Application of central kalimantan coal ash as a sustainable construction material

The current study is related to laboratory investigations to utilize Central Kalimantan coal ash as a sustainable construction material, which is green paving blocks. For this purpose, coal ash from the Pulang Pisau coal-fired power plant, both in the form of fly ash and bottom ash, was used as an additional proportion of cement. The addition of fly ash was set at 10%, 20%, and 30%. Meanwhile, the addition of bottom ash was set at 5%. Water to binder ratio (w/b) was set at 0.45, and the curing times were set at 7, 28, and 56 days for all samples. Moreover, the sample’s compressive strength test was based on BS 6717:1986 regarding the precast concrete paving block. Based on the test results, it was proven that the addition of fly ash and bottom ash could increase the compressive strength of paving blocks. The highest compressive test results were obtained from the addition of 20% fly ash and 5% bottom ash (24.62) MPa at the age of 56 days. This result is 30% higher compared to the ordinary paving blocks test result. Furthermore, according to SNI 03-0691-1996, paving blocks with a compressive strength of 20 MPa until 40 MPa can be applied as parking lots pavements.