Effect of Silica Fume Addition on Mechanical Properties of Concrete in Peat Swamp Water Environment

Hydraulic Portland cement, water, fine and coarse aggregate, and additional ingredients can be added or left out to create concrete. Making and maintaining concrete requires water as a reagent in the cement mixture so that a chemical reaction occurs when it undergoes the hydration process, which is the process where the cement begins to bind the ingredients that make up the concrete and then hardens and forms a solid mass. The need for water in concrete care is to soak it during the hardening process, however, not all types of water can be used. Peat swamp water is water that collects or flows within the peat swamp ecosystem. Peat swamps are a type of swamp formed from organic material accumulated over thousands of years. Silica fume is a material that contains SiO2 greater than 85% and is a very smooth, round material with a diameter of 1/100 the diameter of cement. The swamp water used in this research was taken from Jl. Rappokalling, Tallo District, Makassar City, South Sulawesi. Mix Design uses the Indonesian National Standard (SNI) 03-2834-2000 method with a planned concrete quality (f'c) of 25 MPa. Compressive strength tests were performed on concrete that was 7 and 28 days old for split tensile strength, and on the 28-day old concrete for modulus of elasticity. The concrete's compressive strength ratings after 28 days in variations of immersion in normal water and peat swamp water are 25,842 MPa and 20,749 MPa. From the test results, it was found that the average split tensile strength value of concrete for variations in normal water immersion and peat swamp water was 2.545 MPa and 1.886 MPa. From the results of the modulus of elasticity test, it was found that the average concrete in normal water immersion and peat swamp water variations was 19893.961 MPa, and 17109.75 MPa.