Pengaruh Uji Kuat Lentur terhadap Beton Mutu Tinggi dengan Penggunaan Fly Ash sebagai Bahan Substitusi Semen

Abstract

In the use of conventional concrete, to make high quality concrete requires alarge consumption of cement. The high demand for cement makes limitedrenewable energy, and the occurrence of global warming due to greenhouse gases,encouraging the cement industry to look for alternative environmentally friendlyenergy sources. The purpose of the study was to determine the percentage of Fly Ashoptimization that meets the requirements of flexural strength in high quality beams(SNI 1974: 2011). With the benefit of reducing the level of pollution produced bycement factories by using Fly Ash from the Pangkalan Susu PLTU located inTanjung Pasir Village, Kec. Pangkalan Susu, Kab. Langkat, North Sumatra as asubstitute for cement. In this study, flexural strength testing was carried out with high qualityconcrete specimens measuring 15 cm x 15 cm x 60 cm at the age of 28 days with aUniversal Testing Machine based on procedures and calculations from SNI 4431-2011. Based on this research, it is found that by adding Fly Ash to the cementmixture in concrete, the flexural strength graph tends to be stable until the 30%variation, this is because this combination ratio is the best combination in thecombination of OPC cement and Fly Ash. this is because the Superplasticizeradditive can control the moisture content of the concrete so that the concretemixture does not consume more water which can reduce the quality of the concrete.and decreased from 40% - 50% variation, this is because Fly Ash matrial has aspecific gravity of 2800 kg / m3 which is lower than cement with a specific gravityof 3150 kg / m3, so this can reduce the mortar mixture to the volume of concrete sothat the flexural strength becomes low