The Effect of Variations of Fly Ash Filling Materials on Porous Concrete Using Local Aggregates from South Borneo

Abstract

South Kalimantan has local aggregates that can be used as porous concrete making materials, which is one of the innovations in the infrastructure of environmentally friendly road pavement that serves to drain surface water into the ground. Porous concrete produces a lot of empty space as an air cavity that is 15%-25% of its total volume and also has a slump value that is close to zero. This study uses fly ash filler material as one of the efforts to reduce cement in porous concrete making materials. This research aims to find out the characteristics of the material, the composition of variations of porous concrete mixture, compressive strength and porosity of porous concrete. Testing uses the SNI method which consists of testing cement, fly ash, coarse aggregates and concrete. Concrete testing is done, namely the compressive strenght and porosity of concrete. Based on theresults of research characteristics of cement and fly ash materials have met the specifications of SNI and the results of rough aggregate testing have met the specifications. In porous concrete the fly ash variation of EM0% is obtained the compressive strength is 20.37 MPa and its porosity is 2.34%; in porous concrete the variation of fly ash EM15% obtained the compressive strength of 21.44 MPa and porosity 2.07%, and porous concrete variation fly ash EM30% obtained the compressive strength of 6.05 MPa and porosity by 6.80%. From the results of the analysis, it is found that there is an inverse relationship between compressive strength and porosity. More higher the porosity of the porous concrete, more lower the compressive strength. This happens because the void ratio affects the compressive strength of porous concrete, more greater the void value making higher the porosity value and causes the compressive strength to decrease.