ANALISIS KUAT TEKAN DAN MODULUS ELASTISITAS BETON DENGAN VARIASI PENAMBAHAN ABU SEKAM PADI SEBAGAI SUBSTITUSI SEMEN DAN SUPERPLASTICIZER SEBAGAI BAHAN TAMBAH

The development of construction technology has led to innovations to improve concrete quality, one of which is the use of waste materials as partial substitutes. Concrete is a mixture of cement, fine aggregate, coarse aggregate, water, and additives. This study investigates the use of rice husk ash as a partial cement substitute with the addition of superplasticizer to evaluate the compressive strength and modulus of elasticity of concrete. The variations of rice husk ash were 0%, 4%, 8%, and 12%, with 1% superplasticizer. Tests were conducted on cylindrical specimens sized 150×300 mm at 28 days to determine the effects on compressive strength and modulus of elasticity. The results showed that the compressive strength of normal concrete was 30.56 MPa. With 4% and 8% rice husk ash, the compressive strength increased to 33.20 MPa and 31.12 MPa, but decreased to 29.24 MPa at 12%. The optimum level was obtained at 4.94% with a maximum compressive strength of 32.53 MPa. The modulus of elasticity of normal concrete was 32812 MPa, increased to 37670 MPa at 4%, and decreased to 35308 MPa and 34216 MPa at 8% and 12%. The optimum level was obtained at 6.25% with a maximum modulus of 36866 MPa. In conclusion, rice husk ash with superplasticizer improves concrete performance, with the optimum range at 4–6% for both compressive strength and modulus of elasticity.