【摘要】：混凝土耐久性是指結(jié)構(gòu)在規(guī)定的使用年限內(nèi)，在各種環(huán)境條件作用下，不需要額外的費(fèi)用加固處理而保持其安全性、正常使用的能力。我國地域遼闊，有相當(dāng)一部分地區(qū)處于寒冷地帶，其混凝土結(jié)構(gòu)遭受到不同程度的凍融破壞，嚴(yán)重時(shí)凍脹開裂使混凝土結(jié)構(gòu)的承載能力降低�？箖鲂允腔炷两Y(jié)構(gòu)耐久性設(shè)計(jì)中的一個(gè)重要指標(biāo)，研究混凝土的凍融損傷，對(duì)合理選擇混凝土類型以及采取適當(dāng)防治措施，充分發(fā)揮材料性能，提高設(shè)計(jì)水平，降低工程造價(jià)具有非常重要的意義。 本文依托湖北省自然科學(xué)基金項(xiàng)目(項(xiàng)目批準(zhǔn)號(hào)2012FFB00607)“高性能水泥基復(fù)合材料凍融損傷特性研究”，展開對(duì)凍融循環(huán)作用下混凝土材料抗凍性能的試驗(yàn)研究，主要內(nèi)容如下： 1.總結(jié)了國內(nèi)外研究學(xué)者對(duì)混凝土材料損傷的研究理論以及各種損傷模型，詳細(xì)分析了混凝土的凍融損傷機(jī)理。論文根據(jù)混凝土的凍融破壞可以看作是材料的疲勞損傷這一觀點(diǎn)，利用Aas-Jakobsen材料疲勞損傷壽命公式建立了混凝土凍融損傷模型，經(jīng)過分析，混凝土材料參數(shù)β越大，其抗凍性越差。 2.對(duì)三種強(qiáng)度等級(jí)均為C50的自密實(shí)混凝土、普通混凝土、輕骨料混凝土試塊進(jìn)行了凍融循環(huán)試驗(yàn)，循環(huán)次數(shù)依次為0、50、100、150、200、250、300次，并且每循環(huán)50次進(jìn)行了質(zhì)量損失和動(dòng)彈性模量的測(cè)定。 3.論文根據(jù)試驗(yàn)結(jié)果建立了混凝土質(zhì)量損失率和凍融循環(huán)次數(shù)的關(guān)系曲線以及相對(duì)動(dòng)彈性模量與凍融循環(huán)次數(shù)的關(guān)系曲線，根據(jù)試驗(yàn)現(xiàn)象以及實(shí)驗(yàn)數(shù)據(jù)，分析影響混凝土材料抗凍性的因素。 4.論文根據(jù)建立的凍融損傷模型，通過對(duì)實(shí)驗(yàn)數(shù)據(jù)進(jìn)行非線性擬合，得到模型中相關(guān)的材料參數(shù)β曲線，然后將其代入損傷模型，得到了不同種類混凝土的理論損傷量與凍融循環(huán)次數(shù)的關(guān)系曲線。最后將理論曲線與實(shí)際的損傷量進(jìn)行對(duì)比，結(jié)果表明，理論分析與實(shí)際損傷量基本一致。 5.論文研究結(jié)果表明，輕骨料混凝土的抗凍性最強(qiáng)，自密實(shí)混凝土的抗凍性最差。這主要是因?yàn)樵趦鋈谘h(huán)試驗(yàn)中，影響混凝土抗凍性的材料參數(shù)β會(huì)隨著循環(huán)次數(shù)的遞增，而不斷增大，其中自密實(shí)混凝土的材料參數(shù)增長(zhǎng)速度最快，因此自密實(shí)混凝土最先被凍壞。
[Abstract]:The durability of concrete refers to the ability of the structure to maintain its safety and normal use under various environmental conditions without extra expense for reinforcement and treatment within the specified service life. China has a vast territory and a considerable part of the region is in the cold zone. The concrete structure suffers different degrees of freezing and thawing damage. When the frost heaving cracking seriously reduces the bearing capacity of concrete structure. The frost resistance is an important index in the durability design of concrete structure. To study the freeze-thaw damage of concrete, to select the concrete type reasonably and to take appropriate prevention measures, to give full play to the material performance and to improve the design level. It is of great significance to reduce the project cost. Based on Hubei Natural Science Foundation Project (Project Grant No. 2012FFB00607), "study on Freeze-thaw damage characteristics of High-Performance cement Matrix Composites", an experimental study on frost resistance of concrete under freeze-thaw cycle is carried out in this paper. The main contents are as follows: 1. The research theory of concrete material damage and various damage models are summarized, and the mechanism of freeze-thaw damage of concrete is analyzed in detail. According to the view that the freeze-thaw failure of concrete can be regarded as the fatigue damage of material, the model of freeze-thaw damage of concrete is established by using the formula of fatigue damage life of Aas-Jakobsen material. The worse the frost resistance. 2. The freeze-thaw cycle tests were carried out on three specimens of self-compacting concrete, ordinary concrete and lightweight aggregate concrete with C _ (50) strength grade. The number of cycles was 050100150 200250300 times, respectively. The mass loss and dynamic modulus of elasticity were measured 50 times per cycle. According to the test results, the relationship curves between the mass loss rate and the freeze-thaw cycles of concrete and the relative dynamic modulus of elasticity and the number of freeze-thaw cycles are established. According to the experimental phenomena and experimental data, the relationship between the relative dynamic modulus of elasticity and the number of freeze-thaw cycles is established. Analysis of factors affecting frost resistance of concrete materials. 4. According to the freeze-thaw damage model, the material parameter 尾 curve of the model is obtained by nonlinear fitting of the experimental data, and then the damage model is substituted. The relationship between the theoretical damage of different kinds of concrete and the number of freeze-thaw cycles is obtained. Finally, the theoretical curve is compared with the actual damage amount. The results show that the theoretical analysis is basically consistent with the actual damage amount. The results show that the frost resistance of lightweight aggregate concrete is the strongest, and that of self-compacting concrete is the worst. This is mainly because in the freeze-thaw cycle test, the material parameter 尾, which affects the frost resistance of concrete, will increase with the increase of cycle times, among which the material parameter of self-compacting concrete will increase fastest. As a result, self-compacting concrete is the first to be frozen.
【學(xué)位授予單位】：湖北工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU375

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