Engineering properties of controlled low strength materials using flyash and waste gypsum wall boards

The discarded gypsum wallboards (drywalls) dumped at landfills, release hydrogen sulfide gas, a harmful substance, to the atmosphere along with the leachate at the landfill. In this paper, the discarded drywalls were utilized as secondary cementitious materials in controlled low strength materials (CLSM) with flyash and cement. Quarry dust, a stone industry waste was used as fine aggregates. CLSM mixes were produced for varying water contents, drywall and flyash to cement ratios by weight. Spread flow, Marsh flow time and fresh density properties at fresh state, and un-confined compressive strength, settlement and density properties at 3, 7, 28 and 56 days for hardened state, were investigated. Reduced compressive strengths at later ages due to use of drywalls were observed. Flow and strength phenomenological models were generated using wide range of experimental data and validated for separate set of experimental data, to encourage production of CLSM using waste drywalls, of required parameters instead of conventional trial and error process. (C) 2015 Elsevier Ltd. All rights reserved.