Hydration kinetics of phosphorus slag-cement paste

Abstract

Hydration characteristics of Portland cement paste with phosphorus slag powder incorporated and hydration kinetics was investigated with SEM, X-ray diffraction, DTA-TG and calorimeter Ⅱ80. Results showed that phosphorus slag powder could reduce total amount of hydration products yet had little influence on the type of hydration products. The total amount of heat of hydration was decreased by 49.11% and the final setting was postponed by 2.28 h when phosphorus slag powder substituted 35% Portland cement by mass. The accelerating stage of this composite paste was controlled by catalysis, decreasing stage controlled by both catalysis and diffusion while stabilizing stage by diffusion alone. Hydration resistance and activation energy were reduced and hydration speed was accelerated.

Heat of hydration of low-clinker cements

“…Addition of fly ash more distinctly retards the acceleratory period of cement hydration than slag, this tendency is especially clear for the high substitution rate of fly ashes. This retarding effect of the mineral additions on the cement hydration has been already reported [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”

“…The hydration heat of blended cements has been investigated by several authors . The hydration of blended cements with different substitution rates of GGBFS has been studied, inter alia, by Roy and Idorn [11], De Schutter [12,13], Escalante et al [14], Saeki and Monteiro [15], Pane and Hansen [16], Binici et al [17], Meinhard and Lackner [18], Ježo et al [19], Chen et al [20], Merzouki et al [21], Hana et al [22], Gruyaert et al [23] and Siler [24]. It has been observed in these tests that the evolved heat decreases as slag content increases, but at the same time the heat evolved increases with the fineness of the slag or clinker in the blended cements.…”

Stochastic Modeling of Compressive Strength of Phosphorus Slag Content Cement

“…The CaO:SiO 2 ratio of PHS usually varies from 0.8 to 1.2. From chemical composition, it can be understood that PHS is a latent cementing material but less reactive than BFS [14,15]. The residual phosphorus of PHS has a retarding effect on setting time of Portland cement, and insufficient content of Al 2 O 3 also affects early properties.…”

“…Residual phosphorus in the form of P 2 O 5 leads to the formation of phosphoric acid and consequently pH of the environment decreases. This is a negative factor that acts as a retarder for progress of hydration reactions and prolongs the setting time [14,15,18]. Therefore, it is necessary to apply valid methods like mechanical activation, chemical activation, and thermal curing to tailor early properties [1,12].…”

“…Among these industrial wastes, only slags such as blast furnace slag (BFS) [5,7,8], steel slag [9][10][11], and phosphorus slag (PHS) [1,[12][13][14][15] have latent cementing property and have attracted attention of many researches [5,11,16]. In fact, the production of slag cements and Portlandslag cements results in resource conservation, reducing energy consumption and minimizing emission of GHGs, especially CO 2 [2].…”