Abstract:
To make comparison between destructive and non-destructive tests
Two grades of concrete were considered, grade 25 and grade 30 N/mm² . For each grade 24 cubes and three beams were casted and tested. Two destructive tests were made(crushing test and tensile strength test) and two non- destructive tests were considered(rebound hammer test and ultra-sonic pulse velocity test). These tests were conducted in different intervals of time from the date of cast (7, 14, 28 and 56 days). Cubes were tested for crushing, hammer and ultra-sonic pulse velocity tests. Beams were tested for tensile strength after 28 days.
After seven days the crushing strength test showed that the strength reaches 76.6% of the designated strength, for concrete grade 25, and 78.3% for concrete grade 30. hammer test results in more than 100% for the two grades and, an ultra-sonic pulse test showed about 65%.
After 14 days the crushing strength test resulted in 99.2%, for concrete grade 25, and 90% for concrete grade 30. Hammer test resulted in 121% for grade 25 and 104.4% for concrete grade 30. The ultra-sonic test resulted in 107.2% for concrete grade 25 and 90.4% for concrete grade 30.
After 28 days, the crushing strength test resulted in 110.4% for concrete grade 25 and 100.3% for concrete grade 30. While hammer test resulted in 134% for concrete grade 25 and 110% for concrete grade 30.The ultra-sonic test resulted in 160.5% for concrete grade 25 and 139.6% for concrete grade 30.
After 56 days, crushing strength test resulted in 160.7 and 145.4% for concrete grade 25 and 30 respectively. Hammer test resulted in 148.6 and 121.4% for concrete grade 25 and 30 respectively. the ultra-sonic test resulted in 175.2% for concrete grade 25 and 148.3% for concrete grade 30.Tensile test on beams resulted in 12% from the compressive strength test results at 28 days for the two grades more over its 8% from the 56 day compressive strength test results for the two grades.
According to the designated compressive strength after 28 days crushing test show best results, Non-destructive tests is very sensitive to local variations in the concrete (aggregate particles, voids, steel, cracks, experience of the operator,…,etc) so for a measure of concrete strength can not be as acceptance tests.
