of SPW contributed to reducing the interfacial chemical bonding between fibers and matrix, which leads to the slip hardening behavior of fibers through the matrix and results in enhancement of the tensile strain capacity and mid span deflection capacity.

The PI approach indicated that SS_SPW2 and RS_SPW2 are the most suitable mixtures for strain, durability, and ecological aspects, whereas SS_SPW3 and RS_SPW3 mixtures can be used for strength and economic aspects.

From the low-cost and environmental impact view, the inclusion of various fibers in hybridization and SPW helps to gain cost-effective credits and reduce negative environmental impacts. The utilization of SPW also helps to reduce the carbon dioxide emissions, saves natural resources, energy up to some limit, and promotes the sustainability of the ECC matrix.

Footnotes

Author Contributions

The authors confirm contribution to the paper as follows: study conception and design: Maninder Singh; data collection: Maninder Singh; analysis and interpretation of results: Maninder Singh, Babita Saini; draft manuscript preparation: Maninder Singh, Babita Saini, H.D Chalak. All authors reviewed the results and approved the final version of the manuscript.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors are obliged to the University Grants Commission, New Delhi for financial assistance for the research work (F117.1/2017-18/MANF-2017-18-HAR-78129).

ORCID iDs

Maninder Singh

H. D. Chalak

References

Bentur

Mindess

Fiber Reinforced Cementitious Composite, 2nd ed. CRC Press, Boca Raton, FL, 2006.

Neville

A. M.

Properties of Concrete, 5th ed. Trans-Atlantic Publications, Harlow, England, 2012.

Kumar

Prasad

Mechanical Behavior of Non-Silicate-Based Alkali-Activated Ground Granulated Blast Furnace Slag. Construction and Building Materials, Vol. 198, 2019, pp. 494–500.

Goel

Singh

S. P.

Singh

Flexural Fatigue Strength and Failure Probability of Self Compacting Fibre Reinforced Concrete Beams. Engineering Structures, Vol. 40, 2012, pp. 131–140.

Singh

Saini

Chalak

H. D.

Performance and Composition Analysis of Engineered Cementitious Composite (ECC) – A Review. Journal of Building Engineering, Vol. 26, 2019, p.100851.

V. C.

Engineered Cementitious Composites (ECC) - Tailored Composites Through Micromechanical Modeling. In Fiber Reinforced Concrete ( Banthia

Bentur

Mufti

A. A.

, eds.), Canadian Society for Civil Engineering, Montreal, 1998, pp. 64–97.

V. C.

Kanda

Engineered Cementitious Composites for Structural Applications. Journal of Materials in Civil Engineering, Vol. 10, 1998, pp. 66–69.

Singh

Saini

Chalak

H. D.

Properties of Engineered Cementitious Composites: A Review. Proc., 1st International Conference on Sustainable Waste Management Through Design, Ludhiana, India, 2019, pp. 473–483.

V. C.

Engineered Cementitious Composites (ECC) - Material, Structural, and Durability Performance. In Concrete Construction Engineering Handbook ( Nawy

E. G.

, ed.), CRC Press, Boca Raton, FL, 2008.

10.

Singh

Saini

Chalak

H. D.

Appraisal of Hybrid Fiber Reinforced Engineered Cementitious Composite. Proc., International Conference on Civil, Structural and Transportation Engineering, Ottawa, Canada, 2019, pp. 1–8.

11.

Sahmaran

Yücel

H. E.

Demirhan

Arýk

M. T.

V. C.

Combined Effect of Aggregate and Mineral Admixtures on Tensile Ductility of Engineered Cementitious Composites. ACI Materials Journal, Vol. 109, 2012, pp. 627–638.

12.

de Koker

van Zijl

Extrusion of Engineered Cement-Based Composite Material. Proc., 6th RILEM Symposium on Fiber-Reinforced Concretes (FRC), Italy, 2004, pp. 1301–1310.

13.

K. Q.

J. T.

Dai

J. G.

Z. D.

Shah

S. P.

Development of Ultra-High Performance Engineered Cementitious Composites Using Polyethylene (PE) Fibers. Construction and Building Materials, Vol. 158, 2018, pp. 217–227.

14.

Zhou

Sui

Xing

Mechanical Properties of Hybrid Ultra-High Performance Engineered Cementitious Composites Incorporating Steel and Polyethylene Fibers. Materials, Vol. 11, No. 8, 2018, p. 1448. https://doi.org/10.3390/ma11081448.

15.

Game

Arce

Hassan

M. M.

Noorvand

Subedi

Rupnow

Development of Practical and Cost-Effective Ultra-High-Performance Engineered Cementitious Composites Using Natural Sand and no Silica Fume. Transportation Research Record: Journal of the Transportation Research Board, 2022. https://doi.org/10.1177/03611981221078287.

16.

Steven

M. K.

The UHMWPE Handbook: Ultra-High Molecular Weight Polyethylene in Total Joint Replacement. Academic Press, San Diego, CA, 2004.

17.

Carl Redon

V. C.

Hoshiro

Saito

Ogawa

Measuring and Modifying Interface Properties of PVA Fibers in ECC Matrix. Journal of Materials in Civil Engineering, Vol. 13, 2001, pp. 399–406.

18.

Pan

Liu

Wang

Liu

Study on Mechanical Properties of Cost-Effective Polyvinyl Alcohol Engineered Cementitious Composites (PVA-ECC). Construction and Building Materials, Vol. 78, 2015, pp. 397–404.

19.

Meng

Huang

Zhang

Y. X.

Lee

C. K.

Mechanical Behaviour of a Polyvinyl Alcohol Fibre Reinforced Engineered Cementitious Composite (PVA-ECC) Using Local Ingredients. Construction and Building Materials, Vol. 141, 2017, pp. 259–270.

20.

Pakravan

H. R.

Jamshidi

Latifi

Study on Fiber Hybridization Effect of Engineered Cementitious Composites With Low- and High-Modulus Polymeric Fibers. Construction and Building Materials, Vol. 112, 2016, pp. 739–746.

21.

Ali

M. A. E. M.

Soliman

A. M.

Nehdi

M. L.

Hybrid-Fiber Reinforced Engineered Cementitious Composite Under Tensile and Impact Loading. Materials and Design, Vol. 117, 2017, pp. 139–149.

22.

Ke-Quan

Zhou-Dao

Jian-Guo

Shah

S. P.

Direct Tensile Properties and Stress–Strain Model of UHP-ECC. Journal of Materials in Civil Engineering, Vol. 32, 2020, p. 04019334.

23.

Ranade

Stults

M. D.

Heard

W. F.

Rushing

T. S.

Composite Properties of High-Strength, High-Ductility Concrete. ACI Materials Journal, Vol. 110, 2013, pp. 413–422.

24.

Ding

J. T.

K. Q.

S. L.

Basic Mechanical Properties of Ultra-High Ductility Cementitious Composites: From 40 MPa to 120 MPa. Composite Structures, Vol. 185, 2018, pp. 634–645.

25.

Wang

A Strain-Hardening Cementitious Composites With the Tensile Capacity up to 8%. Construction and Building Materials, Vol. 137, 2017, pp. 410–419.

26.

Yang

E. H.

Guan

Mechanism Study of Crack Propagation in River Sand Engineered Cementitious Composites (ECC). Cement and Concrete Composites, Vol. 128, 2022, p. 104434.

27.

Sahmaran

Lachemi

Hossain

K. M.

Ranade

V. C.

Influence of Aggregate Type and Size on Ductility and Mechanical Properties of Engineered Cementitious Composites. ACI Materials Journal, Vol. 106, No. 3, 2009, p. 308. https://doi.org/10.14359/56556.

28.

Rathod

J. D.

Patodi

S. C.

Interface Tailoring of Polyester-Type Fiber in Engineered Cementitious Composite Matrix Against Pullout. ACI Materials Journal, Vol. 107, 2010, pp. 114–122.

29.

Siddique

Kapoor

Kadri

E. H.

Bennacer

Effect of Polyester Fibres on the Compressive Strength and Abrasion Resistance of HVFA Concrete. Construction and Building Materials, Vol. 29, 2012, pp. 270–278.

30.

Al-Akhras

N. M.

Ababneh

Alaraji

W. A.

Using Burnt Stone Slurry in Mortar Mixes. Construction and Building Materials, Vol. 24, 2010, pp. 2658–2663.

31.

Khodabakhshian

de Brito

Ghalehnovi

Shamsabadi

E. A.

Mechanical, Environmental and Economic Performance of Structural Concrete Containing Silica Fume and Marble Industry Waste Powder. Construction and Building Materials, Vol. 169, 2018, pp. 237–251.

32.

Almeida

Branco

de Brito

Santos

J. R.

High-Performance Concrete With Recycled Stone Slurry. Cement and Concrete Research, Vol. 37, No. 2, 2007, pp. 210–220.

33.

Singh

Srivastava

Bhunia

An Investigation on Effect of Partial Replacement of Cement by Waste Marble Slurry. Construction and Building Materials, Vol. 134, 2017, pp. 471–488.

34.

Singh

Saini

Chalak

H. D.

Long Term Evaluation of Engineered Cementitious Composite Containing Stone Slurry Powder. Construction and Building Materials, Vol. 264, 2020, p. 120183. https://doi.org/10.1016/j.conbuildmat.2020.120183.

35.

Özkan

Ş.

Ceylan

The Effects on Mechanical Properties of Sustainable Use of Waste Andesite Dust as a Partial Substitution of Cement in Cementitious Composites. Journal of Building Engineering, Vol. 58, 2022, p. 104959.

36.

Rana

Kalla

Csetenyi

L. J.

Sustainable Use of Marble Slurry in Concrete. Journal of Cleaner Production, Vol. 94, 2015, pp. 304–311.

37.

Singh

Nagar

Agrawal

Rana

Tiwari

Sustainable Utilization of Granite Cutting Waste in High Strength Concrete. Journal of Cleaner Production, Vol. 116, 2016, pp. 223–235.

38.

ASTM C1611. Standard Test Method for Slump Flow of Self-Consolidating Concrete. ASTM International, West Conshohocken, PA, 2004.

39.

BIS:516-1959. Methods of Tests for Strength of Concrete. Bureau of Indian Standards, New Delhi, 2006.

40.

BS-EN-12390-3. Testing Hardened Concrete-Part 3: Compressive Strength of Test Specimens. British Standard Institution, London, UK, 2009.

41.

BS-EN-12390-5. Testing Hardened Concrete-Part 5: Flexural Strength of Test Specimens. British Standard Institution, London, UK, 2009.

42.

BIS:13311. Code of Practice for Non-Destructive Testing of Concrete-Methods of Test Part 1: Ultrasonic Pulse Test. Bureau of Indian Standards, New Delhi, 2004.

43.

ASTM C597-16. Standard Test Method for Pulse Velocity Through Concrete. ASTM International, West Conshohocken, PA, 2016.

44.

AASHTO T358. Standard Method of Test for Surface Resistivity Indication of Concrete’s Ability to Resist Chloride Ion Penetration. American Association of State Highway and Transportation Officials, Washington, D.C., 2015.

45.

ACI 222R-01. Protection of Metals in Concrete Against Corrosion. American Concrete Institute, Farmington Hills, MI, 2001.

46.

Autoclam Permeability System Operating Manual . Amphora Technologies Ltd, Belfast, UK, 1994.

47.

Koniki

Prasad

D. R.

Influence of Hybrid Fibres on Strength and Stress-Strain Behaviour of Concrete Under Uni-Axial Stresses. Construction and Building Materials, Vol. 207, 2019, pp. 238–248.

48.

Sakulich

A. R.

V. C.

Nanoscale Characterization of Engineered Cementitious Composites (ECC). Cement and Concrete Research, Vol. 41, 2011, pp. 169–175.

49.

Suryanto

Takaoka

McCater

W. J.

Saraireh

Taha

Impedance Measurements on an Engineered Cementitious Composite: A Critical Evaluation of Testing Protocols. Measurement: Journal of the International Measurement Confederation, Vol. 129, 2018, pp. 445–456.

50.

Banthia

Djeridane

Pigeon

Electrical Resistivity of Carbon and Steel Micro-Fiber Reinforced Cements. Cement and Concrete Research, Vol. 22, 1992, pp. 804–814.

51.

Singh

Saini

Chalak

Evaluation of Cost-Effective Hybrid Fiber Reinforced ECC. Sādhanā, Vol. 46, No. 2, 2021, pp. 1–10.

52.

Singh

Saini

Chalak

H. D.

Appraisal on Low Cost and Sustainable ECC Using Microfibers in Hybridization at Later Age. Journal of Engineering Research, Vol. 9, 2021, pp. 147–165.

53.

Forschirm

A. S.

Method for Improving the Water Absorption of Polyester Fibers. U.S. Patent No. 4063887. Celanese Corporation, New York, NY, 1977.

54.

Yao

Lin

Lam

J. Y.

Leung

C. K.

Sham

I. M.

Shih

Tensile Performance of Sustainable Strain-Hardening Cementitious Composites With Hybrid PVA and Recycled PET Fibers. Cement and Concrete Research, Vol. 107, 2018, pp. 110–123.

55.

Choi

W. C.

Yun

H. D.

Kang

J. W.

Kim

S. W.

Development of Recycled Strain-Hardening Cement-Based Composite (SHCC) for Sustainable Infrastructures. Composites Part B: Engineering, Vol. 43, 2012, pp. 627–635.

56.

Sharma

Khan

R. A.

Sustainable Use of Copper Slag in Self-Compacting Concrete Containing Supplementary Cementitious Materials. Journal of Cleaner Production, Vol. 151, 2017, pp. 179–192.

57.

Yang

K. H.

Song

J. K.

Song

K. I.

Assessment of CO2 Reduction of Alkali-Activated Concrete. Journal of Cleaner Production, Vol. 39, 2013, pp. 265–272.

58.

Mastali

Dalvand

Sattarifard

A. R.

Illikainen

Development of Eco-Efficient and Cost-Effective Reinforced Self-Consolidation Concretes With Hybrid Industrial/Recycled Steel Fibers. Construction and Building Materials, Vol. 166, 2018, pp. 214–226.