Effect of wetting-drying cycles on physical and mechanical behavior of soil-aggregate-cement mixtures

Soil-aggregate-cement (SAC) mixtures have been used in Brazil as base and/or subbase in pavements of heavy and very heavy volume roads, however, still lacks standardized protocols concerning material dosage and assessment of its performance and durability. Then, this study aims to understand the durability of the SAC mixtures by investigating their physical and mechanical behavior after wetting and drying cycles (ASTM D 559), and to contribute to creating reference data and constitutive models of this mixture. For this, four SAC mixtures composed of lateritic sandy soil and basaltic aggregate, in two different soil-aggregate proportions (20:80 and 30:70) and using 5% of two types of cement (PC-HE and PCC-S) were produced. Analyses were based on results of volume changes, weight loss, unconfined compression strength (UCS), indirect tensile strength (ITS) and resilient modulus (Mr) by repeated load triaxial test, at 0, 6 and 12 cycles. Findings show that SAC mixtures had small volume changes (±1.3%) and weight loss (from 4.8 to 5.5%) and their strength and stiffness properties were preserved or increased after W-D cycles. The stiffness of 20:80 mixtures was equivalent to the cement treated crushed rock (CTCR) ones, and 30:70 mixtures, to the soil-cement ones. The cycling effect on increasing mechanical properties warns against potential distresses in very high strengthen and stiff materials that can contribute to reduce fatigue performance of the mixture.