Mechanistic and microstructural characteristics of roller compacted geopolymer concrete using reclaimed asphalt pavement

Abstract

ABSTRACT Mechanistic and microstructural characteristics of roller-compacted concrete (RCC) produced from recycled asphalt pavement (RAP) and geopolymer cement binder (GPC) were evaluated and compared with mixtures produced from ordinary Portland cement (OPC). It was found that RCC using geopolymer binder exhibited higher unconfined compressive strength, modulus of elasticity, and flexural strength as compared to the mixture containing ordinary Portland cement. It was also discovered that the mechanical properties of the developed concrete depend on mixture constituents: sodium hydroxide molarity, the ratio of sodium silicate to sodium hydroxide, curing temperature, and gradation of RAP. The experimental results showed that RCC using geopolymer binder exhibited compressive strength, modulus of elasticity, and flexural strength in the range of 8.4–21.1 MPa, 18.3–35.0 GPa, and 2.9–4.1 MPa, respectively. On the other hand, RCC using 12% OPC presented similar mechanical strengths of 13.2 MPa, 32.8 GPa, and 3.32 MPa, respectively. Regression analysis was also performed to establish the relationship between mechanical characteristics and various mixture constituents. Morphological and microstructural analysis proved the formation of geo-polymeric compounds. Based on the mechanistic characteristics, the developed roller-compacted RAP-Geopolymer concrete could be used as a strong pavement base in composite pavement system or wearing course of low volume roads.