Optimization of Flyash Composition and Drying Timein Water Absorption and Compressive Strength Concrete Brick

One of the most crucial components of construction materials is concrete bricks that can be applied to the walls of houses, office buildings and fences. Concrete brick is a ceramic material that has brittle properties and to increase its strength and reduce the weight of concrete brick, fly ash is used as a mixture in concrete brick material. Fly ash which is the residual combustion or coal waste from the Sigantang Sawahlunto Power plants with a variety of composition fly ash and concrete bricks drying time which aims to determine the optimal conditions in water absorption and compressive strength test which refers to SNI 03-0349-1989 standard and light or normal concrete brick. The material used is sand plus aggregate, cement and water as a binder, with fly ash as added material. The composition variations are 0, 5, 10 and 15 wt.% fly ash Then it is compacted manually with size (34 × 12 × 9) cm³ based on SNI 03-0349-1989 standard. After that it is dried for 7, 14, 21, 28, and 35 days. The results showed that the optimal composition was on the addition of 5 wt.% fly ash with a drying time of 28 days resulting in Water Absorption 7.84 % quality and compressiv strength 51.98 kg/cm² quality III of SNI 03-0349-1989 which can be applied to constructions that do not carry loads, for insulating walls (under the roof). (paper)