【作者】 王伟；

【导师】 李玉平；

【作者基本信息】 湖南大学 ， 材料科学与工程， 2017， 硕士

【摘要】 部件化是建筑工业化发展的关键,而轻骨料混凝土是实现建筑工业化部件的主要材料之一。要想制备适合建筑工业化发展的部件,要针对轻骨料混凝土的特点以及建筑工业化部件的要求配制出适合建筑工业化的轻骨料混凝土。本文主要针对轻骨料混凝土从配方设计到脱模的整个配制过程遇到的问题,将研究内容设定为轻骨料混凝土的上浮问题解决以及配合比设计、矿物掺合料对轻骨料混凝土抗压强度的影响以及外加电压加速轻骨料混凝土脱模三个部分。轻骨料混凝土上浮问题,针对骨料力学受力进行分析,找到影响上浮的主要因素,通过控制粘度来解决上浮问题。根据普通混凝土的配合比方法采用等体积替换原则找到适合轻骨料混凝土配合比设计的简单便捷的方法轻骨料混凝土中加入单组分的矿物掺合料(粉煤灰、偏高岭土、钢渣),当掺量为10%时,混凝土在3d、7d和28d的抗压强度均达到最大。当两两掺合这三种矿物掺合料时,结果显示当粉煤灰和偏高岭土以2:1的比例、总掺量为10%时,混凝土的抗压强度最好,28d的抗压强度达到35MPa,与没有加矿物掺合料的混凝土相比,其强度增加了 200%。粉煤灰和偏高岭土的加入不仅可以填充混凝土的孔隙,还可以改善骨料与水泥浆体的接触面,同时改变钙矾石的形貌以及数量,从而对抗压强度具有一定的提高作用。通过给混凝土施加外加电压,从而加速水泥水化,达到快速脱模的效果。随着外加电压的增大,水泥的水化速度增快,当外加电压过大时,3d强度会出现快速增长,28d强度会出现较大程度的下降:当外加电压较小时,3d强度会较低甚至没有,28d强度会出现稳定增长的现象。结合XRD以及SEM能够清楚的看到,外加电压改变了钙矾石的形貌以及数量,当电压较小时钙矾石呈现出纤维状结构,早期几乎不提供强度,而电压较大时钙矾石呈现出粗大的棒状结构并且周围产生较大裂纹导致后期强度迅速下降。当外加电压为18V时,钙矾石的形貌呈现出相互交联的状态,3d以及28d强度均处于较高水平,因此,18V外加电压是硅酸盐水泥为基础胶凝材料的最佳电压。对比与硅酸盐水泥,常用于紧急修补工程的硫铝酸盐水泥呈现出类似的规律。当外加电压为25V时是加速低温下硫铝酸盐水泥水化的最佳电压,在前中期(1-7d)和后期(28d)的强度均表现出了高的强度;低电压加速硫铝酸盐水泥水化能够加快水泥的水化过程,同时得到细化的钙矾石,在水泥的前中后期的强度会有所提高;高电压加速硫铝盐水泥水化,早期强度会有明显的提高,但是后期硫铝酸盐水泥砂浆会出现膨胀,使强度出现大幅下降。电压的变化能够影响硫铝酸盐水泥水化进程,能够改变水化产物中钙矾石的形貌,没有新物质的生成。更多还原

【Abstract】 Components are the key to the development of construction industry and the lightweight aggregate concrete is the main material to realize the building industrial.In order to prepare the parts suitable for the development of industrial construction,it is necessary to prepare light aggregate concrete suitable for industrial construction according to the characteristics of lightweight aggregate concrete and the requirements of building industrial parts.In this paper,we focus on the problem of the whole preparation process of the lightweight aggregate concrete from the formula design to the stripping.The research content is set as the issues of the floating problem of the lightweight aggregate concrete,the mixing ratio design and the effect of applied voltage.As for the floating problem for light aggregate concrete,through the force analysis,we find the main factors affecting the floating and solve those problems by controlling the viscosity.According to the ordinary concrete mix method,equal volume replacement principle is suitable for lightweight aggregate concrete mix to design simple and convenient scheme.In the light aggregate concrete,the single kind of component mineral admixture(fly ash,metakaolin,steel slag)was added.When the content was 10%,the compressive strength of the concrete reached the maximum at 3d,7d and 28d.When the two kinds of mineral admixtures were blended,the results showed that the compressive strength of concrete was the best when the fly ash and metakaolin were 2:1 and the total content was 10%.In this case,the compressive strength of the concrete is 35MPa,which increased by 200%compared to the concrete without mineral admixture.The addition of fly ash and metakaolin can not only fill the pores of concrete,but also improve the contact surface between aggregate and cement slurry,and change the morphology and quantity of ettringite,which can improve the compressive strength.Imposing an applied voltage to the concrete can accelerate the hydration of the cement,leading to rapid stripping.With the increase of the applied voltage,the hydration speed of the cement is getting faster.When the applied voltage is too large,the 3d intensity will increase rapidly,while the 28d intensity will decrease to a large extent.When the applied voltage is too small,the 3d intensity is rarely increased,while the 28d intensity will appear steady growth.XRD and SEM show that the applied voltage changes the morphology and the content of ettringite.When the voltage is too small,the ettringite showed a fibrous structure,offering little strength.When the voltage is too high,ettringite showed a large rod-like structure and large cracks in the surface,leading to rapid decline in late strength.When the applied voltage is 18V,the morphology of ettringite exhibit a cross-linked state,and the 3d and 28d intensity are at a high level.Therefore,18V applied voltage is the best pressure of the cement.Comparied with Portland cement,sulphoaluminate cement commonly used in emergency repair works showed a similar law.Results showed that 25V is the best applied voltage to accelerate the hydration of sulphoaluminate cement at low temperature.The early strength(1-7d)and late strength(28d)both present high level.Low-voltage can accelerate the hydration of sulphoaluminate cement and obtain finer ettringite,which will increase the strength of cement in the middle and late stages.High voltage accelerates the hydration of sulphoaluminate cement,thus,the early strength of cement will be significantly improved.But late,sulphoaluminate cement mortar will expand,resulting in rapidly decline in the late strength.Voltage changes will affect the hydration process of sulphoaluminate cement and morphology of ettringite,but will not generate new material generation.更多还原