Effects of recycled fine glass aggregates on the properties of dry-mixed concrete blocks

The effects of replacement percentages and particle size distribution of recycled fine glass (FG) aggregates on the properties of dry-mixed concrete blocks were investigated. All the mixtures were proportioned with a fixed total aggregate/cement ratio of 4% and 50% of the total aggregate was fine aggregate. A total of 17 concrete block mixes, including a control (0% of glass) mix, were produced using four different particle sizes of FG (un-sieved, <2.36 mm, <1.18 mm and <600 μm) as replacements of sand. The replacement ratios were 25%, 50%, 75% and 100%. Properties such as packing density, hardened density and water absorption, as well as the effects of air and water curing upon 7 and 28-day compressive strength were studied. The results show that the water demand of the mix increased with decreasing fineness modulus of the fine aggregate. All concrete blocks containing FG showed higher water absorption and lower hardened density than the control concrete block. For FG with particle size less than 600 μm, this was more pronounced. Slight reductions in compressive strength were observed with the use of coarser FG, while significant increases in compressive strength occurred when the particle size of FG was reduced to less than 600 μm. This indicates that finer FG exhibited appreciable pozzolanic reactivity.