石粉对混凝土碱骨料反应及强度影响研究

发布时间：2018-04-09 23:03

  本文选题：碱骨料反应　切入点：强度　出处：《西南交通大学》2015年硕士论文

【摘要】：本文结合贵广铁路碱骨料抑制试验课题,以建筑废料——石粉的再生利用为背景,对石粉的粒径及掺量对混凝土碱骨料反应、强度及和易性的影响作了系统研究。从微观角度分析碱骨料反应的膨胀机理并建立数学模型描述碱骨料反应膨胀过程,并提出以极限膨胀率为判断碱骨料反应程度的新思想。另外,对石粉对混凝土抗压强度及流动性的影响也作了系统描述,并分析其原因。主要研究内容和成果如下：(1)结合不同掺量及不同粒径石粉抑制混凝土碱骨料反应的结果,以“最不利掺量”及“最不利粒径”为基础,提出石粉“最有利掺量”及“最有利粒径”且该“掺量”及“粒径”对于不同配比混凝土有所不同。随着石粉粒径减小,混凝土碱骨料反应先变强,后变弱,再变强；随着石粉掺量增大,混凝土碱骨料反应先变弱,后变强,再变弱。并建立微观数学模型,解释“最有利掺量”及“最有利粒径”存在的原因。(2)对碱骨料反应过程做出一定假设,以微分方程及数理统计为理论基础,建立描述碱骨料反应过程的数学模型,并预测快速砂浆棒法中龄期t→∞时,试件的“极限膨胀率”,得出结论,石粉对碱骨料反应的抑制主要存在于两方面：降低试件最终膨胀率和降低碱骨料反应速率。(3)无论石粉在混凝土中粒径及掺量如何,在快速砂浆棒法42d龄期以内,各试件膨胀率差别不大,故建议对于掺入惰性掺合料的混凝土,摒弃以14d、28d膨胀率判断碱骨料反应极限膨胀率大小,若后续研究能找出ASR导致混凝土破坏时的极限膨胀率“阈值”,则可以“极限膨胀率”为依据判断掺合料抑制碱骨料反应的有效性。(4)石粉代替水泥会降低胶砂抗压强度,石粉掺量对强度的影响远比粒径的影响大,随着石粉掺量增加,胶砂流动性先变好后变差。胶砂强度及和易性不仅与石粉粒径及掺量有关,更与石粉及骨料级配有关。
[Abstract]:In this paper, the influence of particle size and content of stone powder on the reaction, strength and easiness of concrete alkali aggregate is studied systematically, based on the background of recycling and utilization of construction waste-stone powder in Gui-Guang Railway.The expansion mechanism of alkali aggregate reaction was analyzed from the microscopic point of view, and a mathematical model was established to describe the expansion process of alkali aggregate reaction. A new idea of judging the degree of alkali aggregate reaction with limit expansion rate was put forward.In addition, the influence of stone powder on the compressive strength and fluidity of concrete is also described systematically, and the reasons are analyzed.The main research contents and results are as follows: (1) combined with the results of inhibiting the reaction of concrete alkali aggregate with different amount of stone powder and different particle size, and based on "most unfavorable amount" and "most unfavorable particle size",It is pointed out that the most favorable amount of stone powder and the most favorable particle size are different for concrete with different proportions.With the decrease of stone particle size, the reaction of concrete alkali aggregate first becomes stronger, then weaker, and then stronger; with the increase of the content of stone powder, the reaction of concrete alkali aggregate first weakens, then becomes stronger, and then weakens.A microscopic mathematical model was established to explain the reasons for the existence of "most favorable dosage" and "most favorable particle size", and to make some assumptions about the reaction process of alkali aggregate, which was based on differential equation and mathematical statistics.A mathematical model describing the reaction process of alkali aggregate is established, and the "limit expansion rate" of the specimen is predicted when the intermediate age of the rapid mortar bar method is t 鈭，

本文编号：1728538