不同材料對混凝土之熱學影響研究

Abstract

巨積混凝土初期中心水化熱過高，若提高混凝土的熱傳導性質，將內部的熱向外傳遞，則可減少裂縫；提高混凝土的熱傳導性質則能快速地將熱傳遞，在火災時迅速把熱導入內部，減少混凝土因溫差產生之應力；在日常若能將混凝土吸收的熱導出並進行發電，更可以節約能源達成綠建築的標準。本研究目的是使用導熱性較佳的材料，添加於混凝土內取代原本的細粒料，藉此提升混凝土的熱傳導性質。 本實驗針對材料b、c、d、g、w作為混凝土細粒料，並進行抗壓強度、熱膨脹試驗、熱傳導試驗、比熱試驗、電阻率試驗，探討不同材料添加對熱學性質的影響。 實驗結果顯示：(1.) 添加細粒料b、w混凝土抗壓強度會比對照組大1.2倍。(2.) 添加細粒料d之混凝土強度會是對照組的0.86倍。(3.) 使用細粒料d的混凝土比熱與對照組相比下降百分比為15%。(4.) 細粒料b、w取代時，熱膨脹係數會大於對照組8%左右。(5.) 同時使用細粒料c、d、g取代，熱傳導係數約高於對照組的1.8倍。

ABSTRACT The center temperature of a mass concrete may be high due to hydration. If the heat conduction of concrete can be increased such that the heat can be dissipated from center to the environment would be a good idea. In addition, if the heat can be absorbed and transferred to other places in a fire, the temperature difference of the concrete may be reduced and the cracks may be minimized. In our daily life, the heat from Sun can be used captured easier for further use and a more sustainable structure can be achieved. This research used a more heat-conducting material to replace conventional fine aggregates for this purpose. Materials b, c, d, g, and w were used as fine aggregates to study the effects on the compressive strength, expansion under heat, heat conduction, specific heat, and electrical resistance. The test results showed the following: 1. The addition of material b and w increases the compressive strength by 20%. 2. The addition of material d decreases the compressive strength by 14%. 3. The specific heat of the specimen with material d was reduced by 15%. 4. The expansion coefficient under heat is increased by 8% for specimens with materials b and w. 5. The heat conduction coefficient of specimens with materials c, d and g increases 80%.

Keywords: concrete, expansion, heat conduction, specific heat, electrical resistance.