Laboratory investigation of soil-aggregate-cement mixture

Abstract

Cement stabilization improves physical and mechanical properties of geotechnical materials. However, numerous combinations of geotechnical materials and cement hinder to establish a pattern of mechanical behavior of cement-stabilized materials. Thus, this study aims to evaluate the mechanical behavior of soil-aggregate-cement mixtures (SAC) using high early-strength cement (HE), to contribute to dosage aspects and to ascertain their recommendation as base and/or subbase layers in heavy and very heavy volume roads. For this, SAC mixtures composed of different proportions of soil and aggregate (20:80 and 30:70) with 3, 5 and 7% of cement were produced and cured at different times (0, 7 and 28 days). Mechanical properties were assessed in terms of unconfined compressive strength (UCS), indirect tensile strength (ITS) and resilient modulus by repeated load triaxial test ( ) and by dynamic indirect tensile test ( ). A cement dosage study compared compressive and tensile strengths with acting stresses computed by mechanistic analysis of hypothetical pavements. This same procedure was also used for verifying the possibility of anticipating construction phases and reducing the traffic opening time, in this case a SAC mixture using Portland composite cement (PCC) was also evaluated. Results indicated that SAC-20:80 presented better mechanical behavior than SAC-30:70. Also, the cement content that led to the best mechanical behavior was 5%. All SAC mixtures with 5% HE had higher strength than the acting stresses interval computed for hypothetical pavements. SAC mixtures reached, at 7 and 3 days of curing, respectively, 80% and 60% of 28-days strength, which is the control parameter of Sao Paulo-DOT instructions for SAC. Findings indicated that, due to their good mechanical behavior, SAC mixtures are viable alternatives as layers in heavy and very heavy traffic pavements. Additionally, SAC’s high strengths at earlier curing times have shown their potential to reduce construction time.