Papers by Author: Dong Ming Wang

Abstract: The effect of substitution of recycled aggregate by natural aggregate on related properties of blended aggregate (without asphalt and mineral filler) and asphalt mixture was investigated in this paper. Demolition waste obtained from Wenchuan earthquake-damaged buildings was used as recycled aggregate in AC-25 asphalt mixture. The absorption, specific gravity and strength of both blended aggregate and asphalt mixture were tested. Results indicate that fine recycled aggregate is not suitable to be used in asphalt mixture because of its high absorption. The substitution of recycled aggregate by natural limestone aggregate can decrease the asphalt absorption and increase the effective specific gravity and indirect tensile strength of asphalt mixture. The quantitative relationship between related properties of blended aggregate and asphalt mixture was obtained. It was concluded that the substitution of recycled aggregate by natural aggregate is a feasible way to use recycled aggregate in asphalt mixture.

Abstract: Some properties of asphalt mastic containing recycled cement mortar powder (CMP) were investigated in this paper. CMP was used as filler in asphalt mastic. The investigated mastic consisted of asphalt and filler at a mass ratio of 1:1. Penetration, softening point and high-temperature viscosity were tested. Dynamic Shear Rheometer (DSR) was used to conduct frequency sweep test of asphalt mastic. The introduction of CMP resulted in reduced penetration, increased softening point, apparent activation energy, complex shear modulus in the low frequency area and high-temperature viscosity. Results indicate that CMP may have some positive effect on high-temperature properties but some negative effect on low-temperature properties of asphalt mastic. It is also believed that the average mixing and compacting temperature of asphalt mixture containing CMP is higher than that containing limestone mineral filler (LMF).

Abstract: Two classification methods for coarse recycled aggregate used in asphalt concrete were investigated in this paper, respectively classifying by coarse recycled aggregate properties and asphalt concrete properties. When classifying by coarse recycled aggregate properties, coarse recycled aggregate was classified into three types by the apparent specific gravity, water absorption, crushed value, Los Angeles abrasion value and brick content of coarse recycled aggregate. When classifying by asphalt concrete properties, coarse recycled aggregate was used to prepare asphalt concrete; and coarse recycled aggregate was classified into three types by the optimum asphalt content ratio (R_OAC), theoretical maximum specific gravity ratio (R_TMSG) and indirect tensile strength ratio (R_ITS) of asphalt concrete containing coarse recycled aggregate. The proposed classification criterions of the two classification methods were respectively given.

Abstract: The construction and maintenance of roads in China require large amounts of aggregates and mineral filler. The use of recycled materials helps conserving natural resources. However, the inferior road performance and additional costs have hindered the widespread use of construction and demolition wastes (C&D wastes) in applications such as surface layers of asphalt pavement that may represent a value application for C&D wastes. Waste concrete, waste bricks and waste glass are selected for this study; and the surface layers of asphalt pavement is considered here as value application. Although there is a large potential for supplying C&D wastes now, a few barriers have effectively depressed the recycling activities. Such barriers are described here and a brief discussion suggests ways of their removal.