機(jī)制砂水泥砂漿流變性能研究
發(fā)布時間：2019-05-06 08:42
【摘要】：隨著基礎(chǔ)設(shè)施建設(shè)的快速發(fā)展和環(huán)境保護(hù)的加強(qiáng)，河砂資源越來越匱乏，機(jī)制砂在混凝土中的應(yīng)用越來越多。由于機(jī)制砂在粒形、級配、石粉含量等方面與河砂存在顯著差異，機(jī)制砂混凝土與河砂混凝土存在很多不同，其中工作性能的差異最為明顯。流變參數(shù)是表征水泥基材料流動性能和工作性能的重要指標(biāo)，描述和控制水泥基材料流變特性，對指導(dǎo)混凝土的工程應(yīng)用，控制新拌混凝土的工作性能，確保工程質(zhì)量都具有重要意義。因此，從流變學(xué)角度研究機(jī)制砂混凝土工作性能具有重要的實用價值和理論意義。 總結(jié)流變學(xué)在混凝土中的應(yīng)用，內(nèi)容包括：賓漢姆體在混凝土研究中的應(yīng)用、觸變性及評價方法、水泥漿及新拌混凝土的物理結(jié)構(gòu)、混凝土的工作性等。 對比研究不同水灰比下機(jī)制砂砂漿與河砂砂漿流變性能，結(jié)果表明：相同配合比條件下，機(jī)制砂砂漿與河砂砂漿相比，屈服應(yīng)力較大，塑性粘度較小，流變參數(shù)經(jīng)時變化較大，觸變性較�。凰冶仍酱�，河砂砂漿與機(jī)制砂砂漿屈服應(yīng)力、塑性粘度越小，兩種砂漿流變參數(shù)的差距也逐漸縮小，河砂砂漿與機(jī)制砂砂漿流變參數(shù)經(jīng)時變化、觸變性越小。 研究不同比表面積粉煤灰、聚羧酸高性能減水劑對機(jī)制砂砂漿流變性能影響，結(jié)果表明：粉煤灰的加入使機(jī)制砂砂漿的屈服應(yīng)力明顯降低，塑性粘度增大，且粉煤灰越細(xì)越明顯；隨著粉煤灰摻量的增加，砂漿流變參數(shù)經(jīng)時變化減小，粉煤灰越細(xì)效果越明顯；粉煤灰摻量小于15%時對機(jī)制砂砂漿的觸變性無明顯影響，粉煤灰摻量大于15%時，比表面積較大的粉煤灰使砂漿觸變性減弱，比表面積較小的粉煤灰則使砂漿觸變性增大；減水劑的加入使機(jī)制砂砂漿的屈服應(yīng)力降低，，對砂漿塑性粘度的影響較小，機(jī)制砂砂漿流變參數(shù)經(jīng)時變化增大，觸變性降低。 從棱角性、形態(tài)學(xué)兩個角度分析機(jī)制砂的粒形特征，并分析機(jī)制砂級配與棱角性、比表面積的關(guān)系，機(jī)制砂級配和石粉含量對砂漿流變性能的影響，結(jié)果表明：隨粒徑和級配的變化，不同巖性機(jī)制砂棱角性變化規(guī)律基本一致；機(jī)制砂圓度隨著粒徑的減少而減小；隨級配變粗，三種巖性的機(jī)制砂砂漿屈服應(yīng)力均先減小后增大，河砂砂漿屈服應(yīng)力減小；石灰?guī)r機(jī)制砂砂漿屈服應(yīng)力與機(jī)制砂棱角性有較好的相關(guān)性；隨級配變粗，四種細(xì)集料砂漿的塑性粘度均下降；河砂砂漿、石灰?guī)r機(jī)制砂砂漿塑性粘度與集料比表面積有良好的相關(guān)性；從石粉引起砂漿屈服應(yīng)力增大的角度來講，機(jī)制砂級配越粗，能夠容許的石粉含量越高；石粉含量增加，機(jī)制砂砂漿塑性粘度增大。
[Abstract]:With the rapid development of infrastructure construction and the strengthening of environmental protection, river sand resources are becoming more and more scarce, and the application of mechanical sand in concrete is more and more. Because there are significant differences between the mechanical sand and the river sand in grain shape, gradation and content of stone powder, there are many differences between the mechanical sand concrete and the river sand concrete, among which the difference of the working performance is the most obvious. Rheological parameters are important indexes to characterize the flow and working properties of cement-based materials. The rheological properties of cement-based materials are described and controlled, which can guide the engineering application of concrete and control the performance of newly mixed concrete. It is of great significance to ensure the engineering quality. Therefore, it is of great practical value and theoretical significance to study the working performance of mechanical sand concrete from the point of view of rheology. This paper summarizes the application of rheology in concrete, including the application of Bingham body in the study of concrete, thixotropy and evaluation method, the physical structure of cement slurry and fresh concrete, the workability of concrete and so on. The rheological properties of mechanical sand mortar and river sand mortar under different water-cement ratios are compared. The results show that under the same mix ratio, the yield stress is larger, the plastic viscosity is small, and the rheological parameters change greatly over time, compared with the river sand mortar under the same mix ratio. Thixotropy is small; The larger the water-cement ratio, the smaller the yield stress and the plastic viscosity of the river sand mortar and the mechanical sand mortar, and the smaller the difference of the rheological parameters between the two mortars. The rheological parameters of the river sand mortar and the mechanical sand mortar change with time, and the thixotropy of the two mortars is smaller. The effects of fly ash with different specific surface area and polycarboxylic acid high performance water reducer on the rheological properties of mechanical sand slurry were studied. The results showed that the yield stress and plastic viscosity of the mortar decreased obviously and the plastic viscosity increased with the addition of fly ash. The finer the fly ash is, the more obvious the fly ash is. With the increase of fly ash content, the rheological parameters of mortar decrease after time, and the finer the fly ash is, the more obvious the effect is. When the content of fly ash is less than 15%, the thixotropy of mortar is not affected obviously. When the content of fly ash is more than 15%, the thixotropy of mortar is weakened by fly ash with larger specific surface area, and the thixotropy of mortar is increased by fly ash with smaller specific surface area. With the addition of water reducing agent, the yield stress of sand mortar is reduced, and the plastic viscosity of mortar is less affected. The rheological parameters of sand mortar are increased and the thixotropy is decreased. The grain shape characteristics of mechanical sand are analyzed from the angles of angularity and morphology, and the relationship between mechanical sand gradation and angularity and specific surface area is analyzed, and the effect of mechanical sand gradation and stone powder content on the rheological properties of mortar is also analyzed. The results show that, with the change of particle size and gradation, the variation rule of sandedges with different lithologic mechanisms is basically the same. The roundness of sand decreases with the decrease of grain size, and the yield stress of sand mortar of three kinds of lithology decreases firstly and then increases, and the yield stress of river sand mortar decreases with the coarsening of gradation. There is a good correlation between the yield stress of limestone sand mortar and the angular property of the sand edge, and the plastic viscosity of the four fine aggregate mortars decreases with the coarsening of gradations, and the plastic viscosity of the four kinds of fine aggregate mortars decreases. There is a good correlation between the plastic viscosity of sand slurry and the specific surface area of aggregate, the thicker the gradation of sand is, the higher the allowable content of stone powder is, from the point of view of the increase of yield stress of mortar caused by stone powder, the plastic viscosity of limestone sand slurry has a good correlation with the specific surface area of aggregate. The plastic viscosity of mechanical sand slurry increases with the increase of stone powder content.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU578.1
本文編號：2470040
[Abstract]:With the rapid development of infrastructure construction and the strengthening of environmental protection, river sand resources are becoming more and more scarce, and the application of mechanical sand in concrete is more and more. Because there are significant differences between the mechanical sand and the river sand in grain shape, gradation and content of stone powder, there are many differences between the mechanical sand concrete and the river sand concrete, among which the difference of the working performance is the most obvious. Rheological parameters are important indexes to characterize the flow and working properties of cement-based materials. The rheological properties of cement-based materials are described and controlled, which can guide the engineering application of concrete and control the performance of newly mixed concrete. It is of great significance to ensure the engineering quality. Therefore, it is of great practical value and theoretical significance to study the working performance of mechanical sand concrete from the point of view of rheology. This paper summarizes the application of rheology in concrete, including the application of Bingham body in the study of concrete, thixotropy and evaluation method, the physical structure of cement slurry and fresh concrete, the workability of concrete and so on. The rheological properties of mechanical sand mortar and river sand mortar under different water-cement ratios are compared. The results show that under the same mix ratio, the yield stress is larger, the plastic viscosity is small, and the rheological parameters change greatly over time, compared with the river sand mortar under the same mix ratio. Thixotropy is small; The larger the water-cement ratio, the smaller the yield stress and the plastic viscosity of the river sand mortar and the mechanical sand mortar, and the smaller the difference of the rheological parameters between the two mortars. The rheological parameters of the river sand mortar and the mechanical sand mortar change with time, and the thixotropy of the two mortars is smaller. The effects of fly ash with different specific surface area and polycarboxylic acid high performance water reducer on the rheological properties of mechanical sand slurry were studied. The results showed that the yield stress and plastic viscosity of the mortar decreased obviously and the plastic viscosity increased with the addition of fly ash. The finer the fly ash is, the more obvious the fly ash is. With the increase of fly ash content, the rheological parameters of mortar decrease after time, and the finer the fly ash is, the more obvious the effect is. When the content of fly ash is less than 15%, the thixotropy of mortar is not affected obviously. When the content of fly ash is more than 15%, the thixotropy of mortar is weakened by fly ash with larger specific surface area, and the thixotropy of mortar is increased by fly ash with smaller specific surface area. With the addition of water reducing agent, the yield stress of sand mortar is reduced, and the plastic viscosity of mortar is less affected. The rheological parameters of sand mortar are increased and the thixotropy is decreased. The grain shape characteristics of mechanical sand are analyzed from the angles of angularity and morphology, and the relationship between mechanical sand gradation and angularity and specific surface area is analyzed, and the effect of mechanical sand gradation and stone powder content on the rheological properties of mortar is also analyzed. The results show that, with the change of particle size and gradation, the variation rule of sandedges with different lithologic mechanisms is basically the same. The roundness of sand decreases with the decrease of grain size, and the yield stress of sand mortar of three kinds of lithology decreases firstly and then increases, and the yield stress of river sand mortar decreases with the coarsening of gradation. There is a good correlation between the yield stress of limestone sand mortar and the angular property of the sand edge, and the plastic viscosity of the four fine aggregate mortars decreases with the coarsening of gradations, and the plastic viscosity of the four kinds of fine aggregate mortars decreases. There is a good correlation between the plastic viscosity of sand slurry and the specific surface area of aggregate, the thicker the gradation of sand is, the higher the allowable content of stone powder is, from the point of view of the increase of yield stress of mortar caused by stone powder, the plastic viscosity of limestone sand slurry has a good correlation with the specific surface area of aggregate. The plastic viscosity of mechanical sand slurry increases with the increase of stone powder content.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU578.1
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