Jian Bo Xiong

Synthesis and Properties of Silicone Modified Acrylate Emulsion

Silicone modified acrylate emulsion was successfully synthesized by pre-emulsion polymerization with the monomers of butyl acrylate(BA), methyl methacrylate(MMA), acrylic acid(AA), vinyl triethoxy silane(DB-151) using APS as initiator. The influence of reaction temperature, emulsifier system and silicone concentration on emulsion properties was discussed. The results showed that the overall performances of obtained emulsion became better with the condition: the reaction temperature 75°C, 6%~8% of silicone concentration, and 3% complex emulsifier system consist of the non-ionic /anionic/amphoteric emulsifier. The study also proved that silicone modified acrylic emulsion can improve water resistance and hardness of the resin.

Influence of Mineral Admixtures on Chloride Diffusion Coefficient of Self-Compacting Concrete

The influence of mineral admixtures on workability of fresh concrete and chloride ion permeability resistance of hardened concrete for C50 self-compacting concrete was investigated by means of the Natural Immersion Test. The results showed that the chloride diffusion coefficient in fly ash concrete decreased first and then increased with increasing fly ash content in cementitious materials, when fly ash content was 30% or 40%, it got the lowest value at 28 days or 90 days, respectively. The chloride diffusion coefficient in specimens decreased with increasing the ground granulated blast furnace slag content in cementitious materials, but it changed little when the replacement was in ranges of 50% to 60%. Furthermore, for the specimens which replaced by fly ash and ground granulated blast furnace slag, the chloride diffusion coefficient decreased first and then increased with increasing the fly ash content in complex cementitious, and when fly ash content was 10% or 20%, it got the lowest value at 28 days or 90 days, respectively.

Influence Mechanism of Complex Admixtures on Chloride Diffusion Coefficient of C50 Self-Compacting Concrete for Marine Environment

The influence of complex admixture on chloride diffusion coefficient of C50 self-compacting concrete for marine environment was investigated by means of the NT BUILD 443 Test, and the influence mechanism of complex admixture on the diffusion coefficient was studied, respectively. The results showed that the chloride diffusion coefficient decreased first and then increased with increasing the fly ash content in complex cementitious, and when fly ash content was 10% or 20%, it got the lowest value at 28 days or 90 days, respectively. Its more helpful to promote the fly hydration degree for extending curing period. Furthermore, the porosity and average pore size decreased first but then increased with increasing the fly ash content in complex cementitious, the porosity and average pore size got the lowest value when the fly ash content was 20% in cementitous.

Service Life Checking Calculation of Marine Reinforced Concrete Structures Based on Monte Carlo Method

Checking some apparent chloride diffusion coefficient of concrete in the marine environment meets the requirements of design life based on Monte Carlo method. Through the project investigations, laboratory test data, statistical analysis and to determine random distribution model of the critical chloride concentration, the surface chloride concentration ,using computer program simulation 5000 random groups critical chloride concentration, surface chloride concentration into the life value calculation model, And obtain the derived distribution of the concrete structures service life, in order to determine Compliance with the design life of concrete structures. For the concrete durability design and service life checking provide the effective analysis under the marine environment.

Influence of Stone Dust in Manufactured Sand on Resisting Chloride Penetration in Marine Concretes

In China, manufactured sand has been widely used as fine aggregate in concrete. Therefore, it is necessary to investigate the effect of manufactured sand on durability of concrete. This research studies the influence of stone dust content in manufactured sand on resisting chloride penetration in marine concrete by strength and other physical mechanical tests, XRD, TGA and pore structure analysis. Test results have shown that the chloride diffusion coefficient increased with increasing the stone dust content in manufactured sand when the stone dust content increasing from 3% to 13%. The stone dust in fine aggregate was participated in hydration procedure of cementitious, which will promote the hydration degree of cementitious and increase the chloride binding capacity of hydration product. The influence of stone dust in fine aggregate on chloride diffusion coefficient were the combined effects of concrete pore structure and cementitious hydration products, and the porosity and pore size distribution were the main factors that influence the changes of diffusion coefficient.

Implementation of Corrosion Intelligent Monitoring and Durability early Warning Expert System for the Large Marine Environmental Engineering Concrete Structures

To ensure 120 years design life of the large marine environmental engineering concrete structures in South China, and assess the status of the development of durability of concrete structure in real time w a research has been performed on embedded-non-destructive corrosion monitoring sensor systems, data acquisition and software integration, combined exposure test of concrete under environment in South China more than 30 years and laboratory test. It is a new type of technology for corrosion monitoring, assessment and early warning, which based on electrochemical principle, network transmission, expert software system, integrated the durability of the project full set of intelligent real-time monitoring and early warning expert systems.

The Effect of Surface Hydrophobation Silane Treatment on Chloride Ion Penetration Resistance for Concrete Structures in Marine Environments

Effect of concrete surface hydropobation treatment against chloride penetration have been studied by in-site exposure test. The results show that the silane impregnated layer can prevent the chlorides penetration into the concrete substrate effectively, reduce the apparent chloride ion diffusion coefficient and surface chloride concentration, and improve the service life of concrete structure; and the depth of concrete convection zone can reduce due to silane impregnated layer for concrete in the marine environment of wetting and drying area.

Influence of Stone Dust Content in Manufactured Sand on Chloride Diffusion Coefficient of C60 Grade Concrete

The influence of stone dust content on chloride diffusion coefficient in C60 grade concrete were investigated by means of the natural immersion test, XRD test, MIP test and TGA test, respectively. The experimental results showed that the chloride diffusion coefficient increased with increasing the stone dust content in manufactured sand, and the chloride diffusion coefficient increased little when the stone dust content increasing from 7% to 13%. The hydration degree for cementitious and compressive strength for concrete was slightly promoted by using stone dust replacing cementitious at a low level. But the porosity and average pore size of concrete increased with increasing the stone dust content from 3% to 13%, and the concrete pore structure was the main factor that influences the changes of chloride diffusion coefficient in concrete.

Effect of Stone Dust Content in Manufactured Sand on Chloride Diffusion Coefficient of Various Strength Grade Concretes

The influence of stone dust content on chloride diffusion coefficient in C30, C40 and C50 grade concretes were investigated by means of the natural immersion test, XRD test, MIP test, SEM and TGA test, respectively. The experimental results showed that the chloride diffusion coefficient in C30 grade concretes decreased with increasing the stone dust content, but it decreased first and then increased with increasing the stone dust content in C40 and C50 grade concretes. The hydration degree for cementitious and compressive strength for concrete was slightly promoted by using stone dust replacing cementitious at a low level. For C30 grade concretes, the porosity decreased with increasing the stone dust content in fine aggregate, but for C40 and C50 grade concretes, the total porosity decreased first then increased with increasing the stone dust content. And the concrete pore structure was the main factor that influences the changes of chloride diffusion coefficient in concrete.

Influence of Mineral Admixtures on Chloride Threshold Value for the Corrosion of Steel Reinforcement

The influence of mineral admixtures on chloride threshold value was investigated by EIS method, MIP test and TG test, respectively. The experimental results showed that the chloride threshold value decreased with increasing the fly ash and slag content in composite cementitious. The increasing of fly ash and slag replacement resulted in the decreasing of porosity, average pore size and Ca(OH)2 content. The effect of mineral admixtures on the chloride threshold value was the comprehensive results of concrete pore structure and Ca(OH)2 content. The chloride threshold value decreased with decreasing the Ca(OH)2 content in concrete, and there was an approximate linear relationship between the logarithm of chloride threshold value and the logarithm of CCa(OH)2 content when the specimens exposed in tidal zone. The specimen exposed in tidal zone has a higher chloride threshold value than that exposed in splash zone was due to the lower dissolved oxygen around steels in concrete.