对一种新型温度控制相变聚合物的实验研究:混凝土:热力学性能和水化热控制
Yejia Wang1, Chengjin Wang2, Aibo Luo2
1Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK.
Materials (Basel, Switzerland)
|August 12, 2023
概括
这项研究开发了相变聚合物 (PCA) 来控制混凝土温度并减少能源使用. 封装PCA显著降低了混凝土质量的温度差异,尽管机械性能需要进行实际应用的调整.
科学领域:
- 土木工程 土木工程是指土木工程.
- 材料科学 材料科学 材料科学
- 可持续建筑 可持续建筑
背景情况:
- 质量混凝土结构易发生热裂变,原因是水化热.
- 固体混凝土的传统冷却方法耗费大量能源.
- 开发创新的聚合物可以减轻这些问题.
研究的目的:
- 准备和评估用于混凝土温度控制的相变聚合物 (PCA).
- 评估封装PCA的热稳定性和机械性能.
- 为了研究相变聚合混凝土 (PCAC) 的温度控制有效性.
主要方法:
- 阶段变化聚合物 (PCA) 通过使用陶和抛进行真空压缩来制备.
- 使用超细水泥和环氧树脂封装PCA.
- 对PCA和PCAC的机械性能,热稳定性和热储效应进行实验室测试.
主要成果:
- 封装增强了PCA强度,而环氧树脂提供了比超细水泥更强的强度.
- 与普通混凝土相比,PCAC显示出高达10°C的显著温度差异.
- PCAC的机械性能降低了,环氧封装PCA显示出更好的性能保留.
结论:
- 封装PCA有效地控制了混凝土质量的温度,减少了热问题.
- 虽然机械性能略有降低,但增加混凝土等级等调整可以补偿.
- 这项技术为节能,耐用的大质量混凝土结构提供了一个有前途的解决方案.
更多相关视频
11:11Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation
Published on: May 2, 2016
11.1K
10:01Thermal Scanning Conductometry TSC as a General Method for Studying and Controlling the Phase Behavior of Conductive Physical Gels
Published on: January 23, 2018
7.7K
相关概念视频
Hot Weather Concreting
91
Concreting at elevated temperatures accelerates the hydration process, leading to quicker setting but potentially reducing the long-term strength of the concrete structure. Additionally, low air humidity fosters rapid moisture loss from the concrete, resulting in reduced workability, pronounced plastic shrinkage, and a higher likelihood of crazing.
Mitigating the heat increase in concrete can be economically achieved by shading aggregate stockpiles to prevent heating from solar radiation,...
Mitigating the heat increase in concrete can be economically achieved by shading aggregate stockpiles to prevent heating from solar radiation,...
91
Mass Concreting
90
Mass concreting refers to the process of placing large volumes of concrete, such as in gravity dams. The heat generated during the cement hydration process and differential cooling rates within the concrete mass can lead to a temperature gradient, which can result in thermal cracks in the concrete mass.
To reduce the risk of such cracking, the concrete mix may incorporate low-heat cement and pozzolans to reduce the temperature rise. Pre-cooled angular aggregates and water-reducing admixtures...
To reduce the risk of such cracking, the concrete mix may incorporate low-heat cement and pozzolans to reduce the temperature rise. Pre-cooled angular aggregates and water-reducing admixtures...
90
Design Example: Managing Concrete Workability
101
This example deals with managing the workability of concrete for a raft foundation project under hot weather conditions. Workability is crucial for ensuring the concrete is easy to place, compact, and finish. In this scenario, a slump test — a common method to measure the workability of fresh concrete — initially indicated low workability. This was attributed to the rapid water loss from the concrete mix, exacerbated by the high temperatures causing the course aggregates to heat up.
101
Cold Weather Concreting
92
When freshly poured concrete is exposed to freezing temperatures before it has set, the water within the concrete can freeze. This expansion disrupts the setting process, delays chemical reactions necessary for hardening, and increases the volume of pores within the hardened concrete, which weakens its overall structure. If the concrete manages to reach an appreciable strength before it freezes, the damage can be somewhat mitigated.
To counteract the negative impacts of cold weather, ensuring...
To counteract the negative impacts of cold weather, ensuring...
92
Strength and Heat of Hydration
274
The hydration of cement is an exothermic reaction in which heat is generated as cement hydrates. This heat of hydration is critical to cement's strength development. The rate at which this heat is generated affects the temperature rise, with a majority of the heat being released early in the hydration process, half within the first three days, and about 75% within the first week.
The heat of hydration for each cement compound is significant; for instance, tricalcium aluminate (C3A) and...
The heat of hydration for each cement compound is significant; for instance, tricalcium aluminate (C3A) and...
274
Alkali Aggregate Reaction in Concrete
132
The alkali-aggregate reaction in concrete involves natural siliceous minerals in aggregates reacting with alkaline hydroxides derived from cement alkalis. This reaction forms an alkali-silica gel that absorbs water, swells, and increases in volume, which is confined by the surrounding cement paste, creating internal pressures that crack and disrupt the concrete. The extent of expansion and damage can be partly attributed to the alkali-silica reaction's osmotic hydraulic pressure and the...
132
