This research focused on using the waste rubber powder as a kind of regenerate resources to improve the mechanical properties of cement mortar.The two kinds of hybrid modified rubber powder TRP and ATRP were prepared ...This research focused on using the waste rubber powder as a kind of regenerate resources to improve the mechanical properties of cement mortar.The two kinds of hybrid modified rubber powder TRP and ATRP were prepared by sol-gel method and then used in cement mortar.The structures and properties of them were studied.It is shown that the nano Si-O-Si network is generated in TRP and ATRP networks and the hydrophilic group is grafted on the surface of ATRP.The mechanical properties of rubber-treated mortar（RTM） were tested and the microstructures of them were also studied.Compared to the mortars with unmodified rubber powders（RP）,NaOH treated rubber powder（SRP） and coupling agent treated rubber powder（CRP）,the RTM with ATRP has the highest compressive strength and flexural strength.The stress-strain curves shown that the peak of stress of RTM with ATRP is increased and indicated the higher compression deformation and toughness.It is found that the interfacial adhesion between the ATRP and cement mortar is increased distinctly by SEM,which results in enhanced ductility and mechanical properties of RTM with ATRP.展开更多
The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO4 solution at certain period...The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO4 solution at certain periods. The experimental results show that the strength of mortar stored in MgSO4 solution increases a little before 28 d, but decreases fast subsequently. The more the contents of limestone powder and fly ash, the less the strength losses. Mortar swells in the MgSO4 solution with the soaking time. And the more the contents of limestone powder and fly ash, the less the expansion rate is. The expansion or strength loss of mortars results from the expansion of gypsum, as well as the loss of Ca（OH）2 and other hydration products of cement. The magnesium sulfate resistance of the mortars containing limestone powder and fly ash is high.展开更多
The compressive strength of mortar containing glass powder（GP） and/or glass aggregate（GA） was tested, and its microstructure was also studied by thermogravimetric and differential thermal analysis（TG-DTA）, scann...The compressive strength of mortar containing glass powder（GP） and/or glass aggregate（GA） was tested, and its microstructure was also studied by thermogravimetric and differential thermal analysis（TG-DTA）, scanning electron microscopy（SEM）, energy dispersive spectroscopic analysis（EDX）, and X-ray diffraction（XRD） techniques. The incorporation of GA would decrease the compressive strength of the mortar in the absence of GP. Incorporating both GA and GP could change the hydration environment, promote pozzolanic reaction of GP and improve the compressive strength. GP does not lead to but can effectively control ASR（Alkali Silica Reaction）. GP and GA do not transform the type of hydrates, but have a great influence on the amounts of hydration products, and generate more calcium silicate hydrate（C-S-H gel） with lower Ca/Si ratio. GP and GA with good gradation will make the microstructure denser.展开更多
The hydration and thermal properties of cement-based materials containing various proportions of limestone powder as a partial replacement for ordinary Portland cement, were investigated and reported. Both compressive...The hydration and thermal properties of cement-based materials containing various proportions of limestone powder as a partial replacement for ordinary Portland cement, were investigated and reported. Both compressive and flexural strengths of cement mortar with various contents of limestone powder were tested to study the influence of limestone powder on the strength development of resulting mixtures. The hydration heat and its rate of evolution were also tested, which clearly showed that the replacement percentage of limestone powder had significant effects on the total hydration heat but only a modest influence on the rate of heat evolution of cement-limestone binder. Importantly, the reduction coefficient of limestone powder on the hydration heat, needed for estimation of adiabatic temperature rise of cement-limestone binder, was found to be approximately 0.51. Fundamental thermal properties of these concrete mixtures containing limestone powder were also studied. Increasing the percentage of limestone powder resulted in a significant reduction in the adiabatic temperature rise but only a slight increase in other thermal properties such as thermal conductivity, thermal diffusivity and specific heat. In addition, thermal analysis using finite-element modelling indicated that inclusion of limestone powder did not significantly affect the rate of temperature rise nor the occurrence time of the highest temperature at early ages.展开更多
The feasibility of flue gas desulphurization （FGD） as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200...The feasibility of flue gas desulphurization （FGD） as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200℃ for 60 min and then mixed with the slag powder to form FGD gypsum-slag powder combined admixture in which the SO3 content was 3.5wt%. Cement was partially and equivalently replaced by slag powder alone or FGD gypsum-slag powder, at concentration of 25wt%, 40wt%, and 50wt%, respectively. The setting times, hydration products, total porosity and pore size distributions of the paste were determined. The compressive strength and drying shrinkage of cement mortar and concrete were also tested. The experimental results show that, in the presence of FGD gypsum, the setting times are much slower than those of pastes in the absence of FGD gypsum. The combination of FGD gypsum and slag powder provides synergistic benefits above that of slag powder alone. The addition of FGD gypsum provides benefit by promoting ettringite formation and forms a compact microstructure, increasing the compressive strength and reduces the drying shrinkage of cement mortar and concrete.展开更多
文摘This research focused on using the waste rubber powder as a kind of regenerate resources to improve the mechanical properties of cement mortar.The two kinds of hybrid modified rubber powder TRP and ATRP were prepared by sol-gel method and then used in cement mortar.The structures and properties of them were studied.It is shown that the nano Si-O-Si network is generated in TRP and ATRP networks and the hydrophilic group is grafted on the surface of ATRP.The mechanical properties of rubber-treated mortar（RTM） were tested and the microstructures of them were also studied.Compared to the mortars with unmodified rubber powders（RP）,NaOH treated rubber powder（SRP） and coupling agent treated rubber powder（CRP）,the RTM with ATRP has the highest compressive strength and flexural strength.The stress-strain curves shown that the peak of stress of RTM with ATRP is increased and indicated the higher compression deformation and toughness.It is found that the interfacial adhesion between the ATRP and cement mortar is increased distinctly by SEM,which results in enhanced ductility and mechanical properties of RTM with ATRP.
基金Funded by the Specialized Research Fund for the Doctoral Program of Higher Education of China (No.200804861060)
文摘The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO4 solution at certain periods. The experimental results show that the strength of mortar stored in MgSO4 solution increases a little before 28 d, but decreases fast subsequently. The more the contents of limestone powder and fly ash, the less the strength losses. Mortar swells in the MgSO4 solution with the soaking time. And the more the contents of limestone powder and fly ash, the less the expansion rate is. The expansion or strength loss of mortars results from the expansion of gypsum, as well as the loss of Ca（OH）2 and other hydration products of cement. The magnesium sulfate resistance of the mortars containing limestone powder and fly ash is high.
基金Funded by the National Natural Science Foundation of China(51208391)the National Basic Research Program of China(973 Program,2013CB035901)
文摘The compressive strength of mortar containing glass powder（GP） and/or glass aggregate（GA） was tested, and its microstructure was also studied by thermogravimetric and differential thermal analysis（TG-DTA）, scanning electron microscopy（SEM）, energy dispersive spectroscopic analysis（EDX）, and X-ray diffraction（XRD） techniques. The incorporation of GA would decrease the compressive strength of the mortar in the absence of GP. Incorporating both GA and GP could change the hydration environment, promote pozzolanic reaction of GP and improve the compressive strength. GP does not lead to but can effectively control ASR（Alkali Silica Reaction）. GP and GA do not transform the type of hydrates, but have a great influence on the amounts of hydration products, and generate more calcium silicate hydrate（C-S-H gel） with lower Ca/Si ratio. GP and GA with good gradation will make the microstructure denser.
基金Project(51579192) supported by the National Natural Science Foundation of ChinaProject(2013BC0359001) supported by the National Basic Research Program of ChinaProject(201506270058) supported by China Scholarship Council
文摘The hydration and thermal properties of cement-based materials containing various proportions of limestone powder as a partial replacement for ordinary Portland cement, were investigated and reported. Both compressive and flexural strengths of cement mortar with various contents of limestone powder were tested to study the influence of limestone powder on the strength development of resulting mixtures. The hydration heat and its rate of evolution were also tested, which clearly showed that the replacement percentage of limestone powder had significant effects on the total hydration heat but only a modest influence on the rate of heat evolution of cement-limestone binder. Importantly, the reduction coefficient of limestone powder on the hydration heat, needed for estimation of adiabatic temperature rise of cement-limestone binder, was found to be approximately 0.51. Fundamental thermal properties of these concrete mixtures containing limestone powder were also studied. Increasing the percentage of limestone powder resulted in a significant reduction in the adiabatic temperature rise but only a slight increase in other thermal properties such as thermal conductivity, thermal diffusivity and specific heat. In addition, thermal analysis using finite-element modelling indicated that inclusion of limestone powder did not significantly affect the rate of temperature rise nor the occurrence time of the highest temperature at early ages.
基金Funded by the National Natural Science Foundation of China(Nos.51208370,51172164)the Doctoral Program of Higher Education of China(No.20110072120046)+1 种基金the Fundamental Research Funds for the Central Universities(No.0500219170)the Opening Measuring Fund of LargeApparatus of Tongji University(No.0002012011)
文摘The feasibility of flue gas desulphurization （FGD） as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200℃ for 60 min and then mixed with the slag powder to form FGD gypsum-slag powder combined admixture in which the SO3 content was 3.5wt%. Cement was partially and equivalently replaced by slag powder alone or FGD gypsum-slag powder, at concentration of 25wt%, 40wt%, and 50wt%, respectively. The setting times, hydration products, total porosity and pore size distributions of the paste were determined. The compressive strength and drying shrinkage of cement mortar and concrete were also tested. The experimental results show that, in the presence of FGD gypsum, the setting times are much slower than those of pastes in the absence of FGD gypsum. The combination of FGD gypsum and slag powder provides synergistic benefits above that of slag powder alone. The addition of FGD gypsum provides benefit by promoting ettringite formation and forms a compact microstructure, increasing the compressive strength and reduces the drying shrinkage of cement mortar and concrete.
