Analysis the effect of moisture content of normal concrete using hammer test.

The Hammer test as one of non-destructive concrete strength test should in a non-moist structural condition to produce a high accuracy reading. Since, the strength is only taken from the concrete surface which can be affected by moisture and does not represent the overall properties of the concrete samples. For this reason, hammer test is necessary to compare between the destructive test using a Compression Testing Machine (CTM) a standard concrete strength test and Hammer test. This research used normal concrete with the concrete strength target of 20 MPa, with variations in moisture measured at 0 day, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 9 days 14 days and 21 days after removal from curing chamber, as well as the dried samples with 2 days oven to obtain low moisture. The concrete strength test includes compressive and split tensile strength using a cube sample with 15 cm size. The result shows that the compressive strength value of the Hammer test is lower than the CTM test of 12.34 MPa at 40% moisture, and the difference is higher as the moisture of the concrete surface increases. At various moisture content, the ratio of split tensile strength towards the compressive strength ranges 9.94% - 13.65%. [ABSTRACT FROM AUTHOR]