Papers by Author: Zhong He Shui

Abstract: Layered double hydroxides (LDH) can provide the ion-exchange ability and the addition of LDH can affect the chloride-ion transfer in the concrete. The effect of LDH on the chloride-ion penetration is investigated in this study. Concrete samples contained different addition of LDH are designed in the experiment and tested by electric flux method and NT Build 443 method. The experimental results show that the addition of LDH can solidify the chloride-ion in concrete and slow down the transfer of chloride-ion, which enhanced the concrete resistance of chloride-ion penetration.

Abstract: The experimental study was performed on the relationship between the mechanical and durability properties of high-strength concrete with metakaolin (MK) and slag. The compressive strength, chloride penetrability and pore structure of the OPC and the concrete with MK and slag were measured. It is found that MK can significantly increase the compressive strength, decrease the chloride ions migration coefficient and improve the pore structure of the steam cured high-strength concrete. The chloride resistance is improved obviously by 5% MK and further increase of the MK dosage performs a little change of the chloride migration coefficient. Better improvement effect on the mechanical and durability properties is obtained with the incorporation of 10% MK and 10% slag. Linear relationship is found between the coarse pore porosity and the compressive strength, while the chloride migration coefficient correlates well with the capillary pore volume.

Abstract: In this paper, infrared imaging and temperature sensor monitoring equipment are used to detect the defect of concrete. By means of experiment and numerical analysis, a nondestructive testing method for concrete based on infrared thermal imaging and the finite element simulation of temperature field was established. Experimental and simulation results show that infrared thermal imaging method and the finite element simulation of temperature field can effectively detect the defect in the sample. When combining such two methods together, the information of internal concrete structure can be revealed more comprehensively and accurately.

Abstract: The concrete containing expansive agent, when limited, is affected by the addition of expansive admixture much, which influence the carbonation resistance. This article makes a comparison with anti-carbonation ability of concrete under restraint and non-restraint condition. The compressive strength and carbonation depth are tested, and the changes of micro-structure are also analyzed with TG-DSC and MIP analysis. The results reveal that single-dimensional restraint condition can efficiently improve the pore structure of concrete. And expansive agent also has a slight improvement to it. Single-dimensional restraint condition can obviously enhance the anti-carbonation ability of concrete containing expansive agent.

Abstract: This paper presents the rehydration performance of binary binders made with dehydrated cement paste (DCP) and phosphogypsum (GP). DCP was obtained by thermal treatment of hardened cement pastes in which the initial water to cement ratio was 0.5. DCP we mixed with phosphogypsum (PG) to prepare the binary binders . The effect of PG on the physical and mechanical properties of the binary binders was investigated. Scanning electron microscope (SEM) was used to indentify the structural characteristics of the rehydration products. The results showed that the setting time was prolonged and the compressive strength increased slightly by mixing DCP with PG. Microstructural observations indicated that an remarkable amount of ettringite intergrows with the hydrated calcium silicate to form a network structure. Thus, the addition of phosphogypsum can not only utilize the industrial by-product, but enhances the hydraulic properties of the DCP.

Abstract: Modification of structure and thermodynamic properties of montmorillonite is studied by molecular dynamics simulation. The simulation results show that the pure montmorillonite system is unstable in nature, while the structure of doping-modified montmorillonite is more stable. In simulation process, the activity between the molecule and impurity ions maintains strong synergistic effect, and the configuration of the analog system is energetically most stable.

Abstract: What kind of role do the reactive aluminous has played during early hydration process of metakaolin-cement paste is investigated in present study. Therefore, metakaolin(MK) samples containing 45.94%, 22.86%, 0% reactive aluminous are prepared, respectively. In addition, X-ray Diffraction (XRD) analysis is employed to identify the crystalline phases of all specimens. The amount of acid-insoluble residue (AIR) of all specimens is used to evaluate the unreacted materials. The results obtained indicate that reactive aluminous can promote development of the early period strength significantly. Reactive silica and reactive aluminous reaction velocity was very slow during the first three days, then increased. The reaction velocity of reactive aluminous was faster than reactive silica between the first day and third day, but it shows an opposite result between the third day and seventh day.