Freeze-Thaw Performance of Fly Ash-Stabilized Materials and Recycled Pavement Materials

A comprehensive research was conducted to study the performance of a variety of stabilized geomaterials against the freeze-thaw (F-T) cycling process. Also included were unstabilized recycled materials, i.e., recycled asphalt pavements (RAP) and recycled concrete aggregates (RCA). Stabilized geomaterials used in this study included natural coarse-grained and fine-grained soils and reclaimed pavement materials (RPM). The stabilizers (binders) included self-cementitious fly ashes (i.e., class C and off-specification fly ashes). Resilient modulus (M-r) performances of geomaterials and geomaterials stabilized by binders were evaluated under a number of F-T cycles. This article also compares the F-T performances of different geomaterials including, stabilized coarse-grained versus fine-grained geomaterials, stabilized natural soils versus stabilized RPMs versus unstabilized RAP versus RCA. Additionally, the impact of fly ash type and fly ash content on F-T performance of stabilized geomaterials was also investigated. Moreover, correlations between the physicochemical properties [CaO, CaO/SiO2, CaO/Al2O3, CaO/(Al2O3 + SiO2), D-60, D-30, gravel-to-sand (G/S) ratio and fines content] of these stabilized and unstabilized geomaterials and their resilient modulus were explored under F-T cycling. M-r decreases (7-50%) in response to F-T cycling and then levels off in approximately 1-5 cycles. Fly ash stabilized coarse-grained geomaterials provided 5% less drop in initial M-r compared to the fly ash stabilized fine-grained soils. RPMs stabilized with fly ash performed better (average reduction of 25%) against F-T cycling than the unstabilized RAP materials (average reduction of 33%) and natural fine-grained soils (average reduction of 29.5%) stabilized with fly ash. No correlations were found between the fly ash types/fly ash contents and M-r performance of fly ash stabilized geomaterials under F-T cycling process. Fly ash stabilized coarse-grained geomaterials with higher D-60, D-30, G/S ratio, and fines content tend to lose more stiffness at higher number of F-T cycles. Such correlations could also be determined for RCA and RAP except G/S ratio. Stabilized fine-grained and coarse-grained geomaterials with fly ashes having higher CaO/SiO2, CaO/Al2O3, and CaO/(SiO2 + Al2O3) ratios experienced lower loss in M-r during F-T. (C) 2017 American Society of Civil Engineers.