【作者】 张媛；

【导师】 吴晓勇； 何仕均；

【作者基本信息】 武汉理工大学 ， 环境工程（专业学位）， 2024， 硕士

【摘要】 我国氟化工行业发展迅速,其工业副产物氟石膏的产量也随之增加,为提高氟石膏的利用率,很多企业将其应用于建材领域,而抹灰石膏作为一种绿色建材,符合国家低碳环保政策,已受到广泛关注。本文以氟石膏为研究对象,通过外加剂对其进行改性,以“氟石膏+水泥”为胶凝材料制备重质抹灰石膏,并系统地研究了各种外加剂、水泥掺合料及机制砂对试件性能的影响。首先,研究了不同粒径氟石膏的pH及可溶性氟含量,并研究了氧化钙、氢氧化钙对其pH及可溶性氟含量的影响,结果表明:不同粒径氟石膏pH基本稳定在1.50～1.80,且pH不随浸出时间延长而发生较大变化;氟石膏中可溶性氟含量随粒径减小而增大,且同一粒径氟石膏可溶性氟含量随浸出时间延长而升高。后续实验所用氟石膏pH为1.70、可溶性氟含量为0.31%,其pH及可溶性氟含量随氧化钙、氢氧化钙用量增加而分别呈现递增及递减趋势,当中和剂用量为3.00%时,pH增至9.00左右,可溶性氟含量降低至0.02%左右,最终选用3.00%CaO中和后的氟石膏进行后续试验。其次,研究了硫酸钠、硫酸钾、草酸钠三种激发剂对氟石膏抗折及抗压强度、水化率及凝结时间的影响,结果表明:硫酸钠激发效果最佳,硫酸钾次之,草酸钠最差,但掺入硫酸钠及草酸钠的石膏硬化体存在泛霜现象,选用硫酸钾为制备抹灰石膏的激发剂。研究了半水石膏、硅酸钾、煅烧磷石膏三种促凝剂对氟石膏性能的影响,结果表明:三种促凝剂皆可提升硬化体强度,缩短其凝结时间,且促凝效果由高到低依次为硅酸钾、半水石膏、煅烧磷石膏,选用促凝效果最佳的硅酸钾为制备抹灰石膏的促凝剂。研究了可再分散乳胶粉对氟石膏性能的影响,结果表明:可再分散乳胶粉延长了氟石膏的凝结时间,且用量越大,凝结时间越长,其用量由0.50%增至2.50%时,氟石膏抗折强度不断提高,抗压强度则呈现先递增后递减的趋势。进一步,采用三因素三水平正交实验研究硫酸钾、硅酸钾、可再分散乳胶粉对抹灰石膏各性能的影响程度,并确定了抹灰石膏的基础药剂配比。研究发现,硅酸钾对抹灰石膏初凝时间的缩短有利;影响抹灰石膏抗压强度的因素排名依次为可再分散乳胶粉、硅酸钾、硫酸钾;影响抹灰石膏抗折强度的因素排名依次为硫酸钾、硅酸钾、可再分散乳胶粉。根据终凝时间确定抹灰石膏的基础配比为:硫酸钾1.00%、硅酸钾0.15%、可再分散乳胶粉1.50%。最后,探究了水泥掺合料及机制砂对抹灰石膏性能的影响。研究表明,水泥掺入缩短了抹灰石膏的凝结时间,其抗压及抗折强度则随水泥掺量增加皆呈现先递增后递减再递增趋势,其软化系数随水泥掺量增大而增大。选用20.00%水泥为适宜掺量,此水泥掺量下抹灰石膏抗折强度为3.35 MPa、抗压强度为14.04 MPa,软化系数为0.53。抹灰石膏凝结时间随机制砂掺量增加而延长,其抗折及抗压强度皆随机制砂用量增加而呈现先递增后降低趋势,当胶砂比为1.00:0.50时,抗折及抗压强度最高为5.83 MPa、18.47 MPa。通过对各试验结果进行分析,确定氟石膏基重质抹灰石膏的配合比为:中和氟石膏:水泥=80:20,胶砂比为1.00:0.50,硫酸钾为胶凝材料的1.00%,硅酸钾为胶凝材料的0.15%,可再分散乳胶粉为胶凝材料的1.50%,标准扩散度用水量为胶凝材料的29.00%。对该重质抹灰石膏进行综合性能检测,结果表明:该重质抹灰石膏各性能均优于国家标准要求。更多还原

【Abstract】 The production of fluorogypsum is increasing,along with the rapid expansion of our country’s fluorine chemical industry.To improve the utilization of fluorogypsum,many enterprises have applied it in the field of building materials,while plaster gypsum,as a green building material,is in line with the national low-carbon and environmental protection policies,has attracted wide attention.In this thesis,fluorogypsum as the research object,through the modification with admixtures,heavy plaster gypsum was prepared using"fluorogypsum+cement"as the cementing material.The effects of various admixtures,cement admixtures,and mechanism sand on the performance of specimens were systematically investigated.Firstly,the pH and soluble fluorine content of fluorogypsum with different particle sizes were studied.The influence of calcium oxide and calcium hydroxide on the pH and soluble fluorine content was also investigated.The results showed that the pH of fluorogypsum with different particle sizes was relatively stable at 1.50-1.80,and the pH did not change greatly with the extension of extraction time.The content of soluble fluorine increased as the particle size decreased,and the soluble fluorine content of fluorogypsum in the same particle size increased with the extension of extraction time.The pH and soluble fluorine content of fluorogypsum used in subsequent experiments were 1.70 and 0.31%,respectively.The pH increased and the soluble fluorine content decreased with the increase of the dosage of calcium oxide or calcium hydroxide.When the dosage of the neutralizer was 3.00%,the pH increased to about 9.00,and the soluble fluorine content decreased to about 0.02%.Fluorogypsum neutralized with 3.00%calcium oxide was used for follow-up tests.Secondly,the effects of sodium sulfate,potassium sulphate and sodium oxalate on the flexural and compressive strength,hydration rate,and setting time of fluorogypsum were investigated.The tests revealed that sodium sulfate had the best activating effect,followed by potassium sulphate,and sodium oxalate was the worst.However,the specimens mixed with sodium sulfate or sodium oxalate had frosting phenomenon.Therefore,potassium sulphate was selected as the activator for preparing plaster gypsum.The effects of hemihydrate gypsum,potassium silicate,calcined phosphogypsum on the properties of fluorogypsum were also investigated.The calculations indicated that all three coagulants could increase the strength of the specimens and shorten the setting time.The effect was ranked from highest to lowest as potassium silicate,hemihydrate gypsum,and calcined phosphogypsum.Therefore,potassium silicate was selected as the coagulant for preparing plaster gypsum.Furthermore,the influence of redispersible emulsion powder on the properties of fluorogypsum was researched.Test results indicated that redispersible emulsion powder extended the setting time of fluorogypsum,and as the dosage increased,the setting time also prolonged.When the dosage of redispersible emulsion powder increased from 0.50%to 2.50%,the flexural strength of specimens continuously increased,while the compressive strength showed an initial increase followed by a decrease trend.Furthermore,a three-factor,three-level orthogonal experiment was conducted to investigate the effects of potassium sulphate,potassium silicate,and redispersible emulsion powder on various properties of plaster gypsum,and the basic formulation of plaster gypsum was determined.The study found that potassium silicate was beneficial for reducing the initial setting time of plaster gypsum.The influence on the compressive strength of plaster gypsum ranked from high to low as redispersible emulsion powder,potassium silicate,and potassium sulphate.The factors affecting the flexural strength of plaster gypsum ranked in the following order:potassium sulphate,potassium silicate,and redispersible emulsion powder.Based on the final setting time,the basic formulation of plaster gypsum was determined as follows:1.00%potassium sulphate,0.15%potassium silicate,and 1.50%redispersible emulsion powder.Finally,the influence of cement and mechanism sand on the properties of plaster gypsum was explored.The research found that the addition of cement reduced the setting time of plaster gypsum.The compressive and flexural strength of plaster gypsum showed an initial increase,followed by a decrease,and then another increase with increasing cement content.The softening coefficient of plaster gypsum increased with higher cement content.A suitable cement content of 20.00%was chosen,resulting in the flexural strength of 3.35 MPa,compressive strength of 14.04 MPa,and the softening coefficient of 0.53.As the amount of mechanism sand increased,the setting time of plaster gypsum increased,the flexural and compressive strength showed an initial increase,followed by a decrease.When the ratio of cement to sand was 1.00:0.50,the highest flexural and compressive strength were 5.83 MPa and18.47 MPa respectively.Based on the analysis of the test results,the formulation for heavy plaster gypsum using fluorogypsum as the base material was as follows:neutralizing fluorogypsum to cement ratio of 80.00:20.00,cementitious sand ratio of 1.00:0.50,potassium sulphate at 1.00%of the cementing material,potassium silicate at 0.15%of the cementing material,redispersible emulsion powder at 1.50%of the cementing material,and the standard diffusion water content at 29.00%of the cementing material.Comprehensive performance testing of the heavy plaster gypsum showed that all properties were better than the requirements of national standards.更多还原