【摘要】：混凝土的早期凍害會(huì)造成其內(nèi)部孔結(jié)構(gòu)的嚴(yán)重?fù)p傷,而混凝土的孔結(jié)構(gòu)特征強(qiáng)烈地影響著混凝土材料的抗?jié)B性能和力學(xué)性能。研究孔隙微觀結(jié)構(gòu)的變化,探討早期受凍環(huán)境下混凝土的強(qiáng)度和抗?jié)B性能的發(fā)展規(guī)律,掌握早期凍害的作用過程具有重要的理論意義和工程應(yīng)用價(jià)值。本文將分形理論應(yīng)用到早期受凍水泥基材料的研究中,根據(jù)分形維數(shù)的無標(biāo)度性對(duì)孔徑進(jìn)行自主劃分,并驗(yàn)證分形維數(shù)的物理意義即定量描述孔結(jié)構(gòu)的復(fù)雜程度。研究了早期受凍條件下,不同試驗(yàn)因素的水泥基材料氯離子擴(kuò)散和強(qiáng)度的發(fā)展變化規(guī)律,并基于孔結(jié)構(gòu)給出了變化規(guī)律的內(nèi)在機(jī)制,研究了早期受凍溫度對(duì)水泥基材料孔結(jié)構(gòu)發(fā)展規(guī)律的影響,并闡述了早期凍害的作用過程。試驗(yàn)結(jié)果表明,早期受凍水泥基材料的孔結(jié)構(gòu)具有明顯的分形特性,利用無標(biāo)度性對(duì)孔徑進(jìn)行自主劃分,發(fā)現(xiàn)其孔徑范圍不受試驗(yàn)因素的影響,但凈漿和砂漿的孔徑分布并不相同。在早期受凍的條件下,對(duì)于預(yù)養(yǎng)24h的凈漿,10~350nm的孔徑影響早期強(qiáng)度增長,350~6000nm的孔徑影響后期強(qiáng)度的增長;對(duì)于預(yù)養(yǎng)24h的砂漿而言,10~2000nm的孔徑是影響強(qiáng)度的主要因素;預(yù)養(yǎng)不充分對(duì)凈漿強(qiáng)度造成的損失非常大,并且預(yù)養(yǎng)24h后大于6000nm的孔徑基本趨于穩(wěn)定;而砂漿中大于2000nm的孔徑在影響強(qiáng)度的同時(shí),也受預(yù)養(yǎng)時(shí)間的影響,同樣預(yù)養(yǎng)24h之后該范圍內(nèi)的孔徑趨于穩(wěn)定。每個(gè)區(qū)域內(nèi)的孔徑對(duì)水泥基材料的抗?jié)B性能都有一定的影響,對(duì)于預(yù)養(yǎng)24h的砂漿,10~100nm范圍內(nèi)孔徑作用效果更大,而對(duì)于預(yù)養(yǎng)24h的凈漿,10~6000nm范圍內(nèi)的孔徑則是影響氯離子擴(kuò)散系數(shù)的主要因素。早期受凍會(huì)改變水泥基材料內(nèi)部的孔徑分布,其中受凍溫度會(huì)影響孔徑的變化范圍,研究發(fā)現(xiàn)早期受凍的作用過程是孔結(jié)構(gòu)劣化和填補(bǔ)修復(fù)同時(shí)進(jìn)行的過程,在這過程中液態(tài)水扮演著重要的角色,水分的遷移、冰晶的形成與擴(kuò)散對(duì)孔結(jié)構(gòu)造成了不可恢復(fù)的損失。
[Abstract]:The early freezing damage of concrete will cause serious damage to its internal pore structure, and the pore structure characteristics of concrete strongly affect the impermeability and mechanical properties of concrete materials. It is of great theoretical significance and engineering application value to study the change of pore microstructure, to discuss the development law of strength and impermeability of concrete under early freezing environment, and to master the action process of early freezing injury. In this paper, fractal theory is applied to the study of early frozen cement based materials. According to the scale-free fractal dimension, the pore size is divided independently, and the physical meaning of fractal dimension is verified, that is, quantitatively describing the complexity of pore structure. The development and variation of chloride ion diffusion and strength of cement based materials under the condition of early freezing were studied, and the internal mechanism of the change law was given based on the pore structure. The effect of early freezing temperature on the development of pore structure of cement based materials was studied, and the process of early freezing injury was described. The experimental results show that the pore structure of the early frozen cement-based material has obvious fractal characteristics, and the pore size range is not affected by the experimental factors by using the scale-free property to divide the pore size independently. But the pore size distribution of mortar and mortar is different. Under the condition of early freezing, the pore size of 10350nm of pre-cultured slurry for 24 hours affects the increase of early strength, the pore size of 350,600 nm affects the increase of later strength, and the pore diameter of 102000nm is the main factor affecting the strength of mortar after 24 hours of pre-culture. The loss of pulp strength caused by insufficient pre-culture is very large, and the pore size larger than 6000nm tends to be stable after 24 hours of preconditioning, while the pore size larger than 2000nm in mortar affects the strength as well as the preconditioning time. The aperture in this range tends to be stable after 24 hours of preconditioning. The pore size in each region has a certain effect on the impermeability of cement-based materials, and it is more effective in the range of 10100 nm for pre-cultured mortar for 24 hours. The pore size in the range of 106000nm is the main factor affecting the diffusion coefficient of chloride ions. Early freezing will change the pore size distribution in cement based materials, in which freezing temperature will affect the range of pore size. It is found that the process of early freezing is the process of pore structure deterioration and repair simultaneously. Liquid water plays an important role in this process. The migration of water and the formation and diffusion of ice crystals cause irrecoverable loss of pore structure.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 韓汪洋;朱雯;劉明亮;謝彥君;張樹輝;;關(guān)于負(fù)溫下水泥強(qiáng)度發(fā)展的研究[J];水泥工程;2016年02期

2 謝超;王起才;李盛;惠兵;;不同水灰比、養(yǎng)護(hù)條件下混凝土孔結(jié)構(gòu)、抗壓強(qiáng)度與分形維數(shù)之間的關(guān)系[J];硅酸鹽通報(bào);2015年12期

3 李盛;李建新;王起才;馬莉;董朝陽;;水泥砂漿封閉孔隙凍脹破壞問題的力學(xué)分析[J];公路交通科技;2015年04期

4 董淑慧;馮德成;江守恒;朱衛(wèi)中;;早期受凍溫度對(duì)負(fù)溫混凝土微觀結(jié)構(gòu)與強(qiáng)度的影響[J];黑龍江科技學(xué)院學(xué)報(bào);2013年01期

5 金珊珊;張金喜;陳春珍;陳煒林;;水泥砂漿孔結(jié)構(gòu)分形特征的研究[J];建筑材料學(xué)報(bào);2011年01期

6 劉陽;賈俊超;王磊;;多孔結(jié)構(gòu)孔隙特征的分形研究[J];河南城建學(xué)院學(xué)報(bào);2011年01期

7 張建波;文俊強(qiáng);王宏霞;葉家元;張文生;;混凝土孔體積分形維數(shù)及其與氯離子滲透性和強(qiáng)度的關(guān)系[J];混凝土;2010年05期

8 馮竟竟;傅宇方;陳忠輝;茍緒軍;;溫度影響下水泥基材料孔隙分形特征試驗(yàn)研究[J];武漢理工大學(xué)學(xué)報(bào);2009年23期

9 韋江雄;余其俊;曾小星;白瑞英;;混凝土中孔結(jié)構(gòu)的分形維數(shù)研究[J];華南理工大學(xué)學(xué)報(bào)(自然科學(xué)版);2007年02期

10 唐明,李曉;多種因素對(duì)混凝土孔結(jié)構(gòu)分形特征的影響研究[J];沈陽建筑大學(xué)學(xué)報(bào)(自然科學(xué)版);2005年03期

相關(guān)博士學(xué)位論文 前2條

1 劉潤清;多因素影響下低溫混凝土抗凍臨界強(qiáng)度的研究[D];大連理工大學(xué);2011年

2 段安;受凍融混凝土本構(gòu)關(guān)系研究和凍融過程數(shù)值模擬[D];清華大學(xué);2009年

，

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