Research On The Properties Of Phosphorous Slag Self-compacting Concrete

With the development of concrete industry,mineral admixtures have become an indispensable component of concrete.Reasonable and effective use of mineral admixtures in construction projects can not only improve the comprehensive performance of concrete,but also solve the problem of environmental pollution caused by industrial waste.However in recent years,with the increasingly mature application in the engineering technology of fly ash,resulting in the shortage of resources,and the cost is also increasing year by year,which makes us have to seek a new mineral admixtures to substitute fly ash.In some areas of our country,on the other hand,phosphorus slag resources are abundant and not effectively used which not only cause the waste of resources but also pollute the environment,and phosphorus slag as concrete mineral admixtures almost have the effect of fairly with fly ash,so it created the market conditions for the application of phosphorus slag.Therefore,in this paper,based on the use of phosphorus slag to prepare self-compacting concrete on the basis of exploring the possibility of phosphorus slag instead of fly ash as mineral admixture,and to achieve the purpose of phosphorus slag resource utilization.In this paper,the effect of phosphorus slag as mineral admixture on the properties of cement paste,cement mortar and self-compacting concrete was studied.The main contents include: Effect of phosphorus slag and fly ash content on the setting time,standard consistency water consumption of composite cementitious materials and the strength of cement mortar;Effects of different phosphorus slag content on the performance,mechanical properties and durability of C50 self-compacting concrete.The results showed that:(1)Phosphorous slag and fly ash can reduce the standard consistency water consumption of cementitious materials,and obviously delay the setting time of cement,the retarding effect of phosphorus slag significantly stronger than fly ash and water reducing effect is better.(2)Phosphorus slag and fly ash can reduce the early strength of cement mortar,and the content is greater the lower early strength,but all contribute to improve the later strength of cement mortar,effects of phosphorus slag on the strength of cement mortar is better than fly ash.(3)Phosphorous slag and fly ash can improve the performance of self-compacting concrete mixture,but more phosphorous slag may cause bleeding and segregation,using phosphorous slag to prepare self-compacting concrete the maximum content should not exceed 30%.The incorporation of fly ash can improve the consistency of the mixture and increase the mixture?s cohesiveness and water retention.Fly ash with phosphorus slag can be prepared with excellent workability of self-compacting concrete.(4)Phosphorous slag and fly ash can reduce the early strength of self-compacting concrete,the lower the dosage,the greater the early strength,but both are conductive to the development of the long-term strength.Phosphorous slag as mineral admixture of concrete is more advantageous to the development of compressive strength of concrete.(5)46%,45%,44% of the sand ratio has little effect on the performance of self-compacting concrete,lower water/cement ratio will increase the compressive strength of concrete in various age.The working performance and mechanical properties of self-compacting concrete are the best with fixed phosphorus slag content of 30%,water to binder ratio of 0.32 and sand ratio of up to 45%.(6)Phosphorous slag has great influence on the drying shrinkage of self-compacting concrete,early drying shrinkage rate increases fast but the later grows relatively slow,and the bigger content of admixture the greater the drying shrinkage of self-compacting concrete.Phosphorous slag can improve the durability of self-compacting concrete,and when the content of phosphorous slag is 30%,the carbonation resistance,impermeability and sulfate resistance of self-compacting concrete are the best.