咖啡渣──水泥砂漿複合材之抗壓強度及隔熱性

Compressive strength and thermal insulation of spent coffee ground (SCG)-cement mortar composites

本研究利用咖啡渣（Spent coffee ground, SCG）作為填料，與水泥砂漿拌合製備對環境友善的咖啡渣-水泥砂漿複合材（SCG-cement mortar composite, SCC），以探討咖啡渣添加量對水泥複合材密度、抗壓強度及隔熱性質之影響。有關密度方面，試驗結果得知SCC密度隨咖啡渣添加量增加而減少。另外，由抗壓強度試驗結果觀察出，添加高咖啡渣含量的SCC具有較低的抗壓強度。其主要原因推測係因添加多孔咖啡渣造成水泥基質的孔隙增加所致。對於熱傳導率方面，隨著咖啡渣含量增加，SCC之熱傳導率隨之降低。添加23.5%咖啡渣含量時，SCC的密度為1.516 g/cm3及熱傳導率為0.27 W/mK，由此結果可看出此SCC具有低密度且有達到國際材料和結構實驗研究聯合會之非結構用輕質混凝土隔熱材之Class III等級（熱傳導率小於0.3 W/mK）。另一方面，SCC之抗壓強度及熱傳導率分別與密度間具有高度指數增長的相關性。由於此特徵，SCC有望成為傳統水泥砂漿的替代品。甚至SCG的添加可適度降低水泥材料成本，也為建築業和廢棄物的利用帶來經濟效益。

This study explore the use of spent coffee grounds (SCGs) as fillers to produce environmental friendly SCG-cement mortar composites (SCCs). We investrigared the effect of varying SCG content on the density, compressive strength, and thermal insulation properties of the SCCs. The results showed that the apparent density and compressive strength of the SCC both decreased as the SCG content increased. This phenomenon may be related to the increased porosity caused by the addition of SCGs in the cement matrix. Conversely, the thermal conductivity (TC) of the SCC decreased with the increasing of the SCG content. Specifically, with the addition of 23.5% SCG, the SCC achieve a low density of 1.516 g/cm3 and the TC value of 0.27 W/mK. Such a low SCC density property has met the Class III standard (less than 0.3 W/mK) for nonstructural lightweight concrete for an insulation material as specified by the RILEM (International Union of Laboratories and Experts in Construction Materials, Systems and Structures). Furthermore, the compressive strength and thermal conductivity of the SCC showed a highly exponential growth correlation with density. These finding suggested that SCC is a promising substitute for traditional cement mortar, offering the additional economic benefits of waste utilization and a moderately reduction in of cement materials cost for the construction industry.