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Wang K.,Shandong Jiaotong University | Sui T.,Sinoma International Engineering Co. | Xu S.,Shandong Provincial Water Resources Research Institute | Liu L.,Ji nan Delitai Building Materials Company
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

Prevention of bedrock concrete cracking can improve the durability and operation safety of hydraulic structures. In this work, the cracking mechanism and restrained strain of rubber aggregate motar were studied through an experiment of restrained loop with resistance strain gauges, scanning electron microscrope and mercury porosimeter. The strain gauges were buried into bedrock concrete for measurement of restrained strain of rubber aggregate concrete. The results reveal that the rubber aggregate material under stressing causes a change in the shape of pores in the cement paste matrix and part of its stress is released. In the condition of ordinary motar cracking, this material develops curing strain and larger restrained strain, so the concrete does not crack. At the ages of 45d and 90d, the restrained strain in ordinary bedrock concrete is reduced quickly and its cracks start developing. Thus, rubber aggregate can improve the performances of bedrock concrete against cracking. This study provides an effective technical measure for prevention of bedrock concrete cracking. Source


Wang K.,Shandong Jiaotong University | Sui T.,Sinoma International Engineering Co. | Liu L.,Ji nan Delitai Building Materials Company | Xu S.,Shandong Provincial Water Resources Research Institute
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2014

The influence of tensile properties of high Belite cement concrete on the crack of concrete was investigated. The tensile strength and ultimate tension of high Belite cement concrete were compared with those of Portland cement concrete by splitting tensile test and axial tensile test. The microstructures of interfacial transition zones of high Belite cement concrete and Portland cement concrete were characterized by microhardness measurement, scanning electron microscopy and X-ray energy dispersive spectroscopy. The results reveal that the tensile strength and ultimate tension of high Belite cement concrete are better than those of Portland cement concrete at the same ages and water cement ratio, and the later-age tensile strength of high Belite cement concrete and its rate are great. The thickness of high Belite cement concrete is 25 μm less than that of Portland cement concrete. The microhardness of high Belite cement concrete is 8. 9MPa more than that of Portland cement concrete. The ratio of Ca to Si is low and the adhesion of interface in high Belite cement concrete is relatively perfect, compared to Portland cement concrete. Therefore, the microstructure of interfacial transition zone and the tensile properties of high Belite cement concrete are better than those of Portland cement concrete. ©, 2014, Chinese Ceramic Society. All right reserved. Source


Li G.,Hohai University | Wu J.,Hohai University | Wu J.,State Key Laboratory for GeoMechanics and Deep Underground Engineering | Ge W.,Shandong Provincial Water Resources Research Institute
Construction and Building Materials | Year: 2015

Abstract In this study, the end anchorage device for large diameter FRP bar was firstly developed, based on which the effect of loading rate on the direct tensile mechanical properties of 25 mm diameter GFRP bars was tested, and the anticorrosion properties of a newly developed type of FRP bar, the basalt-glass fiber reinforced polymer (B-GFRP) bars with different thicknesses of basalt FRP protecting layers (0, 1, 3 and 5 mm) were investigated. The results show that, with the increase of loading rate, the tensile strength and elongation ratio of GFRP bar increase considerably, while the elastic modulus remains roughly constant. The addition of BFRP protecting layer is also proved to be an effective way to enhance the resistance of GFRP bars to the chemical attacks. © 2015 Elsevier Ltd. Source


Wang K.,Shandong Provincial Water Resources Research Institute | Hu T.,Qingzhou Renhe Reservoir Administrative Office | Liu L.,Jinan Delitai Building Materials Concrete Company
Advanced Materials Research | Year: 2012

Influence of permeated crystalline materials on durability of hydraulic concrete was studied by impermeability test methods after sulfate attack and freeze-thaw cycling. Microstructure of concrete was analyzed and characterized with SEM and MIP. The results showed that impermeability pressure of concrete with permeated crystalline materials was more than that of standard concrete after sulfate attack and freeze-thaw cycling. Permeated crystalline materials improved on performance of concrete for sulfate attack and freeze-thaw, because that microstructure of interfacial transition zone of concrete with permeated crystalline materials was compact and its pore size distribution was more than that of standard concrete. There were more content of less harmful pore with diameter 20nm∼100nm and less content of harmful pore with diameter100nm∼200nm and more than 200nm in concrete with permeated crystalline materials than in standard concrete. © (2012) Trans Tech Publications, Switzerland. Source


Wang K.,Shandong Provincial Water Resources Research Institute | Hu T.,Qingzhou Renhe Reservoir Administrative Office | Xu S.,Shandong Provincial Water Resources Research Institute
Advanced Materials Research | Year: 2012

Influence of permeated crystalline waterproof materials on permeability and automation healing of concrete was studied by impermeability test methods for two and a few times. Microstructure of concrete was analyzed and characterized with SEM and MIP. The results showed that permeated crystalline waterproof materials had function of durable self-repairing and impermeability of concrete improved with increasing of permeated crystalline waterproof materials. It was because that reaction crystallization of active component in permeated crystalline materials and Ca(OH) 2 in concrete filled interfacial of concrete and cement paste matrix. In addition, pore size distribution of concrete with permeated crystalline waterproof materials was so good that there were more content of less harmful and less content of harmful pore in concrete. Therefore, most probable pore diameter of concrete reduced and impermeability of concrete improved. © (2012) Trans Tech Publications, Switzerland. Source

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