粉煤灰對(duì)水泥漿體的剪切變稀和剪切增稠作用
本文選題:流變 切入點(diǎn):粉煤灰 出處:《硅酸鹽學(xué)報(bào)》2015年08期
【摘要】:采用RHEOLAB QC型旋轉(zhuǎn)黏度計(jì)測(cè)試了粉煤灰摻量對(duì)水泥漿體流變行為的影響,采用HERSCHEL-BULKEY(H-B)流變模型對(duì)所測(cè)數(shù)據(jù)進(jìn)行了擬合。結(jié)果表明:漿體流變曲線中有1個(gè)拐點(diǎn),拐點(diǎn)所對(duì)應(yīng)的流變參數(shù)為臨界剪切速率(γcrit)、臨界剪切應(yīng)力(τcrit)和最小黏度值(ηmin),拐點(diǎn)左右兩側(cè)的漿體可分為剪切變稀和剪切增稠2個(gè)階段。純水泥漿體在較大的剪切速率下仍表現(xiàn)為剪切變稀。摻入粉煤灰后,漿體的γcrit、τcrit和ηmin均較純水泥漿體降低,當(dāng)粉煤灰摻量大于40%以后,漿體在較低臨界剪切速率下出現(xiàn)了剪切增稠。在剪切變稀階段,當(dāng)粉煤灰摻量不大于50%時(shí),增大粉煤灰摻量則漿體的流變指數(shù)顯著降低,當(dāng)粉煤灰摻量大于50%時(shí),增加粉煤灰摻量,漿體流變指數(shù)增大,但均低于純水泥漿體的流變指數(shù);在剪切增稠階段,隨粉煤灰摻量的增加,漿體的流變指數(shù)增大,漿體剪切增稠的程度也增大。粉煤灰的摻入增大了剪切變稀階段漿體剪切變稀的程度,也增大了剪切增稠階段漿體剪切增稠的程度。
[Abstract]:The effect of fly ash content on the rheological behavior of cement paste was measured by RHEOLAB QC rotary viscometer. The measured data were fitted by HERSCHEL-BULKEYYN H-Bmodel.The results show that there is an inflection point in the rheological curve of the slurry, and the rheological parameters corresponding to the inflection point are critical shear rate (緯 -critn), critical shear stress (蟿 -criterion) and minimum viscosity value (畏 _ min ~). The slurry on both sides of the inflection point can be divided into two stages: shear thinning and shear thickening.The pure cement paste still shows shearing thinning at higher shear rate.When fly ash was added into the slurry, 緯 criterion, 蟿 crit and 畏 min were lower than that of pure cement paste. When the content of fly ash was more than 40%, the slurry had shear thickening at lower critical shear rate.In the shear-thinning stage, when the content of fly ash is less than 50, the rheological index of slurry decreases significantly when the content of fly ash is increased, and when the content of fly ash is greater than 50, the rheological index of slurry increases.In the shear thickening stage, the rheological index of the slurry increases with the increase of the content of fly ash, and the degree of shear thickening of the slurry also increases.The addition of fly ash increases the degree of shear thinning of slurry in shear-thinning stage, and also increases the degree of shear thickening of slurry in shear-thickening stage.
【作者單位】: 中南大學(xué)土木工程學(xué)院高速鐵路建造技術(shù)國(guó)家工程實(shí)驗(yàn)室重載鐵路工程結(jié)構(gòu)教育部重點(diǎn)實(shí)驗(yàn)室;
【基金】:國(guó)家973計(jì)劃(2013CB036201) 中國(guó)鐵路總公司重點(diǎn)課題(2014G012) 中南大學(xué)教師科學(xué)基金項(xiàng)目(2014JSJJ013)
【分類號(hào)】:TU528
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