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1、2014年第2期(總第292期】混凝土理論研究Number2in2014(TotalNo.292)ConcreteTHEORETICALRESEARCHdoi:10.39698.issn.1002-3550.2014.02.002素混凝土抗凍性能試驗(yàn)研究方從啟,張俊萌,段桂珍(上海交通大學(xué)土木工程系,上海200240)摘要:為了進(jìn)一步研究約束混凝土和無(wú)約束混凝土的抗凍性能差異,以約束混凝土模型為參照,制作相同配合比的素混凝土立方體塊并在相同條件下進(jìn)行0、20、4O、60、100、120次的凍融腐蝕試驗(yàn)。主要分析凍融腐蝕下素混凝土試塊抗壓強(qiáng)度,質(zhì)量損失以及吸水率等性能隨凍融次
2、數(shù)的變化規(guī)律,并建立素混凝土抗壓強(qiáng)度和質(zhì)量損失凍融損傷預(yù)測(cè)模型。試驗(yàn)結(jié)果表明:隨凍融循環(huán)次數(shù)增加,素混凝土的抗壓強(qiáng)度呈拋物線下降,干燥質(zhì)量和飽水質(zhì)量呈線性下降,而吸水率則呈雙折線下降。從材料層次方面,粉煤灰對(duì)混凝土抗壓強(qiáng)度損失,質(zhì)量損失率和吸水率影響較大,而水灰比對(duì)以上指標(biāo)影響較小。摻15%粉煤灰的抗壓強(qiáng)度損失比不摻粉煤灰的混凝土大約20%~30%;質(zhì)量損失率比不摻粉煤灰的大5%~6%,粉煤灰不利于抗凍性能。相同粉煤灰含量,低水灰比抗壓強(qiáng)度損失,質(zhì)量損失率和吸水率變化比高水灰tP,d,,使用粉煤灰混凝土?xí)r易降低水灰比。關(guān)鍵詞:素混凝土;凍融循環(huán);抗壓強(qiáng)度;質(zhì)量損失中圖分類號(hào)
3、:TU528.1文獻(xiàn)標(biāo)志碼:A文章編號(hào):1002—3550(2014)02—0005—04Experimentalinvestigationonanti-freezebehaviorofplainconcreteFANGCongqi,ZHANGJunmeng,DUANGuizhen(DepartmentofCivilEngineering,ShanghaiJiaotongUniversity,Shanghai200240,China)Abstract:Inordertofurtherstudy也eantifreezeperformancediferenceofconfine
4、dconcreteandplainconcrete.inconfinedconcretemodelforreference,makingthesameratioofplainconcretecubicblockandunderthesameconditionswerealsotestedunderfreeze-thawcycleofdiferentnumbersas0,20,40,60,100and120times,Asthesecondpart,mainlyanalyzedthecompressivesfengthofplainconcreteunderfreeze—th
5、awtest,masslossofsamplesandwaterabsorptionperformancechangingwiththenumberoffreezingandthawing,andestablishthefreeze-thawdamagepredictionmodelofconcretecompressives~engthandmasslossratio.Experimentshowedthatwiththeincreaseoffreeze-thawcycles,thecompressivestrengthofplainconcretedecreasedpa
6、rabola,dryingqualityandfullwatermasslinearlydecreased,whilewaterabsorptiondecreasedbydoubleline.Fromtheaspectsofmateriallevel,flyashhadagreaterinfluenceonthelOSSofconcretecompressivesfength.masslossrateandwaterabsorption.whilewatercementratiohadliRleinfluenceontheatloveindicators.Thelossof
7、compressivestrengthofmixing15%flyashconcretewasabout20%to30%higherthanmixingnoflyashconcrete;Masslossratewasabout5%to6%largerthannotmixingflyash,flyashisnotconducivetotheantifreezeperformanceofconcrete.Asthesameflyash,thelossofcompressives~ength,massandbibulou