According to the principle and method of drop-weight impact test, the impact resistance of concrete was measured using self-designed U-shape specimens and a newly designed drop-weight impact test apparatus. A series of drop-weight impact tests were carried out with four different masses of drop hammers (0.875, 0.8, 0.675 and 0.5 kg). The test results show that the impact resistance results fail to follow a normal distribution. As expected, U-shaped specimens can predetermine the location of the cracks very well. It is also easy to record the cracks propagation during the test. The maximum of coefficient of variation in this study is 31.2%; it is lower than the values obtained from the American Concrete Institute (ACI) impact tests in the literature. By regression analysis, the linear relationship between the first-crack and ultimate failure impact resistance is good. It can suggested that a minimum number of specimens is required to reliably measure the properties of the material based on the observed levels of variation.

Erosion effect of chloride ions from the marine, deicing salt, saline-alkali land and some industrial environments will cause the corrosion of rebar in concrete, which is one of the most harmful factors affecting the durability of concrete structure. It had been proved that the incorporation of rubber aggregates increase the capillary saturation of cement concrete and reduce the corrosion degree of rebar. This paper investigated the rebar corrosion behavior in rubber aggregate concrete under the chloride electro-accelerated corrosion condition and such an investigation has not been seen in any public literature. Two water-cement ratios (0.45 and 0.55) and four rubber contents (0, 50, 100, and 150 kg/m³) were selected for experiment. Four-point bending tests of concrete beam were conducted before and after chloride ion erosion in order to determine effect of rubber aggregate on the durability of rebar. Results showed that rebar corrosion degree decreased with the increase of rubber aggregate in concrete. Besides, the more the dosage of rubber is, the better the anti-crack performance of cement concrete. This will postpone the crack development and reduce the peak of rebar corrosion.

This study investigates the mechanical and durability properties of fly ash-based engineered cementitious composites (ECC). The effect of various mineral additions, such as wheat husk ash (WHA), rice husk ash (RHA), glass powder (GP), and fibrillated polypropylene (PP) fibers, on mechanical performance, water absorption, and porosity was investigated. Furthermore, the durability of ECC specimens was assessed in terms of sorptivity, acid/sulfate attacks, electric resistivity (ER), rapid chloride penetration (RCPT), and ultrasonic pulse velocity (UPV). The results revealed higher mechanical strength, UPV, and ER values for RHA-based ECC. After 180 days of immersion in acid and sulfate solutions, RHA-based ECC showed a lower loss in compressive strength (23.21% and 1.07% in HCl and Na₂SO₄, respectively) relative to the control mix (44% and 7% in HCl and Na₂SO₄, respectively). Moreover, analytical characterizations such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning Electron Microscopy (SEM), and Energy dispersive X-ray (EDX) analyses were also carried out to corroborate the mechanical and durability properties of ECC.