Study on Measurement of Porosity of Light-weight Aggregate Porous Concrete

[[abstract]]本研究以國內大力推展之水庫淤泥輕質骨材為基本材料研製多孔混凝 土，不但達到綠建材減廢再利用的目標，且輕質骨材多孔混凝土作為舖面材 料，具有提高雨水入滲率、減緩地表逕流、降低地表溫度蓄積及避免都市熱 島效應惡化的優點。 透水係數為評估多孔混凝土透水特性最重要的指標之一。透水性主要取 決於多孔混凝土中連通孔隙的多寡，因此孔隙率的大小可作為評估多孔混凝 土透水性質的重要指標。然而，如何有效的量測多孔混凝土的孔隙，至今尚 未有一套完善的技術方法與規範。再者，以往對於混凝土孔隙率的量測僅限 於實驗室完成，並且受到儀器的限制，所能量測的試體尺度皆相當的微小代 表性不足，也是多孔混凝土孔隙率不易檢測管控的主因之一。 為探討透水係數、孔隙率以及配比三者間之關連性，本文以水膠比、漿 固比、爐石粉取代比以及最大骨材粒徑為試驗因子，應用實驗設計法規劃製 作27 組共81 個多孔混凝土試體進行試驗並加以分析討論。為能有效及簡化 多孔混凝土孔隙率的量測，同時利用自行研發的注汞孔隙測儀以及影像分析 法進行孔隙率的量測。其中，注汞孔隙測儀所測得之孔隙率乃是用於量測多 孔混凝土實際的孔隙率，影像分析則是藉由影像處理的方式，以二維影像孔 隙面積比推估多孔混凝土中的孔隙率。並研析兩種試驗方法的相關性，以評 估影像分析法應用於現場量測孔隙率的可行性。 根據試驗結果發現：本研究所配製試體之孔隙率介於24.03%~ 30.84%， 符合多孔混凝土孔隙率的要求。由全距及變異數分析的結果顯示：骨材粒 徑、水膠比與漿固比為影響透水係數的材料因子；而影響孔隙率的材料因子 則為：漿固比、爐石粉取代比、最大骨材粒徑及水膠比。本研究所量測的孔 隙率為連通孔隙與半連通孔隙，而連通孔隙為影響透水係數的主要因子，以 全距、變異數、離差均方根、t 檢定與F 檢定等統計分析方法，可推估兩者 間具有一定的關係。根據影像分析法所測得之孔隙率與注汞法量測結果誤差 低於10%，符合現場檢測精度的要求，可作為現場簡易品質管制的方法之一。[[abstract]]In order to achieve the goal of waste treatment and reuse of green building material this thesis presents an approach of developing a porous concrete by means of the light weight aggregate of reservoir which is a promising material to be greatly popularized by the internal organizations It can further achieve not only the increasing infiltration rate of rain the retarding surface runoff and the decreasing temperature accumulative effects on ground but also the avoiding deterioration of the Heat Islands Effect except the above benefit The permeability coefficient is one of the most important indexes for evaluating the characteristics of permeability It is mainly dependent upon the amount of continuity of pores in the porous concrete and can be therefore adopted as the critical index to evaluate the permeability characteristics of the porous concrete However there still isn’t a flawless technique and standard to effectively measure the pore of the concrete In addition the previous measurement of concrete porosity was only feasible by the laboratory experiments and the allowable measured sample sizes were quite small That is one of the critical reasons why it can’t be easily tested and monitored To explore the relation between permeability coefficient porosity and mix we apply the experimental method to design a test of porous concrete This test includes 81 concrete samples which can be classified into 27 groups to make an analysis by testing for water/binder ratio the paste/solid ratio the weight of cement in the reductive slag and the maximum diameter of aggregate In order to effectively simplify the process for measuring the porosity of porous concrete a mercury infusion apparatus and an image analysis process were developed to achieve this goal In this process the obtained porosity is used to measure the actual porosity of III porous concrete while the provided 2-D image can be used to evaluate it but also discover their relationship between the two measurement approaches by performing such an image analysis According to the result it shows the porosity range of this study is around 24 03%~30 84% which confirms the requirement of most porous concrete Furthermore the range analysis and the analysis of variance reveal that the material factors of permeability coefficient are the diameter of aggregate the water/binder ratio and the paste/solid ratio In addition the factors of the porosity of paste/solid ratio weight of cement in the reductive slag maximum diameter of aggregate and water/binder ratio have also been discovered The measured porosity in this study is the continuity of pores and the semi- continuity of pores Since continuity of pores is the main factor permeability coefficient we can therefore infer certain relation by means of some statistical techniques such as range analysis variance root mean square T-test and F-test According to the comparison of the measured porosities between image analysis and mercury approaches we can find that it satisfies the need of on-site detecting accuracy of less than 10% inaccuracy Thus the proposed method indeed has the ability to serve as one of the important approaches of on-site quality contro