Analisis Koefisien Korelasi Kuat Tekan dan Kuat Lentur Beton Menggunakan Spent Bleaching Earth (SBE) dan Cangkang Kerang sebagai Subtitusi Semen

The increasing use of concrete in construction has driven innovation in utilizing environmentally friendly materials such as industrial waste. This study aims to evaluate the effect of Spent Bleaching Earth (SBE) and seashells as partial cement replacements on the improvement of concrete’s compressive and flexural strength, as well as to analyze the relationship between them through the efficiency coefficient K. The variations used include normal concrete (BN) and concrete with a mixture of 4% SBE and 3.5% seashells (BSC). Testing was conducted at 7, 28, and 56 days using freshwater and seawater curing media. The results show that BSC concrete exhibited better mechanical performance than normal concrete. The highest compressive strength of BSC was recorded at 26.31 MPa (28 days, freshwater) and 25.23 MPa (28 days, seawater). Meanwhile, thehighest flexural strength was achieved by BSC in seawater at 4.253 MPa and BSC in freshwater at 4.018 MPa. Normal concrete only reached 3.804 MPa and 3.661 MPa, respectively. Additionally, the highest K coefficient of 0.981 was found in normal concrete cured in freshwater, exceeding the theoretical value of 0.62. Overall, the addition of SBE and seashells effectively enhances the mechanical properties of concrete and supports the development of more sustainable construction materials.