预制混凝土构件二次振捣及蒸汽养护技术研究
发布时间：2019-04-11 19:17
【摘要】：现阶段对装配式混凝土结构的研究正处于升温阶段,由于要求实现建筑产业化迈入标准化新阶段,因此对于预制混凝土构件的强度以及其生产时间也愈加重视,而这些都与混凝土构件的养护息息相关。但是在预制构件厂生产流水线的运行过程中,养护占用了大量的时间,而且由于技术的不成熟,时间也存在很大的不可控性。就目前预制构件厂的建立形势来看,大部分预制构件厂均采用蒸汽养护的方式对混凝土构件进行养护,二次蒸汽养护又是较为先进的蒸汽养护方法。因此,对二次蒸汽养护的优化设计以及对二次蒸汽养护窑节能设计的研究就很必要了。本文基于国内外对于蒸汽养护优化的研究现状,通过参考具体的案例,对现有的一些蒸汽养护的优化措施进行了比较研究,并且提出了控制水胶比进行二次振捣以提高混凝土早期强度的措施,其目的在于使得混凝土构件更稳定的适应高温高压蒸汽养护,也能一定幅度减少蒸汽养护的时间,提高效率;同时通过掺入矿粉、粉煤灰以及控制砂率的措施对二次蒸汽养护的优化进行了研究,目的应用改变混凝土材料组分的方式来提高生产效率,并且提高预制混凝土构件后期强度;最后提出几种降低养护窑生产成本,节能减排的假设,并探讨其可能性。科学合理的安排养护流程,既要能够达到产品所要求的使用功能,又要尽量简化操作流程,提高生产的效率,节约生产的成本。通过研究可得出以下结论:(1)通过对现场施工中运用二次振捣案例的分析以及对混凝土构件初凝时间的计算,在恰当时间下的二次振捣可以提高二次蒸汽养护的效率,并且使混凝土后期强度增长更加均匀化。同时通过试验证明了在预制构件厂生产线中加入二次振捣后,混凝土后期强度有明显增加,特别是低标号的混凝土:C30混凝土构件经过二次振捣后可以提高后期强度20%～25%,而C50混凝土构件经过二次振捣后仅仅可以提高后期强度10%～15%;而且在二次蒸汽养护的条件下,二次振捣可以在不影响28d强度的前提下节省10%的水泥用量。同时发现附着式振捣与插入式振捣交替应用效果不如插入式振捣。(2)合理控制常温初级养护的时间,使得混凝土的强度在高温高压阶段可以更好的增长。通过实际案例分析,以及最低成熟度值的计算,常温初级养护的时间在2～4h时,可以有效的改善混凝土内部孔隙结构,并且能够合理的控制流水节拍。(3)通过对案例的分析,对二次蒸汽养护中高温高压阶段的几种影响因素进行了进一步的探究,包括升温速率、恒温时间以及恒温温度。升温速率控制在15℃/h～20℃/h,这样既可以防止升温过程中水汽移动而导致的混凝土内部孔隙率加大甚至开裂,也可以提高蒸汽养护的效率;如果选择过低的恒温温度,则在这个获得强度以及各项性能趋于稳定的阶段混凝土不能得到良好的强度以及性能发展;如果恒温时间过长,在未完全水化的颗粒外则会形成隔离膜,延误甚至阻碍混凝土后期强度的增长,因此恒温温度则选择在50℃～60℃为宜,而恒温时间则在3～4h为宜。(4)在矿粉-粉煤灰双掺的案例中,通过对试验数据的对比以及对双掺比例的研究,双掺量在40%时后期强度最大,脱模强度也可达到50MPa以上;而如果矿粉和粉煤灰的比例为5:3时,则混凝土 28d强度较高,但是90d强度较低,反之相反,这说明矿粉的主要作用在于提高混凝土的前期强度,而粉煤灰则对于混凝土后期强度的发展更加有利。(5)二次蒸汽养护中,提出了循环节能式立式养护窑的设计理念,即在常温初级养护阶段,在“n”式蒸养釜的排气口处加一个管道,将余气引入进气口;在高温高压立式养护窑中,增设供气阀门,在多台蒸养釜连续运作期间,通过对余气的反复利用实现循环节能。并且改善蒸汽喷射系统,使蒸汽喷嘴组合更加合理化、均匀化。对蒸汽蓄热器进行了研究,并且通过计算对拉法尔喷嘴的设计进行了优化。通过对实际案例的分析,根据在辽宁宇辉新型建筑材料有限公司实习所学的知识,整合了以上几点优化二次蒸汽养护的因素,并且提出了预制构件二次振捣的方案,理论联系实际,最终撰写本文。
[Abstract]:At present, the research of the assembled concrete structure is at the temperature rise stage, because it is required to realize the construction industrialization into the new stage of standardization, the strength of the prefabricated concrete component and the production time of the prefabricated concrete component are also more and more important, and these are closely related to the curing of the concrete component. But during the operation of the production line of the prefabricated part factory, the curing takes a great amount of time, and due to the immature technology of the technology, the time also has great incontrollability. In view of the current construction situation of the prefabricated part factory, most of the prefabricated parts are cured by steam curing, and the secondary steam curing is a more advanced method of steam curing. Therefore, it is necessary to study the optimum design of the secondary steam curing and the energy-saving design of the secondary steam curing kiln. Based on the research situation of the optimization of steam curing at home and abroad, this paper makes a comparative study on some of the existing optimization measures for steam curing by referring to the specific case, and puts forward the measures to control the secondary vibration of the water-to-glue ratio to improve the early strength of the concrete. The method has the advantages that the concrete member is more stable to the high-temperature and high-pressure steam curing, the time of the steam curing can be reduced at a certain amplitude, the efficiency is improved, and the optimization of the secondary steam curing is carried out through the measures of incorporating the mineral powder, the fly ash and the control sand ratio, The purpose of this paper is to improve the production efficiency by changing the components of concrete materials, and to improve the later strength of the precast concrete members. Finally, some assumptions to reduce the production cost, energy saving and emission reduction of the curing kiln are put forward, and the possibility is also discussed. And a scientific and reasonable arrangement and maintenance flow can be arranged, so that the use function required by the product can be achieved, the operation flow can be simplified as much as possible, the production efficiency is improved, and the production cost is saved. Through the study, the following conclusions can be drawn: (1) The efficiency of the secondary steam curing can be improved by the analysis of the case of secondary vibration and the calculation of the initial setting time of the concrete member in the field construction. And the later strength of the concrete is increased more uniformly. At the same time, it is proved that after the secondary vibration is added to the production line of the prefabricated part factory, the later strength of the concrete is obviously increased, especially the low-grade concrete: the C30 concrete component can improve the later strength by 20-25% after the secondary vibration, And the C50 concrete component can only improve the later strength by 10 to 15 percent after the secondary vibration, and the secondary vibration can save the cement consumption of 10 percent without affecting the strength of the 28d under the condition that the secondary steam is cured. At the same time, it is found that the alternative application effect of the attached vibration and the plug-in vibration is not as good as the plug-in And (2) reasonably controlling the time of primary curing at normal temperature, so that the strength of the concrete can be better increased in the high-temperature and high-pressure stage. Through the practical case analysis and the calculation of the minimum maturity value, the primary curing time of the room temperature is 2 to 4 hours, the internal pore structure of the concrete can be effectively improved, and the running water beat can be reasonably controlled. (3) Through the analysis of the case, the influence factors of the high-temperature and high-pressure stage in the secondary steam curing are further explored, including the temperature-raising rate, the constant-temperature time and the constant-temperature temperature. the temperature rise rate is controlled at the temperature of 15 DEG C/ h to 20 DEG C/ h, so that the internal porosity of the concrete can be increased or even cracked due to the water vapor movement during the temperature rise process, and the efficiency of the steam curing can be improved; if the low temperature of the constant temperature is selected, the strength and the performance of the concrete can not be obtained at the stage where the obtained strength and various performances are stable; if the constant temperature time is too long, an isolation film is formed outside the completely hydrated particles, and the delay even prevents the increase of the later strength of the concrete, Therefore, the temperature of the constant temperature is selected to be between 50 and 60 DEG C, and the constant temperature time is preferably 3 to 4 hours. and (4) in the case of the double-mixing of the mineral powder and the fly ash, the strength at the later stage and the release strength of the concrete 28d are higher when the proportion of the mineral powder and the fly ash is 5:3, by the comparison of the test data and the research on the double-doping proportion, the strength of the two-mixing is the maximum at the later stage of 40 percent, and the demoulding strength can reach more than 50 MPa; and if the proportion of the mineral powder and the fly ash is 5:3, the strength of the concrete 28d is high, However, that strength of the 90d is low, and vice versa, this indicates that the primary function of the mineral powder is to improve the early strength of the concrete, and the fly ash is more favorable for the development of the later strength of the concrete. (5) in the secondary steam curing, a design concept of a circular energy-saving type vertical maintenance kiln is put forward, namely, a pipeline is added at the exhaust port of the "n"-type steam-curing kettle in the normal-temperature primary curing stage, and the residual gas is introduced into the air inlet; in the high-temperature and high-pressure vertical maintenance kiln, an air supply valve is additionally arranged, During the continuous operation of a plurality of steam-curing kettles, the recycling energy-saving is realized through the repeated utilization of the residual gas. And the steam injection system is improved so that the steam nozzle combination is more reasonable and uniform. The steam heat accumulator was studied and the design of the Laval nozzle was optimized. Through the analysis of practical cases, based on the knowledge obtained in the practice of the new building material limited company in Yonghui, Liaoning, the factors of optimizing the secondary steam curing are completed, and the scheme of secondary vibration of the prefabricated parts is put forward, the theory is in practice, and the paper is finally written.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU755.7
本文编号：2456679
[Abstract]:At present, the research of the assembled concrete structure is at the temperature rise stage, because it is required to realize the construction industrialization into the new stage of standardization, the strength of the prefabricated concrete component and the production time of the prefabricated concrete component are also more and more important, and these are closely related to the curing of the concrete component. But during the operation of the production line of the prefabricated part factory, the curing takes a great amount of time, and due to the immature technology of the technology, the time also has great incontrollability. In view of the current construction situation of the prefabricated part factory, most of the prefabricated parts are cured by steam curing, and the secondary steam curing is a more advanced method of steam curing. Therefore, it is necessary to study the optimum design of the secondary steam curing and the energy-saving design of the secondary steam curing kiln. Based on the research situation of the optimization of steam curing at home and abroad, this paper makes a comparative study on some of the existing optimization measures for steam curing by referring to the specific case, and puts forward the measures to control the secondary vibration of the water-to-glue ratio to improve the early strength of the concrete. The method has the advantages that the concrete member is more stable to the high-temperature and high-pressure steam curing, the time of the steam curing can be reduced at a certain amplitude, the efficiency is improved, and the optimization of the secondary steam curing is carried out through the measures of incorporating the mineral powder, the fly ash and the control sand ratio, The purpose of this paper is to improve the production efficiency by changing the components of concrete materials, and to improve the later strength of the precast concrete members. Finally, some assumptions to reduce the production cost, energy saving and emission reduction of the curing kiln are put forward, and the possibility is also discussed. And a scientific and reasonable arrangement and maintenance flow can be arranged, so that the use function required by the product can be achieved, the operation flow can be simplified as much as possible, the production efficiency is improved, and the production cost is saved. Through the study, the following conclusions can be drawn: (1) The efficiency of the secondary steam curing can be improved by the analysis of the case of secondary vibration and the calculation of the initial setting time of the concrete member in the field construction. And the later strength of the concrete is increased more uniformly. At the same time, it is proved that after the secondary vibration is added to the production line of the prefabricated part factory, the later strength of the concrete is obviously increased, especially the low-grade concrete: the C30 concrete component can improve the later strength by 20-25% after the secondary vibration, And the C50 concrete component can only improve the later strength by 10 to 15 percent after the secondary vibration, and the secondary vibration can save the cement consumption of 10 percent without affecting the strength of the 28d under the condition that the secondary steam is cured. At the same time, it is found that the alternative application effect of the attached vibration and the plug-in vibration is not as good as the plug-in And (2) reasonably controlling the time of primary curing at normal temperature, so that the strength of the concrete can be better increased in the high-temperature and high-pressure stage. Through the practical case analysis and the calculation of the minimum maturity value, the primary curing time of the room temperature is 2 to 4 hours, the internal pore structure of the concrete can be effectively improved, and the running water beat can be reasonably controlled. (3) Through the analysis of the case, the influence factors of the high-temperature and high-pressure stage in the secondary steam curing are further explored, including the temperature-raising rate, the constant-temperature time and the constant-temperature temperature. the temperature rise rate is controlled at the temperature of 15 DEG C/ h to 20 DEG C/ h, so that the internal porosity of the concrete can be increased or even cracked due to the water vapor movement during the temperature rise process, and the efficiency of the steam curing can be improved; if the low temperature of the constant temperature is selected, the strength and the performance of the concrete can not be obtained at the stage where the obtained strength and various performances are stable; if the constant temperature time is too long, an isolation film is formed outside the completely hydrated particles, and the delay even prevents the increase of the later strength of the concrete, Therefore, the temperature of the constant temperature is selected to be between 50 and 60 DEG C, and the constant temperature time is preferably 3 to 4 hours. and (4) in the case of the double-mixing of the mineral powder and the fly ash, the strength at the later stage and the release strength of the concrete 28d are higher when the proportion of the mineral powder and the fly ash is 5:3, by the comparison of the test data and the research on the double-doping proportion, the strength of the two-mixing is the maximum at the later stage of 40 percent, and the demoulding strength can reach more than 50 MPa; and if the proportion of the mineral powder and the fly ash is 5:3, the strength of the concrete 28d is high, However, that strength of the 90d is low, and vice versa, this indicates that the primary function of the mineral powder is to improve the early strength of the concrete, and the fly ash is more favorable for the development of the later strength of the concrete. (5) in the secondary steam curing, a design concept of a circular energy-saving type vertical maintenance kiln is put forward, namely, a pipeline is added at the exhaust port of the "n"-type steam-curing kettle in the normal-temperature primary curing stage, and the residual gas is introduced into the air inlet; in the high-temperature and high-pressure vertical maintenance kiln, an air supply valve is additionally arranged, During the continuous operation of a plurality of steam-curing kettles, the recycling energy-saving is realized through the repeated utilization of the residual gas. And the steam injection system is improved so that the steam nozzle combination is more reasonable and uniform. The steam heat accumulator was studied and the design of the Laval nozzle was optimized. Through the analysis of practical cases, based on the knowledge obtained in the practice of the new building material limited company in Yonghui, Liaoning, the factors of optimizing the secondary steam curing are completed, and the scheme of secondary vibration of the prefabricated parts is put forward, the theory is in practice, and the paper is finally written.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU755.7
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