PROSES PEMBUATAN DAN ANALISA STRUKTUR GENTENG BETON BERBAHAN SEMEN, CaCO3, AIR DIPERKUAT ABU BOILER

Abstract

In residential construction, the roof is a crucial component that protects the building from weather elements. Conventional concrete roof tiles typically require large amounts of cement, resulting in relatively high production costs. Costs can be reduced by partially substituting cement with boiler ash and calcium carbonate (CaCO3) and optimizing the water content; this approach aims to produce concrete tiles that are more economical, lightweight, environmentally friendly, and possess adequate compressive strength. Therefore, scientific research into the production of concrete tiles using cement, boiler ash, CaCO3, and water is warranted.

This study was conducted in the Workshop Engineering laboratory at the Institut Teknologi Sawit Indonesia (ITSI) Medan from October to December 2025. A non-factorial Completely Randomized Design (CRD) was employed, featuring three treatments and four replications: S1 (40% cement, 30% boiler ash, 5% CaCO3, 25% water), S2 (35% cement, 30% boiler ash, 5% CaCO3, 30% water), and S3 (30% cement, 30% boiler ash, 5% CaCO3, 35% water), resulting in a total of 12 concrete tile samples. Data were analyzed using quantitative descriptive methods—specifically by calculating the mean values ​​for each treatment—to identify differences resulting from varying material compositions. The observed parameters were water absorption (%) and compressive strength (MPa).

The research results indicate that treatment S1 produced the highest quality concrete tiles, evidenced by the lowest water absorption (2.44%) and the highest compressive strength (18.33 MPa), compared to S2 (4.91% absorption, 10.20 MPa strength) and S3 (11.55% absorption, 3.31 MPa strength). These differences demonstrate that variations in material composition influence the density and strength of the tiles. A higher cement-to-water ratio has been shown to increase material density and the compressive strength of roof tiles, whereas increased water content tends to raise porosity and reduce tile quality. Utilizing boiler ash solid waste as a substitute for fine aggregates can reduce cement consumption without compromising tile quality, while CaCO3 serves effectively as a filler to enhance structural density and surface smoothness; thus, both materials can be optimally utilized to produce high-quality concrete roof tiles.