轻质多孔混凝土防水剂的研究进展
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摘要
多孔混凝土具有质量轻、保温隔热、防火不燃等特性,是一种新型节能建筑材料。但多孔混凝土因孔隙率高、表面自由能大,导致其易吸水,严重影响了其强度和保温性能。因此,多孔混凝土的防水问题亟需研究解决。多孔混凝土的防水研究主要集中在两个方面:一是基体结构优化,二是利用防水剂改性。基体结构优化主要通过改善混凝土的孔结构及孔间壁的晶胶比,以降低其吸水性。由于基体结构优化的防水效果有很大的局限性,因此通过防水剂改性提高多孔混凝土防水性能的研究更受关注。防水剂在多孔混凝土表面或在气孔和毛细孔内形成疏水膜层,由此可降低混凝土的吸水性或是静水压力下的透水性。常用的防水剂为有机硅类、脂肪酸盐类及石蜡乳液类等。有机硅系主要通过长链有机基团取代,以获得具有良好疏水性的端基。脂肪酸盐系通过羧酸基与Ca2+形成"反毛细管效应"的沉淀物,或者是活性物质与基体结合,阻塞孔道而防水;石蜡乳液则通过对颗粒物形成包裹,使其表面由亲水性转化为憎水性,由此降低吸水率。防水剂的作用方式分为两种:一是防水剂对基体表面的隔离,包括封闭型和开放型;二是防水剂与基体的结合,包括反应型和结合型。多孔混凝土的防水方法主要有两种:一是在表面涂覆、浸渍或喷涂防水剂的表面防水;二是在混凝土制备过程中掺加防水剂的内掺防水。表面防水效果因防水剂的渗透深度不同而异,与混凝土连通孔的比例、孔隙率的大小及防水剂的粘度和表面张力有关。内掺防水受防水剂的类型及其与硅酸盐基体的相容性等影响较大。但从防水的持久性和综合效果方面考量,内掺防水法更具优势。目前,主要通过吸水率、氯离子渗透系数和静态水接触角测量等方法来表征与评价多孔混凝土的防水效能,这方面的研究相对滞后,亟需建立一套完整的评价体系。本文综述了轻质多孔混凝土的防水研究进展,重点阐述了防水剂的类型及其作用机理、防水剂的作用方式、防水剂的改性方法及表征与评价方法,提出了存在的问题及今后的发展趋势,以期为多孔混凝土材料防水性能的研究提供参考。
Porous concrete is a novel energy-saving building material,which features light weight,excellent thermal insulation,outstanding fire resistance and non-combustibility. However,it suffers a severe water-absorbing problem due to its high porosity and high surface free energy.The issue,degrading seriously the strength and thermal insulation properties,restrains their further applications. Therefore,it is imperative to address the waterproof problem of the porous concrete.The matrix structure optimization and water repellent modification are two primary directions in current waterproof researches. The matrix structure is optimized by adjusting of the pore structure of the concrete and the crystal/gel ratio of pore walls to reduce the water absorption of concretes. Yet,the waterproof performance,achieved by the optimization of matrix structure,exhibits severe limitations. Hence,the method of the waterproofing agent modification to improve the waterproof performance gains more attentions.The water repellent accomplishes the reduction of water absorption of the concrete or the water permeability under hydrostatic pressure through forming a hydrophobic film on the surface of porous concretes and/or in pores. Commonly,water repellents consist of silicones,fatty acid salts and paraffin emulsions. The silicone system achieves a good hydrophobicity via the substitution of long-chain organic group. The waterproof performance of the fatty acid salt is obtained by two methods:( ⅰ) forming a precipitate,which shows"anti-capillary effect",by the reaction of carboxylic acid group and Ca~(2+); or( ⅱ) blocking pores through the active substance,which binds to the matrix. The paraffin emulsion achieves the reduced water absorption property through converting the surface property of particles from hydrophilicity into water repellency by encapsulation.The action mode of the water repellent includes two types. One is the isolation of the substrate's surface,including the closed-type and the opened-type. The other is the combination with the matrix,including the reaction and the binding type. Two main methods are utilized for the waterproofing of porous concrete. One is the surface waterproof,including coating,impregnating or spraying water repellent onto the surface. The other is the interior waterproofing,achieved by adding the water repellent into concretes during the preparation. The surface waterproofing performance varies depending on the penetration depth of the water repellent,and is related with the ratio of the communication hole of the concrete,the porosity,the viscosity of the water repellent,and the surface tension. The internal waterproofing is greatly affected by the type of the waterproofing agent and the compatibility of the silicate matrix. Therefore,the internal waterproofing method exhibits superiorities from the view of durability and comprehensive effects of waterproofing.For the characterization and evaluation of the waterproof performance of porous concrete,the measurement of water absorption,chloride ion permeability and static water contact angle are mainly employed. However,the research in this aspect is relatively lagging. It is urgent to establish a complete evaluation system.Herein,we reviewed the research progress of lightweight porous concrete waterproofing. The types,action mechanism and the action mode of water repellent,waterproof modification methods and characterization and evaluation methods were emphasized. The existing problems and future development trends were proposed. The insight gained by this work could provide reference for the further study of waterproof performance of porous concrete materials.
Porous concrete is a novel energy-saving building material,which features light weight,excellent thermal insulation,outstanding fire resistance and non-combustibility. However,it suffers a severe water-absorbing problem due to its high porosity and high surface free energy.The issue,degrading seriously the strength and thermal insulation properties,restrains their further applications. Therefore,it is imperative to address the waterproof problem of the porous concrete.The matrix structure optimization and water repellent modification are two primary directions in current waterproof researches. The matrix structure is optimized by adjusting of the pore structure of the concrete and the crystal/gel ratio of pore walls to reduce the water absorption of concretes. Yet,the waterproof performance,achieved by the optimization of matrix structure,exhibits severe limitations. Hence,the method of the waterproofing agent modification to improve the waterproof performance gains more attentions.The water repellent accomplishes the reduction of water absorption of the concrete or the water permeability under hydrostatic pressure through forming a hydrophobic film on the surface of porous concretes and/or in pores. Commonly,water repellents consist of silicones,fatty acid salts and paraffin emulsions. The silicone system achieves a good hydrophobicity via the substitution of long-chain organic group. The waterproof performance of the fatty acid salt is obtained by two methods:( ⅰ) forming a precipitate,which shows"anti-capillary effect",by the reaction of carboxylic acid group and Ca~(2+); or( ⅱ) blocking pores through the active substance,which binds to the matrix. The paraffin emulsion achieves the reduced water absorption property through converting the surface property of particles from hydrophilicity into water repellency by encapsulation.The action mode of the water repellent includes two types. One is the isolation of the substrate's surface,including the closed-type and the opened-type. The other is the combination with the matrix,including the reaction and the binding type. Two main methods are utilized for the waterproofing of porous concrete. One is the surface waterproof,including coating,impregnating or spraying water repellent onto the surface. The other is the interior waterproofing,achieved by adding the water repellent into concretes during the preparation. The surface waterproofing performance varies depending on the penetration depth of the water repellent,and is related with the ratio of the communication hole of the concrete,the porosity,the viscosity of the water repellent,and the surface tension. The internal waterproofing is greatly affected by the type of the waterproofing agent and the compatibility of the silicate matrix. Therefore,the internal waterproofing method exhibits superiorities from the view of durability and comprehensive effects of waterproofing.For the characterization and evaluation of the waterproof performance of porous concrete,the measurement of water absorption,chloride ion permeability and static water contact angle are mainly employed. However,the research in this aspect is relatively lagging. It is urgent to establish a complete evaluation system.Herein,we reviewed the research progress of lightweight porous concrete waterproofing. The types,action mechanism and the action mode of water repellent,waterproof modification methods and characterization and evaluation methods were emphasized. The existing problems and future development trends were proposed. The insight gained by this work could provide reference for the further study of waterproof performance of porous concrete materials.
引文
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38 Luo Y,Li H L,Li Y L. New Building Materials,2007,34(12),48(in Chinese).罗逸,李海玲,李云朗.新型建筑材料,2007,34(12),48.
39 Horgnies M,Willieme P,Gabet O. Progress in Organic Coatings,2011,72(3),360.
40 Herb H,Gerdes A,Brenner-WeiG. Cement and Concrete Research,2015,70,77.
2 Zhou C Y,Wei J X,Yu Q J,et al. Journal of Wuhan University of Technology,2007,29(4),22(in Chinese).周春英,韦江雄,余其俊,等.武汉理工大学学报,2007,29(4),22.
3 Muhammad N Z,Keyvanfar A,Majid M Z A,et al. Construction and Building Materials,2015,101(1),80.
4 Ding M. A study on the property of foam concrete with water repellents.Master’s Thesis,Hunan University,China,2011(in Chinese).丁曼.防水性泡沫混凝土研究.硕士学位论文,湖南大学,2011.
5 Xiang Q D,Wu Y,Li J,et al. New Building Materials,2014,41(10),46 (in Chinese).相秋迪,吴叶,李菊,等.新型建筑材料,2014,41(10),46.
6 Wei Y R. Influence of durability to modified organosilicon waterproofing agent on concrete. Master’s Thesis,Xi’an University of Architecture and Technology,China,2005(in Chinese).卫亚儒.改性有机硅防水剂的试验研究.硕士学位论文,西安建筑科技大学,2005.
7 Stupart A W. Chemistry and Industry,1993,10,809.
8 Zhao M X,Wu S P,Liu J S,et al. The World of Building Materials,2009,30(3),51(in Chinese).赵满喜,吴少鹏,刘杰胜,等.建材世界,2009,30(3),51.
9 Gao J F. Effects of aqueous SAP frost resistance and impermeability the concrete. Master’s Thesis,Harbin Institute of Technology,China,2014(in Chinese).高健夫.憎水处理SAP对混凝土抗渗抗冻性的影响.硕士学位论文,哈尔滨工业大学,2014.
10 Zhu H J. Silicone Materials,2007,21(6),338(in Chinese).朱淮军.有机硅材料,2007,21(6),338.
11 Shen C Y,Huang J J,Wang Q,et al. Construction Technology,2016,45(9),80.沈川越,黄佳健,汪群,等.施工技术,2016,45(9),80.
12 Mu Y,Zhou M,Luo L. Shanghai Coatings,2013,51(9),26(in Chinese).穆颖,周铭,罗琳.上海涂料,2013,51(9),26.
13 Sudbrink B,Moradllo M K,Hu Q,et al. Cement and Concrete Research,2017,92,121.
14 Wang Z P. Effect of superhydrophobic coating on the frost resistance and anti-ice performance of concrete. Master’s Thesis,Harbin Institute of Technology,China,2015(in Chinese).王宗鹏.超疏水涂层对混凝土抗冻性及防冰性影响研究.硕士学位论文,哈尔滨工业大学,2015.
15 Wu P. New Building Materials,2003(6),55(in Chinese).吴平.新型建筑材料,2003(6),55.
16 Zhang J. Journal of Yangzhou Polytechnic Institute,2008(2),55(in Chinese).张杰.扬州工业职业技术学院论丛,2008(2),55.
17 Wang Y,Mu M Y. Construction and Budget,2017(11),39(in Chinese).王野,慕明晏.建筑与预算,2017(11),39.
18 Weisheit S,Unterberger S H,Bader T,et al. Construction and Building Materials,2016,110,145.
19 Hu Y Y,He T S,Li J H. Sichuan Building Science,2010,36(3),214(in Chinese).胡延燕,何廷树,李家辉.四川建筑科学研究,2010,36(3),214.
20 Zeng C H,Zhang Y Q,Li X W,et al. New Building Materials,2007,34(4),46(in Chinese).曾昌洪,张玉奇,李兴旺,等.新型建筑材料,2007,34(4),46.
21 Wang X F. Experimental study on the property and optimization of autoclaved aerated concrete. Master’s Thesis,Xi’an University of Architecture and Technology,China,2006(in Chinese).王秀芬.加气混凝土性能及优化的试验研究.硕士学位论文,西安建筑科技大学,2006.
22 Li S J,Qian H P,Huang X H,et al. Journal of Building Materials,2017(6),970(in Chinese).李书进,钱红萍,黄小红,等.建筑材料学报,2017(6),970.
23 Hosoda A,Matsuda Y,Kobayashi K. Journal of Advanced Concrete Technology,2010,8(3),291.
24 Teng L W,Huang R,Zou S Y,et al. Advanced Materials Research,2013,834,749.
25 Tao X M,Hang J R,Wu J,et al. China Building Waterproofing,2010(18),17.陶新明,黄金荣,吴璟,等.中国建筑防水,2010(18),17.
26 Shan X B,Zhu W Z. Low Temperature Architecture Technology,2015,37(2),9(in Chinese).单星本,朱卫中.低温建筑技术,2015,37(2),9.
27 Beben D,Manko Z. Construction and Building Materials,2011,25(1),282.
28 Li Y,Li Z G,Qin X M,et al. China Sciencepaper,2016,11(1),49(in Chinese).李悦,李战国,秦宪明,等.中国科技论文,2016,11(1),49.
29 Li X L,Li G Z,Wang L,et al. Applied Mechanics and Materials,2014,541,57.
30 Ma C,Chen B. Construction and Building Materials,2016,123,106.
31 Almusallam A A,Khan F M,Dulaijan S U,et al. Cement and Concrete Composites,2003,25(4),473.
32 Rodrigues M P M C,Costa M R N,Mendes A M,et al. Materials and Structures,2000,33(10),618.
33 Hao C L,Zhou Y C,Li Z,et al. Low Temperature Architecture Technology,2012,34(12),14(in Chinese).郝聪林,周运灿,李治,等.低温建筑技术,2012,34(12),14.
34 Jiang R,Zhang P,Zhao T J,et al. New Building Materials,2010,37(9),61(in Chinese).姜蓉,张鹏,赵铁军,等.新型建筑材料,2010,37(9),61.
35 Zhang P,Zhao T J,Dai J G,et al. China Civil Engineering Journal,2011,44(3),72(in Chinese).张鹏,赵铁军,戴建国,等.土木工程学报,2011,44(3),72.
36 Tian L,Gu X F,Yang K,et al. China Concrete and Cement Products,2017(10),6(in Chinese).田砾,顾晓帆,杨可,等.混凝土与水泥制品,2017(10),6.
37 Falchi L,Zendri E,Müller U,et al. Cement and Concrete Composites,2015,59,107.
38 Luo Y,Li H L,Li Y L. New Building Materials,2007,34(12),48(in Chinese).罗逸,李海玲,李云朗.新型建筑材料,2007,34(12),48.
39 Horgnies M,Willieme P,Gabet O. Progress in Organic Coatings,2011,72(3),360.
40 Herb H,Gerdes A,Brenner-WeiG. Cement and Concrete Research,2015,70,77.