Kinetics and mechanism of slag cement hydration

Abstract

Granulated blastfurnace slag and Portland cement were first ground separately into samples of different fineness, covering the range 2500 to 6OOO cm2 g-l in Blaine areas. For each sample, various slag-cement mixtures were prepared using Portland cement with the same Blaine area. Paste-hydration of the various slag-cement mixtures was carried out at room temperature for different curing periods; the initial W/C ratios used were 0.30 and 0.40. From the results of combined (non-evaporable) water, free slag and free lime contents of the hardcned pastes at various hydration ages, and their relation to the development in compressive strength, the mechanism of the hydration process could be specified. The suggested mechanism includes six hydration stages; these are (i) pre-dormant, (ii) first dormant, (iii) first acceleration, (iv) second dormant, (v) second acceleration and (vi) diffusion period. The beginning and duration of each hydration period depended primarily on the fineness and the constitution of the slag-cement dry mixture.

Preparation and Properties of Sustainable Concrete Using Activated Sludge of Industrial By-Products

“…Figure 5 shows the XRD pattern of the plain and recycled water with desulfurized gypsum concrete (R-3-5). It can be seen from this figure that plain as well as R-3-5 concrete showed the C-S-H, C-A-H, ettringite, calcium hydroxide, and gypsum [43]. The ettringite and C-A-H led to the improved early strength of concrete, and thus the desired strength, i.e., 24 MPa, was observed by both types of concrete.…”

“…The ettringite and C-A-H led to the improved early strength of concrete, and thus the desired strength, i.e., 24 MPa, was observed by both types of concrete. Moreover, it can be seen in the R-3-5 specimen that the XRD intensity of the gypsum peak was most attributed to the desulfurized gypsum, which is the main component of activated sludge [43]. Gypsum from the activated sludge accelerated the hydration reaction of the cement; thus, ettringite and C-A-H were observed in XRD [44][45][46][47].…”

“…It can be seen from this Figure that the compressive strength of recycled water and activated sludge concrete specimens exhibited higher compressive strength compared to plain concrete. At 3 days of curing, the compressive strength of recycled water and activated sludge specimen was higher compared to plain concrete (Figure 4a), attributed to the higher pH of recycled water, which accelerated the hydration reaction of cement particles [43,44].…”

CO2 Capture Performance of Portland Cement‐Based Carbide Slag and the Enhancement of Its CO2 Capture Capacity

“…Hydration, which is defined as the reaction of materials with water in the first steps, is a necessary process for the pelletization of PCCS. Some studies have proved that hydration could improve the compressive strength of concrete . Far too little attention has been focused on the effects of the HT on the CO 2 capture performance of PCCS.…”

Effect of Some Acrylate—Poly(Ethylene Glycol) Copolymers as Superplasticizers on the Mechanical and Surface Properties of Portland Cement Pastes

“…The pastes were then cured at 100% relative humidity (R.H.) for up to 24 h, followed by curing under water for time intervals of 3, 7, 28 and 90 d, respectively. After the elapse of each time interval, the hydration of the hardened cement pastes was stopped using the methods described in an earlier publication (Abo-El-Enein et al 1982). The samples were then dried and maintained in a desiccator until used for testing purposes.…”