A model of damage to fresh concrete in a corrosive sulphate environment was formulated to investigate how and why the strength of corroded concrete changes over time. First, a corroded concrete block was divided into ...A model of damage to fresh concrete in a corrosive sulphate environment was formulated to investigate how and why the strength of corroded concrete changes over time. First, a corroded concrete block was divided into three regions: an expanded and dense region; a crack-development region; and a noncorroded region. Second, based on the thickness of the surface corrosion layer and the rate of loss of compressive strength of the corroding region, a computational model of the concrete blocks' corrosion-resistance coefficient of compressive strength in a sulphate environment was generated. Third, experimental tests of the corrosion of concrete were conducted by immersing specimens in a corrosive medium for 270 d. A comparison of the experimental results with the computational formulae shows that the calculation results and test results are in good agreement. A parameter analysis reveals that the corrosion reaction plays a major role in the corrosion of fresh concrete containing ordinary Portland cement,but the diffusion of the corrosion medium plays a major role in the corrosion of concrete mixtures containing fly ash and sulphate-resistant cement. Fresh concrete with a high water-to-cement ratio shows high performance during the whole experiment process whereas fresh concrete with a low water-to-cement ratio shows poor performance during the late experiment period.展开更多
This investigation was carried out to study the effect of aggregate roughness on ITZ （interfacial transition zone） at same water/cement ratio and the influence of silica fume on the bond strength. On the experimenta...This investigation was carried out to study the effect of aggregate roughness on ITZ （interfacial transition zone） at same water/cement ratio and the influence of silica fume on the bond strength. On the experimental side, two types of aggregates （limestone and granite） were used, which were prepared with broken surface. Cement （Type I） was used with same w/c ratio for all batches. In order to study the effect of silica fume on the bond, the same mixes were produced with 8% silica fume. Three different tests were performed： ＂pull a part＂, Brazilian test and compressive strength test. The specimens for Brazilian and compressive strength were tested after 28 days, while the ＂pull a part＂ specimens were tested after 29 days. The result showed that the bond strength is influenced by the surface roughness of aggregate. For the same mix, limestone recorded higher bond strength than granite. Moreover, the bond strength is increased by adding the silica fume.展开更多
基金Project(51078176) supported by the National Natural Science Foundation of ChinaProject(JK2010-58) supported by the Construction Science and Technology Research Project in Gansu Province,China
文摘A model of damage to fresh concrete in a corrosive sulphate environment was formulated to investigate how and why the strength of corroded concrete changes over time. First, a corroded concrete block was divided into three regions: an expanded and dense region; a crack-development region; and a noncorroded region. Second, based on the thickness of the surface corrosion layer and the rate of loss of compressive strength of the corroding region, a computational model of the concrete blocks' corrosion-resistance coefficient of compressive strength in a sulphate environment was generated. Third, experimental tests of the corrosion of concrete were conducted by immersing specimens in a corrosive medium for 270 d. A comparison of the experimental results with the computational formulae shows that the calculation results and test results are in good agreement. A parameter analysis reveals that the corrosion reaction plays a major role in the corrosion of fresh concrete containing ordinary Portland cement,but the diffusion of the corrosion medium plays a major role in the corrosion of concrete mixtures containing fly ash and sulphate-resistant cement. Fresh concrete with a high water-to-cement ratio shows high performance during the whole experiment process whereas fresh concrete with a low water-to-cement ratio shows poor performance during the late experiment period.
文摘This investigation was carried out to study the effect of aggregate roughness on ITZ （interfacial transition zone） at same water/cement ratio and the influence of silica fume on the bond strength. On the experimental side, two types of aggregates （limestone and granite） were used, which were prepared with broken surface. Cement （Type I） was used with same w/c ratio for all batches. In order to study the effect of silica fume on the bond, the same mixes were produced with 8% silica fume. Three different tests were performed： ＂pull a part＂, Brazilian test and compressive strength test. The specimens for Brazilian and compressive strength were tested after 28 days, while the ＂pull a part＂ specimens were tested after 29 days. The result showed that the bond strength is influenced by the surface roughness of aggregate. For the same mix, limestone recorded higher bond strength than granite. Moreover, the bond strength is increased by adding the silica fume.
