SiO_(2)气凝胶对超细水泥基材料性能影响的试验研究  

Experimental Study on the Influence of Silica Aerogel on the Properties of Superfine-cement Composites

作　　者：韩风雷[1,2] 刘艳[1,2] 刘涛[1,2] 张学富[1,2] 吕洋[1,2] 扎西尼玛[3] HAN Fenglei;LIU Yan;LIU Tao;ZHANG Xuefu;LYU Yang;ZHAXI Nima(State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing Jiaotong University,Chongqing 400074,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Tibet Tianlu Co.,Ltd.,Lhasa 850000,China)

机构地区：[1]重庆交通大学山区桥梁及隧道工程国家重点实验室,重庆400074 [2]重庆交通大学土木工程学院,重庆400074 [3]西藏天路股份有限公司,拉萨850000

出　　处：《材料导报》2023年第15期93-99,共7页Materials Reports

基　　金：在渝本科高校与中科院所属院所合作项目(HZ2021009);中国博士后基金(2020M683710XB);西藏自治区自然基金(XZ202101ZR0036G);峨汉高速公路工程科研项目(LH-HT-45);重庆交通大学创新创业训练项目(2020S0015)。

摘　　要：SiO_(2)气凝胶水泥基材料具有优异的隔热、防火、轻质等性能,但较低的力学强度限制了其应用潜力。而超细水泥活性高、水化速度快的特点可促进其抗压、抗折强度的生长,因此为获得兼具强度和隔热特性的气凝胶水泥基材料,试验选用超细水泥胶凝材料,以SiO_(2)气凝胶颗粒等体积替换砂的方法来制备试件。基于室内试验研究了SiO_(2)气凝胶和砂的总体积分数固定为60%的情况下,SiO_(2)气凝胶掺量对超细水泥基材料的流动度、干密度、吸水率、导热系数、力学性能和微观结构的影响。结果表明:随气凝胶掺量从0%增至60%,材料的流动度下降了7.3%~22.3%,干密度逐渐降低而吸水率增加,导热系数急剧减小,饱水状态下的导热系数从2.58 W/(m·K)下降到0.49 W/(m·K),干燥状态下的导热系数从2.55 W/(m·K)下降到0.24 W/(m·K),保温隔热性能显著提升;抗压强度从66.3 MPa降至14.1 MPa,下降了76.0%,抗折强度从12.9 MPa降至3.1 MPa,下降了78.7%。SEM电镜扫描与EDS元素能谱分析表明,气凝胶颗粒与水泥基质之间存在界面间隙,其Ca/Si物质的量比为0.64~1.13,SiO_(2)气凝胶颗粒与超细水泥孔隙溶液发生碱-硅反应生成低钙硅比的C-S-H(水化硅酸钙)凝胶,从而提高了界面过渡区的密实度。Due to the lower mechanical strength,the application potential of silica aerogel cement-based materials with excellent thermal insulation,fireproofing and lightweight properties was greatly under restriction.The characteristics of high activity and fast hydration speed of superfine cement could promote the growth of compressive and flexural strength.Therefore,the superfine cement was chosen as the cementitious material in this experiment,to prepare aerogel cement-based materials with the property of both thermal insulation and strength.Based on replacing the equal volume of sand by SiO_(2)aerogel particles,the fluidity,dry density,water absorption,thermal conductivity,mechanical properties,and microstructure of cementitious materials were investigated under the different dosages of silica aerogel(the volume of sand and aerogel was 60%).The results showed that with the increase of aerogel content from 0%to 60%,the material fluidity decreased by 7.3%—22.3%,and the dry density gradually decreased while the water absorption increased.The thermal conductivity in the saturated and dry state decreased separately from 2.58 W/(m·K)to 0.49 W/(m·K)and from 2.55 W/(m·K)to 0.24 W/(m·K),indicating a significant improvement on the perfor-mance of thermal insulation.The compressive strength and flexural tensile strength ranged from 66.3 MPa to 14.1 MPa,and from 12.9 MPa to 3.1 MPa,which was decreased by 76.0%and 78.7%respectively compared with the sample unincorporated aerogel.Based on the analysis of SEM and EDS,there was a gap between the aerogel particles and surrounding cement matrix,and the Ca/Si atomic number ratio between the gape ranged from 0.64 to 1.13.The product of alkali-silicate reaction was C-S-H(calcium silicate hydrate)between silica aerogel and ultra-fine cement pore solution,which was helpful to improve the strength of interfacial transition zone.

关 键 词：SiO_(2)气凝胶 超细水泥 力学性能 导热系数 碱-硅酸盐反应 微观结构 

分 类 号：TU528[建筑科学—建筑技术科学]