A study on the potential use of paper sludge ash in concrete with glass aggregate

This short communication focuses on the potential use of paper sludge ash, a waste product of the paper making industry, as an innovative binder partially replacing cement in concrete with glass aggregate. After preliminary testing using binary or ternary CEM-II mixes with paper sludge ash/pulverised fly ash, a suitable mix for concrete with glass aggregate was identified. Concrete mixes with partial or full natural sand replacement by waste glass aggregate were then produced and showed appropriate strengths and overall similar or better water absorption characteristics than control mixes with natural aggregates, without manifest alkali-silica reaction problems. This shows potential for applications in precast dry mix concrete units based on the required strengths that were achieved

A study on low energy demand materials used in glasscrete to counteract alkali-silica reactions

The potential of waste glass use in concrete as an alternative outlet to landfilling is excellent; however glasscrete (i.e. concrete with glass aggregate) suffers from durability problems caused by alkali-silica reactions (ASR). The use of pozzolanic materials to counteract ASR has been increasingly studied. This paper investigates the ability of selected low-energy demand binders/pozzolans to counteract ASR in glasscrete: these include paper sludge ash (PSA), a by-product of the paper making industry, used together with a standardised pozzolanic material for concrete, i.e. Pulverised Fly Ash (PFA) an industrial byproduct of electric power stations. A number of laboratory tests were performed on the different glasscrete mixes to assess properties (workability, compressive and tensile strengths and elasticity moduli and water absorption). Mortars were also tested for alkali-silica reaction (ASR) using the accelerated mortar bar test, which showed that ASR was effectively counteracted, towards better glasscrete durability. Glasscrete mixes were identified, with similar strengths as the respective control mixes with natural aggregates. Workability was however affected in all mixes and should be addressed in further research