3. Properties of Recycled Aggregates

This chapter emphasizes the physical and mechanical characteristics of recycled aggregate along with findings of different researchers. The physical properties such as grading, size and texture, density, specific gravity, water absorption, flakiness and elongation indices of recycled aggregates are discussed in detail. The factors such as crushing methodology, crushing age and quality of old concrete greatly affect the gradation of recycled aggregates and the findings reported by different researchers are elaborated. The main factors that influence the density of RA are particle size, amount of adhered mortar and strength of parent concrete from which the recycled aggregate derived are illustrated in this chapter. The relationship between water absorption and adhered mortar content, water absorption and density are described. Further, the influence of strength of parent concrete from which the RA derived and its size are also illustrated. In general, the recycled aggregates are found to be weaker than the natural aggregates against mechanical resistance such as aggregate crushing value, ten percent fines value, impact value and Los Angeles abrasion loss value. The results of mechanical properties of RA reported by various researchers are discussed in this chapter.