Exploring the Influence Factors of Early Hydration of Ultrafine Cement

Abstract

This work intends to contribute to the understanding of the influence factors of early hydration of ultrafine cement by focusing on the different fineness, different kinds of hardening accelerators, and different curing temperatures. Isothermal calorimetry, thermogravimetry, and X-ray diffraction (XRD) were performed to compare the hydration and chemical evolution of pastes containing accelerators with different fineness and curing temperatures; meanwhile, mechanical properties and water absorption were tested. The results showed that the cement fineness had a significant effect on the early hydration process; the smaller the cement particle size, the higher the early compressive strength. The 24 h compressive strength of ultrafine cement with a particle diameter of 6.8μm could reach 55.94 MPa, which was 118% higher than the reference cement. Water absorption test results indicated that adding 1% Ca(HCOO)2 to ultrafine cement can effectively reduce the water absorption, and it was only 1.93% at 28 d, which was 46% lower than the reference cement. An increase in curing temperature accelerated the activation of ultrafine cement in terms of the strength development rate, and the content of Ca(OH)2 in the ultrafine cement paste could reach 13.09% after being mixed with water for 24 h, which was 22% higher than that of the reference cement.

Influence of Accelerators on Cement Mortars Using Fluid Catalytic Cracking Catalyst Residue (FCC): Enhanced Mechanical Properties at Early Curing Ages

“…Other authors have found similar results. Shi et al [ 34 ] have observed a smaller amount of bound water and a lower degree of hydration at short curing ages in cement pastes containing SIL. However, these values were compensated at longer ages.…”

Effect of Ultrafine Cement (UFC) on the Corrosion Resistance of Cement Soil in Peat Soil Environment

“… The complete test results show that an increase in the UFC proportion will significantly improve cement soil’s durability in peat soil. Based on previous studies [ 3 , 4 , 5 , 6 , 7 , 8 ], this study adopts the test method of adding UFC to form a composite curing agent and discusses the influence of UFC content changes on the humic acid erosion res istance of cement soil in a peat soil environment from the perspective of strength test and microscopic test. Therefore, in future research and actual engineering of the peat soil environment in Dianchi Lake and Erhai Lake in Yunnan, we can combine the conclusions of this study with exploring more reasonable and effective ways to improve the mechanical properties and durability of cement soil in peat soil environment and reduce the amount of cement.…”

“…Its replacement rate for ordinary cement is 30% to 40%, and the improvement of mortar strength is the most significant. Yi Shi et al [ 6 ] described the influence of cement particle fineness on cement hydration. They concluded that cement fineness significantly impacts the early hydration process.…”

Evaluating the environmental safety of shotcrete as preliminary lining for tunnel: New insights from occurrence of fluorine in hydration products

“…Obviously, due to the limitations of the test and diversity of cement hydration products [41], the presence or absence of fluoride in the hydration products could not be effectively observed by XRD analysis. Therefore, the authors further selected pure clinker minerals to explore the influence of HF-AFA on hydration products composition.…”