掺硅藻土的保水水泥混凝土组成设计与水热性能评价

发布时间：2018-05-04 07:19

本文选题：保水路面 + 硅藻土　；参考：《长安大学》2017年硕士论文

【摘要】：保水路面是指路面结构内部可以保持水分,并通过水分的蒸发带走大量潜热,抑制路面表面的温度上升进而降低空气温度的一种功能型路面。本文主要涉及保水水泥混凝土的材料组成设计及性能评价等。此研究可以为缓解城市热岛效应,建设“海绵城市”提供一种技术方案和相关技术支持。本文在研究硅藻土掺量对混凝土性能影响的同时,确定最佳硅藻土掺量。通过对比不同保水材料的经济技术等特性,确定了保水材料的种类与粒径。经由试验计算,确定了母体材料的配合比。采用拌和的方式使保水材料与母体材料结合成型,通过对比不同拌和工艺,确定了拌和流程;分析了不同硅藻土掺量的保水试件的抗冻性和强度;设计了保水试件在不同环境条件下的吸水试验以及室内外的蒸发试验,根据试验结果分析了不同硅藻土掺量的保水试件的吸水蒸发性能;观测了试件在洒水前后的温度变化特征,并根据地表能量平衡理论、温度及试件参数等,计算分析了不同保水量的混凝土试件的温度和能量行为,使用温度行为与显热、潜热评价了试件的降温特性。结果发现:硅藻土掺量为3.0%时,保水试件的吸水高度和吸水速率最大,分别为70.35%和0.118 g/cm~3,其抗冻指数、抗压和抗弯拉强度、饱水吸水量、洒水吸水量较大且与最大值差别不大,其值分别为99.1%、21.0和2.64 MPa、0.140 g/cm~3、0.140 g/cm~3(40 min)。掺3.0%硅藻土的保水试件在开始时的蒸发率为0.254 g/(m~2·s),在第8.5个小时的蒸发率为0.023 g/(m~2·s)。掺硅藻土的保水试件可以维持8.5个小时的较强蒸发作用。相较于普通水泥混凝土,掺3.0%硅藻土的保水水泥混凝土的表面温度在洒水后的第一天最大降低5.1°C,而第二天最大降低2.1°C。相较于普通水泥混凝土,掺硅藻土的保水水泥混凝土能够明显降低显热的释放并增大潜热的释放,尤其是掺量达到3.0%及以上时(3.0%掺量下显热降低量在白天和晚上分别为29.6 W/m~2和14.9 W/m~2,潜热平均值的增加量为57.2 W/m~2)。因此,最后硅藻土的最佳掺量为3.0%。掺3.0%硅藻土的保水水泥混凝土路面系统的降温效果显著,对城市热岛具有一定的缓解作用。
[Abstract]:Water-retaining pavement is a kind of functional pavement which can keep moisture inside the pavement structure and take away a large amount of latent heat by evaporation of moisture to restrain the surface temperature rising and then reduce the air temperature. This paper mainly deals with the material composition design and performance evaluation of water-retaining cement concrete. This study can provide a technical scheme and related technical support for alleviating the urban heat island effect and constructing "sponge city". In this paper, the effect of diatomite content on concrete performance is studied, and the optimum diatomite content is determined. By comparing the economic and technological characteristics of different water-retaining materials, the types and particle sizes of water-retaining materials were determined. The mixture ratio of the parent material was determined by experimental calculation. The mixing method was used to combine the water-retaining material with the parent material, the mixing process was determined by comparing different mixing processes, and the freezing resistance and strength of the water-retaining specimen with different diatomite content were analyzed. The water absorption test and the indoor and outdoor evaporation test of the water-retaining specimen under different environmental conditions were designed. According to the test results, the water absorption and evaporation performance of the water-retaining specimen with different diatomite content was analyzed. The characteristics of temperature change before and after sprinkling are observed. According to the theory of surface energy balance, the temperature and the parameters of the specimen, the temperature and energy behavior of concrete specimens with different water holding capacity are calculated and analyzed, and the temperature behavior and sensible heat are used. The latent heat was used to evaluate the cooling characteristics of the specimen. The results showed that when the amount of diatomite was 3.0, the water absorption height and water absorption rate were 70.35% and 0.118 g / cm ~ (-3), respectively. The freezing resistance index, compressive strength and flexural tensile strength, saturated water absorption and sprinkling water absorption were not different from the maximum values. The values were 99.1 and 2.64 MPA 0.140 g / cm ~ (-1) and 0.140 g/cm~3(40 路min ~ (-1), respectively. The evaporation rate of the water-retaining specimen doped with 3.0% diatomite was 0.254 g/(m~2 / s at the beginning and 0.023 g/(m~2 / s at 8.5h. The water retention specimen with diatomite can maintain strong evaporation for 8.5 hours. Compared with ordinary cement concrete, the surface temperature of water-retaining cement concrete with 3.0% diatomite decreases 5.1 掳C on the first day after sprinkling, and 2.1 掳C on the second day. Compared with ordinary cement concrete, diatomite cement concrete can obviously reduce the release of sensible heat and increase the release of latent heat. In particular, the apparent heat decrease is 29.6 W/m~2 during the day and 14.9 W / m ~ (2) at night when the dosage is 3.0% or more, and the increase of latent heat is 57.2 W / m ~ (2) 路m ~ (2) ~ (-1). Therefore, the best addition of diatomite is 3.0. The cooling effect of the water-retaining cement concrete pavement system with 3.0% diatomite is remarkable, and it can alleviate the urban heat island to some extent.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U414

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