The Strength Characteristics of Concrete Blended with Recycled Concrete, Quarry Dust and Broken Glass

Conventional concrete mixes produced from naturally occurring aggregates offer benefits in strength, workability, volume stability and permeability, as well as a wide range of properties. However, with increasing availability of construction waste materials, such as demolished concrete and broken glass, there is the need to explore the feasibility of using recycled concrete and glass as replacement for natural crushed aggregates in Portland cement concrete, and determine their compressive and tensile strength in comparison with conventional concrete. Concrete specimens produced with varying percentages of replacement aggregates using recycled concrete and glass were tested for their workability, compressive strength and tensile strength. Six different concrete mixes were designed for the study, with percentage replacement of recycled concrete and broken glass of 0, 25, 50 and 75 by volume of natural aggregate in 1:2:4 concrete mix. In total, 54 cubes and 54 cylinders were cast for compressive strength and split tensile strength, respectively. Recycled concrete and broken / crushed glass were found to be good replacements for natural aggregates in concrete production, although the percentage by volume of recycled concrete and glass used in the concrete mix was an important controlling parameter. With regard to the workability of the concrete, it was found that recycled concrete and broken / crushed glass concrete had similar characteristics to conventional concrete mixes. Partially replaced recycled concrete and broken glass aggregates showed strength variation of between 15% to 30% from natural crushed aggregate concrete. It is recommended that concrete produced using recycled concrete and glass can be utilised for mass concrete works and structural members subjected to low loads.