PENGARUH KADAR AIR AGREGAT TERHADAP KUAT TEKAN BETON

Sari

ABSTRACT

Concrete mix design with the volume proportions are often used because it is very easy in implementation. The volume proportion of cement, sand, and split / gravel that often used are 1 : 2 : 3 and 1 : 1.5 : 2.5 with the specific water cement ratio (wcr). The water content of aggregate (split / gravel and sand) in the field can be either air dry or wet. The difference of water content on aggregate increase or decrease the water cement ratio, and result of concrete compressive strength also varies. Based on these issues then examined the influence of water content of aggregate on concrete compressive strength with the volume proportions 1: 2: 3 and 1 : 1.5 : 2.5 and with water cement ratio 0.6.

The samples that used in this research are a concrete cylinder 150 mm x 300 mm,  fine aggregate of sand and coarse aggregate of crushed stone/split and gravel. The water content of aggregate used be varied such as: wet, saturated surface dry (SSD), and air dry (5 variations). The number of specimens of each variation 3, and total specimen 84. Concrete compressive strength testing performed at 28 days.

From these results obtained: a decrease water content in aggregate will decrease the slump value in volume proportion 1 : 2 : 3 and 1 : 1.5 : 2.5. Slump value of volume  proportion 1 : 2 : 3 less than 1: 1.5: 2.5 in any condition of the water content on aggregate. Condition of the water content on aggregate that  larger or smaller than the SSD condition in volume proportion 1 : 2 : 3 are resulted decreased concrete compressive strength. In volume proportion 1 : 1.5 : 2.5 with aggregate water content greater than the SSD resulted in decreased concrete compressive strength  and on the condition of the water content is smaller than SSD resulted in increased concrete compressive strength. On SSD condition, concrete compressive strength by volume proportion 1 : 2 : 3 are almost equal to 1 : 1.5 : 2.5, while in the wet and air dry conditions aggregate, compressive strength of concrete with the volume proportion  1 : 2 : 3 less than the volume proportion 1 : 1.5 : 2.5.

Keywords: water content of aggregates, proportions by volume, compressive strength.