Use of coal ash as geopolymer binder and coarse aggregate in pervious concrete

• Waste from coal ash was used to produce pervious geopolymer concrete (PGC).
• Fly ash was used as geopolymer binder and bottom ash as coarse aggregate.
• NaOH concentration, level OPC replacement, and curing temperature were varied.
• The obtained PGCs are suited for use as an environment friendly concrete.

Fly ash (FA) and bottom ash (BA) are wastes from coal combustion power plant. Due to its coarse and porous particle, BA is usually disposed of at landfill sites. While, as-received FA can be used as pozzolanic material and source material to produce geopolymer binder. This study focused on the use of FA as geopolymer binder and BA as coarse aggregate to produce pervious concrete. The effect of NaOH concentration, partial replacement of FA with ordinary Portland cement (OPC), and curing temperature on the properties of pervious geopolymer concrete (PGC) were investigated. The results showed that the strengths of PGC increased with both NaOH concentration and level of OPC replacement. The curing at elevated temperature (90 °C) was a significant factor for the strength development. The PGCs containing BA had the thermal conductivity of 0.30–0.33 W/m K, density of 1466–1502 kg/m3, and compressive strength of 5.7–8.6 MPa and are suited for use as an environment friendly concrete.