ASSESSMENT OF WATER AND TEMPERATURE SUSCEPTIBILITIES OF COLD RECYCLED BITUMINOUS EMULSION MIXTURES USING THE NAT IN THE ITSM MODE OF TESTING

摘要

Energy efficiency, cost effectiveness and the need to minimise the impact of construction activities on the environment are major drivers responsible for cold recycled asphalt mixtures being considered as alternatives to hot mixtures in road works. However such mixtures are still regarded in some quarters as second class asphalts mainly because of durability problems. The Indirect Tensile Stiffness Modulus (ITSM) of such materials under the individual or combined effects of water and temperature could serve as an indicative property for quickly ranking such materials and also assessing their durability at the design stage. The work reported herein involved the assessment of five cold bituminous emulsion mixtures (CBEMs) for ITSM under the effects of water and temperature. The results of the water and temperature susceptibility tests indicated that irrespective of the CBEM type and the condition of curing and testing temperature for ITSM, CBEMs prepared at 32℃ consistently performed better than those prepared at 20℃ even at an ITSM test temperature of 40℃, and overall, the RAP CBEMs performed better than the VACBEM. A trend which indicates that as the penetration of residual bitumen in RAP CBEMs increases, performance similarly increases was observed. These results suggest that problems associated with durability could be minimised when adequate quality control measures based on laboratory results are put in place and followed on site during production and the laying of such materials as a road pavement layer.