DURABILITY OF CONCRETE CONTAINING RECYCLED ASPHALTIC CONCRETE AGGREGATE AND HIGH CALCIUM FLY ASH

Abstract

In this research, the durability of concrete containing Recycled Asphaltic Concrete (RAC) aggregate and fly ash were studied. The concrete was made from Ordinary Portland Cement (OPC), fly ash, water, sand and combination of natural limestone and RAC aggregates. The RAC aggregate was obtained from the discarded asphaltic pavement. The RAC aggregate was used to replace natural limestone aggregate at the replacement levels of 0, 10, 20, and 30 % of the total weight of aggregate. In addition, the high calcium fly ash from Mae Moh power station in the north of Thailand was used to partially replace OPC at the dosages of 0, 20, and 40 % by mass. The compressive strength, water absorption, porosity, flexural strength, modulus of elasticity and resistance to sulfuric acid were tested. The results showed that concretes with 28-day compressive strengths between 22.5 and 33.0 MPa, water absorption between 5.3-5.9 %, porosity between 12.2 and 13.5 %, flexural strength between 4.4 and 5.5 MPa, modulus of elasticity between 25.6 and 30.0 GPa were obtained. The replacement levels of RAC at 10 % and fly ash at 20 % gave the optimum compressive strength and mechanical properties of concrete for use as pavement concrete. In addition, the using of RAC aggregate together with fly ash in concrete work improved water absorption, porosity and sulfuric acid resistance and the use of RAC and high calcium fly ash will also increase the sustainability of the construction industry.