基于電阻率法的水泥水化與收縮特性研究
發(fā)布時間：2018-08-25 11:02
【摘要】：電阻率法通過監(jiān)測水泥基材料在水化過程中的電阻率變化情況，可以用于水泥基材料的水化特性研究。因水泥水化而產(chǎn)生的化學收縮和自收縮是影響水泥基材料體積穩(wěn)定性的重要因素。礦物摻合料和混凝土外加劑對混凝土的水化過程和體積穩(wěn)定性也有重要影響。本文以電阻率法為基本研究方法，以水泥漿體為主要研究對象，主要研究內(nèi)容和結(jié)論如下： (1)采用美國標準ASTM C1608-07規(guī)定的體積法測試了硅酸鹽水泥漿體的化學收縮。研究表明，水泥漿體的化學收縮與水泥的水化度之間具有較好的線性關(guān)系；當齡期在12h以上時，水泥漿體的化學收縮與電阻率之間存在較好的線性關(guān)系，可以根據(jù)水泥漿體的電阻率預測水泥的水化度。 (2)研究了粉煤灰對硅酸鹽水泥漿體的電阻率和硬化水泥漿體自收縮的影響。結(jié)果表明，在水化早期階段(約12h以前)，隨著粉煤灰摻量的增大，水泥漿體的電阻率也逐漸增大；在水化后期階段(約12h以后)，隨著粉煤灰摻量的增大，，水泥漿體的電阻率逐漸減小，硬化水泥漿體的自收縮也逐漸減小。 (3)研究了萘系高效減水劑對固定水灰比的硅酸鹽水泥漿體的凝結(jié)過程和電阻率的影響。結(jié)果表明，水泥漿體的剪切強度變化曲線與電阻率變化速率曲線的走勢基本一致；電阻率變化速率曲線峰值的出現(xiàn)時間與終凝時間存在較好的關(guān)系；隨著減水劑摻量的增大，硬化水泥漿體的抗壓強度逐漸減小，電阻率極大值也逐漸減小。 (4)研究了硫鋁酸鹽水泥水化過程中的電阻率變化規(guī)律。結(jié)果表明，硫鋁酸鹽水泥水化時的電阻率變化曲線在1440min (24h)內(nèi)出現(xiàn)兩個峰，峰值的出現(xiàn)時間基本不受水灰比的影響。出現(xiàn)峰值的原因是鈣礬石(AFt)與單硫型水化硫鋁酸鈣(AFm)發(fā)生相互轉(zhuǎn)變。對于不同水灰比的水泥漿體而言，在凝結(jié)硬化前，水灰比越大時，水泥漿體的電阻率越��；在凝結(jié)硬化后，水灰比越大時，水泥漿體的電阻率也越大。在24h齡期時，隨著水灰比的增大，硬化水泥漿體的抗壓強度逐漸降低，電阻率逐漸增大。
[Abstract]:The resistivity method can be used to study the hydration characteristics of cement-based materials by monitoring the change of resistivity during hydration. Chemical shrinkage and autogenous shrinkage due to cement hydration are important factors affecting the volume stability of cement based materials. Mineral admixtures and concrete admixtures also have important effects on the hydration process and volume stability of concrete. In this paper, the resistivity method is taken as the basic research method and the cement paste as the main research object. The main contents and conclusions are as follows: (1) the chemical shrinkage of silicate cement paste has been measured by the volume method specified in the American standard ASTM C1608-07. The results show that there is a good linear relationship between the chemical shrinkage of cement paste and the hydration degree of cement, and when the age is more than 12 hours, there is a good linear relationship between the chemical shrinkage and the resistivity of cement paste. The hydration degree of cement can be predicted by the resistivity of cement paste. (2) the effect of fly ash on resistivity and autogenous shrinkage of Portland cement paste is studied. The results show that at the early stage of hydration (about 12 h before), the resistivity of cement paste increases with the increase of fly ash content, and at the later stage of hydration (about 12 h), with the increase of fly ash content, The resistivity of cement paste decreases and the self-shrinkage of hardened cement paste decreases gradually. (3) the effect of naphthalene superplasticizer on the setting process and resistivity of silicate cement paste with fixed water-cement ratio is studied. The results show that the shear strength curve of cement paste is basically consistent with the trend of resistivity change rate curve, the time of peak value of resistivity change rate curve has a good relationship with the final setting time, and with the increase of water reducer content, The compressive strength of hardened cement paste decreases and the maximum resistivity decreases gradually. (4) the variation of resistivity during hydration of sulphoaluminate cement is studied. The results show that the resistivity change curve of sulphoaluminate cement during hydration has two peaks within 1440min (24 h), and the time of peak value is not affected by the ratio of water to cement. The peak value is due to the mutual transformation between ettringite (AFt) and monosulfide calcium sulphoaluminate (AFm). For cement paste with different water-cement ratio, the resistivity of cement paste is smaller when the ratio of water to cement is higher before setting and hardening, and the resistivity of cement paste also increases when the ratio of water to cement increases after setting. The compressive strength and resistivity of hardened cement paste decreased gradually with the increase of water-cement ratio at 24 h.
【學位授予單位】：華中科技大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TQ172.1
本文編號：2202682
[Abstract]:The resistivity method can be used to study the hydration characteristics of cement-based materials by monitoring the change of resistivity during hydration. Chemical shrinkage and autogenous shrinkage due to cement hydration are important factors affecting the volume stability of cement based materials. Mineral admixtures and concrete admixtures also have important effects on the hydration process and volume stability of concrete. In this paper, the resistivity method is taken as the basic research method and the cement paste as the main research object. The main contents and conclusions are as follows: (1) the chemical shrinkage of silicate cement paste has been measured by the volume method specified in the American standard ASTM C1608-07. The results show that there is a good linear relationship between the chemical shrinkage of cement paste and the hydration degree of cement, and when the age is more than 12 hours, there is a good linear relationship between the chemical shrinkage and the resistivity of cement paste. The hydration degree of cement can be predicted by the resistivity of cement paste. (2) the effect of fly ash on resistivity and autogenous shrinkage of Portland cement paste is studied. The results show that at the early stage of hydration (about 12 h before), the resistivity of cement paste increases with the increase of fly ash content, and at the later stage of hydration (about 12 h), with the increase of fly ash content, The resistivity of cement paste decreases and the self-shrinkage of hardened cement paste decreases gradually. (3) the effect of naphthalene superplasticizer on the setting process and resistivity of silicate cement paste with fixed water-cement ratio is studied. The results show that the shear strength curve of cement paste is basically consistent with the trend of resistivity change rate curve, the time of peak value of resistivity change rate curve has a good relationship with the final setting time, and with the increase of water reducer content, The compressive strength of hardened cement paste decreases and the maximum resistivity decreases gradually. (4) the variation of resistivity during hydration of sulphoaluminate cement is studied. The results show that the resistivity change curve of sulphoaluminate cement during hydration has two peaks within 1440min (24 h), and the time of peak value is not affected by the ratio of water to cement. The peak value is due to the mutual transformation between ettringite (AFt) and monosulfide calcium sulphoaluminate (AFm). For cement paste with different water-cement ratio, the resistivity of cement paste is smaller when the ratio of water to cement is higher before setting and hardening, and the resistivity of cement paste also increases when the ratio of water to cement increases after setting. The compressive strength and resistivity of hardened cement paste decreased gradually with the increase of water-cement ratio at 24 h.
【學位授予單位】：華中科技大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TQ172.1
【參考文獻】
相關(guān)期刊論文 前10條
1 韓寶國,關(guān)新春,歐進萍;碳纖維水泥石電阻測試方法研究[J];玻璃鋼/復合材料;2003年06期
2 張暢;魏小勝;田凱;;電阻率法研究聚羧酸減水劑對水泥水化的影響[J];長江科學院院報;2009年06期
3 李東旭;朱建平;李宗津;;應用電阻率方法研究粉煤灰持堿效應[J];材料科學與工程學報;2007年03期
4 閻培渝;鄭峰;;水泥水化反應與混凝土自收縮的動力學模型[J];鐵道科學與工程學報;2006年01期
5 劉志勇;張云升;姜騫;孫國文;;原位監(jiān)測水泥基材料早期電阻率的變化過程[J];東南大學學報(自然科學版);2012年02期
6 丁華濤;胡曙光;丁慶軍;耿健;;無機礦物摻合料對水泥石電阻率影響規(guī)律的研究[J];國外建材科技;2008年02期
7 金賢玉,李宗津;早齡期混凝土的電特性研究[J];硅酸鹽學報;2000年S1期
8 魏小勝,肖蓮珍,李宗津;采用電阻率法研究水泥水化過程[J];硅酸鹽學報;2004年01期
9 肖蓮珍,李宗津,魏小勝;用電阻率法研究新拌混凝土的早期凝結(jié)和硬化[J];硅酸鹽學報;2005年10期
10 閻培渝;鄭峰;;水泥基材料的水化動力學模型[J];硅酸鹽學報;2006年05期
相關(guān)博士學位論文 前1條
1 蘇安雙;高性能混凝土早期收縮性能及開裂趨勢研究[D];哈爾濱工業(yè)大學;2008年
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