Influence of Phosphorus Slag on Physical and Mechanical Properties of Cement Mortars

Abstract

Influences of phosphorus slag from 10% to 50% (by mass) on the setting time and the water requirement of the normal consistency of cement pastes, flowability, resistance to carbonation, and the compressive strength of cement mortars were investigated. The physical activation by improving fineness and the chemical activation by adding the chemical activator were evaluated by the compressive strength of cement mortars with 30% by mass of phosphorus slag. Hydration heat, X-ray diffraction, and scanning electron microscopy were used to study the microstructure of cement pastes and mortars with 30% by mass of phosphorus slag and the chemical activator. Results showed that the setting time of cement pastes was delayed by phosphorus slag from 10% to 50%. Phosphorus slag had nearly no effects on the water requirement of the normal consistency of cement pastes and the flowability of cement mortars. The resistance to carbonation of cement mortars was decreased by phosphorus slag from 10% to 50% according to the acceleration carbonation. The compressive strength of cement mortars was also decreased by phosphorus slag from 10% to 50% and the low activity of phosphorus slag was concluded based on compressive strength of cement mortars. The effect of the chemical activator on the compressive strength of cement mortars with 30% by mass of phosphorus slag was better than improving fineness of phosphorus slag from 300 m2/kg to 450 m2/kg. Both hydration heat and cement hydrates were inhibited by phosphorus slag and could be partly compensated by the chemical activator. Loose morphology and propagations of microcracks were found in cement pastes and mortars with 30% by mass of phosphorus slag.

Development and research of the influence of the composition and concentration of activators on the strength of phosphorus slag binders

“…In [14], the effect of phosphorus slag from 10 % to 50 % (by weight) on the setting time and water demand of cement pastes of normal consistency, fluidity, resistance to carbonization and compressive strength of cement slurries was investigated. The compressive strength of the cement slurry was also reduced by the phosphorus slag from 10 % to 50 %, and based on the compressive strength of the cement slurry, it was concluded that the activity of the phosphorus slag was low, which is confirmed by its structural feature [1].…”

“…Knowing the limits of the existence of various forms of orthosilicic acid and its ions according to the ideas [22], the content of the following individual forms of orthosilicic acid can be determined depending on the pH value in the systems under study.…”

“…A number of strength parameters correspond to a number of values of the dissociation constants of the acids forming the corresponding solid bases in the system: KH 2 СО 3 (4.4×10 -7 )<KHF (6.6×10 -4 )<KH 3 PO 4 (7.5×10 -3 )< <KH 2 SO 4 (2×10 3 ) [22,23].…”

Study on Preparation and Interfacial Transition Zone Microstructure of Red Mud-Yellow Phosphorus Slag-Cement Concrete

“…The YPS composition is also different. Compared to furnace slag, YPS has a similar material composition but lower cementing activity [ 4 , 5 , 6 ]. Additionally, for one ton of yellow phosphorus, eight to ten tons of YPS are generated.…”

Sustainable and Clean Utilization of Yellow Phosphorus Slag (YPS): Activation and Preparation of Granular Rice Fertilizer

“…In industrial production, this process consumes about 12.7 t of solid raw materials, which usually include 9.5 t of phosphate rock, 1.5 t of coke, and 1.7 t of silica to produce 1 t of yellow phosphorous [ 24 , 25 ], concomitantly generating 8–10 t of YPS. Some attempts were tried to use the slag to produce building materials, glass ceramics, and ceramic materials [ 13 , 26 , 27 , 28 ]. However, most of this slag is stockpiled in factories because of its limited utilization, currently.…”