Cracks easily generate in concrete at early age owing to the shrinkage deformation.CaO-based expansion agent(CEA)and superabsorbent polymers(SAP)have been extensively used for the mitigation of concrete shrinkage.The ...Cracks easily generate in concrete at early age owing to the shrinkage deformation.CaO-based expansion agent(CEA)and superabsorbent polymers(SAP)have been extensively used for the mitigation of concrete shrinkage.The macroscopic properties of concrete are highly determined by the microstructure.In this study,the influence of CEA and SAP addition on the pore structure evolution of cement paste under different curing temperatures was evaluated via low-field nuclear magnetic resonance spectroscopy.Test results indicated that,in cement paste,a higher CEA content led to a higher porosity and a larger most probable pore diameter(MPPD).Meanwhile,SAP addition increased the porosity and MPPD of CEA cement paste at early age but decreased them after 7 d,and a higher SAP content always brought a higher porosity and MPPD.Furthermore,the addition of SAP led to a lower porosity and MPPD of CEA cement paste than that of plain cement paste after 14 d.Moreover,the porosity and MPPD of CEA cement paste decreased first and subsequently increased as the curing temperature raised.展开更多
采用Anton Paar MCR 302型流变仪研究了乳胶粉掺量对纤维素醚改性水泥浆体流变性能和触变性的影响。结果表明,掺入乳胶粉的纤维素醚改性水泥浆体表现为剪切稀化的流变特性,当剪切速率较小时,浆体黏度下降显著。乳胶粉掺量越大,浆体基于H...采用Anton Paar MCR 302型流变仪研究了乳胶粉掺量对纤维素醚改性水泥浆体流变性能和触变性的影响。结果表明,掺入乳胶粉的纤维素醚改性水泥浆体表现为剪切稀化的流变特性,当剪切速率较小时,浆体黏度下降显著。乳胶粉掺量越大,浆体基于Herschel-Bulkey模型拟合得到的屈服应力和黏度系数均越大。并且乳胶粉能够增大浆体的触变滞后环面积和三段式触变测试的结构恢复率。掺入乳胶粉和纤维素醚的水泥浆体屈服应力和触变环面积呈正向线性关系。展开更多
基金Projects(51878245,U1965105)supported by the National Natural Science Foundation of ChinaProject(2019GSF110006)supported by the Key Research and Development Program of Shandong Province,China+2 种基金Project(2020Z035)supported by the Ningbo 2025 Science and Technology Major Project,ChinaProject(KJ2017B01)supported by the Scientific Research Project of Department of Education of Anhui Province,ChinaProject(2019CEM001)supported by the State Key Laboratory of High Performance Civil Engineering Materials,China。
文摘Cracks easily generate in concrete at early age owing to the shrinkage deformation.CaO-based expansion agent(CEA)and superabsorbent polymers(SAP)have been extensively used for the mitigation of concrete shrinkage.The macroscopic properties of concrete are highly determined by the microstructure.In this study,the influence of CEA and SAP addition on the pore structure evolution of cement paste under different curing temperatures was evaluated via low-field nuclear magnetic resonance spectroscopy.Test results indicated that,in cement paste,a higher CEA content led to a higher porosity and a larger most probable pore diameter(MPPD).Meanwhile,SAP addition increased the porosity and MPPD of CEA cement paste at early age but decreased them after 7 d,and a higher SAP content always brought a higher porosity and MPPD.Furthermore,the addition of SAP led to a lower porosity and MPPD of CEA cement paste than that of plain cement paste after 14 d.Moreover,the porosity and MPPD of CEA cement paste decreased first and subsequently increased as the curing temperature raised.
文摘采用Anton Paar MCR 302型流变仪研究了乳胶粉掺量对纤维素醚改性水泥浆体流变性能和触变性的影响。结果表明,掺入乳胶粉的纤维素醚改性水泥浆体表现为剪切稀化的流变特性,当剪切速率较小时,浆体黏度下降显著。乳胶粉掺量越大,浆体基于Herschel-Bulkey模型拟合得到的屈服应力和黏度系数均越大。并且乳胶粉能够增大浆体的触变滞后环面积和三段式触变测试的结构恢复率。掺入乳胶粉和纤维素醚的水泥浆体屈服应力和触变环面积呈正向线性关系。
