干湿循环作用对非饱和锂渣混凝土氯离子扩散性能的影响
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摘要
针对经受干湿循环作用下氯离子侵蚀致使混凝土耐久性劣化的问题,采用在不同环境相对湿度条件下浸泡和喷淋的方式模拟干湿循环作用,通过测定侵入混凝土试件内部不同深度的自由氯离子含量和氯离子总含量,借鉴生长曲线函数中的Hill模型,探讨了干湿循环作用下,锂渣的掺量、环境相对湿度以及侵蚀氯盐质量分数等因素对混凝土氯离子扩散性能的影响。研究结果表明:干湿循环作用下,随着环境相对湿度的降低和侵蚀氯化钠溶液质量分数的增大,侵入混凝土内部的氯离子总含量达到阀值所需要的时间逐渐延长。锂渣替代水泥20%时,Hill系数n值最小,侵入混凝土内部氯离子总含量达到阀值所需要的时间最长。锂渣混凝土内部取样深度1～5 mm时,自由氯离子含量排序为(RH=40%条件)>(RH=80%条件)>(RH=60%条件)>(RH=100%条件)。干湿循环作用下,混凝土内部的氯离子总含量并不随着相对湿度的递减而单调增加。
The deterioration of concrete durability was caused by chloride ion erosion under the action of dry and wet circulation. The dry and wet circulation was simulated by immersion and spray under different relative humidity conditions. By measuring the free chloride ion content and the total chloride ion content in different depths of the intrusive concrete specimens,based on the Hill model in the growth curve function,the effects of lithium slag content,environmental relative humidity and erosive chloride mass fraction on the chloride ion diffusion properties of concrete under dry and wet cycles were investigated. The result indicates that under the dry-wet cycle,the time required for the total content of chloride ions in the interior of the concrete to reach the threshold is gradually prolonged as the relative humidity of the environment decreases and the mass fraction of the etched sodium chloride solution increases. When the lithium slag replaces the cement by 20% and the Hill coefficient n is the smallest,the total time required for the total chloride ion content in the intrusive concrete to reach the threshold is the longest. When the internal sampling depth of lithium slag concrete is 1 mm to 5 mm,the order of free chloride ion content is( RH = 40% condition) >( RH = 80% condition) >( RH = 60%condition) >( RH = 100% condition). The total chloride ion content inside the concrete under the dry and wet cycle does not increase monotonously with the decreasing of relative humidity.
The deterioration of concrete durability was caused by chloride ion erosion under the action of dry and wet circulation. The dry and wet circulation was simulated by immersion and spray under different relative humidity conditions. By measuring the free chloride ion content and the total chloride ion content in different depths of the intrusive concrete specimens,based on the Hill model in the growth curve function,the effects of lithium slag content,environmental relative humidity and erosive chloride mass fraction on the chloride ion diffusion properties of concrete under dry and wet cycles were investigated. The result indicates that under the dry-wet cycle,the time required for the total content of chloride ions in the interior of the concrete to reach the threshold is gradually prolonged as the relative humidity of the environment decreases and the mass fraction of the etched sodium chloride solution increases. When the lithium slag replaces the cement by 20% and the Hill coefficient n is the smallest,the total time required for the total chloride ion content in the intrusive concrete to reach the threshold is the longest. When the internal sampling depth of lithium slag concrete is 1 mm to 5 mm,the order of free chloride ion content is( RH = 40% condition) >( RH = 80% condition) >( RH = 60%condition) >( RH = 100% condition). The total chloride ion content inside the concrete under the dry and wet cycle does not increase monotonously with the decreasing of relative humidity.
引文
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[18]鲍玖文,王立成.干湿交替下水分及氯离子在混凝土中传输的细观数值模拟[J].海洋工程,2014,32(1):68-74,83.
[19]朱红光,易成,孙辅延,等.氯盐浓度对混凝土中氯离子渗透的影响规律[J].建筑材料学报,2016,19(4):725-729.
[2]焦俊婷.荷载与环境综合作用混凝土结构耐久性研究进展[J].混凝土,2015(8):35-38.
[3]姜慧,喻孟雄,刘荣桂,等.矿物掺合料混凝土氯离子渗透性能试验研究[J].混凝土,2016(4):82-85.
[4] RAGAB A M,ELGAMMAL M A,HODHOD O A,et al. Evaluation of field concrete deterioration under real conditions of seawater attack[J]. Construction and building materials,2016,119:130-144.
[5]杨海成,杜安民,范志宏,等.温度对混凝土氯离子扩散性能的影响[J].水运工程,2015(10):20-26.
[6]徐文冰,孙策,李进辉,等.温度对海工混凝土抗氯离子侵蚀性能的影响及寿命预测[J].公路,2014,59(10):50-54.
[7]陆春华,刘荣桂,崔钊玮,等.干湿交替作用下受弯开裂钢筋混凝土梁内氯离子侵蚀特性[J].土木工程学报,2014,47(12):82-90.
[8]关博文,杨涛,於德美,等.干湿循环作用下钢筋混凝土氯离子侵蚀与寿命预测[J].材料导报,2016,30(20):152-157.
[9]彭小芹,胡灿,兰聪,等.矿物掺合料对低水胶比混凝土抗氯离子渗透性能的影响[J].硅酸盐通报,2013,32(12):2435-2439,2448.
[10]王丹,刘子键,郑晓宁,等.海水干湿循环下疲劳损伤钢筋混凝土梁氯离子扩散试验研究[J].建筑结构学报,2015,36(S2):250-256.
[11]王晨飞,牛荻涛,焦俊婷.海洋潮汐环境纤维混凝土中氯离子迁移规律研究[J].混凝土,2017(1):20-23.
[12]陈树鑫,庞森,刁波,等.干湿循环下损伤混凝土中氯离子传输模型[J].混凝土,2016(6):24-26,30.
[13]中华人民共和国住房和城乡建设部.混凝土结构耐久性设计规范:GB/T 50476—2008[S].北京:中国建筑工业出版社,2009.
[14]王成,葛广华,侯建国,等.南疆地区混凝土结构耐久性现状与影响因素研究[J].武汉大学学报(工学版),2017,50(3):447-453.
[15]李一,张广泰,田虎学,等.锂渣聚丙烯纤维混凝土基本力学性能试验[J].河南科技大学学报(自然科学版),2016,37(4):60-65.
[16]中华人民共和国交通部.水运工程混凝土试验规程:JTJ 270—98[S].北京:人民交通出版社,1999.
[17]刘均利,方志.多因素作用下混凝土中氯离子扩散计算新方法[J].建筑材料学报,2013,16(5):777-781.
[18]鲍玖文,王立成.干湿交替下水分及氯离子在混凝土中传输的细观数值模拟[J].海洋工程,2014,32(1):68-74,83.
[19]朱红光,易成,孙辅延,等.氯盐浓度对混凝土中氯离子渗透的影响规律[J].建筑材料学报,2016,19(4):725-729.