本文選題：水泥凈漿 + 化學(xué)收縮　； 參考：《長(zhǎng)沙理工大學(xué)》2013年碩士論文

【摘要】：繼礦物摻合材與外加劑雙摻技術(shù)日趨成熟后，混凝土又引入納米級(jí)超細(xì)組分，其早期體積變形是現(xiàn)代混凝土材料的關(guān)鍵性基礎(chǔ)問題之一，而化學(xué)收縮行為無疑更加復(fù)雜。本文以水泥凈漿的化學(xué)收縮為主題，采用ASTM C1608實(shí)驗(yàn)方法（恒溫水浴環(huán)境密閉小容器絕對(duì)體積法），，系統(tǒng)研究復(fù)合水泥凈漿化學(xué)收縮的影響因素，包括：水泥品種及細(xì)度、水膠比、礦物摻合材、外加劑、納米材料以及養(yǎng)護(hù)溫度等。主要結(jié)論如下： 1、水泥熟料含量對(duì)水泥凈漿化學(xué)收縮值起決定性作用。在四種礦物熟料成分中，C_3A收縮最大，C_2S早期反應(yīng)較慢，所引起的早期化學(xué)收縮相應(yīng)較小。細(xì)度越大，水泥顆粒早期水化越快，引起早期化學(xué)收縮值越大。 2、水泥凈漿化學(xué)收縮隨著水灰比/水膠比增大而增大，如水灰比為0.38水泥漿7d化學(xué)收縮值較0.26水灰比的增加48%。不同水膠比復(fù)合水泥漿早期化學(xué)收縮差異非常顯著。 3、采用粉煤灰、礦渣、硅粉和石膏，按不同比例等質(zhì)量取代水泥，制備復(fù)合水泥凈漿，研究礦物摻合材對(duì)其化學(xué)收縮的影響： （1）粉煤灰由于其微集料密實(shí)填充作用，對(duì)早期化學(xué)收縮表現(xiàn)出極強(qiáng)的抑制效果。摻加45%I級(jí)粉煤灰3d收縮值較水泥凈漿收縮值減小41%；而粉煤灰后期參與二次水化，對(duì)化學(xué)收縮抑制作用顯著減小。摻加II級(jí)粉煤灰復(fù)合水泥漿對(duì)早期收縮的抑制效果明顯小于I級(jí)粉煤灰。 （2）硅粉的加入使復(fù)合水泥漿早期化學(xué)收縮值較水泥凈漿略有增加，且隨著摻量增大，收縮值增大。如：硅粉摻量為12%時(shí)，3d化學(xué)收縮值較水泥凈漿增長(zhǎng)12%。而摻8%納米SiO_2復(fù)合水泥漿28d化學(xué)收縮值較水泥凈漿降低19%。顯然，摻納米SiO_2復(fù)合水泥漿后期化學(xué)收縮增長(zhǎng)速度明顯降低。 （3）礦渣復(fù)合水泥漿早期化學(xué)收縮值較水泥凈漿顯著減小，且收縮值隨著礦渣摻量的增大而減小。摻45%礦渣復(fù)合水泥漿3d化學(xué)收縮值比同水灰比凈漿收縮值減少53%。隨著齡期增長(zhǎng)，礦渣參與水化反應(yīng)，抑制收縮的作用逐漸減緩。 （4）粉煤灰與脫硫石膏復(fù)摻時(shí)，粉煤灰在30%摻量不變的條件下，石膏摻量越大，化學(xué)收縮值越小，這與石膏在水泥水化過程中結(jié)晶自膨脹有關(guān)。采用I、II級(jí)粉煤灰與脫硫石膏復(fù)摻，3d化學(xué)收縮值較水泥凈漿分別減小11%和37%。 （5）粉煤灰與礦渣復(fù)摻復(fù)合水泥漿早期化學(xué)收縮較水泥凈漿明顯降低，復(fù)摻比例在一定范圍內(nèi)波動(dòng)對(duì)收縮值的影響不顯著。如：25%粉煤灰和15%礦渣復(fù)合水泥漿3d化學(xué)收縮較水泥凈漿降低超過35%，中后期化學(xué)收縮增長(zhǎng)速率加快，至28d收縮值達(dá)3.15ml/100g。 4、采用三種納米材料：活性材料納米SiO_2、功能型材料納米TiO_2、惰性材料納米CaCO_3。在同摻量同水膠比條件下，摻不同納米材料復(fù)合水泥漿化學(xué)收縮值排序?yàn)椋篠iO_2TiO_2CaCO_3。其中，低摻量（1-3%）納米SiO_2增加化學(xué)收縮，且收縮值隨著摻量增加而增長(zhǎng)。高摻量（4-8%）SiO_2對(duì)中后期化學(xué)收縮有明顯抑制作用。納米材料與礦物摻合材復(fù)摻能顯著降低化學(xué)收縮值，如在粉煤灰和礦渣雙摻體系中摻5%納米CaCO_3，復(fù)合水泥漿3d收縮值較同齡期水泥凈漿減少46%，較未摻納米材料粉煤灰和礦渣復(fù)合水泥漿減小11%。這與納米材料的摻入使得復(fù)合粉體形成更緊密堆積狀態(tài)納米效應(yīng)有關(guān)。 5、在實(shí)驗(yàn)采用的外加劑及其摻量范圍內(nèi)，緩凝劑摻量為0.15%水泥漿3d化學(xué)收縮較水泥凈漿減少63%，這說明摻緩凝劑水泥漿早期化學(xué)收縮發(fā)展緩慢，中后期化學(xué)收縮發(fā)展迅速，甚至超過水泥凈漿；萘系減水劑由于含膨脹劑成分，導(dǎo)致早期出現(xiàn)細(xì)微膨脹現(xiàn)象，且整個(gè)齡期內(nèi)收縮值都非常小。引氣劑與早強(qiáng)劑在常用摻量范圍內(nèi)對(duì)化學(xué)收縮值影響不顯著。 6、養(yǎng)護(hù)溫度顯著影響水化速率，進(jìn)而顯著影響水泥漿體的化學(xué)收縮。較高溫度養(yǎng)護(hù)條件下，水泥凈漿早期化學(xué)收縮增長(zhǎng)迅速。40℃恒溫水浴環(huán)境養(yǎng)護(hù)與15℃養(yǎng)護(hù)相比，水泥漿早期（7d前）化學(xué)收縮值增長(zhǎng)超過50%，后期（7-28d）不同養(yǎng)護(hù)溫度引起的差異減小。 此外，本文通過自創(chuàng)等效堆積密度及流動(dòng)度實(shí)驗(yàn)，探索不同粒度分布干態(tài)復(fù)合粉體顆粒堆積狀態(tài)及其對(duì)填充水和吸附水的影響，進(jìn)而分析顆粒堆積對(duì)水泥凈漿化學(xué)收縮的影響，得出初步結(jié)論。
[Abstract]:In this paper , the influence factors of chemical shrinkage of cement paste are studied by using ASTM C1608 experiment method ( constant temperature water bath environment closed small container absolute volume method ) , including cement variety and fineness , water - cement ratio , mineral admixture , admixture , nano - material and curing temperature . The main conclusions are as follows :

1 . The cement clinker content plays a decisive role in the chemical shrinkage value of cement paste . In the four kinds of mineral clinker components , the shrinkage of C _ 3A is the largest , the early reaction of C _ 2S is slow , the early chemical shrinkage is correspondingly small . The larger the fineness , the faster the early hydration of cement particles , the greater the early chemical shrinkage value .

2 . The chemical shrinkage of cement paste increases with the increase of cement ratio / water cement ratio , such as the ratio of water to cement ratio is 0.38 , the chemical shrinkage value of cement paste is increased by 48 % than that of 0.26 % .

3 . Fly ash , slag , silicon powder and gypsum are used to replace the cement according to different proportions , so as to prepare the composite cement paste , and the influence of the mineral admixture on the chemical shrinkage of the cement is studied :

( 1 ) The fly ash has strong inhibition effect on early chemical shrinkage due to the dense filling effect of its micro - aggregate , and the shrinkage value of cement paste with 45 % grade I fly ash is reduced by 41 % than that of cement paste .
however , that effect of compound cement slurry with grade II fly ash on early shrinkage is obviously less than that of grade I fly ash .

( 2 ) The chemical shrinkage value of the composite cement paste increased slightly with the addition of silicon powder , and the shrinkage value increased with the increase of the mixing amount . For example , the chemical shrinkage value of the 3d chemical shrinkage was 12 % when the content of silicon powder was 12 % . The chemical shrinkage value of the 28 % nano - SiO _ 2 composite cement slurry decreased by 19 % than that of cement paste .

( 3 ) The early chemical shrinkage value of the slag composite cement paste is obviously reduced than that of the cement paste , and the shrinkage value decreases with the increase of the slag content . The 3d chemical shrinkage value of the 45 % slag composite cement slurry is reduced by 53 % than that of the cement mortar . As the age increases , the slag participates in the hydration reaction , and the effect of inhibiting shrinkage gradually slows down .

( 4 ) When the fly ash is mixed with the desulfurization gypsum , the larger the amount of the fly ash is added , the smaller the amount of gypsum is , the smaller the chemical shrinkage value , which is related to the self - expansion of the crystal self - expansion during the hydration of the cement .

( 5 ) The early chemical shrinkage of fly ash and slag complex compound cement slurry is obviously lower than that of cement paste , and the effect of fluctuation on shrinkage value is not obvious within a certain range . For example : 25 % fly ash and 15 % slag composite cement paste 3d chemical shrinkage is more than 35 % lower than that of cement paste , the rate of chemical shrinkage increase in middle and late stage is accelerated , and the shrinkage value of 28d is 3.15ml / 100g .

4 . Three kinds of nano - materials : nano - SiO _ 2 of active material , nano - TiO _ 2 of functional material and nano - CaCO _ 3 of inert material were used . The chemical shrinkage of nano - SiO _ 2TiO _ 2CaCO _ 3 was increased with the ratio of co - doping with water - cement ratio .

5 . During the experiment , the amount of retarder added is 0.15 % , the chemical shrinkage of cement slurry is reduced by 63 % than that of cement paste , which indicates that the early chemical shrinkage of the retarder cement slurry is slow , the chemical shrinkage develops rapidly in the middle and late stages , and even exceeds the cement paste ;
Due to the swelling agent component , naphthalene series water reducing agent causes early slight swelling phenomenon , and the shrinkage value in the whole age is very small . The influence of entraining agent and early strength agent on chemical shrinkage value is not significant in the range of common doping amount .

6 . The curing temperature significantly affects the hydration rate , which can significantly affect the chemical shrinkage of cement slurry . The chemical shrinkage of cement paste increases rapidly at the higher temperature curing condition . Compared with the curing at 15 鈩

本文編號(hào)：1894878