Papers by Author: Ping Duan

Abstract: Layered double hydroxides (LDHs) materials could be used in cement and concrete for their ions capturing capacity and to enhance durability of concrete. In this work, properties and chloride binding capacity of different types of LDHs were compared, micro-mechanism of chloride binding of LDHs were analyzed and chloride binding of cement paste incorporating LDHs were investigated. The experimental results show that Mg-Al-NO₃ LDHs presents higher chloride ion binding capacity at initial time compared to LDOs calcinated at 500 °C while ion binding capacity of LDHs calms down and LDOs increases with increasing mixing time. Cement paste incorporating LDHs presents higher chloride binding capacity compared with reference sample. All types of LDHs performed beneficial effect on the chloride penetration resistance especially with addition of 1% Mg-Al-NO₃ LDOs.

Abstract: The effect of mineral admixture and curing condition in pore structure of concrete was studied in this paper. Concrete samples with different component were prepared firstly, and then they were put into standard condition, fresh water and salt environment that produced artificially respectively at 20 °C. After the experiments of curing at 3, 28 and 180 days pore structure were tested by mercury intrusion porosimetry (MIP). The results obtained reveal that with the increase of the age, the pore structure degradation impact in salt environment of concrete increase dramatically. When at 28 days, total pore volume and porosity of concretes in fresh water is lower by 20% and 5% respectively than the ones with larger mean pore size and critical aperture in salt environment, which represents pore refinement in fresh water had a good effect. Compared to the salt environment erosion, it can be found that the impact of pore refinement in fresh water is more significant.