混凝土氯离子扩散系数随养护龄期演化的试验研究
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摘要
通过试验研究了普通混凝土和矿物掺合料混凝土氯离子扩散系数随养护龄期的变化规律。在试验中考虑了水胶比、骨料体积率、矿物掺合料种类和替代率的影响,用NEL法测定养护龄期为28、56、84、112 d的混凝土氯离子扩散系数。试验结果表明,随着水胶比的增大或骨料体积率的减小,混凝土氯离子扩散系数增大。在混凝土中掺入粉煤灰和矿渣都能有效地减小氯离子扩散系数。基于试验结果,给出了普通混凝土、粉煤灰混凝土和矿渣混凝土氯离子扩散系数与养护龄期的经验公式,为混凝土材料的耐久性设计提供参考。
The variations of chloride diffusivity of ordinary concrete and mineral admixture concrete with the curing age are studied through experiment.In this experiment,the water/binder ratio,the aggregate volume fraction,and the type and replacement ratio of mineral admixtures are considered.The NEL method is used to measure the chloride diffusivity of concrete cured for 28,56,84,and 112 days.The experimental results show that,as the water/binder ratio increases or the aggregate volume fraction decreases,the chloride diffusivity of concrete increases.Addition of fly ash and slag into concrete can effectively reduce the chloride diffusivity.Based on the experimental results,three empirical formulae of chloride diffusivity of ordinary concrete,fly ash concrete,and slag concrete are given in terms of the curing age,which provides a reference for the durability design of concrete materials.
The variations of chloride diffusivity of ordinary concrete and mineral admixture concrete with the curing age are studied through experiment.In this experiment,the water/binder ratio,the aggregate volume fraction,and the type and replacement ratio of mineral admixtures are considered.The NEL method is used to measure the chloride diffusivity of concrete cured for 28,56,84,and 112 days.The experimental results show that,as the water/binder ratio increases or the aggregate volume fraction decreases,the chloride diffusivity of concrete increases.Addition of fly ash and slag into concrete can effectively reduce the chloride diffusivity.Based on the experimental results,three empirical formulae of chloride diffusivity of ordinary concrete,fly ash concrete,and slag concrete are given in terms of the curing age,which provides a reference for the durability design of concrete materials.
引文
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[13]MANGAT P S,LIMBACHIYA M C.Effect of initial curing on chloride diffusion in concrete repair material[J].Cement and Concrete Research,1999,29(4):487-495.
[14]MAAGE M,HELLAND S,POULSEN E,et al.Service life prediction of existing concrete structures exposed to marine environment[J].ACI Materials Journal,1996,93(6):602-608.
[15]余红发,孙伟.混凝土氯离子扩散理论模型[J].东南大学学报,2006,36(S2):68-76.
[16]ZHENG J J,ZHOU X Z.Percolation of ITZs in concrete and effects of attributing factors[J].Journal of Materials in Civil Engineering,2007,19(9):784-790.
[17]LU X Y.Application of the nernst-einstein equation to concrete[J].Cement and Concrete Research,1997,27(2):293-302.
[2]CADY P D,WEYERS R E.Deterioration rates of bridge concrete decks[J].Journal of Transportation Engineering,1984,110(1):34-44.
[3]BUENFELD N R,GLASS G K,HASSANEIN A M,et al.Chloride transport in concrete subjected to electric field[J].Journal of Materials in Civil Engineering,1998,10(4):220-228.
[4]SUMRANWANICH T,TANGTERMSIRIKUL S.A model for predicting time-dependent chloride binding capacity of cement-fly ash cementitious system[J].Materials and Structures,2004,37(6):387-396.
[5]AMPADU K O,TORII K,KAWAMURA M.Beneficial effect of fly ash on chloride diffusivity of hardened cement paste[J].Cement and Concrete Research,1999,29(4):585-590.
[6]NGALA V T,Page C L.Effects of carbonation on pore structure and diffusional properties of hydrated cement pastes[J].Cement and Concrete Research,1997,27(7):995-1007.
[7]ZHENG J J,ZHOU X Z,XING H Y,et al.Differential effective medium theory for the chloride diffusivity of concrete[J].ACI Materials Journal,2015,112(1):3-10.
[8]ZHENG J J,ZHOU X Z,HUANG X F,et al.Experiment and modeling of the effect of aggregate shape on the chloride diffusivity of concrete[J].Journal of Materials in Civil Engineering,2014,26(9):04014048(1-6).
[9]王立峰,李家和,朱广祥,等.水灰比对混凝土强度及氯离子渗透性的影响[J].低温建筑材料,2011,155(5):7-8.
[10]张磊,郑建军,周欣竹,等.水灰比、养护龄期和表面涂料对混凝土氯离子扩散系数的试验研究[J].甘肃水利水电技术,2012,48(3):14-16.
[11]施珂文.养护龄期对混凝土氯离子扩散系数的影响[D].杭州:浙江工业大学,2014.
[12]施慧生,施韬,陈宝春,等.掺矿渣活性粉末混凝土的抗氯离子渗透性研究[J].同济大学学报,2006,34(1):93-96.
[13]MANGAT P S,LIMBACHIYA M C.Effect of initial curing on chloride diffusion in concrete repair material[J].Cement and Concrete Research,1999,29(4):487-495.
[14]MAAGE M,HELLAND S,POULSEN E,et al.Service life prediction of existing concrete structures exposed to marine environment[J].ACI Materials Journal,1996,93(6):602-608.
[15]余红发,孙伟.混凝土氯离子扩散理论模型[J].东南大学学报,2006,36(S2):68-76.
[16]ZHENG J J,ZHOU X Z.Percolation of ITZs in concrete and effects of attributing factors[J].Journal of Materials in Civil Engineering,2007,19(9):784-790.
[17]LU X Y.Application of the nernst-einstein equation to concrete[J].Cement and Concrete Research,1997,27(2):293-302.
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