Influence of Beam Geometry and Aggregate Size on the Flexural Strength and Elastic Moduli of Cement-Stabilized Materials

Because of the depletion of good-quality materials, the use of cement stabilization for subbase and base layer materials often offers a feasible solution. As with all pavement materials, the design inputs must be determined, and this process requires comprehension of material engineering properties such as flexural strength and elastic moduli. Usually, four-point beam loading is preferred for flexural testing because the test simulates the stress–strain gradient as generated within a pavement layer. However, beam geometry, maximum aggregate particle size, and test configuration influence property measurements, which affect the mechanistic design input values. This study examines the influence of beam geometry and aggregate particle size used with respect to the span–depth ratio in the four-point beam test in monotonic loading. An increase in beam depth at a fixed loading span was shown to result in a decrease in flexural strength and elastic modulus but an increase in beam shear stresses. However, an increase of the span–depth ratio significantly reduced the resultant shear stresses in the beam. Additionally, the presence of large aggregate particles in a small beam generated localized zones of weakness, which significantly influenced the resultant flexural strength and elastic modulus.