【作者】 李欣；

【导师】 丁向群；

【作者基本信息】 沈阳建筑大学 ， 材料工程（专业学位）， 2020， 硕士

【摘要】 本文首先研究了促凝凝组分三乙醇胺、硫酸铝单掺和复掺,缓凝组分柠檬酸、六偏磷酸钠对水泥试样凝结时间和强度的影响,试验后得出结论:三乙醇胺促凝作用不稳定,会降低强度;硫酸铝单掺时掺量在4%时凝结时间与强度最佳,复合掺入三乙醇胺后终凝时间变得稳定,但强度损失较大;柠檬酸与六偏磷酸钠对水泥试样都有明显的缓凝作用,柠檬酸对强度的影响先减小后增大,而六偏磷酸钠使强度降低。最后选取单掺硫酸铝掺量为4%掺入砂浆中作为清水混凝土的基础材料。在此基础上,以水灰比、胶砂比和减水剂掺量为基础流变因素设计正交试验,分别测试基础材料流动度、抗压抗折强度、以收缩率为指标的体积稳定性,并对胶砂流动度、3d和28d抗压强度、3d收缩率的值进行极差与方差分析,得出以下结论:(1)各基础流变因素对胶砂流动度的影响程度大小依此为:减水剂的掺量>水灰比>胶砂比。当减水剂掺量为1.5%、水灰比为0.35、胶砂比为1:0.8时,胶砂流动度最大。减水剂掺量的改变对清水混凝土的胶砂流动度有显著影响,水灰比和胶砂比对胶砂流动度无显著影响。(2)3d和28d的抗压与抗折强度均以第1组最高,其配比为:水灰比为0.33、胶砂比为1:0.8、减水剂的掺量为1.3%;各因素对清水混凝土3d抗压强度的影响程度大小顺序为:水灰比>减水剂的掺量>胶砂比,28d抗压强度的影响程度大小顺序为:减水剂的掺量>水灰比>胶砂比。(3)3d和7d的收缩率均以第9组最大,其配比为:水灰比为0.35、胶砂比为0.8:1、减水剂的掺量为1.4%;14d和28d的收缩率均以第八组最大,其配比为:水灰比为0.35、胶砂比为0.8:1、减水剂的掺量为1.3%;各因素对3d收缩率的影响程度大小顺序为:水灰比>减水剂的掺量>胶砂比。当水灰比为0.33、减水剂掺量为1.5%、胶砂比为1:0.8时,清水混凝土3d收缩率最小。选取胶砂流动性最好配比(减水剂掺量为1.5%、水灰比为0.35、胶砂比为1:0.8)进行下一步试验,在此基础上掺加掺合料(硅灰、粉煤灰)和外加剂(膨胀剂、消泡剂)进行平行试验,测试其对净浆流动度、抗压抗折强度和收缩率的影响,结果如下:硅灰会降低流动度,强度先增加后降低,在8%掺量时最大,掺量超过8%会增大收缩率;粉煤灰对流动度的影响先增加后降低,掺量为20%时最大,3d强度变化无明显规律,28d强度先增大后减小,15%掺量时最大;硅灰和粉煤灰的复掺,硅灰8%,粉煤灰15%流动度最好,充分了发挥硅灰提高早期强度的优势,也通过粉煤灰的加入,减小干燥收缩,体现了复合材料的“超叠效应”。膨胀剂在掺量为6%时流动度最小,但强度最高,收缩率基本减为零;消泡剂掺量为0.3%时流动性最好,在掺量为0.5%时强度最高,随掺量增加,收缩率逐渐减小。更多还原

【Abstract】 In this paper,the effects of the coagulation component triethanolamine,aluminum sulfate single doping and complex doping,the retarding component citric acid and sodium hexametaphosphate on the setting time and strength of cement samples were studied.After the test,it was concluded that triethanolamine The coagulation inhibition is unstable,which will reduce the strength;the coagulation time and strength are best when the content of aluminum sulfate single doping is 4%,and the final setting time becomes stable after compounding with triethanolamine,but the strength loss is large;citric acid and Sodium hexametaphosphate has a significant retarding effect on cement samples.The effect of citric acid on strength is first reduced and then increased,while sodium hexametaphosphate is used to reduce strength.Finally,the amount of aluminum sulphate mixed with 4% was mixed into the mortar as the base material of the fair-faced concrete.On this basis,the orthogonal test is designed based on the rheological factors of water-cement ratio,rubber-sand ratio and water-reducing agent.The fluidity,compressive and flexural strength of the base material and the volume stability of the shrinkage rate are tested respectively.And the extreme difference and variance analysis of the sand flow,3d and 28 d compressive strength,3d shrinkage value,the following conclusions are drawn:(1)The influence degree of each basic rheological factor on the fluidity of the mortar is as follows: the amount of water reducing agent > water-cement ratio > mortar ratio.When the amount of water reducing agent is 1.5%,the water-cement ratio is 0.35,and the ratio of rubber to sand is 1:0.8,the fluidity of the mortar is the largest.The change of the amount of water reducing agent has a significant effect on the fluidity of the clear water concrete.The ratio of water to cement and the ratio of rubber sand have no significant effect on the fluidity of the sand.(2)The compressive and flexural strengths of 3d and 28 d were the highest in Group 1,the ratio of water-cement ratio was 0.33,the ratio of sand to sand was 1:0.8,and the amount of water-reducing agent was 1.3%.The influence degree of the factors on the 3D compressive strength of fair-faced concrete is as follows: water-cement ratio>additive amount of water-reducing agent>sand-sand ratio,the influence degree of 28 d compressive strength is as follows: the amount of water reducing agent> Water-cement ratio > mortar ratio.(3)The shrinkage rates of 3d and 7d were the largest in Group 9,and the ratio was: water-cement ratio of 0.35,mortar ratio of 0.8:1,water-reducing agent dosage of 1.4%;14d and 28 d shrinkage.The ratio is the largest in the eighth group,and the ratio is: water-cement ratio is 0.35,rubber-sand ratio is 0.8:1,and water-reducing agent is 1.3%;the influence degree of each factor on 3d shrinkage is : Water-cement ratio > dosage of water reducing agent > mortar ratio.When the water-cement ratio is 0.33,the water reducing agent dosage is 1.5%,and the rubber sand ratio is 1:0.8,the 3d shrinkage rate of the fair-faced concrete is the smallest.Select the best ratio of fluidity of the mortar(1.5% water reducing agent,0.35 water-cement ratio,1:0.8 sand ratio)for the next step,on which the admixture(silica ash)is added.,fly ash)and admixtures(expansion agent,defoamer)were tested in parallel to test the effect on the slurry fluidity,compressive flexural strength and shrinkage.The results are as follows:Silica fume will reduce the fluidity,the strength will increase first and then decrease,and the maximum will be at 8%.The amount of more than 8% will increase the shrinkage rate;the effect of fly ash on the fluidity will increase first and then decrease,and the dosage will be 20%.The maximum time,3d intensity change has no obvious law,28 d strength first increases and then decreases,15% dosage is the largest;silica fume and fly ash recombination,silica fume 8%,fly ash 15% fluidity is best Give full play to the advantages of silica fume to improve early strength,and also reduce the drying shrinkage by the addition of fly ash,reflecting the "super-stacking effect" of composite materials.When the amount of expansion agent is 6%,the fluidity is the smallest,but the strength is the highest,and the shrinkage rate is basically reduced to zero.When the amount of defoaming agent is 0.3%,the fluidity is the best,and when the dosage is 0.5%,the strength is the highest.As the amount increases,the shrinkage rate gradually decreases.更多还原