Utilization of by Product Kappaphycus alvarezii as Earthquake Resistant Material Lightweight Concrete

Increasing seaweed production in Indonesia is the result of industrial demand that continues to soar, especially Kappaphycus alvarezii, and has an impact on the accumulation of seaweed processing waste. The use of waste as a substitute for sand in making lightweight concrete can be done because there is a cellulose content that can make bonds between materials which can be used as earthquake-resistant building materials. The purpose of this study was to determine the industrial waste treatment of K. alvarezii can be used as a lightweight concrete for earthquake resistant building materials. This study uses a complete random range with six treatments and four replications by testing compressive strength, flexural strength, and water absorption. The best treatment is a substitution with a 60% waste concentration with the results of the compressive strength test of 1.15 MPa, the flexural strength of 5.37 MPa, and a water absorption capacity of 62.25%. The suggestion from this research is to do mass production with the substitution formulation of carrageenan waste by 60%.