PENGARUH PERBANDINGAN AGREGAT HALUS DENGAN AGREGAT KASAR TERHADAP WORKABILITY DAN KUAT TEKAN BETON

Sari

ABSTRACT

Aggregates generally occupy 70% to 80% by volume of concrete so it has important influence to concrete properties. The proportion of fine aggregate and coarse aggregate in the concrete mix required to obtain a good combined aggregate gradation. Good proportion of fine aggregate and coarse aggregate is in accordance with the standard curve of the combined aggregate gradation as the Concrete Mix Design Procedure. The most important properties of hardened concrete is compressive strength and the most important properties of fresh concrete is workability. Based on these problems, the research about influence of fine aggregate to coarse aggregate ratio to workability and compressive strength of concrete was carried out.

The ratio of the mixture used for 1 m³ of concrete was 356 kg cement: 842 kg sand: 1093 kg split, and water cement ratio (wcr) 0.52. Variation of fine aggregate to coarse aggregate weight ratio used is 0%: 100%, 30%: 70%, 35%: 65%: 40%: 60%, 43.5%: 56.5%, 45%: 55% , 50%: 50%, 55%: 45%, 60%: 40%, 65%: 35%, 70%: 30%, and 100%: 0%. There were 3 speci mens of each variation and the total of specimens were 36. The samples used in this research were concretes cylinder 150 mm x 300 mm. Concrete compressive strength testing was carried out at 28 days concrete age.

From the results of this study, it can be concluded that reduction of sand and addition of split can increase workability. Addition of sand and reduction of split can decrease workability. Ratio of fine aggregate (sand) to coarse aggregate (split) affects the compressive strength of concrete although water cement ratio (wcr) fixed. Ratio of fine aggregate (sand) to coarse aggregate (split) affects the unit weight of the concrete.  

Keywords: ratio of aggregate, workability, compressive strength.