水胶比对掺粉煤灰超高性能混凝土施工与力学性能影响
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摘要
使用粉煤灰代替部分水泥有利于减少资源消耗,降低超高性能混凝土(UHPC)造价。同时,水胶比对掺粉煤灰UHPC的施工性能和力学性能具有重要影响。为此,将水胶比设定为唯一变量,研究水胶比对UHPC施工与力学性能的影响规律。开展了水胶比为0. 16～0. 25UHPC的扩展度、抗压强度和弯曲韧性试验,得到了UHPC充分湿拌时间、静停一段时间后的扩展度、抗压、抗折强度和弯曲应力-挠度曲线;对抗压、抗折强度结果进行了变异性分析;基于应力-挠度曲线,并结合CECS 13:2009和Nemkumar法计算了UHPC弯曲韧性指标。试验结果显示:UHPC充分湿拌时间为6 min; UHPC扩展度随水胶比增大基本呈线性增长,且水胶比每增加0. 01,UHPC扩展度平均增幅65 mm;当静停4 h,水胶比分别为0. 16、0. 2、0. 25时,UHPC扩展度损失分别为70 mm、65 mm和50 mm,损失率为21. 5%、10. 4%和5. 5%; UHPC抗压、抗折强度皆随水胶比的增大而减小,两者的变异性无明显规律,但总体而言随着水胶比的增大,两者的变异系数存在减小的趋势,且后者的变异系数大于前者; UHPC的弯曲韧性性能随水胶比的增大而上下波动,并在水胶比为0. 19时达到最优。
The use of fly ash instead of some cement is beneficial to reduce resource consumption and reduce the cost of ultra-high performance concrete( UHPC). At the same time,the water-to-binder ratio has an important influence on the construction performance and mechanical properties of UHPC mixed with fly ash. Therefore,the water-to-binder ratio was set as the only variable to study the effect of waterto-binder ratio on the construction and mechanical properties of UHPC. The sufficient wet mixing time,Slump extension under a standing time,compression strength,flexural strength and flexural stressdeflection curve of UHPC were obtained by carring out slump extension,compression strength and flexural toughness tests with the water-to-binder ratio of 0. 16-0. 25. Subsequently,the variability of compressive strength and flexural strength test results were analyzed. The flexural toughness index of UHPC were calculated by using stress-deflection curve,the standard of CECS 13: 2009 and the Nemkumar methods.The test results show that the sufficient wet mixing time of UHPC is 6 min. The slump extension of UHPC increases linearly with the increasing of water-to-binder ratio,and the average slump extension of UHPC increases to 65 mm when the water-to-binder radio increases by 0. 01. Under a standing time of 4 h,and as the water-to-binder ratio is 0. 16,0. 2,and 0. 25,the loss of slump extension of UHPC is 70 mm,65 mm and 50 mm respectively,and the loss rates are 21. 5%,10. 4% and 5. 5%. The compressive strength andflexural strength of UHPC decrease with the increase of water-to-binder ratio,and there is no obvious law of variability between the two. Generally speaking,the coefficients of variation of compressive strength and flexural strength of UHPC decrease with the increasing of water-to-binder ratio,and the coefficient of variation of the later is greater than that of the former. The flexural toughness of UHPC fluctuates up and down with the increase of water-to-binder ratio,and reaches the optimum when the water-to-binder ratio is 0. 19.
The use of fly ash instead of some cement is beneficial to reduce resource consumption and reduce the cost of ultra-high performance concrete( UHPC). At the same time,the water-to-binder ratio has an important influence on the construction performance and mechanical properties of UHPC mixed with fly ash. Therefore,the water-to-binder ratio was set as the only variable to study the effect of waterto-binder ratio on the construction and mechanical properties of UHPC. The sufficient wet mixing time,Slump extension under a standing time,compression strength,flexural strength and flexural stressdeflection curve of UHPC were obtained by carring out slump extension,compression strength and flexural toughness tests with the water-to-binder ratio of 0. 16-0. 25. Subsequently,the variability of compressive strength and flexural strength test results were analyzed. The flexural toughness index of UHPC were calculated by using stress-deflection curve,the standard of CECS 13: 2009 and the Nemkumar methods.The test results show that the sufficient wet mixing time of UHPC is 6 min. The slump extension of UHPC increases linearly with the increasing of water-to-binder ratio,and the average slump extension of UHPC increases to 65 mm when the water-to-binder radio increases by 0. 01. Under a standing time of 4 h,and as the water-to-binder ratio is 0. 16,0. 2,and 0. 25,the loss of slump extension of UHPC is 70 mm,65 mm and 50 mm respectively,and the loss rates are 21. 5%,10. 4% and 5. 5%. The compressive strength andflexural strength of UHPC decrease with the increase of water-to-binder ratio,and there is no obvious law of variability between the two. Generally speaking,the coefficients of variation of compressive strength and flexural strength of UHPC decrease with the increasing of water-to-binder ratio,and the coefficient of variation of the later is greater than that of the former. The flexural toughness of UHPC fluctuates up and down with the increase of water-to-binder ratio,and reaches the optimum when the water-to-binder ratio is 0. 19.
引文
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[8]万朝均,尹亚柳,王小茜,等.超高性能混凝土的制备[J].硅酸盐通报,2015,34(12):3676-3681.
[9]鞠杨,刘红彬,陈健,等.超高强度活性粉末混凝土的韧性与表征方法[J].中国科学(E辑:技术科学),2009,39(4):793-808.
[10]邓宗才,肖锐,申臣良.超高性能混凝土的制备与性能[J].材料导报,2013,27(5):66-69,95.
[11]陈宝春,季韬,黄卿维,等.超高性能混凝土研究综述[J].建筑科学与工程学报,2014,31(3):1-23.
[12]梁兴文,胡翱翔,于婧,等.钢纤维对超高性能混凝土受弯力学性能的影响[J].复合材料学报,2018,35(15):1-10.
[13] ASTM. ASTM C 1018 Standard test method for flexural toughness and first-crack strength of fiber reinforced concrete(using beam with third-point loading)[S]. West Conshohocken:ASTM International,1997:544-551.
[14] JCI. JSCE-SF4 Method of test for flexural strength and flexural toughness of steel fiber reinforced concrete[S]. Tokyo:Japan Concrete Institute,1984:45-51.
[15]中国工程建设协会标准. CECS 13:2009纤维混凝土试验方法标准[S].北京:中国计划出版社,2010:54-59.
[16] Nemkumar B,Trottier J F. Test methods for flexural toughness characterization of fiber reinforced concrete:some concerns and a proposition[S].ACI Materials Journal,1995,92(1):48-57.
[2]王海涛,王立成.钢纤维高强轻骨料混凝土弯曲韧性与抗冲击性能[J].建筑材料学报,2013,16(6):1082-1086.
[3]邓宗才,刘国平,杜超超,等.新型粗聚丙烯纤维高性能混凝土弯曲韧性[J].建筑材料学报,2014,17(2):228-233.
[4] Soleimanl S. M,Anthia N. Flexural response of hybrid fiber-reinforced cementitions composites[J]. ACI Materials Journal,2005,102(6):382-389.
[5] Wille K,Naaman A E,EI-Tawil S,et al. Ultra-high performance concrete and fiber reinforced concrete:achieving strength and ductility without heat curing[J]. Materials and Structures,2012,45(3):309-324.
[6] Zain M F M,Safiuddin Md,Mahmud H. Development of high performance concrete using silica fume at relatively high water-binder ratios[J].Cement and Concrete Research,2000,30(9):1501-1505.
[7]史才军,肖江帆,曹张,等.材料组成对UHPC性能的影响[J].硅酸盐通报,2013,32(6):1005-1011.
[8]万朝均,尹亚柳,王小茜,等.超高性能混凝土的制备[J].硅酸盐通报,2015,34(12):3676-3681.
[9]鞠杨,刘红彬,陈健,等.超高强度活性粉末混凝土的韧性与表征方法[J].中国科学(E辑:技术科学),2009,39(4):793-808.
[10]邓宗才,肖锐,申臣良.超高性能混凝土的制备与性能[J].材料导报,2013,27(5):66-69,95.
[11]陈宝春,季韬,黄卿维,等.超高性能混凝土研究综述[J].建筑科学与工程学报,2014,31(3):1-23.
[12]梁兴文,胡翱翔,于婧,等.钢纤维对超高性能混凝土受弯力学性能的影响[J].复合材料学报,2018,35(15):1-10.
[13] ASTM. ASTM C 1018 Standard test method for flexural toughness and first-crack strength of fiber reinforced concrete(using beam with third-point loading)[S]. West Conshohocken:ASTM International,1997:544-551.
[14] JCI. JSCE-SF4 Method of test for flexural strength and flexural toughness of steel fiber reinforced concrete[S]. Tokyo:Japan Concrete Institute,1984:45-51.
[15]中国工程建设协会标准. CECS 13:2009纤维混凝土试验方法标准[S].北京:中国计划出版社,2010:54-59.
[16] Nemkumar B,Trottier J F. Test methods for flexural toughness characterization of fiber reinforced concrete:some concerns and a proposition[S].ACI Materials Journal,1995,92(1):48-57.