Study of Coarse RAP Using Different Mineral Admixtures in Pavement Quality Concrete

Abstract

Due to a scarcity of virgin aggregates, the use of reclaimed asphalt pavement (RAP) as a substitute for natural aggregates has gained popularity. The present study includes the use of new processing technique in order to remove the agglomerated particles and reduce the binder content present in RAP aggregates. Therefore, experimentally investigating the strength, durability, and time dependent properties of coarse RAP for use in Pavement quality concrete (PQC) and to study the properties of PQC made with different percentages of RAP along with the effect of various supplementary cementitious material like Silica Fume (SF) and Ground Granulated Blast Furnace slag (GGBS) on various properties of RAP. A total of 12 concrete mixes with various proportions of coarse RAP (20%, 40% and 60%) and a fixed percentage (10% and 40%) of SF and GGBS were prepared to enhance the interfacial transition zone in PQC. Study of fresh properties like slump value and compaction factor, hardened properties like density, mechanical properties like compressive strength, split tensile strength and flexural strength, durability properties such as water absorption, abrasion resistance and sand blasting, time dependent properties such as shrinkage and non-destructive properties like rebound hammer and ultrasonic pulse velocity (UPV) of PQC was carried out in the present study. The new processing technique enhanced the properties of RAP inclusive PQC mixes and the strength of all the concrete mixes was above the design target strength. It was observed that there was a reduction of more than 60% in binder content of RAP aggregates as a result of processing of RAP. Partial replacement of cement by SF and GGBS also enhanced the properties of concrete mixes. However, with the increase in the percentage of replacement levels the properties of concrete mixes got reduced but the reduction was very less as compared to the previous researches. As per the study RAP can be use in PQC up to 60% after processing technique is done. Hence, this study proves to be effective in utilization of RAP aggregates as a replacement of Natural aggregates in PQC.