2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Dai, JG

Jin, ZQ

Wittmann, FH

Zhang, P

Zhao, TJ

PolyU Institutional Repository

? 13 ?? 1 ?2010? 2??　?　?　?　?　?JOURNAL OF BUILDING M ATERIALS　 Vol.13 , No.1Feb., 2010????:2009-03-02;????:2009-04-22????:????????????(973)??(2009CB623203);????????????(50739001);????????????(50708046);?????????????(Z2006F02;ZR2009FQ014)????:?　?(1981—),? ,????? ,?????????.E-mail:zh p0221@163.com　　????:1007-9629(2010)01-0070-05???????????????????张　鹏1 , 　戴建国2 , 　赵铁军1 , 　F .H.Wittmann1 , 3 , 　金祖权1(1.?????? ???????? ,?? ?? 266033;2.?????? ????????? ,??;3.Aedif icat Inst itute Freiburg , Freiburg , Germany)??:对小尺寸钢筋混凝土梁诱导了不同宽度的裂缝 ,通过吸水试验研究了带裂缝混凝土的吸水性能 ,以及混凝土表面涂覆硅烷和内掺硅烷对水分侵入的抑制效果.结果显示 ,带裂缝混凝土在吸水 4 h 内 ,其吸水量与时间平方根呈良好的线性关系;混凝土吸水系数随裂缝宽度的增大而增大 ,且呈“S”形状;经表面防水处理的混凝土 ,水分以气态形式沿裂缝进入混凝土 ,贯穿憎水区后逐渐凝结并最终与外界建立吸水通道 ,防水效果取决于憎水层厚度和裂缝宽度;内掺硅烷的混凝土整体憎水 ,即使裂缝宽度达 0.4 mm ,其防水效果仍保持不变.???:裂缝;防水处理;硅烷;憎水层;吸水系数?????:TU528.1　　　?????:A 　　　doi:10.3969/ j.i ssn.1007-9629.2010.01.015Water Absorption Property of Cracked Concrete andEffect of Water Repellent TreatmentZ H ANG Peng1 , 　DA I J ian-g uo2 , 　Z H AO Tie-jun1 , 　F.H .Wittmann1 , 3 , 　J IN Z u-quan 1(1.Centre for Durability of Concre te , Qingdao Technological University , Qingdao 266033 , China;2.Depar tment o f Civil and Structural Engineering , Hong Kong Po ly technic University , Hong Kong , China;3.Aedificat Institute Freiburg , Freiburg , Germany)Abstract:A series of small size RC beams w ere int roduced w ith different crack w idths and then treatedwi th si lane-based w ater repellent on the surface and inside the concrete.Their w ater abso rption propert ieswere then evaluated.The results indicate that a linear function of square roo t of time could describe w ellthe w ater absorption fo r cracked concrete w ithin 4 h o f the test , the coeff icient of w ate r abso rption increa-ses w ith the increase of crack w idth fo llow ing an “S” shape.Fo r the cracked concrete wi th surface w aterrepellent treatment , water v apor dif fuses into concrete along the crack depth and then devapo rates behindthe hydrophobic layer , and f inally a w ater abso rpt ion pathw ay w i th the outside is established.The effi-ciency of w ater repellent t reatment depends on the thickness o f hydrophobic laye r and the crack width.While the internal w ater repellent concrete is integ ral ly hydrophobic , the eff iciency o f treatment is w ell-maintained even the crack w idth is increased up to 0.4 mm .Key words:crack;water repellent t reatment;si lane;hydrophobic layer;coef ficient of w ater abso rpt ion　　?????????????????? ,????????????? ,?????????????(?? 、?? 、???? 、?-???? 、???? 、?????)? ,??????????????????????????[ 1-3] .????????????????????????????? ,?????????????????????? ,????????????????????????.?? ,???????????????????????????? ,?????????????????? ,???????????????????? ,???????????????????????.???????? ,??????????????????????????????????????????[ 4-7] .??????????? ,?????????????????????.??????????????? 2?????????????????????(0.1 ～ 0.5mm)??? ,????????????????????????????.1　??1.1　?????????????????????????????? ,???????????(100 mm×100 mm×300 mm)??????????? ,????????????????.???????:P ·O42.5??????? ,???342 m2/kg ,??????? 1;????? 2.5 mm ???????;???.?????????????????? 2.?????????????? ,???????????????? 6???? 8 mm 、??? 305mm ?????(?? 1).???? 24 h ??? ,???????((20±3)°C , RH >95%)?????　? 1　???????Table 1　Chemical composition(by mass)of cement %SiO 2 Fe2O 3 Al2O 3 CaO MgO SO3 K2O Na2O IL22.90 3.10 7.35 57.50 4.07 1.52 0.47 0.99 2.72? 2　?????????Table 2　Mix proportion of concrete and i ts compressive strengthm(W)m(C)Mix proportion/(kg·m-3)Cemen t S an d WaterCompressive st rength/MPa3 d 7 d 28 d0.6 500 1 650 300 10.3 20.0 29.2? 1　???????Fig.1　Loca tion of steel reinfor cements(size:mm)???.?? ,???????????????????? ,??????????.1.2　????????????????????????????? ,?????????????????? ,???????????????? 2%(???????)?????.2 ?????? 、????????????? 3??.????????????? 14 d?????????? ,???????(RH ≈50%)????? 7 d ,??????? ,???????????? 7 d;?????????????? 14 d?????????? ,???????????? 14 d.? 3　???????????Table 3　Component of si lane-based products used in this project and their dosagesCode Type C om ponen t Act ive silane content/ % Dosage Method00 No t reatmentG100G400S toC ryl H G200(silane gel) Alkylalkoxy si lane 100 100 g/m2400 g/m2 Surface pain tingIW P rotectosil MH 50(silane em ulsion) S ilane 50 2% mass of cement Internal addit ion1.3　??????????? ,?????????? 3 ???? 25 ～ 30 mm ???????????? ,???????????????????????????(?? 2).????????????? ,??????????????.???????????????????????????????.??????? 0.10 mm ? 0.50 mm ??.?? ,????????? 100 mm ???(?? 2??)???????????.???????????? 4?? ,????????? 2??? ,?????????.1.4　????????? ,?????? 55°C ?????4d ,?????????? ,?????? ,??????????????????????? 4??71　? 1 ? ?　? ,?:???????????????????　　　????? ,????????? ,????????????????????.?????? ,???????????(5±1)mm.????????????????? ,???????.? 4　??????????????Table 4　Crack width on bottom surface of specimens and specimens' codeSpecim en code 00 00-15 00-25 00-50 G100 G100-12 G100-28Crack wid th/mm — 0.15 0.25 0.50 — 0.12 0.28Specim en code G400 G400-10 G400-35 IW IW-10 IW-30 IW-40Crack wid th/mm — 0.10 0.35 — 0.10 0.30 0.40? 2　?????????Fig.2　Schema tic o f specimen for crack-inducing2　?????2.1　?????????????????????????????????????????? , ?????????????????[ 8-9] .?????? ,?????????? ,???????????????????.???????????????? ,????? ,????????????????[ 8-9] :ΔW =A · t (1)??:ΔW ???????????? , g/m2 ;A ????? , g ·m-2 ·h-0.5 ;t????? , h.????????????????????????? 3??.?? 3???? ,??????????? ,???????? ,????????????????????????????.?????????4 h? ,???????????????? ,??????????? ,????? 3　????????????????????Fig.3 　Wate r abso rption curves fo r untreated specimenswithout and with crack?????????????????????? ,?????????????[ 10] .??????????????????????????.　　?? 4 h???????????(?? 3???),???????????????????0.15 ,0.25 ,0.50 mm ?????? ,???? 4???????.?? 4??:(1)?????????????????? ,??????????? ,??????????.???????????????????“S”?????(2)??? ,????????? 4?????.A = A1 -A21 +e(wc-A3)/ A4 +A2 (2)??:wc ????????;A1 , A2 , A3 ? A4 ????????.???? , A1 ? A2 ???“S”??????????;A3 ????????? ,??????????? A3 ????????? ,???????????? ,????????????;A4 ?????????????.(2)“S”????????????? 0.200 mm ,?0.135 ～0.265 mm ????????????????.(3)?????? 0.135 mm ? ,????????????? 2?;?????? 0.135 ～ 0.265 mm? ,????????????? 2 ～ 5?;??????? 0.265 mm ? ,??????????????.　　????????????????????? ,???????????????????????? ,????????????.???????? ,???????????????? ,??????????????????.???? ,????????????????????????????????????? 0.135 mm ,??? JTJ 268 —96《???????????》?????????.72 ?　?　?　?　?　? ? 13 ?　? 4　???????????????????F ig.4　Coefficient of w ater absorption as a function ofcrack w idth for untrea ted specimen2.2　????????????????????????????????????????????????.????????????? ,????????? ,??????????????????????????? ,????????????? ,?????????? ,????????.??????? G100? G400????????????(?????)??? 2.2 mm? 4.4 mm ,??????? IW ??????.?5???????????????????????.?? ,2?????????????????? ,????????? G100????????? ,?????????.? 5　??????????????????????Fig.5　Wate r abso rption cur ves fo r w ate r repellent t reatedand untreated specimens w ithout cr ack　　?????????????????? 6.?? 6(a)???? ,????????????????? 2??? ,?????? 48 h??? ,????????????????????????? ,??????;48 h ? , G400 ?????????????????? ,? 0.10 mm ???G400-10????????????(G400)??????? ,? G100?????????? ,???????? 0.28 mm ????????? ,?????????????????????????? ,??????????????.??6(b)?? ,????????????????????? ,???????????????? ,???????????????????????.(a)Su rface w ater repellent t reated specimen(b)In ternal w ater repellent specimen? 6　????????????????Fig.6　Water absorption curve s fo r w ater repellent treatedspecemens befo re and af te r cracking　　???????????????????????? 7(a)???[ 11] .??????????? ,?????????? ,??????????? ,???????????????.????????? ,????????????????????? ,??????????? ,??????????????? ,???????????????? ,????????????? ,????6(a)?G100-28??? 48 h???????????.???????????????? ,??????????????????????;?? ,???????????? ,?????????????.????? , ???????????0.1 mm ????? ,????????????????? 4.4 mm ??????????????.???????????? ,?????? ,???????? ,???????????? ,???????????????????? ,?????????????????(?? 7(b)??),??????? ,??????????? ,????????? 0.4 mm ,??????? ,????73　? 1 ? ?　? ,?:???????????????????　　　???????.????????????? ,??400 g/m2 ??????????? ,??????? ,??? 100 g/m2 ???????????;?????????????? ,???????????????? ,??????????? ,??????????.　　　　　(a)Water uptake th rough cracked surface water repellent concrete　　　　　　　　(b)In contact w ith water for crackedinternal w ater repellent concrete? 7　???????????????????Fig.7　Schema tic o f wa te r penetr ation into cracked wa te r repellent concre te3　??1.??????? 4 h ? ,???????????????????;???? ,?????????;????????????????“ S”??;???????? 0.135 ～ 0.265 mm ? ,???????????? ,???????????.2.?????????????? ,??????????????????????? ,?????????????? ,???????????;????????(≤2.2 mm)、???????(≥0.28 mm)? , ??? 48 h ???????;????????(≤0.1 mm)???? , 132 h??????? 4.4 mm ????.???? ,????????? ,??????????????????????.3.?????????????? 0.4 mm ,??????? ,???????????? ,?????????? ,???????????????? ,???????????????????????.????:[ 1 ] 　M EHTA P K.Durabilit y—Crit ical i ssues for the future[ J] .C on crete International , 1997 , 19(7):69-76.[ 2 ] 　???.??????[ M] .??:????? , 2006:121-149.　　　ZHAO Tie-jun.Permeabili ty of concrete[ M ] .Beijing:SciencePress , 2006:121-149.[ 3 ] 　NEVILLE A M.Properties of concrete[ M ] .4 th Edit ion.U K:Prent ice Hall , 1995:412-525.[ 4 ] 　MEIER S J , BA UML M F.Internal imp regnation of concreteby m eans of silanes[ J] .Restoration of Buildings and Monu-men ts , 2006 , 12(1):43-52.[ 5 ] 　WI TTM ANN F H ,??? ,???.???????????????????[ J] .??????, 2005 , 8(1):1-6.　　　WI TTM ANN F H , ZHAN H ong-yan , ZHAO Tie-ju n.Waterrepellent t reatmen t of concrete surface and es tabli shment ofch loride barrier[ J] .J ournal of Building M aterial s , 2005 , 8(1):1-6.[ 6 ] 　??? ,??? ,???.???????????????????[ J] .?????? , 2005 , 25(1):26-30.　　　JIANG Zheng-w u , SUN Zhen-ping ,WANG Pei-ming.Ef fectsof silane on ant i-corrosion proper ties of high-performan ce ma-rine concrete[ J] .China Harbou r Engineering , 2005 , 25(1):26-30.[ 7 ] 　DAI J G , AKIRA Y , YOKOT A H.Various su rface impregna-ti on t reatments of pre-condi tioned con crete sub jected to sea-w ater immersion test[ J] .Restoration of Buildings and Monu-men ts , 2007 , 13(4):1-12.[ 8 ] 　HALL C.Barrier performance of concrete—A review of fluidt ran sport theory[ J] .M aterial s and St ructu res , 1994 , 27(5):291-306.[ 9 ] 　DANIE L A Q.Microst ructure and t ransport p ropert ies ofporous building m aterial s[ J] .Materials and S t ru ctures , 1998 ,31(5):317-324.[ 10] 　KRUS M , SEDLBAUER K , RUCKER P.Redist ribut ion ofthe pore w ater in the cem ent gel of concrete[ A] .Transpor t inConcrete:Nano- to Macrost ructu re[ C] .Freib urg:Aedif icatioPublis her , 2007:61-70.[ 11] 　LUNK P ,WIT TMANN F H .T he behaviou r of crack s in w a-t er repellent concrete st ructu res wi th respect to capillary w a-t er t ransport[ A] .Proceeding s of 2nd Internat ional Conferenceon Water Repel len t Treatment of Building Materials[ C] .ET H Zǜ rich , Swi tz erland:Aedi ficat io Pub lisher , 1998:63-76.74 ?　?　?　?　?　? ? 13 ?　

Water absorption property of cracked concrete and effect of water repellent treatment

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