自密实混凝土自生约束收缩下应力松弛性能研究
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摘要
以水胶比、胶凝材料用量为主要参数,研究较长龄期内自密实混凝土的自由自生收缩性能及圆环约束收缩下钢环应变的发展规律,通过分析得到自密实混凝土在自生约束收缩下的应力松弛性能。结果表明:自密实混凝土自生变形在经过1d左右的小幅膨胀后开始收缩,3～7d内收缩增长较快,接下来在长达100d的测试过程中缓慢而持续地增长;自生收缩在受约束时应力增长也有类似的规律。自生约束收缩引起的应力松弛主要发生在3～7d的早龄期,之后应力松弛的增长几乎停滞;自密实混凝土的应力松弛率随水胶比的提高显著增大,随胶结料用量的增加有增大的趋势。
Internal stress development and stress relaxation induced by restrained autogenous shrinkage of self-compacting concrete(SCC)were investigated under different water/binder ratios and different amounts of cementitious material.Test results show that the free autogenous deformation expanded within 1 dand then shrank rapidly from 3 dto 7 d;afterward,the autogenous shrinkage grew slowly and steadily.The development of stress during restrained autogenous shrinkage also had a similar trend.The stress relaxation mainly developed at early ages within 7 d,and then its growth was almost stagnant.The stress relaxation rate of SCC increased significantly with the increase of water/binder ratio;it also increased with increasing cementitious contents.
Internal stress development and stress relaxation induced by restrained autogenous shrinkage of self-compacting concrete(SCC)were investigated under different water/binder ratios and different amounts of cementitious material.Test results show that the free autogenous deformation expanded within 1 dand then shrank rapidly from 3 dto 7 d;afterward,the autogenous shrinkage grew slowly and steadily.The development of stress during restrained autogenous shrinkage also had a similar trend.The stress relaxation mainly developed at early ages within 7 d,and then its growth was almost stagnant.The stress relaxation rate of SCC increased significantly with the increase of water/binder ratio;it also increased with increasing cementitious contents.
引文
[1]Dong W,Zhou X,Wu Z.A fracture mechanics-based method for prediction of cracking of circular and elliptical concrete rings under restrained shrinkage[J].Engineering Fracture Mechanics,2014,131:687-701.
[2]李飞.混凝土早期约束应力发展与松弛过程研究[D].北京:清华大学,2009.Li F.Research on the development of restraint stress and relaxation of concrete at early age[D].Beijing:Tsinghua University,2009.(in Chinese)
[3]王辉明.自密实混凝土圆环约束收缩试验研究[D].福州:福州大学,2010.Wang H M.Exprimental study on restrained shrinkage of self-compacting concrete by ring test[D].Fuzhou:Fuzhou University,2010.(in Chinese)
[4]Hossain A B,Weiss W J.Assessing residual stress development and stress relaxation in restrained concrete ring specimens[J].Journal of Cement&Concrete Composites,2004,26:531-540.
[5]Dally J W,Riley W F.Experimental stress analysis[M].3rd ed.New York:McGraw Hill,1991.
[6]普通混凝土长期性能和耐久性能试验方法标准:GB/T50082-2009[S].北京:中国建筑工业出版社,2009.Standard for test methods of long-term performance and durability of ordinary concrete:GB/T 50082-2009[S].Beijing:China Architecture&Building Press,2009.(in Chinese)
[7]Standard test method for determining age at cracking and induced tensile stress characteristic of mortar and concrete under restrained shrinkage:ASTM C 1581-04[S].West Conshohocken,PA:ASTM International,2004.
[8]王国杰.自密实混凝土早龄期收缩、开裂性能研究[D].福州:福州大学,2011.Wang G J.Shrinkage and cracking performance of selfcompacting-concrete at early age[D].Fuzhou:Fuzhou University,2011.(in Chinese)
[9]刘积丁.自密实混凝土自生约束收缩下应力松弛性能研究[D].福州:福州大学,2017.Liu J D.Study on the stress relaxation properties of self-compacting concrete under autogenous shrinkage[D].Fuzhou:Fuzhou University,2017.(in Chinese)
[2]李飞.混凝土早期约束应力发展与松弛过程研究[D].北京:清华大学,2009.Li F.Research on the development of restraint stress and relaxation of concrete at early age[D].Beijing:Tsinghua University,2009.(in Chinese)
[3]王辉明.自密实混凝土圆环约束收缩试验研究[D].福州:福州大学,2010.Wang H M.Exprimental study on restrained shrinkage of self-compacting concrete by ring test[D].Fuzhou:Fuzhou University,2010.(in Chinese)
[4]Hossain A B,Weiss W J.Assessing residual stress development and stress relaxation in restrained concrete ring specimens[J].Journal of Cement&Concrete Composites,2004,26:531-540.
[5]Dally J W,Riley W F.Experimental stress analysis[M].3rd ed.New York:McGraw Hill,1991.
[6]普通混凝土长期性能和耐久性能试验方法标准:GB/T50082-2009[S].北京:中国建筑工业出版社,2009.Standard for test methods of long-term performance and durability of ordinary concrete:GB/T 50082-2009[S].Beijing:China Architecture&Building Press,2009.(in Chinese)
[7]Standard test method for determining age at cracking and induced tensile stress characteristic of mortar and concrete under restrained shrinkage:ASTM C 1581-04[S].West Conshohocken,PA:ASTM International,2004.
[8]王国杰.自密实混凝土早龄期收缩、开裂性能研究[D].福州:福州大学,2011.Wang G J.Shrinkage and cracking performance of selfcompacting-concrete at early age[D].Fuzhou:Fuzhou University,2011.(in Chinese)
[9]刘积丁.自密实混凝土自生约束收缩下应力松弛性能研究[D].福州:福州大学,2017.Liu J D.Study on the stress relaxation properties of self-compacting concrete under autogenous shrinkage[D].Fuzhou:Fuzhou University,2017.(in Chinese)