聚羧酸减水剂对改性生土材料性能的影响
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摘要
在石膏粉煤灰改性生土材料中掺加聚羧酸减水剂,研究聚羧酸减水剂对改性生土材料工作性能、力学性能、耐水性能以及体积稳定性的影响.结果表明:聚羧酸减水剂能显著改善石膏粉煤灰改性生土浆体的流动度,当聚羧酸减水剂掺量为0.80%时,改性生土材料在浆体水固比性低于生土液限的条件下也可浇筑成型;在一定范围内,改性生土材料的抗压强度和抗折强度随聚羧酸减水剂掺量的提高而增大;当改性生土材料掺15%石膏、5%粉煤灰和1%氧化钙时,加入0.80%的聚羧酸减水剂后,其28d抗压强度可达8.30MPa,抗折强度可达2.98MPa,相较于未加聚羧酸减水剂的改性生土材料,两者分别提高了4.5和2.1倍.采用耐水指数评价了改性生土材料的耐水性能,结果表明:聚羧酸减水剂不仅能显著提高改性生土材料的耐水性能,还能显著降低改性生土材料的干燥收缩率,当其掺量为0.80%时,改性生土材料的干燥收缩率稳定在0.06%左右.扫描电子显微镜(SEM)和X射线衍射(XRD)结果显示,聚羧酸减水剂对改性生土材料水化产物影响较小,但能使改性生土材料结构更加密实.
Polycarboxylate water reducing agent was added to the gypsum fly ash modified adobe, and its effect on working performances, mechanical properties, water resistance and volume stability of modified adobe were experimentally studied. It can be found that the polycarboxylate water reducing agent can significantly improve the fluidity of the modified adobe slurry. When the content of water reducing agent is 0.80%, the slurry can be poured forming under the water-solid ratio which is lower than the liquid limit of the adobe; within a certain range, the compressive strength and flexural strength of modified adobe increase with the polycarboxylate water reducing agent content. When mix proportion of modified adobe is 15% gypsum, 5% fly ash, 1% calcium oxide, by adding 0.80% polycarboxylate water reducing agent, the 28 d compressive strength of modified adobe can reach 8.30 MPa, and the flexural strength can reach 2.98 MPa. Compared to the modified adobe without water reducing agent, the compressive strength and the flexural strength are increased by 4.5 times and 2.1 times respectively. The water resistance index is used to evaluate the water resistance of the modified adobe. It can be found that the polycarboxylate water reducing agent can significantly improve the water resistance and reduce the shrinkage rate of the modified adobe. When the content of water reducing agent is 0.80%, the shrinkage rate can be as low as 0.06%. SEM and XRD results show that the polycarboxylate water reducing agent can make the internal structure of modified adobe more compact, and it has little effect on the hydration products of the modified adobe.
Polycarboxylate water reducing agent was added to the gypsum fly ash modified adobe, and its effect on working performances, mechanical properties, water resistance and volume stability of modified adobe were experimentally studied. It can be found that the polycarboxylate water reducing agent can significantly improve the fluidity of the modified adobe slurry. When the content of water reducing agent is 0.80%, the slurry can be poured forming under the water-solid ratio which is lower than the liquid limit of the adobe; within a certain range, the compressive strength and flexural strength of modified adobe increase with the polycarboxylate water reducing agent content. When mix proportion of modified adobe is 15% gypsum, 5% fly ash, 1% calcium oxide, by adding 0.80% polycarboxylate water reducing agent, the 28 d compressive strength of modified adobe can reach 8.30 MPa, and the flexural strength can reach 2.98 MPa. Compared to the modified adobe without water reducing agent, the compressive strength and the flexural strength are increased by 4.5 times and 2.1 times respectively. The water resistance index is used to evaluate the water resistance of the modified adobe. It can be found that the polycarboxylate water reducing agent can significantly improve the water resistance and reduce the shrinkage rate of the modified adobe. When the content of water reducing agent is 0.80%, the shrinkage rate can be as low as 0.06%. SEM and XRD results show that the polycarboxylate water reducing agent can make the internal structure of modified adobe more compact, and it has little effect on the hydration products of the modified adobe.
引文
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[12] 尚建丽.传统夯土民居生态建筑材料体系的优化研究[D].西安:西安建筑科技大学,2005.SHANG Jianli.A study of optimization of the ecological building material system of traditional rammed earth dwellings[D].Xi'an:Xi'an University of Architecture and Technology,2005.(in Chinese)
[13] OUHADI V R,YONG R N.Ettringite formation and behaviour in clayey soils[J].Applied Clay Science,2008,42(1/2):258-265.
[14] 钱觉时,余金城,孙化强,等.钙矾石的形成与作用[J].硅酸盐学报,2017,45(11):1569-1581.QIAN Jueshi,YU Jincheng,SUN Huaqiang,et al.Formation and function of ettringite in cement hydrates[J].Journal of the Chinese Ceramic Society,2017,45(11):1569-1581.(in Chinese)
[2] 钱觉时,王琴,贾兴文,等.燃煤电厂脱硫废弃物用于改性生土材料的研究[J].新型建筑材料,2009,36(2):28-31.QIAN Jueshi,WANG Qin,JIA Xingwen,et al.Research on preparation of adobe materials with desulfurized wastes from coal-fired power plant[J].New Building Materials,2009,36(2):28-31.(in Chinese)
[3] 刘俊霞,海然,张茂亮,等.植物纤维增强生土材料结构与性能[J].建筑材料学报,2016,19(6):1068-1072.LIU Junxia,HAI Ran,ZHANG Maoliang,et al.Structure and properties of stabilized earth materials modified by plant fiber[J].Journal of Building Materials,2016,19(6):1068-1072.(in Chinese)
[4] 刘俊霞,张磊,杨久俊.生土材料国内外研究进展[J].材料导报,2012,26(23):14-17.LIU Junxia,ZHANG Lei,YANG Jiujun.International advances in raw soil[J].Materials Review,2012,26(23):14-17.(in Chinese)
[5] DEGIRMENCI N.The using of waste phosphogypsum and natural gypsum in adobe stabilization[J].Construction and Building Materials,2008,22(6):1220-1224.
[6] 王毅红,仲继清,石以霞,等.国外生土结构研究综述[J].土木工程学报,2015,48(6):81-88.WANG Yihong,ZHONG Jiqing,SHI Yixia,et al.Review of overseas research on raw soil structure[J].China Civil Engineering Journal,2015,48(6):81-88.(in Chinese)
[7] 刘军,褚俊英,赵金波,等.掺和料对生土墙体材料力学性能的影响[J].建筑材料学报,2010,13(4):446-451.LIU Jun,CHU Junying,ZHAO Jinbo,et al.Effect of admixtures on mechanical properties of raw clay material for wall[J].Journal of Building Materials,2010,13(4):446-451.(in Chinese)
[8] HALL M,ALLINSON D.Assessing the effects of soil grading on the moisture content-dependent thermal conductivity of stabilised rammed earth materials[J].Applied Thermal Engineering,2009,29(4):740-747.
[9] 刘志华,曲烈,刘刚,等.自密实生土材料制备及力学性能的研究[J].天津建设科技,2016,26(4):1-4.LIU Zhihua,QU Lie,LIU Gang,et al.Study on preparation and mechanical properties of self-compacting raw material[J].Tianjin Construction Science and Technology,2016,26(4):1-4.(in Chinese)
[10] 曲烈,李剑,张娜,等.掺复合减水剂生土改性材料流变与力学性能研究[J].粉煤灰综合利用,2013(2):8-11.QU Lie,LI Jian,ZHANG Na,et al.Research on the rheological and mechanical properties of modified raw soil material adding compound reducing water agent[J].Fly Ash Comprehensive Utilization,2013(2):8-11.(in Chinese)
[11] 余帆,黄煜镔,孙大权.石灰土和水泥土的减水剂改性效果[J].建筑材料学报,2017,20(2):283-287.YU Fan,HUANG Yubin,SUN Daquan.Modification effect of lime soil and cement soil by water reducing agent[J].Journal of Building Materials,2017,20(2):283-287.(in Chinese)
[12] 尚建丽.传统夯土民居生态建筑材料体系的优化研究[D].西安:西安建筑科技大学,2005.SHANG Jianli.A study of optimization of the ecological building material system of traditional rammed earth dwellings[D].Xi'an:Xi'an University of Architecture and Technology,2005.(in Chinese)
[13] OUHADI V R,YONG R N.Ettringite formation and behaviour in clayey soils[J].Applied Clay Science,2008,42(1/2):258-265.
[14] 钱觉时,余金城,孙化强,等.钙矾石的形成与作用[J].硅酸盐学报,2017,45(11):1569-1581.QIAN Jueshi,YU Jincheng,SUN Huaqiang,et al.Formation and function of ettringite in cement hydrates[J].Journal of the Chinese Ceramic Society,2017,45(11):1569-1581.(in Chinese)