水泥基材料中氯离子结合机理及其影响因素研究进展

摘要/Abstract

摘要： 氯离子侵蚀是造成钢筋混凝土中钢筋锈蚀的主要原因,水泥基材料中氯离子的结合可以有效延缓钢筋的锈蚀。本文主要从三个方面进行了综述:(1)氯离子结合机理;(2)氯离子结合的测试方法及表征;(3)氯离子结合影响因素。具体研究了水泥组分及水化产物对氯离子的结合情况,以及不同测试方法及表征的应用范围、优缺点等,分析了辅助胶凝材料、养护龄期、氯盐阳离子类型、孔隙液pH值对氯离子结合的影响规律,并提出了还需进一步研究的问题,以便为今后钢筋混凝土寿命预测研究提供参考。

关键词: 水泥基材料, 氯离子结合, 水化产物, 测试方法, 影响因素

Abstract: Chloride ion erosion is the main cause of steel corrosion in cement-based materials.When chloride binding in cement,the corrosion of steel bars can be effectively delayed.This article summarizes from three aspects:(1) chloride binding mechanism;(2) test methods and characterization of chloride binding;(3) the influencing factors of chloride binding.Specific research are the cement components and hydration products how to binding chloride ion,as well as applicability of different test methods.Some factors that influenced chloride binding are analyzed,such as supplementary cement materials,curing time and pH etc.A further study is proposed in order to provide reference for the future study of reinforced concrete life prediction.

Key words: cement-based material, chloride binding, hydration product, test method, influencing factor

中图分类号:

TU528.04

史天尧, 陈星宇, 张敏, 刘倩. 水泥基材料中氯离子结合机理及其影响因素研究进展[J]. 硅酸盐通报, 2021, 40(1): 13-24.

SHI Tianyao, CHEN Xingyu, ZHANG Min, LIU Qian. Mechanism of Chloride Binding and Its Influence Factors inCement-Based Materials[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(1): 13-24.

参考文献

[1] 聂建国.钢-混凝土组合结构在海洋工程中的应用研究[J].钢结构(中英文),2020,35(1):20-33.
NIE J G.Application of steel-concrete composite structure in ocean engineering[J].Steel Construction,2020,35(1):20-33 (in Chinese).
[2] 牛荻涛,王庆霖.锈蚀开裂前混凝土中钢筋锈蚀量的预测模型[J].工业建筑,1996,26(4):8-10.
NIU D T,WANG Q L.Predeterminate model of steel corrosion extent in reinforced concrete structures before rpoducing corrosion crack[J].Industrial Construction,1996,26(4):8-10 (in Chinese).
[3] 宋宇峰,徐亦冬,弓扶元,等.氯盐侵蚀作用下混凝土内钢筋锈胀效应的化学-力学转化[J].硅酸盐学报,2020,48(8):1249-1255.
SONG Y F,XU Y D,GONG F Y,et al.Chemical-mechanical transformation of reinforcement corrosion expansion effect on concrete under chloride attack[J].Journal of the Chinese Ceramic Society,2020,48(8):1249-1255 (in Chinese).
[4] 马宏强,易成,朱红光,等.辅助胶凝材料对硬化水泥浆体结合氯离子的影响综述[J].材料导报,2018,32(S1):469-474.
MA H Q,YI C,ZHU H G,et al.Effect of auxiliary cementatious materials on the hardened cement paste chloride binding:an overview[J].Materials Review,2018,32(S1):469-474 (in Chinese).
[5] 王小刚,史才军,何富强,等.氯离子结合及其对水泥基材料微观结构的影响[J].硅酸盐学报,2013,41(2):187-198.
WANG X G,SHI C J,HE F Q,et al.Chloride binding and its effects on microstructure of cement-based materials[J].Journal of the Chinese Ceramic Society,2013,41(2):187-198 (in Chinese).
[6] YUAN Q,SHI C J,DE SCHUTTER G,et al.Chloride binding of cement-based materials subjected to external chloride environment-A review[J].Construction and Building Materials,2009,23(1):1-13.
[7] 郭明磊,肖佳,左胜浩.铝酸三钙水化浆体固化氯离子能力研究[J].建筑材料学报,2019,22(3):341-347.
GUO M L,XIAO J,ZUO S H.Chloride binding capacity of hydrated C₃A pastes[J].Journal of Building Materials,2019,22(3):341-347 (in Chinese).
[8] 马保国,姜文斌,谭洪波,等.铝酸三钙对盐溶液中氯离子的固化研究[J].武汉理工大学学报,2017,39(5):1-5.
MA B G,JIANG W B,TAN H B,et al.The binding of chloride ions in salt solution by tricalcium aluminate[J].Journal of Wuhan University of Technology,2017,39(5):1-5 (in Chinese).
[9] 蔡跃波,罗睿,王昌义.水泥-磨细矿渣水化产物—F盐的微结构分析[J].水利水运工程学报,2001(1):45-49.
CAI Y B,LUO R,WANG C Y.Microstructure analysis on Friedel's salt in hydrate of cement and GGBS[J].Hydro-Science and Engineering,2001(1):45-49 (in Chinese).
[10] SAITO M,KAWAMURA M.Effects of sodium chloride on the hydration products in the interfacial zone between cement paste and alkali-reactive aggregate[M]//Interfaces in Cementitious Composites.CRC Press,1992:49-58.
[11] 姜文斌.水泥矿物及其水化产物对氯离子的固化机理[D].武汉:武汉理工大学,2018.
JIANG W B.Binding mechanism of chloride ion by cement minerals and their hydration products[D].Wuhan:Wuhan University of Technology,2018 (in Chinese).
[12] 臧文洁,郭丽萍,曹园章,等.内掺氯离子与硫酸根离子在水泥净浆中的交互作用[J].材料导报,2019,33(8):1317-1321.
ZANG W J,GUO L P,CAO Y Z,et al.The interaction between chloride ion and sulfate ion doped in cement paste[J].Materials Reports,2019,33(8):1317-1321 (in Chinese).
[13] 曹园章,郭丽萍,臧文洁,等.氯盐和硫酸盐交互作用下水泥基材料的破坏机理综述[J].材料导报,2018,32(23):4142-4149.
CAO Y Z,GUO L P,ZANG W J,et al.Failure mechanism of cement-based materials subjected to the interaction between chloride and sulfate-a review[J].Materials Review,2018,32(23):4142-4149 (in Chinese).
[14] LI C B,MA B G,TAN H B,et al.Effect of triisopropanolamine on chloride binding of cement paste with ground-granulated blast furnace slag[J].Construction and Building Materials,2020,256:119494.
[15] GLASSER F.Role of chemical binding in diffusion and mass transportation[C].International Conference on Ion and Mass Transport in Cement-Based Materials,Toronto,Canada,1999:129-154.
[16] 臧文洁.南海环境多种侵蚀性介质与水泥基材料的交互作用研究[D].南京:东南大学,2018.
ZANG W J.Study on the interaction of cementitious materials and various aggressive media in the South China sea environment[D].Nanjing:Southeast University,2018 (in Chinese).
[17] 王绍东,黄煜镔,王智.水泥组分对混凝土固化氯离子能力的影响[J].硅酸盐学报,2000,28(6):570-574.
WANG S D,HUANG Y B,WANG Z.Concrete resistance to chloride ingress:effect of cement composition[J].Journal of the Chinese Ceramic Society,2000,28(6):570-574 (in Chinese).
[18] TALERO R,TRUSILEWICZ L.Morphological differentiation and crystal growth form of friedel’s salt originated from pozzolan and Portland cement[J].Industrial & Engineering Chemistry Research,2012,51(38):12517-12529.
[19] 严建华,宋娅琪,郝挺宇,等.氢氧化铁-硅灰改性水泥浆体系结合氯离子性能的研究[C]//第六届“全国先进混凝土技术及工程应用”研讨会论文集.广州,2018:51-58.
YAN J H,SONG Y Q,HAO T Y,et al.Study on the combined chloride ion performance of ferric hydroxide-silica fume modified cement slurry system[C]//Proceedings of the 6th “National Advanced Concrete Technology and Engineering Application” Symposium.Guangzhou,2018:51-58.
[20] SUI S Y,WILSON W,GEORGET F,et al.Quantification methods for chloride binding in Portland cement and limestone systems[J].Cement and Concrete Research,2019,125:105864.
[21] ZIBARA H.Binding of external chloride by cement pastes[D].Toronto:University of Toronto,2001.
[22] 肖佳,郭明磊,王大富,等.基于不同阳离子条件下硅酸盐水泥氯离子固化性能研究[J].硅酸盐通报,2016,35(9):2956-2961.
XIAO J,GUO M L,WANG D F,et al.Chloride binding capacity of Portland cement under the condition of different cations[J].Bulletin of the Chinese Ceramic Society,2016,35(9):2956-2961 (in Chinese).
[23] 肖佳,郭明磊.复合盐类侵蚀对硅酸盐水泥固化氯离子影响研究[J].功能材料,2016,47(12):12019-12024.
XIAO J,GUO M L.Chloride binding capacity of Portland cement subjected to complex salt corrosion[J].Journal of Functional Materials,2016,47(12):12019-12024 (in Chinese).
[24] FLOREA M V A,BROUWERS H J H.Chloride binding related to hydration products:part I:ordinary Portland cement[J].Cement and Concrete Research,2012,42(2):282-290.
[25] BALONIS M,LOTHENBACH B,LE SAOUT G,et al.Impact of chloride on the mineralogy of hydrated Portland cement systems[J].Cement and Concrete Research,2010,40(7):1009-1022.
[26] FLOREA M V A,BROUWERS H J H.Chloride binding related to hydration products:part I:ordinary Portland cement[J].Cement and Concrete Research,2012,42(2):282-290.
[27] 徐金霞,冯伟,蒋林华,等.表面活性剂对水泥浆体结合氯离子性能的影响[J].湖南大学学报(自然科学版),2017,44(12):74-81.
XU J X,FENG W,JIANG L H,et al.Effect of surfactants on property of binding chloride in cement paste[J].Journal of Hunan University (Natural Sciences),2017,44(12):74-81 (in Chinese).
[28] 胡晨光,王娟,白瑞英,等.氯离子侵蚀下水泥浆体中铝离子配位分布机理[J].功能材料,2018,49(6):6206-6212.
HU C G,WANG J,BAI R Y,et al.Distribution of aluminum ions coordination in cement pastes under chloride ions corrosion[J].Journal of Functional Materials,2018,49(6):6206-6212 (in Chinese).
[29] RAMACHANDRAN V S.Possible states of chloride in the hydration of tricalcium silicate in the presence of calcium chloride[J].Matériaux et Construction,1971,4(1):3-12.
[30] HU X,SHI C J,YUAN Q,et al.Changes of pore structure and chloride content in cement pastes after pore solution expression[J].Cement and Concrete Composites,2020,106:103465.
[31] 万小梅,刘国强,赵铁军,等.C-(A)-S-H对氯离子的吸附性能研究[J].建筑材料学报,2019,22(1):31-37.
WAN X M,LIU G Q,ZHAO T J,et al.Investigation on adsorption behavior of chloride by calcium silicate hydrate and calcium aluminum silicate hydrate[J].Journal of Building Materials,2019,22(1):31-37 (in Chinese).
[32] 王婷婷,储洪强,蒋林华,等.杂散电流与SO^2-₄共同作用下Cl^-浓度对砂浆结合氯离子稳定性的影响[J].混凝土,2019(12):23-28.
WANG T T,CHU H Q,JIANG L H,et al.Effect of chloride concentration on stability of bound chloride under the action of stray current and sulfate[J].Concrete,2019(12):23-28 (in Chinese).
[33] HIRAO H,YAMADA K,TAKAHASHI H,et al.Chloride binding of cement estimated by binding isotherms of hydrates[J].Journal of Advanced Concrete Technology,2005,3(1):77-84.
[34] TANG L P,NILSSON L O.Chloride binding capacity and binding isotherms of OPC pastes and mortars[J].Cement and Concrete Research,1993,23(2):247-253.
[35] 杨栎珩,余红发,卢一亭,等.混凝土氯离子结合能力的快速测定法[J].硅酸盐通报,2015,34(8):2304-2309.
YANG L H,YU H F,LU Y T,et al.Rapid determination method of chloride ion binding capability of concrete[J].Bulletin of the Chinese Ceramic Society,2015,34(8):2304-2309 (in Chinese).
[36] 王娟霞,杨元武.水泥结合氯离子的机理及影响因素[J].公路交通科技·应用技术版,2015,11(11):196-198+205.
WANG J X,YANG Y W.Mechanism and influencing factors of cement binding chloride ions[J].Journal of Highway and Transportation Research and Development,2015,11(11):196-198+205 (in Chinese).
[37] 陈书苹.改善混凝土结合氯离子性能的研究[D].长沙:中南大学,2007.
CHEN S P.Research on improving the performance of concrete combining chloride Ion[D].Changsha:Central South University,2007.
[38] 刘诗群,孙丛涛,牛荻涛.钢筋腐蚀临界氯离子浓度研究综述[J].硅酸盐通报,2014,33(1):83-91.
LIU S Q,SUN C T,NIU D T.Research review of critical chloride concentration in the corrosion of steel bar[J].Bulletin of the Chinese Ceramic Society,2014,33(1):83-91 (in Chinese).
[39] 王娟霞.水泥结合氯离子能力测试方法与影响因素研究[D].重庆:重庆大学,2015.
WANG J X.Study on determination of chloride method and influence factors of chloride binding of cement[D].Chongqing:Chongqing University,2015 (in Chinese).
[40] 何富强.硝酸银显色法测量水泥基材料中氯离子迁移[D].长沙:中南大学,2010.
HE F Q.Measurement of chloride migration in cement-based materials using AgNO₃ colorimetric method[D].Changsha:Central South University,2010 (in Chinese).
[41] TUUTTI K.Analysis of pore solution squeezed out of cement and mortar[J].Nordic Concr Res,1982,25(1):1-16.
[42] MOHAMMED T U,HAMADA H.Relationship between free chloride and total chloride contents in concrete[J].Cement and Concrete Research,2003,33(9):1487-1490.
[43] 金祖权,孙伟,赵铁军,等.在不同溶液中混凝土对氯离子的固化程度[J].硅酸盐学报,2009,37(7):1068-1072+1078.
JIN Z Q,SUN W,ZHAO T J,et al.Chloride binding in concrete exposed to corrosive solutions[J].Journal of the Chinese Ceramic Society,2009,37(7):1068-1072+1078 (in Chinese).
[44] WANG Y Z,LIU C X,TAN Y,et al.Chloride binding capacity of green concrete mixed with fly ash or coal gangue in the marine environment[J].Construction and Building Materials,2020,242:118006.
[45] JIANG W Q,SHEN X H,HONG S X,et al.Binding capacity and diffusivity of concrete subjected to freeze-thaw and chloride attack:a numerical study[J].Ocean Engineering,2019,186:106093.
[46] SANDBERG P.Studies of chloride binding in concrete exposed in a marine environment[J].Cement and Concrete Research,1999,29(4):473-477.
[47] 卢一亭.混凝土氯离子结合能力及其测试方法研究[D].南京:南京航空航天大学,2012.
LU Y T.Research on chloride binding capacity of concrete and its test method[D].Nanjing:Nanjing University of Aeronautics and Astronautics,2012 (in Chinese).
[48] MUTHULINGAM S,RAO B N.Chloride binding and time-dependent surface chloride content models for fly ash concrete[J].Frontiers of Structural and Civil Engineering,2016,10(1):112-120.
[49] XU J X,FENG W,JIANG L H,et al.Influence of surfactants on chloride binding in cement paste[J].Construction and Building Materials,2016,125:369-374.
[50] UKPATA J O,BASHEER P A M,BLACK L.Slag hydration and chloride binding in slag cements exposed to a combined chloride-sulphate solution[J].Construction and Building Materials,2019,195:238-248.
[51] TREJO D,SHAKOURI M,VADDEY N P,et al.Development of empirical models for chloride binding in cementitious systems containing admixed chlorides[J].Construction and Building Materials,2018,189:157-169.
[52] 勾密峰,管学茂,张海波.单硫型水化硫铝酸钙对氯离子的固化作用[J].建筑材料学报,2012,15(6):863-866.
GOU M F,GUAN X M,ZHANG H B.Chloride binding in monosulfoaluminate hydrate[J].Journal of Building Materials,2012,15(6):863-866 (in Chinese).
[53] CHEN Y J,JIANG L H,YAN X C,et al.Role of swelling agent and set-controlling admixtures on chloride binding and diffusion in cement matrix[J].Construction and Building Materials,2020,230:117009.
[54] THOMAS M D A,HOOTON R D,SCOTT A,et al.The effect of supplementary cementitious materials on chloride binding in hardened cement paste[J].Cement and Concrete Research,2012,42(1):1-7.
[55] YI C,MA H Q,ZHU H G,et al.Study on chloride binding capability of coal gangue based cementitious materials[J].Construction and Building Materials,2018,167:649-656.
[56] RAMÍREZ-ORTÍZ A E,CASTELLANOS F,CANO-BARRITA P F D J.Ultrasonic detection of chloride ions and chloride binding in Portland cement pastes[J].International Journal of Concrete Structures and Materials,2018,12(1):1-12.
[57] 王中平,杨浩宇,赵亚婷,等.不同养护温度下氯化钠对铝酸盐水泥水化的影响[J].材料导报,2019,33(14):2343-2347.
WANG Z P,YANG H Y,ZHAO Y T,et al.Effect of sodium chloride on hydration of calcium aluminate cement at different temperatures[J].Materials Reports,2019,33(14):2343-2347 (in Chinese).
[58] 陈友治,殷伟淞,孙涛,等.高掺量矿物掺合料对水泥基材料固化氯离子能力的影响[J].硅酸盐通报,2016,35(6):1664-1668.
CHEN Y Z,YIN W S,SUN T,et al.Effect of high addition of SCMs on the capacity of cement-based materials binding chloride ions[J].Bulletin of the Chinese Ceramic Society,2016,35(6):1664-1668 (in Chinese).
[59] 黄政宇,李涛.超高性能混凝土基体中氯离子结合特性的研究[J].铁道科学与工程学报,2016,13(10):1912-1918.
HUANG Z Y,LI T.Study of chloride binding property in ultra high performance concrete matrix[J].Journal of Railway Science and Engineering,2016,13(10):1912-1918 (in Chinese).
[60] 金祖权,孙伟,赵铁军,等.在不同溶液中混凝土对氯离子的固化程度[J].硅酸盐学报,2009,37(7):1068-1072+1078.
JIN Z Q,SUN W,ZHAO T J,et al.Chloride binding in concrete exposed to corrosive solutions[J].Journal of the Chinese Ceramic Society,2009,37(7):1068-1072+1078 (in Chinese).
[61] 莫利伟,耿健,柳俊哲,等.粉煤灰和矿粉双掺对水泥基材料固化氯离子能力的研究[J].硅酸盐通报,2013,32(12):2443-2448.
MO L W,GENG J,LIU J Z,et al.Study on fly ash and slag on binding of chloride ion into cement based materials[J].Bulletin of the Chinese Ceramic Society,2013,32(12):2443-2448 (in Chinese).
[62] 胡翔,史才军,李庆玲,等.矿物掺合料对水泥基材料孔溶液中氯离子浓聚的影响[J].硅酸盐学报,2015,43(4):376-385.
HU X,SHI C J,LI Q L,et al.Influence of mineral admixtures on chloride ion condensation of pore solution in cement-based materials[J].Journal of the Chinese Ceramic Society,2015,43(4):376-385 (in Chinese).
[63] 卢一亭,余红发,马好霞,等.海洋环境下混凝土自由氯离子扩散系数试验[J].建筑科学与工程学报,2011,28(4):86-91.
LU Y T,YU H F,MA H X,et al.Experiment on free chloride diffusion coefficient of concrete exposed to marine environment[J].Journal of Architecture and Civil Engineering,2011,28(4):86-91 (in Chinese).
[64] WANG Y Y,SHUI Z H,GAO X,et al.Understanding the chloride binding and diffusion behaviors of marine concrete based on Portland limestone cement-alumina enriched pozzolans[J].Construction and Building Materials,2019,198:207-217.
[65] SHI Z G,GEIKER M R,DE WEERDT K,et al.Role of calcium on chloride binding in hydrated Portland cement-metakaolin-limestone blends[J].Cement and Concrete Research,2017,95:205-216.
[66] 申世贵,耿健,孙家瑛,等.硫酸钠侵蚀对蒸养粉煤灰水泥石氯离子固化性能的影响[J].硅酸盐通报,2019,38(5):1516-1521.
SHEN S G,GENG J,SUN J Y,et al.Effect of sodium sulfate solution attack on chloride ions binding capacity of fly ash harden cement paste with steam curing[J].Bulletin of the Chinese Ceramic Society,2019,38(5):1516-1521 (in Chinese).
[67] 廖灵青.大掺量矿物掺合料混凝土抗氯盐侵蚀性能研究[D].南宁:广西大学,2016.
LIAO L Q.Research on the performance of resistance to chloride ion erosion of the concrete with high volume mineral admixtures[D].Nanning:Guangxi University,2016 (in Chinese).
[68] 李东,朱月圆,耿健,等.矿物掺合料和CLDH对水泥基材料氯离子固化性能研究[J].西安建筑科技大学学报(自然科学版),2019,51(3):344-349.
LI D,ZHU Y Y,GENG J,et al.A study on curing charateristics of chloride ions binding in cement based materials with mineral admixture and CLDH[J].Journal of Xi’an University of Architecture & Technology (Natural Science Edition),2019,51(3):344-349 (in Chinese).
[69] 张士萍,沙学成,宗兰.氯盐环境下粉煤灰及矿粉对砂浆性能的影响[J].硅酸盐通报,2017,36(3):893-898.
ZHANG S P,SHA X C,ZONG L.Effect of fly ash and slag on performance of mortar exposed to chloride solution[J].Bulletin of the Chinese Ceramic Society,2017,36(3):893-898 (in Chinese).
[70] 勾密峰,黄飞,管学茂.矿渣对氯离子的固化作用[J].材料导报,2014,28(10):120-122+144.
GOU M F,HUANG F,GUAN X M.The binding effect of slag on the chloride ions[J].Materials Review,2014,28(10):120-122+144 (in Chinese).
[71] 岳青滢,丁宁,王石付,等.阳离子类型对混凝土固化氯离子能力的影响机理[J].混凝土,2014(1):12-16+20.
YUE Q Y,DING N,WANG S F,et al.Effect of cationic types on concrete resistance to chloride ingress[J].Concrete,2014(1):12-16+20 (in Chinese).
[72] ARYA C,BUENFELD N R,NEWMAN J B.Factors influencing chloride-binding in concrete[J].Cement and Concrete Research,1990,20(2):291-300.
[73] WOWRA O S M.Sorption of chlorides on hydrated cements and C₃S pastes[M]//Frost Resistance of Concrete.London:CRC Press,1997:156-164.
[74] 勾密峰,管学茂,孙倩.水化硅酸钙对氯离子的吸附[J].建筑材料学报,2015,18(3):363-368.
GOU M F,GUAN X M,SUN Q.Adsorption of chloride ion by calcium silicate hydrate[J].Journal of Building Materials,2015,18(3):363-368 (in Chinese).
[75] CHEN P,MA B G,TAN H B,et al.Effects of amorphous aluminum hydroxide on chloride immobilization in cement-based materials[J].Construction and Building Materials,2020,231:117171.
[76] TRITTHART J.Chloride binding in cement II.The influence of the hydroxide concentration in the pore solution of hardened cement paste on chloride binding[J].Cement and Concrete Research,1989,19(5):683-691.
[77] 潘从玲,储洪强,蒋林华,等.氯盐-硫酸盐共存环境中阳离子类型对氯离子结合能力的影响[J].混凝土,2019(4):28-32+36.
PAN C L,CHU H Q,JIANG L H,et al.Influence of cation types on binding capacity of chloride in chloride-sulfate coexistent environment[J].Concrete,2019(4):28-32+36 (in Chinese).
[78] 勾密峰,管学茂,张海波.水化程度对水泥基材料固化氯离子的影响[J].材料导报,2011,25(20):125-127.
GOU M F,GUAN X M,ZHANG H B.Effect of degree of hydration of cement-based materials on chloride binding[J].Materials Review,2011,25(20):125-127 (in Chinese).
[79] HEMSTAD P,MACHNER A,DE WEERDT K.The effect of artificial leaching with HCl on chloride binding in ordinary Portland cement paste[J].Cement and Concrete Research,2020,130:105976.
[80] 于丽波,蒋林华,储洪强,等.混凝土中结合氯离子研究综述[J].科学技术与工程,2020,20(9):3387-3393.
YU L B,JIANG L H,CHU H Q,et al.Review of researches on binding chloride ions in concrete[J].Science Technology and Engineering,2020,20(9):3387-3393 (in Chinese).