Lightweight geopolymer binder base on sidoarjo mud

Sidoarjo mud has been a disaster for society and government of Indonesia, but this material contains of SiO₂, Al₂O₃ and Fe₂O₃ so that significantly to be expected as a potential pozzolanic material. It would be very useful to take the advantages of the material. Moreover, lightweight concrete is widely applied especially at high-rise buildings in order to reduce the risk of earthquake. In general lightweight concrete is made with less Portland Cement associated with lime and pozzolanic materials as a binder. In this paper, calcined-Sidoarjo mud was introduced as pozzolanic material to create geopolymer paste. Geopolymer binders were made with a mixture of calcined-Sidoarjo mud, fly ash and alkaline activator. The specimens were then mixed with a commercial chemical foamed agent to get lightweight geopolymer binders. The results showed that the mixing with the ratio of fly ash: NaOH: Na₂SiO₃ were 33, 3%: 33, 3%: 9, 52%: 23, 81% and superplasticizer was 2, 5% of binder weight achieved the compressive strength of 55, 6 MPa. With additional 1% of foaming agent, the compressive strength of lightweight geopolymer binder was 7.1 MPa.