复杂环境下混凝土改性问题研究
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摘要
混凝土的耐久性问题一直是混凝土材料科学的重大研究课题。在外部环境恶劣的情况下,混凝土结构的耐久性问题和强度同样重要,它将直接影响到工程的安全性。
随着高性能混凝土技术的广泛应用,优质矿物掺合料的使用已不仅仅是有利于解决环保和节能问题,它己经成为混凝土改性的一种重要组分。为改善混凝土的结构与性能,在混凝土中常采用不同的活性矿物掺合料复掺技术。本论文研究的目的是以粉煤灰、矿渣、硅藻土和沸石作为矿物掺合料,通过设计矿物掺合料种类和掺量对混凝土改性的正交试验,研究在氯盐、硫酸盐和冻融复杂环境下掺活性矿物掺合料混凝土的耐久性,寻求最佳的矿物掺合料种类和掺量,找到在氯盐、硫酸盐和冻融复杂环境下改善混凝土耐久性的途径。最后,通过X射线衍射和扫描电子显微镜分析,研究了矿物掺合料对混凝土改性的微观机理,揭示了微观结构与混凝土性能间的内在联系。
主要研究结论如下:
1.矿物掺合料的掺入可以改善混凝土的耐久性,但掺入量大时混凝土的早期强度降低,而后期强度迅速增加,赶上甚至超过不加掺合料的混凝土。
2.四种矿物掺合料对混凝土耐久性都有一定的改性作用,但硅藻土和沸石的改性作用要优于粉煤灰和矿渣,且粉煤灰、矿渣、硅藻土和沸石的最佳掺量分别是15%、20%、10%和5%。
3.矿渣的CaO含量相对很高,它能加速二次水化反应的进行,所以矿渣的掺入在一定程度上提高了混凝土的早期强度。
4.X射线衍射和扫描电子显微镜分析表明矿物掺合料的适量掺入能够改变水泥水化产物的组成,并改善混凝土的孔结构,孔分布更加合理,有害大孔减少,结构更密实,从而显著改善了混凝土的耐久性。
Concrete durability is a significant subject in concrete science at all times. Under abominable external environment conditions, the concrete structure durability is as important as its strength, because it has direct impact on the safety of work.
With the development of high performance concrete technology, using high-quality mineral admixtures is not only advantageous to solving the problem of environmental protection and energy conservation, Moreover, it has been a kind of important component in improving concrete. In order to improve the structure and function of concrete, there is often the usage of the technique which put various different active mineral admixtures in concrete. In this paper, the purpose of the study is using fly ash, slag, diatomite and zeolite as mineral admixtures, by designing orthogonal test with types and dosages of mineral admixtures for concrete improvement, to study the concrete durability adding various different active mineral admixtures under the complex conditions of chloride, sulfate and freeze-thaw erosion, to get the types and dosages of mineral admixtures of the best durability concrete by analyze of experimental results, to find the way to improve the durability of concrete under the complex conditions of chloride, sulfate and freeze-thaw erosion. Finally, with the aid of analysis methods such as x-ray diffraction and scanning electron microscope, study micro-mechanism of concrete improvement in mineral admixtures, in order to reveal the internal relation between micro-structure and concrete performance.
The main study conclusions are as follows:
1. Adding active mineral admixtures can improve the durability of concrete, but the early age strength can be decreased, and the late age strength can be increased quickly, catching up with even more than concrete without mineral admixtures in strength.
2. The four kinds of mineral admixtures all have some function in improving the concrete durability, but function of diatomite and zeolite is superior to slag and fly ash for concrete improvement, and cement replaced by 15%, 20%, 10% and 5% is the best for fly ash, slag, diatomite and zeolite.
3. CaO content of the slag is higher by comparison, it can speed up the second hydration reaction, so the concrete early strength can be improved with the incorporation of the slag for a certain extent.
4. With the aid of analysis methods such as x-ray diffraction and scanning electron microscope, the results demonstrate that adding mineral admixtures in a suitable dosage can improve the pores structure and distribution, reduce the harmful big pores, concrete makes denser, thereby improving concrete durability obviously.
随着高性能混凝土技术的广泛应用,优质矿物掺合料的使用已不仅仅是有利于解决环保和节能问题,它己经成为混凝土改性的一种重要组分。为改善混凝土的结构与性能,在混凝土中常采用不同的活性矿物掺合料复掺技术。本论文研究的目的是以粉煤灰、矿渣、硅藻土和沸石作为矿物掺合料,通过设计矿物掺合料种类和掺量对混凝土改性的正交试验,研究在氯盐、硫酸盐和冻融复杂环境下掺活性矿物掺合料混凝土的耐久性,寻求最佳的矿物掺合料种类和掺量,找到在氯盐、硫酸盐和冻融复杂环境下改善混凝土耐久性的途径。最后,通过X射线衍射和扫描电子显微镜分析,研究了矿物掺合料对混凝土改性的微观机理,揭示了微观结构与混凝土性能间的内在联系。
主要研究结论如下:
1.矿物掺合料的掺入可以改善混凝土的耐久性,但掺入量大时混凝土的早期强度降低,而后期强度迅速增加,赶上甚至超过不加掺合料的混凝土。
2.四种矿物掺合料对混凝土耐久性都有一定的改性作用,但硅藻土和沸石的改性作用要优于粉煤灰和矿渣,且粉煤灰、矿渣、硅藻土和沸石的最佳掺量分别是15%、20%、10%和5%。
3.矿渣的CaO含量相对很高,它能加速二次水化反应的进行,所以矿渣的掺入在一定程度上提高了混凝土的早期强度。
4.X射线衍射和扫描电子显微镜分析表明矿物掺合料的适量掺入能够改变水泥水化产物的组成,并改善混凝土的孔结构,孔分布更加合理,有害大孔减少,结构更密实,从而显著改善了混凝土的耐久性。
Concrete durability is a significant subject in concrete science at all times. Under abominable external environment conditions, the concrete structure durability is as important as its strength, because it has direct impact on the safety of work.
With the development of high performance concrete technology, using high-quality mineral admixtures is not only advantageous to solving the problem of environmental protection and energy conservation, Moreover, it has been a kind of important component in improving concrete. In order to improve the structure and function of concrete, there is often the usage of the technique which put various different active mineral admixtures in concrete. In this paper, the purpose of the study is using fly ash, slag, diatomite and zeolite as mineral admixtures, by designing orthogonal test with types and dosages of mineral admixtures for concrete improvement, to study the concrete durability adding various different active mineral admixtures under the complex conditions of chloride, sulfate and freeze-thaw erosion, to get the types and dosages of mineral admixtures of the best durability concrete by analyze of experimental results, to find the way to improve the durability of concrete under the complex conditions of chloride, sulfate and freeze-thaw erosion. Finally, with the aid of analysis methods such as x-ray diffraction and scanning electron microscope, study micro-mechanism of concrete improvement in mineral admixtures, in order to reveal the internal relation between micro-structure and concrete performance.
The main study conclusions are as follows:
1. Adding active mineral admixtures can improve the durability of concrete, but the early age strength can be decreased, and the late age strength can be increased quickly, catching up with even more than concrete without mineral admixtures in strength.
2. The four kinds of mineral admixtures all have some function in improving the concrete durability, but function of diatomite and zeolite is superior to slag and fly ash for concrete improvement, and cement replaced by 15%, 20%, 10% and 5% is the best for fly ash, slag, diatomite and zeolite.
3. CaO content of the slag is higher by comparison, it can speed up the second hydration reaction, so the concrete early strength can be improved with the incorporation of the slag for a certain extent.
4. With the aid of analysis methods such as x-ray diffraction and scanning electron microscope, the results demonstrate that adding mineral admixtures in a suitable dosage can improve the pores structure and distribution, reduce the harmful big pores, concrete makes denser, thereby improving concrete durability obviously.
引文
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[2]谢友均,许辉,龙广成.混凝土在不同溶液中的抗冻融循环性能研究.高强与高性能混凝土及其应用专题研讨会论文集
[3]刘连新.察尔汗盐湖及超盐渍土地区混凝土腐蚀及预防初探.建筑材料学报,2001,4(4):395-400
[4]王复生,孙瑞莲,秦小鹃.察尔汗盐湖条件下水泥混凝土耐久性调查研究,硅酸盐通报,2002(4):16-22
[5]Maher.A.Bader.Performance of concrete in a coastal environment.Cement & Concrete Composites,2003(25):539-548
[6]赵铁军,李秋义.高强与高性能混凝土及其应用.北京:中国建材工业出版社,2004,4
[7]Sun W,Zhang Y M,Yan H D.Damage and Damage Resistance of High Strength-Concrete Under the Action ofLoad and Freezing-thawing Cycles.Cement and Concrete Research,1999,29(6):1519-1523
[8]Schneider U,Chen S W.Behavior of High Performance Concrete Under Ammonium Nitrate Solution and Sustained Load,ACI Materials Journal,1999,96(1):47-51
[9]龙庆.冻融循环与碱一硅酸反应对混凝土及砂浆体的复合效应研究.西南交通大学研究生学位论文,2005.11
[10]龚洛书,柳春圃.混凝土的耐久性及其防护修补.北京:中国建筑工业出版社,1990
[11]李清富,赵国藩,王恒栋.混凝土结构的耐久性预评估.混凝土,1995(1):65-68
[12]金祖权.西部地区严酷环境下混凝土的耐久性与寿命预测(国家863计划项目资助2003AA33X100).东南大学博士学位论文,2006年8月.分类号:Tu528.01
[13]杜天玲,孟云芳,王治虎.提高混凝土抗冻耐久性技术的研究综述.宁夏农学院报,2002(2):33-35
[14]Yamato,T.,Emotoy,Soeda M,Strength and Thawing Resistance of Concrete Incorporating Condensed Silica Fume.ACI SP-91,1986,PP.1095-1117
[15]Malhotra,V.M,Mechanical Properties andThawing Resistance of Non-air-entrained and Air -entrained Condensed Silica Fume Concrete Using ASIMTest c666 ProceedingsA&B.ACI SP-91,1986,pp.1069-1094
[16]Darette,G.G.,Malhotra,V.M,Mechanical Properties,durability and drying shrinlage of Portland Cement conrete incorporating silica fume.Cement,concrete and aggregtes,ASTM,Vol.5,No.1,1983,pp.3-13
[17]丁雁飞,孙景进.硅粉混凝土抗冻性研究.混凝土,1991,6(3):41-45
[18]范沈抚.高强硅粉混凝土抗冻性及气泡结构的试验研究.水利学报,1990,7(7):20-24
[19]张思德,成秀珍.矿渣混凝土的长期强度和抗冻融耐久性研究.西北建筑工程学院学报,1999,9(3):6-9
[20]PKMehta Advancements in Concrete Technology Concrete InternationalJune 1999
[21]PowersTC.Void spacing as basis for producing air-entrained concrete[J].ACI Joumal,Proceedings,1954,50(9):741-760
[22]PowersTC.Freezing effect in concrete[J].ACI Publication SP 47,durability of Concrete 1975,sp,47-1:1-10
[23]Linhua Jiang Baoyu Lin,and Yuebo Cai,Studies onHydration inHigh-Volum Fly Ash Concrete Binders.ACI Matenals Journd,V96,No.6,Novenmber-December1999
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