Effect of Matric Suction on Resilient Modulus for Compacted Recycled Base Course in Postcompaction State

Abstract

The demand for recycled material as the unbound base course in roadway construction has increased in recent decades because of the excellent mechanical properties of the recycled base course and inherent life-cycle benefits. However, concerns have been expressed about postconstruction changes in the resilient modulus (Mr) caused by moisture variation. This study investigated the relationship of Mr to soil matric suction (ψ) at an in-service stress state for recycled asphalt pavement, recycled pavement material, and recycled concrete aggregate compared with crushed limestone as a conventional base course control. Resilient modulus tests were conducted in accordance with NCHRP Project 1–28A Procedure 1a. Equipment modifications allowed for an applied ψ ranging from 1.5 kPa to 65 kPa during testing. A proposed model incorporated parameters from the soil–water characteristic curve to predict a summary resilient modulus (SRM), that is, the in-service Mr at a representative field stress state. The SRM increased with increasing ψ for all compacted base courses studied. An SRM ratio, defined as the ratio of the SRM at a particular ψ to the as-compacted SRM at optimum water content, was empirically quantified. The modulus ratio increased linearly with logarithmic ψ for the studied recycled and natural aggregates. The findings indicate that the Mr–ψ relationship is highly relevant for predicting in-service performance of pavement layers.

Research on Resilient Modulus Prediction Model and Equivalence Analysis for Polymer Reinforced Subgrade Soil under Dry–Wet Cycle

“…[8][9][10]. In order to study the effect of moisture content on the resilient modulus, in a prediction model employed to study the direct effect of moisture, suction was considered to be significant, and adopted as an independent term [3,11,12]; suction also has an influence on confining or shear stress [13][14][15]. In addition, the soil specimens that suffered from drying and wetting have a larger permanent deformation and lower resilient modulus compared to those specimens that are not subjected to the fluctuation in moisture content [16].…”

Integrated approaches for predicting soil-water characteristic curve and resilient modulus of compacted fine-grained subgrade soils

“…On the other hand, variation in the M R with moisture content can be interpreted and predicted by establishing the M R s relationships. Such an approach has been successfully used by several researchers for various pavement materials (Caicedo et al 2009;Sawangsuriya et al 2009;Cary and Zapata 2011;Ng et al 2013;Gu et al 2014;Nokkaew et al 2014;Salour et al 2014;Abu-Farsakh et al 2015;Zou et al 2015;Coronado et al 2016) Han and Vanapalli (2016a). The measurement of the SWCC and the variation of the M R with s and moisture content however is cumbersome and time-consuming.…”