Strategies to improve the impact resistance of self-compacting concrete (SCC) after freeze-thaw cycles

Abstract

Three strategies including rubber particles, steel fibers and asphalt-coated coarse aggregate (ACCA) were introduced to improve the impact resistance of self-compacting concrete (SCC) after freeze-thaw cycles. The impact compression properties of SCC after 200 freeze-thaw cycles were investigated using a 75-mm split Hopkinson pressure bar (SHPB). The fineness modulus of residue (Mr) and impact toughness index (ITi) were defined to evaluate the impact-resistance performances of SCC. Results show that dynamic properties of SCC including peak stress, peak strain, Mr and ITi show remarkable strain rate effect. The decrease scale of Mr for SCC with modifying materials is considerably lower than that of the control group, indicating a less damage degree caused by freeze-thaw cycles. The ITi of SCC is greatly improved by three types of modifying materials, and the efficiency of improvement is ordered as: SCC-SF > SCC-ACCA > SCC-R. The average ITi decrease rate of SCC-R, SCC-SF and SCC-ACCA in all strain-rate range is 3.3%, 2.0% and 1.3%, respectively, which is much lower than that of SCC0 (7.8%), indicating a reduced impact toughness loss caused by freeze-thaw cycles. The enhancement of impact resistance for SCC with three types of modifying materials is highly related to their crack propagation effect during the impact compression process.