Research On The Cementitious Characteristics Of Phosphorus Slag Powder And Properties Of C50 T-shaped Beam Concrete

With the rapid development of yellow phosphorous industry, the annual emission of phosphorous slag(PS) has increased yearly, which causes environmental pollution. At present, PSP of ordinary fineness is usually used in low-strength concrete of hydropower project, while PSP of ultra fine is mainly used in high-strength concrete of housing construction. However little research has been conducted on application of PSP of ordinary fineness in bridge engineering. In this paper, the cementitious characteristics of PSP and performance of C50 T-shaped beam concrete prepared by PSP of ordinary fineness were studied, which provides theoretical basis for application of phosphorus slag powder concrete in bridge engineering.Indoor minitype ball mill was conducted to study the effect of the grinding aids-TIPA on PS grinding efficiency, as well as the influences of the content and specific surface area of PSP, and the chemical activator on the cementitious properties of PSP. Results show that the grinding aids can improve the grinding efficiency of PS and the mechanical performance of PS cement. The setting time of PSP cement is linear to the content of PSP and lengthens as the specific surface area of PSP increases. Incorporation of PSP decreases the early strength of mortar and increases its later strength. With the increases of the content of PSP, the trend of strength rise first and fall later. However, the activation of PSP can not be improved remarkably when the specific surface area is more than 450m2/kg. It is suggested that the specific surface area of PSP has a less effect on the setting time and strength of mortar than the content of. The most appropriate specific surface area and content of PSP are 350-450m2/kg and≤40%respectively. The use of proper chemical activator such as 0.5%Na2SiO3 is crucial to the activation of PSP.The influence of PSP with the specific surface area of 380m2/kg on mechanical properties and permeability of C50 T-shaped beam concrete have been studied. Results show that the addition of PSP with content≤25%can improve concrete performance obviously. The best addition ratio is 20%. With the content of 20%, PSP has a similar performance to S95 grade slag powder, and better thanⅠgrade fly ash. Based On experimental results above, the influence of PSP, fly ash and slag powder of same addition on the hydration heat of cementitious materials has been studied. Results show that PSP is more effective than the other two to reduce the early hydration heat and its release rate of cementitious materials. Finally, Microscopic test methods such as XRD and SEM were applied to study the composition and microstructure of hydration product as well as the hydration mechanism for cement paste with PSP. The influence of PSP on setting time and strength of concrete was also investigated.