蔗糖超缓凝水泥基材料水化恢复及性能研究

发布时间：2018-05-06 20:45

本文选题：水泥水化 + 超缓凝　；参考：《浙江工业大学》2017年硕士论文

【摘要】：目前,对于商品混凝土搅拌站产生的废弃塑性混凝土,国内常通过水洗后回用砂石骨料与洗刷水进行再生利用,国外则通过加入水化中止和恢复外加剂实现其未水化水泥颗粒的高效再利用。对于湿拌砂浆,为减少因未及时使用完毕而导致的浪费,目前国内已开发一种砂浆开放时间调节剂,以控制湿拌砂浆可工作时间。本文则尝试选用蔗糖作为水化中止外加剂和砂浆开放时间调节剂,并研制开发了一种水化恢复外加剂(HRA),主要研究了HRA对蔗糖超缓凝水泥基材料水化恢复及性能的影响,研究结果表明:(1)掺蔗糖有助于改善新拌水泥浆体的流动性,且随掺量增加,改善效果越好;掺HRA亦可改善水泥浆体的流动性,且掺量越大,浆体流动性越好,但与蔗糖相比,其改善作用较小。(2)掺蔗糖对新拌水泥浆体具有明显缓凝作用,且掺量越大,缓凝效果越明显。蔗糖的掺入使浆体放热速率有一定程度下降,电阻率发展滞后,当掺量为0.2%时,水泥浆体放热温升峰值出现时间长达64.6 h。(3)同掺或后掺HRA均可有效缓解蔗糖的严重缓凝作用,使水泥开始加速水化时间大幅提前,同掺2.0%HRA时,开始水化时间提前至20 h;后掺时间为24h时,掺入HRA后2h内水泥净浆即开始加速水化。(4)掺蔗糖对硬化水泥基材料抗折强度有明显提高,但对抗压强度影响不大。随掺量增加,水泥胶砂抗折强度呈先增大后减小趋势,掺量为0.15%其增强效果最明显,其原因可能是由于蔗糖的掺入促进钙矾石快速生成所致。(5)掺HRA均导致蔗糖缓凝水泥基材料抗折和抗压强度略有下降,其原因可能是掺加胶态HRA导致水泥胶砂水灰比略有增大所致。(6)在对洗刷水未水化水泥颗粒再利用研究中,洗刷水掺量、放置时间及蔗糖掺量对新拌水泥砂浆力学性能均表现出不同程度的影响,其中洗刷水掺量是最主要影响因素,而洗刷水放置时间对新拌水泥基材料28 d力学性能影响最小。
[Abstract]:At present, the waste plastic concrete produced by commercial concrete mixing station is often recycled with sand aggregate and washing water after washing in our country. Abroad, the high-efficiency reuse of unhydrated cement particles is realized by adding hydration suspension and recovery admixture. For wet mix mortar, in order to reduce the waste caused by not using it in time, a kind of mortar open time regulator has been developed in our country to control the working time of wet mix mortar. In this paper, sucrose was chosen as hydration suspension admixture and mortar opening time regulator, and a hydration recovery admixture was developed. The effect of HRA on hydration recovery and properties of sucrose super-retarding cement-based material was studied. The results show that sucrose can improve the fluidity of fresh cement paste, and the better the effect is with the increase of the content of sucrose, the fluidity of cement paste can be improved by adding HRA, and the fluidity of slurry is better with the addition of sucrose, but compared with sucrose, the fluidity of cement paste can be improved by adding sucrose. The effect of sucrose on the fresh cement paste is obviously retarded, and the more the content of sucrose is, the more obvious the retarding effect is. With the addition of sucrose, the exothermic rate of slurry decreased to a certain extent, and the development of resistivity lagged behind. When the dosage of sucrose was 0.2, the peak time of exothermic temperature rise of cement paste appeared as long as 64.6 h 路m3) the serious retarding effect of sucrose could be effectively alleviated by adding or adding HRA to cement paste. When cement is mixed with 2.0%HRA, the starting time of hydration is advanced to 20 h, and the later mixing time is 24 h, when the cement begins to accelerate hydration, the hydration time is much earlier than that when the cement is mixed with 2.0%HRA. The cement paste was accelerated hydration within 2 hours after the addition of HRA.) Sucrose addition significantly improved the flexural strength of hardened cement-based materials, but had little effect on the compressive strength. With the increase of the content of cement mortar, the flexural strength of cement mortar increases first and then decreases, and the reinforcement effect is the most obvious when the content of 0.15% is 0.15%. The reason may be that the addition of sucrose to ettringite can promote the rapid formation of ettringite. The addition of HRA can decrease the flexural strength and compressive strength of sucrose retarding cement-based materials. The reason may be that the ratio of cement sand to cement water to cement is slightly increased due to the addition of colloidal HRA) in the study of the reuse of unhydrated cement particles in washing water, the amount of washing water is added. The effect of storage time and sucrose content on the mechanical properties of fresh cement mortar was different, among which the amount of washing water was the most important factor, while the time of storage of washing water had the least effect on the mechanical properties of fresh cement based material for 28 days.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

【参考文献】