有机—无机复合混凝土内养护材料设计、合成与性能研究

发布时间：2018-03-22 11:02

本文选题：有机-无机复合　切入点：内养护材料　出处：《武汉理工大学》2013年博士论文　论文类型：学位论文

【摘要】：高强高性能混凝土因水胶比低、胶材用量大、过量使用超细矿物掺合料等，而普遍存在早期开裂问题。通过预先内置的吸水性材料适时释水，提高混凝土内部相对湿度，降低其自收缩的内养护(Internal curing)已成为解决混凝土收缩裂缝的有效方法。本文依托国家自然科学基金(51202039)，，设计、合成了新型聚合物内养护材料，围绕材料的组成、结构、性能开展了研究与工程应用，取得了如下创新成果：针对离子型聚合物碱性环境下吸水倍率低且失水导致工作性能和强度劣化，以及非离子型聚合物吸水倍率低导致混凝土后期内养护不足的问题，提出了“高吸水-稳定储水-可控释水”内养护材料的设计方法。以木薯淀粉、丙烯酰胺（AM）、2-丙烯酰胺-2-甲基丙磺酸（AMPS）为主要原料，合成了吸水倍率达210~287、保水率80%以上、负压释水率75%以上的阴-非离子型聚合物内养护材料(AN-ICA)。运用FT-IR、SEM和13C NMR等表征了其组成、形貌和结构特征，系统研究了其吸水-储水性能等与组成、网络结构之间关系。研究表明，AN-ICA淀粉主链上同时成功接枝了单体AM和AMPS，并形成了连续、多孔、三维条带状网络结构。该结构具有足够吸水空间并具有良好弹性和伸展能力，在水中溶胀而不溶解，从而提高了AN-ICA吸液能力；亲水性基团-SO3H、-CONH2提供了聚合物吸液动力，并降低了混凝土中孔溶液同离子效应使聚合物网络收缩释水，提高了其在碱性溶液中储水稳定性。提出了在AN-ICA网络结构中复合刚性无机Si-O网络，限制柔性阴-非离子型聚合物网络结构在碱性环境下的收缩行为，进一步提高内养护材料的储水稳定性-释水可控性的技术思路。制备的有机-无机复合内养护材料(OIM-ICA)吸水倍率达188~270、保水率85%以上、释水率80%以上。SEM-EDS分析表明OIM-ICA具有复合交联网络结构。系统研究了合成工艺对吸水-储水-释水性能的影响，确定了原料配比及工艺参数：水玻璃8%~12%、交联剂0.12%~0.18%、单体滴加时间1.5~2.5h、反应温度60~70℃。系统研究了OIM-ICA掺量、细度、水胶比等因素对混凝土早期收缩影响，结果表明，随掺量增加、粒径减小及水胶比降低，混凝土内部相对湿度降幅减小，早期自收缩显著降低。OIM-ICA掺量为胶凝材料的0.07%时，掺15%粉煤灰、水灰比0.35的C50混凝土7d自收缩可降低120με以上；OIM-ICA内养护作用减小了对自收缩贡献最大的9~50nm毛细孔数量。基于毛细张力理论，引入内养护水化因子和内养护体积弹性模量因子，建立了OIM-ICA掺量、细度、水胶比与混凝土自收缩关系模型。研究了OIM-ICA对胶凝浆体水化及混凝土力学性能、耐久性能等的影响规律。随OIM-ICA掺量增加，胶凝浆体水化速率和放热量降低，混凝土早期抗压强度降低，后期与未掺OIM-ICA强度相近，后期抗氯离子渗透性能、抗冻性能、抗硫酸盐侵蚀性能和抗碳化性能均提高。其影响机理为：早期胶凝浆体水化受OIM-ICA抑制并占据较大空间，提高了孔隙率，导致混凝土早期强度降低；后期OIM-ICA释水内养护作用使胶凝浆体水化程度提高，9~50nm毛细孔数量降低，水化产物在OIM-ICA周围形成了能够分散压应力的致密“拱壳结构”，从而提高了混凝土后期强度和抗冻性，并有效阻止了Cl-、SO42-、CO32-等有害离子在毛细孔中的迁移，提高了抗氯离子渗透性、抗硫酸盐侵蚀性和抗碳化性。根据本文提出的内养护材料设计方法和合成工艺，设计了年产2万吨工业化生产线，批量生产了内养护材料，并进行了工程应用。结果表明掺入OIM-ICA提高了混凝土抗裂性能，有效解决了工程裂缝问题。
[Abstract]:High strength and high performance concrete with low water binder ratio, cement amount, excessive use of superfine mineral admixture, and the common problems of early cracking. Through the absorption of the pre built timely release of water, improve the internal relative humidity of concrete, reduce its self curing shrinkage (Internal curing) has become an effective method to solve concrete shrinkage crack. Based on the National Natural Science Fund (51202039), design, new polymer curing materials were synthesized on the composition of the material, structure, performance research and engineering application, the main contributions are as follows:
Aiming at the low water absorbency and water loss result working performance and strength deterioration under alkaline environment and ionic polymer, a nonionic polymer water absorbent rate due to the low late in the curing of concrete problems, put forward the "high water - stable water - controlled release design method of water" curing materials. With cassava starch, acrylamide (AM, 2- -2-) acrylamide methyl propyl sulfonic acid (AMPS) as the main raw material, water absorbency of 210~287 was synthesized, the water retention rate above 80%, the negative pressure water release rate of more than 75% anionic nonionic polymer curing materials (AN-ICA). The use of FT-IR, SEM and 13C NMR characterized their composition, morphology the structure and characteristics of the system, the water absorbing and water storage performance and composition, the relationship between network structure. The research results show that the AN-ICA backbone and starch was successfully grafted monomer AM and AMPS, and the formation of a continuous, porous, three-dimensional banded structure of the network. The structure has enough water space and has good elasticity and stretch ability, swelling in water and dissolved, thus improving the AN-ICA absorption capacity; hydrophilic groups of -SO3H, -CONH2 provides power and reduce the absorption of polymer, concrete pore solution with ion effect of the polymer network contraction release water improves the alkaline the solution of water storage stability.
Based on the AN-ICA network structure in the composite rigid inorganic Si-O network, limit the flexibility of anionic nonionic polymer network structure in alkaline environment the shrinkage behavior, to further improve the technical ideas of water storage stability of internal curing materials in water release control. The preparation of organic-inorganic composite curing materials (OIM-ICA) water rate of 188~270, the water retention rate of more than 85%, water release rate of more than 80%.SEM-EDS analysis showed that the OIM-ICA composite has a crosslinked network structure. The system of synthesis technology on the impact of water - water - water release performance, determine the ratio of raw materials and process parameters of water glass 8%~12%, crosslinking agent 0.12%~0.18%, monomer dropping time 1.5~2.5h, the reaction temperature is 60~70 degrees Celsius.
The system of fineness OIM-ICA dosage, effects of water binder ratio, and other factors on the early shrinkage of concrete. The results showed that with the dosage increase, the decrease of particle size and water cement ratio decreased, decreasing the internal relative humidity of concrete, autogenous shrinkage significantly decreased the content of.OIM-ICA as cementitious materials 0.07%, containing 15% fly ash the water cement ratio of concrete, C50 7d 0.35 can reduce the self shrinkage of 120 mu epsilon above; OIM-ICA curing effect reduce the autogenous shrinkage of the largest contribution to the 9~50nm number of pores. The capillary tension theory based on the introduction of internal curing hydration factor and maintenance volume elastic modulus factor, established OIM-ICA content, fineness, water cement compared with the autogenous shrinkage of concrete model.
The effects of OIM-ICA on body hydration and mechanical properties of concrete cement slurry, influence of durability. With increasing OIM-ICA dosage, cement paste hydration rate and reduce heat, reduce the compressive strength of concrete early, late and close to UN doped OIM-ICA strength, resistance to chloride ion permeability of late frost resistance,, sulfate resistance and carbonization resistance were improved. The influence mechanism is: early cementitious paste hydration inhibition by OIM-ICA and occupy a larger space, improve the porosity, which leads to the decrease of the early strength of concrete; late OIM-ICA water release maintenance effect of cementitious paste hydration degree increases. The number of pores decreased 9~50nm in OIM-ICA, the hydration products formed around to disperse dense "stress arch shell structure, so as to improve the concrete strength and frost resistance, and effectively prevent the Cl-, SO42-, CO32- and other harmful ions in the hair The migration in the pores, improve the permeability resistance of chloride ion, sulfate resistance and carbonization resistance.
According to the internal curing material design method proposed in this paper and the synthesis process, designed annual production capacity of 20 thousand tons of industrial production line, the production of maintenance materials, and the engineering application. The results showed that the incorporation of OIM-ICA improves the crack resistance of concrete engineering crack, effectively solve the problem.

【学位授予单位】：武汉理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528

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