Piles of material suspected to be B3 waste (hazardous and toxic materials) were found in Kemloko Hamlet, Jotangan Village, Mojosari District, Mojokerto Regency. The pile of material suspected to be waste from coal with the type of bottom ash and fly ash was first discovered by Gangsar Aji Santoso, Friday (31/5/2019). Gangsar added, the effect that occurs when exposed to bottom ash will be itching on the skin, if it rains water infiltration will pollute the surrounding water flow and cannot be consumed (jatimnow.com, 2019).
Concerned about these environmental problems, the PKM Team for Research Sector of the Semarang State Polytechnic led by Havilah Probahapsara, with its members, Gana Sasena Aji PS and Aqil Alifian, students of the S.Tr Study Program-Building Maintenance and Repair Engineering, Civil Engineering Department with Drs. Sutarno, MM. as a companion lecturer succeeded in developing cement-free concrete with the polymerization method from the basic material of coal waste in the form of fly ash (fly ash) PLTU Tanjung Jati which is reacted with an alkaline solution and bottom ash instead of sand.
From the results of this study, it was obtained that the composition of the geopolymer concrete mixture was able to approach the minimum quality of conventional concrete, namely the quality of K100 so that it could be used as a non-structural building material. , Pb and Zn below the quality standard stipulated by the Government Regulation of the Republic of Indonesia No. 101 of 2014. So that this research is expected to be able to overcome the coal waste produced by the power plant as an alternative material for making concrete in order to realize sustainable development (sustainable development) and of course produce environmentally friendly concrete products that are of high quality, cheap and safe to be used as building construction materials.