【摘要】：近年來,城市建筑垃圾再利用受到廣泛的重視,許多國家將破碎后的混凝土廢棄物作為骨料重新利用,不僅能有效地節(jié)約天然的優(yōu)質(zhì)骨料,而且對合理利用自然資源和保護(hù)生態(tài)環(huán)境具有重要現(xiàn)實(shí)意義。再生混凝土由于再生骨料孔隙,界面,吸水性等缺陷,導(dǎo)致耐久性問題成為阻礙再生混凝土應(yīng)用于工程結(jié)構(gòu)的主要影響因素。為了推廣再生混凝土在實(shí)際工程結(jié)構(gòu)中的應(yīng)用,其抗氯離子滲透性能成為亟待研究和解決的問題。本文針對再生混凝土的自身的特點(diǎn),進(jìn)行了以下方面的研究：1.采用ASTM1202方法進(jìn)行再生混凝土電通量試驗(yàn),研究再生粗骨料取代率、礦物摻合料種類、不同的拌制方法和養(yǎng)護(hù)齡期對再生混凝土抗氯離子滲透性能的影響,同時(shí)分析以上因素對再生混凝土宏觀力學(xué)性能的影響。試驗(yàn)的結(jié)果表明：隨著再生粗骨料取代率的增加,再生混凝土的抗壓強(qiáng)度和抗氯離子滲透性呈下降趨勢。延長養(yǎng)護(hù)齡期有助于抗壓強(qiáng)度的和抗氯離子滲透性的提高,其提高幅度與拌制方法及再生粗骨料取代率有關(guān)。2.研究再生混凝土抗壓強(qiáng)度與抗氯離子滲透性的關(guān)系,結(jié)果表明：養(yǎng)護(hù)齡期為28d與60d的再生混凝土與電通量值之間的線性相關(guān)性較差。但齡期為28d的再生混凝土的抗壓強(qiáng)度與電通量呈二次多項(xiàng)式關(guān)系。3.通過課題組設(shè)計(jì)的應(yīng)力加載裝置研究再生粗骨料取代率、彎曲應(yīng)力水平、礦物摻合料種類、加載齡期對再生混凝土抗氯離子滲透性能的影響。試驗(yàn)結(jié)果表明：隨著再生粗骨料取代率的增加,再生混凝土的擴(kuò)散系數(shù)也隨之增大。隨著彎曲應(yīng)力水平的提高,礦物摻合料種類對氯離子擴(kuò)散系數(shù)的影響變小。當(dāng)加載應(yīng)力為0.5Pu時(shí),彎曲荷載對取代率為100%的再生混凝土的滲透性影響顯著大于50%取代率。因此荷載應(yīng)力成為影響再生混凝土滲透的主要因素。氯離子滲透深度與加載浸泡齡期的平方根具有較好的線性關(guān)系。4.依據(jù)現(xiàn)有普通混凝土的氯離子擴(kuò)散模型和本文試驗(yàn)結(jié)果初步擬合考慮再生粗骨料取代率、加載應(yīng)力水平的再生混凝土氯離子擴(kuò)散模型,采用經(jīng)驗(yàn)公式初步估算再生混凝土在氯鹽環(huán)境下的使用壽命。結(jié)果表明：改進(jìn)拌制方法,添加礦物摻合料均能不同程度的提高再生混凝土的耐久性。
[Abstract]:In recent years, the reuse of urban construction waste has received extensive attention. In many countries, broken concrete waste can be reused as aggregate, which can not only save natural high-quality aggregate effectively. Moreover, it is of great practical significance for the rational utilization of natural resources and the protection of ecological environment. The durability of recycled concrete has become the main factor which hinders the application of recycled concrete in engineering structure due to the defects such as pore interface and water absorption of recycled aggregate. In order to popularize the application of recycled concrete in practical engineering structures, the chloride penetration resistance of recycled concrete has become an urgent problem to be studied and solved. In this paper, according to the characteristics of recycled concrete, the following aspects of research have been carried out: 1. The electric flux test of recycled concrete was carried out by using ASTM1202 method. The influence of the substitution rate of recycled coarse aggregate, the type of mineral admixture, different mixing methods and curing age on the resistance to chloride ion penetration of recycled concrete was studied. At the same time, the influence of the above factors on the macro-mechanical properties of recycled concrete is analyzed. The experimental results show that the compressive strength and chloride ion permeability of recycled concrete decrease with the increase of the substitution rate of recycled coarse aggregate. Prolongation of curing age contributes to the improvement of compressive strength and resistance to chloride ion permeability, which is related to the mixing method and the replacement rate of recycled coarse aggregate. 2. The relationship between compressive strength and chloride ion permeability of recycled concrete is studied. The results show that the linear correlation between reclaimed concrete with age of 28 days and 60 days is poor. But the relationship between compressive strength and electric flux of recycled concrete aged 28 days is quadratic polynomial. 3. The influence of substitution rate of recycled coarse aggregate, bending stress level, type of mineral admixture and loading age on chloride ion penetration resistance of recycled concrete was studied by stress loading device designed by our research group. The experimental results show that the diffusion coefficient of recycled concrete increases with the increase of the substitution rate of recycled coarse aggregate. With the increase of bending stress, the effect of mineral admixtures on chloride diffusion coefficient becomes smaller. When the loading stress is 0.5Pu, the influence of bending load on the permeability of recycled concrete with 100% replacement rate is significantly greater than that of 50% replacement rate. Therefore, the load stress has become the main factor affecting the permeability of recycled concrete. There is a good linear relationship between chloride penetration depth and square root of immersion age. 4. According to the existing chloride ion diffusion model of ordinary concrete and the experimental results of this paper, the chloride ion diffusion model of recycled concrete considering the substitution rate of recycled coarse aggregate and loading stress level is preliminarily fitted. An empirical formula is used to estimate the service life of recycled concrete in chloride environment. The results show that the durability of recycled concrete can be improved by improving mixing method and adding mineral admixture.
【學(xué)位授予單位】：福州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU528

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