Effect of Concrete Samples Humidity on the Mechanical Properties of High-Strength Concrete Hariyadi (a*), Baiq Fany Anistya (a), I Nyoman Merdana (a), Ni Nyoman Kencanawati (a), Akmaluddin (a), Buan Anshari (a), Siti Nur Rahmah Anwar (b)
a) Dept. of Civil Engineering, University of Mataram, Jl. Majapahit No. 62 Mataram, Indonesia
* hariyadi[at]unram.ac.id
b) Dept. of Civil Engineering and Planning, State University of Malang, Jl. Semarang No. 5 Malang, Indonesia
Abstract
The hammer test is commonly used as a non-destructive technique for measuring concrete strength in the field. Optimally, this tool is utilized in dry (not moist) structure conditions, yielding tool measurements with exceptional precision. Therefore, it is necessary to compare it with a destructive test conducted using a Compression Testing Machine (CTM), which is a commonly used technique for measuring the strength of concrete. The objective of this study is to assess the impact of humidity on the compressive strength of high-strength concrete by both destructive and non-destructive testing methods, as well as evaluate its split tensile strength.
This research employs high-strength concrete with a strength of 45 MPa at 28 days, with humidity variations measured at 0, 1, 2, 3, 4, 5, 6, 9, 14, and 21 days after samples are removed from immersion. One variation of the test object was an oven for 2 days to obtain low humidity. The strength of the cube-shaped test sample with dimensions of 15 cm is determined by the CTM and the Hammer Test.
The research findings indicate that humidity has a significant effect on the compressive strength of concrete, using destructive and non-destructive tests. However, it has no significant effect on the split tensile strength of concrete. An increase in humidity of 10% causes a decrease in compressive strength of 7.68% for the hammer test and 2.16% for CTM. The reduction in CTM test results, which assess the actual condition of all concrete elements, indicates the decrease in compressive strength due to humidity. The hammer test exhibits a lower compressive strength of 8.90 MPa compared to the CTM at 40% humidity. Furthermore, the disparity between the two tests increases as the humidity of the concrete surface rises. The split tensile strength-to-compressive strength ratio varies between 8.48% and 11.84% under different humidity conditions.
Keywords: high-strength concrete, humidity, compressive and split tensile strength, hammer test
