Compressive Strength assessment of self-compacted concrete with Nano materials using ultrasonic pulse velocity method

In this paper the compressive strength (f’c) of self-compacted concrete (SCC) containing Nanomaterials (NM) is evaluated by non-destructive ultrasonic pulse velocity method. This study involves about 13 different mixtures containing Nano oxides of Silica (NS), Aluminum (NA) and Copper (NC) with amounts ranging from 0.25 to 2 percent, as the binder in replacement of Portland cement, tested between 3 and 90 days for f’c ranging from about 20 to 54 MPa. The influence of different parameters such as type of NM, wet and dry curing conditions on the relationship between ultrasonic pulse velocity (UPV) and f’c is examined. Also, the effect of rebar on UPV is evaluated in this type of SCCs. Results show that the specimens containing NS, NA and NC with amounts of 1.5, 0.25 and 0.25% of the cement weight (optimum percentage), respectively, have the highest UPV and f’c. The specimens containing the optimum amount of NS in wet curing condition with a 22% increase in f’c compared to the control specimen has the highest f’c. In the specimen containing the optimum percentage of NM, UPV became less in the first ages and higher in the older ages more than control specimens. Exponential relationships between UPV and f’c of the specimens were determined whose coefficients are different for each added Nano. The addition of NM reduced the difference in UPV between wet and dry curing conditions so that this difference from 5% for control SCC decreased to 3.8%, 3, and 4% for SCCs containing NS, NA, and NC, respectively. The effect of steel bars on the UPV was introduced by means of correction coefficients (CC) and it was observed that the CC obtained with the proposed CC are consistent with CC recommended by BS 1881: Part 203