Influence of aggregate surface characteristics on pavement performance

Abstract

Aggregate surface characteristics such as texture, shape, surface electrical charge, and mineralogy affect the performance of Portland cement concrete. Negative performance of concrete pavement such as spalling is greatly influenced by material characteristics and environmental factors. Surface characteristics of aggregate play a major role in occurrence of spalling in the concrete pavement. Previous studies show that concrete pavements with siliceous gravel aggregates develop more spalling problem than that of with limestone aggregate as siliceous aggregates show more affinity to water due to a preexisting electronegative charge on their surfaces. Better aggregate-cement bonding at the interfacial region will reduce the spalling problem. Several researches have been taken places in the past and are still going on to improve the aggregate-cement paste bonding by improving the interfacial microstructure. Use of surface treatment agent on aggregate surface might produce positive result in this regard. In this research, numbers of specimens were prepared for different types of surface treatment agents on siliceous aggregate surface. Elemental compositions of the specimens at the interfacial region were analyzed using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Hydrated lime as a surface treatment showed improvements in the microstructural composition at the interfacial region. Silica fume also showed similar results. Fracture toughness test on the beam with lime treated aggregate showed better performance than normal concrete beam and the beam with silica fume as admixture only. Lime treatment on aggregate surface produce more fatigue resistant and durable concrete against spalling.