本文選題：減縮劑 + 收縮��； 參考：《北京交通大學(xué)》2013年碩士論文

【摘要】：各種混凝土外加劑在工程中發(fā)揮著越來(lái)越重要的作用。在實(shí)際工程施工及使用的過(guò)程中發(fā)現(xiàn),摻加減水劑混凝土的收縮、裂縫問(wèn)題比普通混凝土更加凸顯。摻減水劑會(huì)使得混凝土早期自收縮和干燥收縮增大,并且使收縮的時(shí)間提前。研究表明,采用摻減縮劑的方法在降低收縮率、減小裂縫的同時(shí)能夠保持混凝土力學(xué)性能,改善拌合物性能和耐久性。 本文通過(guò)對(duì)三種減縮劑分別進(jìn)行干縮試驗(yàn),得到一種減縮效果明顯、力學(xué)性能改善顯著的減縮高性能混凝土外加劑,之后研究該復(fù)合外加劑對(duì)混凝土抗裂性能、新拌性能及耐久性的影響。主要成果和結(jié)論如下： 1、通過(guò)對(duì)現(xiàn)有干燥收縮測(cè)量?jī)x器的比較和分析,提出一種立桿式收縮測(cè)量方法,這種方法不僅精度高,而且適用于長(zhǎng)期收縮的測(cè)量。 2、在保持坍落度相同的條件下,對(duì)不同摻量的減縮劑A、B進(jìn)行水泥膠砂干燥收縮試驗(yàn),結(jié)合力學(xué)性能試驗(yàn)結(jié)果,得到減縮劑B減縮率高于減縮劑A的結(jié)論。 3、相同條件下,對(duì)不同摻量的減縮劑B、D進(jìn)行混凝土干燥收縮和力學(xué)性能試驗(yàn),結(jié)果表明,摻量為1%的減縮劑B減縮效果最明顯,且力學(xué)性能較好。 4、對(duì)不同規(guī)范提出的圓環(huán)開裂試模進(jìn)行比較分析,得到適用于不同骨料粒徑的圓環(huán)試模尺寸。 5、在圓環(huán)開裂試驗(yàn)中,摻加復(fù)合型減縮外加劑的膠砂圓環(huán)試件沒有產(chǎn)生開裂,說(shuō)明該復(fù)合外加劑抗裂效果良好。 6、對(duì)比減縮率、力學(xué)性能及抗裂試驗(yàn)結(jié)果,相同種類和摻量的減縮防裂高性能外加劑效果呈現(xiàn)一致性。 7、減縮防裂型高性能外加劑既能配成早強(qiáng)型混凝土又能配成緩凝型混凝土,以適應(yīng)不同工程的實(shí)際需要。 8、減縮防裂型高性能外加劑改善了混凝土內(nèi)部孔結(jié)構(gòu)和孔徑分布,因此能有效提高混凝土的抗氯離子滲透性能和力學(xué)性能。
[Abstract]:All kinds of concrete admixtures play a more and more important role in engineering. In the course of practical construction and application, it is found that the shrinkage and crack problem of concrete with water reducing agent is more prominent than that of ordinary concrete. The addition of water reducing agent increases the early self-shrinkage and drying shrinkage of concrete and advances the shrinkage time. The results show that the shrinkage rate and crack can be reduced by adding shrinkage reducing agent, while the mechanical properties of concrete can be maintained, and the performance and durability of the mixture can be improved. In this paper, through dry shrinkage test of three kinds of shrinkage reducing agents, a shrinkage reducing high performance concrete admixture with obvious shrinkage reduction effect and significant improvement in mechanical properties is obtained, and then the anti-cracking performance of the composite admixture to concrete is studied. Effects of fresh mix performance and durability. The main results and conclusions are as follows: 1. Through the comparison and analysis of the existing dry shrinkage measuring instruments, a vertical rod shrinkage measurement method is proposed, which not only has high precision, And it is suitable for the measurement of long-term shrinkage. 2. Under the condition of keeping the same slump, the dry shrinkage test of cement sand with different content of shrinkage reducer AZB is carried out, and the results of mechanical properties test are combined. The conclusion that the shrinkage rate of reducing agent B is higher than that of reducing agent A is obtained. 3. Under the same conditions, the dry shrinkage and mechanical properties of concrete with different content of shrinkage reducer BfD are tested, the results show that, The shrinkage reduction effect of 1% reducer B is the most obvious, and the mechanical properties are better. 4. The size of ring test die suitable for different aggregate particle size was obtained. 5. In the ring cracking test, no cracking was found in the cemented sand ring specimen with compound reducing admixture. The results show that the anti-cracking effect of the compound admixture is good. 6. The results of shrinkage reduction, mechanical properties and crack resistance test are compared. The effect of the same kind and amount of anti-shrinkage and anti-crack high performance admixture is consistent. 7. The shrinkage and anti-crack type high performance admixture can be used to make both early-strength concrete and retarded concrete. In order to meet the practical needs of different projects. 8, the anti-shrinkage and anti-cracking high performance admixture can improve the pore structure and pore size distribution of concrete, so it can effectively improve the chloride ion permeability and mechanical properties of concrete.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU528.042

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