不同分子結(jié)構(gòu)聚羧酸系減水劑對水泥漿體早期性能的影響
發(fā)布時間：2018-10-31 09:25
【摘要】：聚羧酸系減水劑（Polycarboxylate ether type superplasticizer，PCE）具有摻量低、分散性好、分子結(jié)構(gòu)靈活等優(yōu)點，在現(xiàn)代混凝土中獲得了廣泛應(yīng)用。典型的聚羧酸系減水劑有陰離子型聚羧酸系減水劑（Anionic polycarboxylate ether typesuperplasticizer，anPCE）和兩性聚羧酸系減水劑（Amphoteric polycarboxylate ethertype superplasticizer，amPCE），其分子結(jié)構(gòu)對水泥漿體早期性能的影響很大。本文中合成了側(cè)鏈長度、側(cè)鏈密度不同的anPCE，以及陽離子含量、主側(cè)鏈橋接基團、側(cè)鏈長度不同的amPCE，并通過宏觀與微觀實驗相結(jié)合的方法，研究了不同分子結(jié)構(gòu)聚羧酸系減水劑對水泥漿體流動性、早期強度、水化放熱速率等早期性能的影響。 對于陰離子型聚羧酸系減水劑，分子中吸附基團數(shù)量、側(cè)鏈密度相同時，長側(cè)鏈anPCE的吸附量低，分散能力及分散保持能力強。摻入質(zhì)量相同情況下，與摻短側(cè)鏈anPCE水泥漿體相比，摻長側(cè)鏈anPCE水泥漿體的水化誘導期持續(xù)時間較短，早期水泥水化產(chǎn)物生成量較多，早期強度較高。根據(jù)Juilland、Nicoleau等提出的C3S早期水化礦相溶解機理，本文推測吸附在C3S表面的anPCE可能會提高此處產(chǎn)生新刻蝕點的能量，減緩C3S的溶解速率，從而延長水泥水化誘導期持續(xù)時間。與短側(cè)鏈anPCE相比，長側(cè)鏈anPCE的相對分子質(zhì)量較大，在質(zhì)量相同情況下，分子數(shù)量較少，因此其延緩C3S溶解的程度較小。摻入分子數(shù)量相同情況下，摻不同側(cè)鏈長度anPCE水泥漿體的水化誘導期差異較小。但在水化加速階段，摻長側(cè)鏈anPCE水泥漿體的水化放熱速率比摻短側(cè)鏈的慢。因此anPCE在影響C3S溶解的同時可能也影響C3S水化產(chǎn)物成核及生長過程。分子中吸附基團數(shù)量、吸附基團與側(cè)鏈的質(zhì)量比相同時，側(cè)鏈較長、側(cè)鏈密度較低anPCE的吸附量較多，初始分散能力較強。并且摻此類anPCE的水泥漿體較早進入水化加速階段，早期水泥水化產(chǎn)物生成量較多，水泥漿體早期強度較高。分子中吸附基團數(shù)量、側(cè)鏈長度相同時，與高側(cè)鏈密度anPCE相比，低側(cè)鏈密度anPCE的吸附量較多，初始分散能力較強，但分散保持能力較弱，并且會延緩C3A及C3S的水化過程，降低水泥漿體早期強度。 對于兩性聚羧酸系減水劑，，隨著主鏈吸附基團中陽離子比例提高，amPCE的吸附量先增加后減少。含一定比例（10%，15%）陽離子的amPCE能夠促進水泥早期水化，提高水泥漿體早期強度。與橋接基團為醚鍵的amPCE相比，酯鍵橋接amPCE的吸附量較少、分散能力較弱。摻酯類amPCE水泥漿體水化速率較快，早期強度較高。隨著側(cè)鏈長度的增加，amPCE的吸附能力及分散能力先上升后下降。側(cè)鏈較長的amPCE能夠促進水泥早期水化，從而提高水泥漿體早期強度。 本文系統(tǒng)研究了陰離子型和兩性聚羧酸系減水劑對水泥漿體早期性能的影響規(guī)律，研究結(jié)果有助于進一步了解聚羧酸系減水劑分子結(jié)構(gòu)參數(shù)與水泥漿體性能的構(gòu)效關(guān)系，探明聚羧酸系減水劑在水泥水化過程的作用機理，從而為后續(xù)聚羧酸系減水劑的分子結(jié)構(gòu)設(shè)計及工程應(yīng)用提供一定理論依據(jù)。
[Abstract]:Polyacetal type superplasticizer (PCE) has the advantages of low doping amount, good dispersivity, flexible molecular structure and the like, and is widely applied in modern concrete. Typical polyvinyl alcohol-based water-reducing agents include anionic water-reducing agent (ANPCE) and amphoteric water-reducing agent (amPCE). Its molecular structure has great influence on the early performance of cement paste. In this paper, the length of the side chain, the anPCE with different side chain densities and the amPCE with different cationic content, main chain bridging group and side chain length are synthesized, and the fluidity of the cement slurry is studied by means of combining macroscopic and microscopic experiments. Early strength, hydration heat release rate and other early properties. When the number of adsorption groups in the molecule and the density of the side chains are the same, the adsorption amount of the long-side chain anPCE is low, the dispersing ability and the dispersion are maintained. Compared with the short side chain anPCE cement paste, the hydration induction period of the long side chain anPCE cement slurry has short duration, and the early cement hydration products produce more and early strength compared with the short side chain anPCE cement slurry. According to the mechanism of the early hydration of C3S from Juilland, Nicoleau et al., this paper speculates that the anPCE adsorbed on the surface of C3S may increase the energy of the new etching point here and decrease the dissolution rate of C3S so as to prolong the duration of hydration induction of cement. Compared with the short side chain anPCE, the relative molecular mass of the long side chain anPCE is large, and in the case of the same mass, the number of molecules is small, The hydration-induced phase difference of the length anPCE cement paste with different side chains in the same conditions as the number of molecules is smaller. At the hydration acceleration stage, the hydration heat release rate of the long side chain anPCE cement slurry is lower than that of the short side chain. slow. Therefore, the anPCE may also influence the nucleation and growth of C3S hydration products while affecting the dissolution of C3S. In the process, the number of adsorption groups in the molecule, the mass ratio of the adsorption group to the side chain are the same, the side chain is longer, the side chain density is lower than that of the low anPCE, and the initial dispersion capacity It is strong that the cement paste with such anPCE can enter the hydration acceleration stage earlier, and the early cement hydration products produce more, and the early strength of the cement paste body is high. When the number of adsorption groups in the molecule and the length of the side chain are the same, the adsorption amount of the low-side chain-density anPCE is much larger than that of the high-side chain-density anPCE, the initial dispersion capacity is strong, the dispersion retention capacity is weak, the hydration process of the C3A and the C3S is retarded, For amphoteric polyacrylate water reducer, the adsorption capacity of amPCE is first increased with the increase of cationic proportion in main chain adsorption group. After the increase, the amPCE containing a certain proportion (10%, 15%) of the cation can promote early hydration of the cement and improve the cement slurry. Compared with amPCE with bridging group as ether bond, the adsorption amount of ester bond bridge amPCE is less, The dispersion ability is weak. The hydration rate of cement paste with ester-doped amPCE is faster and early. With the increase of the length of the side chain, the adsorption capacity and the dispersing ability of the amPCE were first increased. LPCE with long side chain can promote early hydration of cement to improve cement slurry In this paper, the influence of anionic and amphoteric water reducing agents on the early properties of cement slurry is studied. The results of this study are helpful to further understand the molecular structure parameters and cement paste of the water reducer. The structure and effect relationship of the performance of the cement and the mechanism of the water reducing agent in the cement hydration process are proved, and the molecular structure design and engineering application of the water reducing agent for the subsequent polymethyl methacrylate water reducing agent are provided.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU528.042.2
本文編號：2301658
[Abstract]:Polyacetal type superplasticizer (PCE) has the advantages of low doping amount, good dispersivity, flexible molecular structure and the like, and is widely applied in modern concrete. Typical polyvinyl alcohol-based water-reducing agents include anionic water-reducing agent (ANPCE) and amphoteric water-reducing agent (amPCE). Its molecular structure has great influence on the early performance of cement paste. In this paper, the length of the side chain, the anPCE with different side chain densities and the amPCE with different cationic content, main chain bridging group and side chain length are synthesized, and the fluidity of the cement slurry is studied by means of combining macroscopic and microscopic experiments. Early strength, hydration heat release rate and other early properties. When the number of adsorption groups in the molecule and the density of the side chains are the same, the adsorption amount of the long-side chain anPCE is low, the dispersing ability and the dispersion are maintained. Compared with the short side chain anPCE cement paste, the hydration induction period of the long side chain anPCE cement slurry has short duration, and the early cement hydration products produce more and early strength compared with the short side chain anPCE cement slurry. According to the mechanism of the early hydration of C3S from Juilland, Nicoleau et al., this paper speculates that the anPCE adsorbed on the surface of C3S may increase the energy of the new etching point here and decrease the dissolution rate of C3S so as to prolong the duration of hydration induction of cement. Compared with the short side chain anPCE, the relative molecular mass of the long side chain anPCE is large, and in the case of the same mass, the number of molecules is small, The hydration-induced phase difference of the length anPCE cement paste with different side chains in the same conditions as the number of molecules is smaller. At the hydration acceleration stage, the hydration heat release rate of the long side chain anPCE cement slurry is lower than that of the short side chain. slow. Therefore, the anPCE may also influence the nucleation and growth of C3S hydration products while affecting the dissolution of C3S. In the process, the number of adsorption groups in the molecule, the mass ratio of the adsorption group to the side chain are the same, the side chain is longer, the side chain density is lower than that of the low anPCE, and the initial dispersion capacity It is strong that the cement paste with such anPCE can enter the hydration acceleration stage earlier, and the early cement hydration products produce more, and the early strength of the cement paste body is high. When the number of adsorption groups in the molecule and the length of the side chain are the same, the adsorption amount of the low-side chain-density anPCE is much larger than that of the high-side chain-density anPCE, the initial dispersion capacity is strong, the dispersion retention capacity is weak, the hydration process of the C3A and the C3S is retarded, For amphoteric polyacrylate water reducer, the adsorption capacity of amPCE is first increased with the increase of cationic proportion in main chain adsorption group. After the increase, the amPCE containing a certain proportion (10%, 15%) of the cation can promote early hydration of the cement and improve the cement slurry. Compared with amPCE with bridging group as ether bond, the adsorption amount of ester bond bridge amPCE is less, The dispersion ability is weak. The hydration rate of cement paste with ester-doped amPCE is faster and early. With the increase of the length of the side chain, the adsorption capacity and the dispersing ability of the amPCE were first increased. LPCE with long side chain can promote early hydration of cement to improve cement slurry In this paper, the influence of anionic and amphoteric water reducing agents on the early properties of cement slurry is studied. The results of this study are helpful to further understand the molecular structure parameters and cement paste of the water reducer. The structure and effect relationship of the performance of the cement and the mechanism of the water reducing agent in the cement hydration process are proved, and the molecular structure design and engineering application of the water reducing agent for the subsequent polymethyl methacrylate water reducing agent are provided.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU528.042.2
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