掺碱激发剂粉煤灰水泥混凝土力学性能试验研究
时间：2021-01-09 12:00:23 来源：雅意学习网 本文已影响 人 
基金项目:水利部公益性行业科研专项经费项目(201301033)
作者简介:刘飞鹏 （1988），男，湖南娄底人，硕士研究生，主要从事水工结构与材料研究工作。Email：1219667499@qq.ComDOI：10.13476/j.cnki.nsbdqk.2014.04.029
摘要：通过C30混凝土实验室配合比，配制掺30％粉煤灰的粉煤灰水泥混凝土，在三个实验组中分别掺入最佳掺量的NaOH、水玻璃和CaO，振捣成型，测定碱对流动度和凝结时间的影响，用扫描电镜探求胶砂的微观结构，随后养护至龄期。按照《普通混凝土力学性能试验方法标准》测定混凝土抗压强度和劈拉强度，通过强度比较，算出强度提高率；可以得出掺碱对早期和后期强度发展的影响。结果表明，掺碱能促凝且胶砂流动度减小；掺碱粉煤灰早期强度发展快，后期发展较缓慢，90 d强度基本能够满足设计要求；扫描电镜中，由于水泥水化加快，粉煤灰活性得以激发，早期强度得到改善；经济技术效益显著。
关键词：粉煤灰；掺碱粉煤灰水泥；碱激发剂；混凝土；力学性能
中图分类号：TU528.2文献标志码：A文章编号：16721683（2014）04013404
Mechanical Performance Test of Fly Ash Cement Concrete Mixed with Alkali Excitant
LIU Feipeng1,GONG Aiming1,WANG Liangzenan1,YANG Yanling2
(1.College of Water Conservancy,Yunnan Agricultural University,Kunming 650201,China
2.Tangchi Street Agency of Kunming Yangzonghai Scenic Area Management Committee,Kunming 652103,China)
Abstract:Based on the laboratory mix ratio of C30 concrete，the fly ashcement concrete was mixed with 30% fly ash to make three experimental groups which were also mixed with the best dosages of NaOH,sodium silicate,and CaO,respectively.After vibration molding,the impactsof alkali on the mobility and setting time were determined.The microstructure of mortar was investigated using the scanning electron microscope,and then the samples were maintained to age.According to the 《Standard for test method of mechanical properties on ordinary concrete》,the compressive strength and splitting tensile strength of the concrete were measured.Through the comparison of strengths,the intensity increasing rate was determined,which can help understand the impacts of mixing alkali on the strength development in the early and late times.The results showed that (1) mixing with alkali can coagulate and decrease the mobility of mortar；(2) the fly ash mixed with alkali has a rapid strength development in the early time and a slow strength development in the late time,and the strength at 90 days can meet the design requirements;(3) In the scanning electron microscope experiment,due to the quick cement hydration speed,the activity of fly ash motivates,and so the strength in the early time improves;and (4) the economic and technical benefit is remarkable for the fly ashcement concrete mixed with alkali excitant.
Key words:fly ash;fly ashcement mixed with alkali;alkali excitant;concrete;mechanical property
碱激发粉煤灰的理论研究认为［1］，在化学组成上，粉煤灰中的CaO、MgO、SO3等含量越高，粉煤灰的活性就越高；从相组成来看，粉煤灰中的玻璃体含量越高，粉煤灰的活性就越高；从玻璃相的结构来看，玻璃体中［SiO4］4聚合度越低，玻璃体的稳定性越差，玻璃体解聚越容易，活性就越高。沈旦申［2］提出了四种粉煤灰效应假说。①形态效应。粉煤灰的物理性状促使水泥浆体的需水量减小，保水性和均匀性增强，改善了浆体的初始结构；②活性效应。粉煤灰中以酸性氧化物为主的玻璃体能与水泥水化所产生的氢氧化钙发生火山灰效应，生成水化硅酸钙凝胶和水化铝酸钙晶体，从而起到增强作用;③微集料效应。粉煤灰颗粒本身强度很高，参加反应后在粉煤灰表面生成的低钙的CS凝胶使界面粘接力增强，明显增强了水泥石的结构强度；A.L.A.Fraay通过溶出实验发现在pH>134的碱性条件下粉煤灰结构会被破坏［3］。
粉煤灰应用于混凝土早被工程界普遍接受，但同时掺入碱性激发剂在目前的研究当中并不多见。
本文通过试验分析掺碱激发剂粉煤灰水泥混凝土材料的力学性能。
1试验原材料及试验设计
11试验原材料
水泥：本试验所采用的水泥是P·O425硅酸盐水泥，水泥各项指标符合GB 1752007《通用硅酸盐水泥》要求。
Ⅱ级粉煤灰：本试验所采用的Ⅱ级粉煤灰，其物理性能指标见表1。
表1Ⅱ级粉煤灰物理性能指标
Table 1The physical performance parameters
of Ⅱlevel fly ash
