CaSO_4·2H_2O-C_3A压实体水化产生膨胀应力的机理
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摘要
本工作采用自行设计的一套膨胀应力测试装置测试了在三维约束条件下CaSO_4·2H_2O-C_3A压实体在40℃的水溶液、饱和Ca(OH)_2溶液和1 mol/L NaOH溶液中水化生成钙矾石过程中产生的膨胀应力,并测试了压实体中水化生成的钙矾石的吸水肿胀应力。结果表明,CaSO_4·2H_2O-C_3A压实体在水溶液、饱和Ca(OH)_2溶液和1 mol/L NaOH溶液中水化生成钙矾石产生的最大膨胀应力为23.9 MPa、27.3 MPa和26.4 MPa,在水溶液中水化膨胀应力最小,表明Ca(OH)_2溶液和OH~-均会促进钙矾石产生的膨胀应力;生成的钙矾石45℃干燥再吸水,在约束条件下40℃的吸水肿胀应力分别为1.23 MPa、1.27 MPa和1.26 MPa,远小于钙矾石形成过程产生的膨胀应力,表明钙矾石吸水肿胀应力对CaSO_4·2H_2O-C_3A压实体水化膨胀应力的贡献很小,钙矾石形成时产生的膨胀应力主要源于结晶压力。
The expansive stress produced by compacted CaSO_4·2H_2O-C_3A soaked in water,Ca(OH)_2-saturated solution and 1 mol/L NaO H solution was measured by a self-designed device,and the swelling expansive stress of the ettringite hydrated by CaSO_4·2H_2O-C_3A compact.The results show thatettringite was the only product in compacts immersed in water and solutions. The maximum expansive stress produced by the compacts cured in 40 ℃ water,Ca( OH)_2-saturated solution and 1 mol/L NaO H solution was 23. 9 MPa,27. 3 MPa and 26. 4 MPa,respectively.Lower expansive stress of the compact hydrated in water than that hydrated in Ca( OH)2-saturated solution and 1 mol/L NaO H solution seems to indicate that both Ca(OH)_2-saturated and NaO H solution may promote the expansive stress of ettringite formation. However,the maximum expansion stresses due to the swelling of the generated ettringitein compacts cured in 40 ℃ water,1 mol/L NaO H solution and Ca( OH)_2-satura-ted solution only were about 1. 23 MPa,1. 27 MPa and 1. 26 MPa,respectively. The swelling pressure is much lower than the expansive stress generated by hydration of CaSO_4·2H_2O-C_3A compacts. This indicates that crystallization pressure of the ettringitewas the main reason of expansion stress and the swelling stress of ettringite had little contribution.
The expansive stress produced by compacted CaSO_4·2H_2O-C_3A soaked in water,Ca(OH)_2-saturated solution and 1 mol/L NaO H solution was measured by a self-designed device,and the swelling expansive stress of the ettringite hydrated by CaSO_4·2H_2O-C_3A compact.The results show thatettringite was the only product in compacts immersed in water and solutions. The maximum expansive stress produced by the compacts cured in 40 ℃ water,Ca( OH)_2-saturated solution and 1 mol/L NaO H solution was 23. 9 MPa,27. 3 MPa and 26. 4 MPa,respectively.Lower expansive stress of the compact hydrated in water than that hydrated in Ca( OH)2-saturated solution and 1 mol/L NaO H solution seems to indicate that both Ca(OH)_2-saturated and NaO H solution may promote the expansive stress of ettringite formation. However,the maximum expansion stresses due to the swelling of the generated ettringitein compacts cured in 40 ℃ water,1 mol/L NaO H solution and Ca( OH)_2-satura-ted solution only were about 1. 23 MPa,1. 27 MPa and 1. 26 MPa,respectively. The swelling pressure is much lower than the expansive stress generated by hydration of CaSO_4·2H_2O-C_3A compacts. This indicates that crystallization pressure of the ettringitewas the main reason of expansion stress and the swelling stress of ettringite had little contribution.
引文
1 Qian J S.Journal of the Chinese Ceramic Society,2017(11),1569(in Chinese).钱觉时.硅酸盐学报,2017(11),1569.
2 Cohen M D.Cement and Concrete Research,1983,13,809.
3 Mehta P K.Cement and Concrete Research,1973,3,1.
4 Wang S B,Zhou M.In:Proceedings of International Symposium on Cement and Concrete.China,Beijing,1986,pp.43.
5 Rossetti V A,Chiocchio G,Paolini A E.Cement and Concrete Research,1983,12(1),23.
6 Deng M,Tang M S.Cement and Concrete Research,1994,24,119.
7 Alexandra Quennoz,Scrivener K L.Cement and Concrete Research,2012,42,1032.
8 Liu M,Deng M,Mo L W.Journal of Materials Science and Engineering,2017(4),626(in Chinese).刘猛,邓敏,莫立武.材料科学与工程学报,2017(4),626.
9 Wang L.Concrete,2013(8),83(in Chinese).王露.混凝土,2013(8),83.
10 Kamile Tosun,Bulent Baradan.Cement and Concrete Composites,2010,32,271.
11 Wang S B.Journal of the Chinese Ceramic Society,1994(4),399(in Chinese).王善拔.硅酸盐学报,1994(4),399.
12 Shi Y X,Wang Z Y,et al.Concrete,2000(8),52(in Chinese).石云兴,王泽云,等.混凝土,2000(8),52.
13 Ma H Z,Deng M.Journal NanJing Tech University,2007(4),626(in Chinese).马惠珠,邓敏.南京工业大学学报,2007(4),626.
14 Vahid R,Ouhadi.Applied Clay Science,2008,42,258.
2 Cohen M D.Cement and Concrete Research,1983,13,809.
3 Mehta P K.Cement and Concrete Research,1973,3,1.
4 Wang S B,Zhou M.In:Proceedings of International Symposium on Cement and Concrete.China,Beijing,1986,pp.43.
5 Rossetti V A,Chiocchio G,Paolini A E.Cement and Concrete Research,1983,12(1),23.
6 Deng M,Tang M S.Cement and Concrete Research,1994,24,119.
7 Alexandra Quennoz,Scrivener K L.Cement and Concrete Research,2012,42,1032.
8 Liu M,Deng M,Mo L W.Journal of Materials Science and Engineering,2017(4),626(in Chinese).刘猛,邓敏,莫立武.材料科学与工程学报,2017(4),626.
9 Wang L.Concrete,2013(8),83(in Chinese).王露.混凝土,2013(8),83.
10 Kamile Tosun,Bulent Baradan.Cement and Concrete Composites,2010,32,271.
11 Wang S B.Journal of the Chinese Ceramic Society,1994(4),399(in Chinese).王善拔.硅酸盐学报,1994(4),399.
12 Shi Y X,Wang Z Y,et al.Concrete,2000(8),52(in Chinese).石云兴,王泽云,等.混凝土,2000(8),52.
13 Ma H Z,Deng M.Journal NanJing Tech University,2007(4),626(in Chinese).马惠珠,邓敏.南京工业大学学报,2007(4),626.
14 Vahid R,Ouhadi.Applied Clay Science,2008,42,258.