【摘要】：混凝土材料的大量消耗導(dǎo)致天然砂石資源短缺,而由工業(yè)污染形成的酸雨致使混凝土構(gòu)筑物耐久性顯著下降。針對上述問題,本文主要以廢瓷磚為再生粗細(xì)骨料、以廢瓷磚粉為摻合料,制備新型綠色再生混凝土。根據(jù)湖南省酸雨的特點,進(jìn)行室內(nèi)模擬酸雨溶液干濕循環(huán)試驗,研究酸雨侵蝕對再生混凝土中性化深度的影響,并將之與室外暴露一年的實測數(shù)據(jù)相比較。通過測試分析不同侵蝕環(huán)境條件下混凝土的外觀侵蝕、質(zhì)量變化率、抗壓強(qiáng)度、相對動彈性模量以及中性化深度等指標(biāo),探討再生骨料對混凝土抗酸雨侵蝕能力的影響,并從微觀角度分析其侵蝕機(jī)理。研究結(jié)果表明:在室外暴露試驗中,與原生碎石混凝土相比,未摻廢瓷磚粉摻合料的廢瓷磚再生骨料混凝土的質(zhì)量損失率略大,但其抗壓強(qiáng)度較高,而摻有廢瓷磚粉的廢瓷磚再生混凝土,其質(zhì)量損失率更大,抗壓強(qiáng)度較低。在模擬酸雨溶液侵蝕條件下,與原生碎石混凝土相比,未摻廢瓷磚粉摻合料的廢瓷磚再生粗骨料混凝土的抗壓強(qiáng)度較高,質(zhì)量變化率較小,經(jīng)酸雨侵蝕后的中性化深度最小,表明廢瓷磚再生粗骨料混凝土的抗侵蝕能力優(yōu)于原生碎石混凝土;而摻入廢瓷磚粉的再生混凝土抗壓強(qiáng)度隨廢瓷磚粉摻量的增加而降低,中性化深度隨廢瓷粉摻量的增加而增大,建議廢瓷磚粉摻量控制在20%以內(nèi)為宜。廢瓷磚再生混凝土中性化深度隨p H值的降低而增大。在侵蝕早期,p H值大小對混凝土受酸雨侵蝕程度影響較小;但在侵蝕后期,隨p H值降低,混凝土受酸雨侵蝕加劇。與標(biāo)準(zhǔn)養(yǎng)護(hù)環(huán)境相比,在室內(nèi)模擬酸雨侵蝕下再生混凝土的化學(xué)結(jié)合水含量較低,且廢瓷磚再生混凝土的化學(xué)結(jié)合水含量隨廢瓷磚粉摻量的增加而降低。在相同酸雨侵蝕條件下,混凝土表層堿度降低,水化產(chǎn)物分解引起表層脫落;隨侵蝕程度加深,混凝土內(nèi)部生成大量石膏晶體,造成體積膨脹引起開裂。與原生碎石混凝土相比,廢瓷磚再生混凝土的化學(xué)結(jié)合水含量較低,內(nèi)部顯微結(jié)構(gòu)更致密。
[Abstract]:The large consumption of concrete materials leads to the shortage of natural sand and stone resources, while the acid rain caused by industrial pollution significantly decreases the durability of concrete structures. In order to solve the above problems, a new type of green recycled concrete was prepared by using waste ceramic tile as recycled coarse aggregate and waste ceramic tile powder as admixture. According to the characteristics of acid rain in Hunan province, the dry and wet cycle tests of simulated acid rain solution were carried out in laboratory to study the effect of acid rain erosion on the neutralization depth of recycled concrete, and compared it with the measured data of outdoor exposure for one year. The influence of recycled aggregate on the corrosion resistance of concrete to acid rain is discussed by testing and analyzing the indexes of concrete under different erosion environment, such as appearance erosion, quality change rate, compressive strength, relative dynamic modulus of elasticity and neutralization depth. The erosion mechanism is analyzed from the microscopic point of view. The results show that in outdoor exposure test, the mass loss rate of recycled aggregate concrete without waste ceramic tile powder admixture is slightly larger than that of primary crushed stone concrete, but its compressive strength is higher. The mass loss rate and compressive strength of recycled concrete with waste ceramic tile powder are higher and lower. Under the condition of simulated acid rain solution erosion, the recycled coarse aggregate concrete without waste ceramic tile powder has higher compressive strength, lower quality change rate and the smallest neutralization depth after acid rain erosion, compared with the original crushed stone concrete. The results show that the anti-erosion ability of recycled coarse aggregate concrete of waste ceramic tile is better than that of original crushed stone concrete. However, the compressive strength of recycled concrete mixed with waste ceramic tile powder decreases with the increase of waste ceramic tile powder content, and the neutralization depth increases with the increase of waste ceramic powder content. It is suggested that the content of waste ceramic tile powder should be controlled within 20%. The neutralization depth of recycled concrete increases with the decrease of pH value. At the early stage of erosion, the value of, p H has little effect on the degree of acid rain erosion of concrete, but at the late stage of erosion, with the decrease of pH value, the corrosion of concrete is aggravated by acid rain. Compared with the standard curing environment, the chemical binding water content of recycled concrete under simulated acid rain is lower, and the chemical binding water content of recycled concrete decreases with the increase of waste ceramic tile powder content. Under the same condition of acid rain erosion, the alkalinity of the surface layer of concrete decreases, the decomposition of hydration products results in shedding of the surface layer, and with the deepening of the erosion degree, a large number of gypsum crystals are formed in the concrete, resulting in volume expansion and cracking. Compared with primary crushed stone concrete, recycled concrete of waste ceramic tile has lower water content and denser microstructure.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TU528

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