基于电阻率法的激发硬石膏水化过程的研究

发布时间：2018-01-28 02:56

本文关键词： 硬石膏电阻率激发剂水化率离子浓度　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文以天然硬石膏、单一硫酸盐激发硬石膏和复合激发硬石膏为研究对象,通过对其水化硬化阶段的电阻率及微分曲线的研究,结合硬石膏在不同激发状态下的水化率、强度和离子浓度的变化,将激发硬石膏的水化硬化过程划分为溶解期、成核期、加速期和稳定期。研究发现,电阻率能够正确反映激发硬石膏在水化过程中的离子浓度的变化,不同激发剂在电阻率曲线中的起始值、最低值及微分值的不同反映了硬石膏在不同激发条件下水化硬化的不同特点。电阻率曲线的初始值反映激发剂种类及掺量的不同,最低值反映总体离子浓度及相对二水石膏的过饱和浓度的大小,微分曲线反映硬石膏在激发水化状态下的溶解和成核结晶的速率。通过对无激发天然硬石膏的水化电阻率曲线的研究发现,初始电阻率和最低电阻率都较高,因电阻率可以反映浆体的液相离子浓度,从而初始电阻率和最低电阻率值都较高与浆体过饱和浓度较低相一致,所以天然硬石膏水化硬化速度缓慢,电阻率曲线上升平缓,强度较低且增长缓慢。研究发现无激发的天然硬石膏没有加速结晶阶段,这正是由于它的过饱和浓度较低的缘故。对硫酸盐激发硬石膏的水化电阻率曲线及其阶段划分的研究发现,其初始电阻率比天然硬石膏水化电阻率低,最低电阻率也比天然硬石膏水化电阻率低,微分曲线峰值更高,微分值零点出现更靠前。硫酸盐激发硬石膏的水化电阻率曲线都有明显的加速结晶期,这是激发硬石膏与无激发天然硬石膏的电阻率曲线最明显区别(煅烧明矾除外,煅烧明矾激发有明显的膨胀作用)。观察电阻率曲线及微分曲线发现激发剂的主要作用是增大了硬石膏的过饱和浓度,并且使整个水化过程加快,成核结晶过程提前。通过对强度、水化率、电阻率的分析比较发现,电阻率与水化率,电阻率与强度之间都存在明显相关性。对盐-水泥复合激发硬石膏的水化电阻率的研究表明,复合激发硬石膏的电阻率值也很低,电阻率微分曲线的峰值较大。虽然其溶解结晶过程没有像硫酸盐激发硬石膏那样显著提前,但在早期水化过程中,电阻率曲线上升幅度强劲,电阻率微分值较高,且维持时间较长。这说明在盐和硅酸盐水泥的共同作用下,不仅大大促进了硬石膏的溶解结晶,而且水泥的水化硬化也被加快,复合激发比单一激发效果更好,强度增长更快更高。激发硬石膏电阻率的研究表明,硬石膏的水化硬化过程遵从“溶解-成核-结晶”理论。凡是能加速硬石膏溶解,增加二水石膏结晶过饱和度的激发剂都能够促进硬石膏的水化硬化,但激发剂的效果有明显的不同,通过电阻率曲线能快速加以区分。
[Abstract]:In this paper, the resistivity and differential curves of natural anhydrite, single sulfate activated anhydrite and compound activated anhydrite were studied. The hydration hardening process of anhydrite can be divided into dissolution period, nucleation period, accelerated period and stable period according to the change of hydration rate, strength and ion concentration of anhydrite under different excitation conditions. The resistivity can accurately reflect the change of ion concentration in the hydration process of the excited anhydrite and the initial values of different activators in the resistivity curve. The difference of minimum value and micro-score reflects the different characteristics of hydration hardening of anhydrite under different excitation conditions. The initial value of resistivity curve reflects the different types of activator and the amount of activator. The lowest value reflects the total ion concentration and the relative supersaturated concentration of gypsum dihydrate. The differential curve reflects the rate of dissolution and nucleation of anhydrite in the excited hydration state. By studying the hydration resistivity curve of the anhydrite, it is found that both the initial resistivity and the lowest resistivity are higher. Because the resistivity can reflect the liquid ion concentration of the slurry, the initial resistivity and the lowest resistivity value are consistent with the lower supersaturated concentration of the slurry, so the hydration hardening rate of natural anhydrite is slow. The resistivity curve rises slowly, the strength is low and the growth is slow. It is found that the unstimulated natural anhydrite does not accelerate the crystallization stage. This is due to its low supersaturated concentration. The hydration resistivity curve and its phase division of sulfate stimulated anhydrite are found to be lower than that of natural anhydrite. The lowest resistivity is also lower than that of natural anhydrite, the peak value of differential curve is higher, and the micro-score is higher than that of natural anhydrite at 00:00. The hydration resistivity curve of sulfate excited anhydrite has obvious accelerated crystallization period. This is the most obvious difference between the resistivity curve of activated anhydrite and that of unstimulated natural anhydrite (except calcined alum. Observation of resistivity curve and differential curve show that the main function of activator is to increase the supersaturated concentration of anhydrite and accelerate the whole hydration process. Through the analysis and comparison of strength, hydration rate and resistivity, the resistivity and hydration rate are found. There is an obvious correlation between resistivity and strength. The hydration resistivity of anhydrite excited by salt-cement composite is also very low. The peak value of the differential resistivity curve is larger. Although the dissolution and crystallization process of the resistivity curve is not as obvious as that of sulfate stimulated anhydrite, the resistivity curve rises strongly in the early hydration process. The resistivity micro-score is higher and the maintenance time is longer, which indicates that under the joint action of salt and Portland cement, not only the dissolution and crystallization of anhydrite are greatly promoted, but also the hydration hardening of cement is accelerated. The composite excitation is better than the single excitation, and the strength increases faster and higher. The study on the resistivity of anhydrite shows that the composite excitation is more effective than the single excitation. The hydration hardening process of anhydrite follows the theory of dissolution-nucleation-crystallization. Any activator that can accelerate anhydrite dissolution and increase the crystallization supersaturation of gypsum dihydrate can promote hydration hardening of anhydrite. But the effect of activator is obviously different and can be quickly distinguished by resistivity curve.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ177.31

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