The effect of mixture composition on the compressive strength and absorption of geopolymer paving blocks

Paving blocks as a material for road infrastructure, the quality is influenced by many factors, one of which is the composition of the materials that make up it. This geopolymer paving blocks is made using several materials, namely a fly ash-based geopolymer binder (B), sand (S), rock ash (RA), and coarse aggregate (CA). Comparison of the composition of the materials forming geopolymer paving blocks is the focus of the study to determine its effect on the compressive strength and absorption of geopolymer paving blocks. A total of 4 variations of mixture composition were made using weight ratios, namely 1B:2S:1CA, 1B:2S:1RA, 1B:2S:0.5CA:0.5RA, and 1B:1S:1CA:1RA. The geopolymer binder was made with a composition of 10M sodium hydroxide (NaOH), a sodium silicate (Na2SiO3)/NaOH ratio of 2.5, and an alkali activator/fly ash solution ratio of 0.4. Paving blocks are cured at ambient temperature. The test results show that there is an influence of the mixture composition on the compressive strength and absorption of geopolymer paving blocks. The highest compressive strength and lowest absorption values were obtained in the mixture composition 1B:1P:1BP:1AB. The smaller the paving absorption value, the greater the compressive strength. The grain size distribution of each material plays an important role in producing interlocking properties which have an impact on the strength and absorption of paving blocks.