废弃混凝土的水热固化与力学强度
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摘要
为实现废弃混凝土的资源化规模利用,将废弃混凝土回收、粉碎后,掺入适量氢氧化钙(Ca(OH)_2)、碱性激发剂(NaOH)和水,经均匀混合、模压成型后,在高温饱和水蒸气环境中转化为具有较高机械强度的块状制品。实验系统考察了原料配比以及反应温度和时间等因素对水热固化样品劈裂抗拉强度(简称劈拉强度)和微观结构的影响。研究结果表明:Ca(OH)_2掺量为20%时对于结晶性水化硅酸钙(托勃莫来石相)的形成最为有利,水化产物彼此交织成密实结构,实现了最高的样品力学强度;NaOH的引入可激发废弃混凝土的水热反应活性,但掺量不宜过高;水热反应条件下,样品的劈拉强度随环境温度的升高或反应时间的延长而明显增大,但温度过高、时间过长,会因晶型转变及内部结晶应力等原因而导致样品力学强度降低。
Discarded concrete( DC) was collected,finely ground,and subsequently mixed with Ca( OH)_2,NaOH,and water in designed proportions to explore the resource utilization of building discards. After a moldcompressing process,cylindrical specimens of the evenly-dispersed mixture were hydrothermally solidified under a moisture-saturated hot atmosphere to yield a material of appreciable mechanical strength. Systematic investigations were performed to determine the dependence of the measured strength( splitting tensile strength) on the proportion of raw materials and their hydrothermal treatments,i. e.,time and temperature. The results suggested that a weight proportion of 20% Ca(OH)_2 was most favorable to form hydrated calcium silicates with high crystallinity( e. g.,tobermorite),thereby giving rise of an enhanced mechanical strength for hydrothermally solidified DC. Use of Na OH was beneficial in increasing the reaction activity of DC,but the NaOH content should not be more than10%. Under the hydrothermal reaction atmosphere,the tensile strength of hydrothermally solidified DC increased on increasing the temperature or time. Excessive temperature or time negatively affected the corresponding strength,with the most possible reasons being a phase transformation of the products or internal stress caused by overcrystallization.
Discarded concrete( DC) was collected,finely ground,and subsequently mixed with Ca( OH)_2,NaOH,and water in designed proportions to explore the resource utilization of building discards. After a moldcompressing process,cylindrical specimens of the evenly-dispersed mixture were hydrothermally solidified under a moisture-saturated hot atmosphere to yield a material of appreciable mechanical strength. Systematic investigations were performed to determine the dependence of the measured strength( splitting tensile strength) on the proportion of raw materials and their hydrothermal treatments,i. e.,time and temperature. The results suggested that a weight proportion of 20% Ca(OH)_2 was most favorable to form hydrated calcium silicates with high crystallinity( e. g.,tobermorite),thereby giving rise of an enhanced mechanical strength for hydrothermally solidified DC. Use of Na OH was beneficial in increasing the reaction activity of DC,but the NaOH content should not be more than10%. Under the hydrothermal reaction atmosphere,the tensile strength of hydrothermally solidified DC increased on increasing the temperature or time. Excessive temperature or time negatively affected the corresponding strength,with the most possible reasons being a phase transformation of the products or internal stress caused by overcrystallization.
引文
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[20]王立久.建筑材料工艺原理.北京:中国建材工业出版社,2006
[21]熊远柱,万慧文.石灰石粉对混凝土性能的影响.混凝土,2010(9):89-91XIONG Yuanzhu,WAN Huiwen.Study on performance of concrete mixed with limestone powder.Concrete,2010(9):89-91(in Chinese)
[22]张兰芳,岳瑜.磨细石灰石粉配制超早强、高强混凝土.混凝土,2010(10):107-108ZHANG Lanfang,YUE Yu.Study on high-strength concrete made with fine limestone powder.Concrete,2010(10):107-108(in Chinese)
[23]谢慧东,张云飞,栾佳春.石灰石粉对水泥-粉煤灰混凝土性能的影响.硅酸盐通报,2012,31(2):371-376XIE Huidong,ZHANG Yunfei,LUAN Jiachun.Influence of limestone powder on properties of concrete prepared from cement and fly ash.Bulletin of the Chinese Ceramic Society,2012,31(2):371-376(in Chinese)
[2]肖建庄.再生混凝土.北京:中国建筑工业出版社,2008
[3]杨俊,黎新春,陈峻松,等.废旧混凝土用作水泥稳定基层的实验研究.环境工程学报,2014,8(5):2097-2103YANG Jun,LI Xinchun,CHEN Junsong,et al.Experimental study on waste concrete used as cement stabilized base.Chinese Journal of Environmental Engineering,2014,8(5):2097-2103(in Chinese)
[4]单双成,陈满.废弃水泥混凝土道面在路面半刚性基层中再生利用的试验研究.公路工程,2013,38(3):192-195SHAN Shuangcheng,CHEN Man.Experimental study on recycling of waste concrete cement pavement in semi-rigid base course.Highway Engineering,2013,38(3):192-195(in Chinese)
[5]付亮,郭进京,孟庆新.废弃混凝土作水泥土填料的试验研究.土工基础,2012,26(1):77-79FU Liang,GUO Jinjing,MENG Qingxin.Experimental study on recycled concrete as a roadbed filling material.Soil Engineering and Foundation,2012,26(1):77-79(in Chinese)
[6]李琴,孙可伟,蒋卓吟.固化剂固化建筑渣土试验研究.硅酸盐通报,2012,31(5):1247-1251LI Qin,SUN Kewei,JIANG Zhuoyin.Test research on the solidified mass made of building residues by stabilizer.Bulletin of the Chinese Ceramic Society,2012,31(5):1247-1251(in Chinese)
[7]王超,古松,李路,等.再生混凝土空心砌块的经济性分析.混凝土,2012(10):114-115WANG Chao,GU Song,LI Lu,et al.Economic analysis on regeneration concrete hollow block.Concrete,2012(10):114-115(in Chinese)
[8]程国淡,张凯松,寇世聪,等.典型建筑固体废弃物再生骨料对环保砖性能的影响.环境工程学报,2013,7(7):2716-2720CHENG Guodan,ZHANG Kaisong,KOU Shicong,et al.Effect of typical construction solid waste on properties of environmental-friendly block.Chinese Journal of Environmental Engineering,2013,7(7):2716-2720(in Chinese)
[9]崔正龙,大芳賀義喜,北迁政文,等.再生骨料混凝土耐久性能的试验研究.硅酸盐通报,2007,26(6):1107-1111CUI Zhenglong,OHAGA Y.S.,Kitatsuji M.H.,et al.Durability test investigation on the recycled aggregate concrete.Bulletin of the Chinese Ceramic Society,2007,26(6):1107-1111(in Chinese)
[10]王玲玲,陈彦文,潘文浩,等.湿处理工艺对再生混凝土物理力学性能影响研究.混凝土,2012(12):24-26WANG Lingling,CHEN Yanwen,PAN Wenhao,et al.Effects of wet processing technology on physical properties and mechanical behaviors of recycled concrete.Concrete,2012(12):24-26(in Chinese)
[11]侯永利,郑刚.再生骨料混凝土不同龄期的力学性能.建筑材料学报,2013,16(4):683-687HOU Yongli,ZHENG Gang.Mechanical properties of recycled aggregate concrete in different age.Journal of Building Materials,2013,16(4):683-687(in Chinese)
[12]陈会凡,李福恩,党玲博.不同母体的再生粗骨料对混凝土强度影响.混凝土,2011(5):109-135CHEN Huifan,LI Fuen,DANG Lingbo.Influence of different parent concrete aggregates on strength properties of recycled concrete.Concrete,2011(5):109-135(in Chinese)
[13]李佳彬,肖建庄,孙振平.再生粗集料特性及其对再生混凝土性能的影响.建筑材料学报,2004,7(4):390-395LI Jiabin,XIAO Jianzhuang,SUN Zhenping.Properties of recycled coarse aggregate and its influence on recycled concrete.Journal of Building Materials,2004,7(4):390-395(in Chinese)
[14]孙光耀,蒋采玲,李川东,等.低温常压下废弃混凝土的固化再利用研究.新型建筑材料,2013(3):14-18SUN Guangyao,JIANG Cailing,LI Chuandong,et al.Research on utilization of discarded concrete by solidifying with low temperature and atmospheric pressure.New Building Materials,2013(3):14-18(in Chinese)
[15]JING Zhenzi,RAN Xianqiang,JIN Fangming,et al.Hydrothermal solidification of municipal solid waste incineration bottom ash with slag addition.Waste Management,2010,30(8/9):1521-1527
[16]MAEDA H.,ISHIDA E.H.Hydrothermal preparation of diatomaceous earth combined with calcium silicate hydrate gels.Journal of Hazardous Materials,2011,185(2/3):858-861
[17]佟钰,朱长军,刘俊秀,等.低品位硅藻土的水热固化过程及其力学性能研究.硅酸盐通报,2013,32(3):379-383TONG Yu,ZHU Changjun,LIU Junxiu,et al.Hydrothermal solidification of low-grade diatomite and its mechanical property.Bulletin of the Chinese Ceramic Society,2013,32(3):379-383(in Chinese)
[18]JING Z.,JIN F.,HASHIDA T.,et al.Influence of additions of coal fly ash and quartz on hydrothermal solidification of blast furnace slag.Cement and Concrete Research,2008,38(7):976-982
[19]孙光耀,景镇子,徐鹏亮,等.水热固化废旧混凝土为新型建筑材料.材料导报网刊,2012,7(3):30-34SUN Gungyao,JING Zhenzi,XU Pengliang,et al.Hydrothermal solidification of construction materials from discarded concrete.Materials Review(Network Publication),2012,7(3):30-34(in Chinese)
[20]王立久.建筑材料工艺原理.北京:中国建材工业出版社,2006
[21]熊远柱,万慧文.石灰石粉对混凝土性能的影响.混凝土,2010(9):89-91XIONG Yuanzhu,WAN Huiwen.Study on performance of concrete mixed with limestone powder.Concrete,2010(9):89-91(in Chinese)
[22]张兰芳,岳瑜.磨细石灰石粉配制超早强、高强混凝土.混凝土,2010(10):107-108ZHANG Lanfang,YUE Yu.Study on high-strength concrete made with fine limestone powder.Concrete,2010(10):107-108(in Chinese)
[23]谢慧东,张云飞,栾佳春.石灰石粉对水泥-粉煤灰混凝土性能的影响.硅酸盐通报,2012,31(2):371-376XIE Huidong,ZHANG Yunfei,LUAN Jiachun.Influence of limestone powder on properties of concrete prepared from cement and fly ash.Bulletin of the Chinese Ceramic Society,2012,31(2):371-376(in Chinese)