Portland Cement Hydration Behavior at Low Temperatures: Views from Calculation and Experimental Study

Liu, Zhuangzhuang; Jiao, Wenxiu; Sha, Aimin; Gao, Jie; Han, Zhenqiang; Xu, Wei

doi:10.1155/2017/3927106

Cited by 16 publications

(12 citation statements)

References 18 publications

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“…Calcite formed on Surface 1 in Exposure 9 (40 °C) and a mixture of calcite and Ettringite in Exposure 4 (20 °C) and Exposure 10 (5 °C) (Figure 10a,b). The Ettringite formation was evident, particularly in the low temperature exposure (Figure 10c,d), also observed by others [30,31]). None of those three exposures supported internal self-healing, with only few calcite crystals being present in Cross-sections 1 and 2 for both Exposure 9 (40 °C) and 10 (5 °C).…”

Section: Resultssupporting

confidence: 87%

The Effect of Exposure on the Autogenous Self-Healing of Ordinary Portland Cement Mortars

et al. 2019

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Exposure conditions are critical for the autogenous self-healing process of Portland cement based binder matrixes. However, there is still a significant lack of fundamental knowledge related to this factor. The aim of this paper was to investigate and understand the effects of various potentially applicable curing solutions on the efficiency of the crack closure occurring both superficially and internally. Four groups of exposures were tested, including exposure with different water immersion regimes, variable temperatures, application of chemical admixtures, and use of solutions containing micro particles. The self-healing process was evaluated externally, at the surface of the crack, and internally, at different crack depths with the use of optical and scanning electron microscopes (SEM). The phase identification was done with an energy dispersive spectrometer combined with the SEM. The results showed very limited self-healing in all pure water-based exposures, despite the application of different cycles, temperatures, and water volumes. The addition of a phosphate-based retarding admixture demonstrated the highest crack closure, both internally and externally. The highest strength recovery and a very good crack closure ratio was achieved in water exposure containing micro silica particles. The main phase observed on the surface was calcium carbonate, and internally, calcium silicate hydrate, calcium carbonate, and calcium phosphate compounds. Phosphate ions were found to contribute to the filling of the crack, most likely by preventing the formation of a dense shell composed of hydration phases on the exposed areas by crack unhydrated cement grains as well as by the additional precipitation of calcium and phosphate-based compounds. The micro sized silica particles presumably served as nucleation sites for the self-healing products growth. Changes in the chemical composition of the self-healing material were observed with a distance from the surface of the specimen.

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Section: Resultssupporting

confidence: 87%

The Effect of Exposure on the Autogenous Self-Healing of Ordinary Portland Cement Mortars

et al. 2019

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“…OPC-based paste exposed to a temperature of −5 • C showed a hydration rate of 16.7% after 1 day and continued to hydrate to approximately 63.2% after 90 days, which is significantly lower in comparison with specimens cured at 20 • C (91.9%). Despite the low temperature of −5 • C, the hydration continued since the ions Ca 2+ , K + , Na + , OH − , and SO 4 2− present in the cement, which was dissolved in water, prevented ice formation to a certain extent [5]. However, in the solidified state, the formed ice expands by up to 9% in concrete causing significant stresses and strains on the pore walls of the concrete.…”

Section: Ordinary Portland Cement (Opc)-based Concretementioning

confidence: 99%

“…At lower temperatures its magnitude is reduced, and the setting time is elongated and the strength development is decreased by 20–40% [ 1 , 2 , 3 ]. During freezing, when the temperature drops around or below −4 °C, the moisture migrates within the binder matrix and ice starts to form hindering hydration processes and phase conversions of ettringite to monosulfate, as seen in Figure 1 a [ 4 , 5 , 6 ]. OPC-based paste exposed to a temperature of −5 °C showed a hydration rate of 16.7% after 1 day and continued to hydrate to approximately 63.2% after 90 days, which is significantly lower in comparison with specimens cured at 20 °C (91.9%).…”

Section: Introductionmentioning

confidence: 99%

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A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

et al. 2020

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Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

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“…Keeping the concrete cylinders frozen at an early age could be very harmful and caused more damage to the concrete strength. The water in the concrete mix was frozen and the final product would be irreparably damaged because the temperature dipped too low [29]. Therefore, it is particularly important to protect concrete against freezing at an early age if possible, to complete the hydration process and gain most of the strength.…”

Section: Compressive Strengthmentioning

confidence: 99%

Temperature Effect on the Compressive Behavior and Constitutive Model of Plain Hardened Concrete

El‐Zohairy

Hammontree

et al. 2020

Materials

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Concrete is one of the most common and versatile construction materials and has been used under a wide range of environmental conditions. Temperature is one of them, which significantly affects the performance of concrete, and therefore, a careful evaluation of the effect of temperature on concrete cannot be overemphasized. In this study, an overview of the temperature effect on the compressive behavior of plain hardened concrete is experimentally provided. Concrete cylinders were prepared, cured, and stored under different temperature conditions to be tested under compression. The stress–strain curve, mode of failure, compressive strength, ultimate strain, and modulus of elasticity of concrete were evaluated between the ages of 7 and 90 days. The experimental results were used to propose constitutive models to predict the mechanical properties of concrete under the effect of temperature. Moreover, previous constitutive models were examined to capture the stress–strain relationships of concrete under the effect of temperature. Based on the experimental data and the proposed models, concrete lost 10–20% of its original compressive strength when heated to 100 °C and 30–40% at 260 °C. The previous constitutive models for stress–strain relationships of concrete at normal temperatures can be used to capture these relationships under the effect of temperature by using the compressive strength, ultimate strain, and modulus of elasticity affected by temperature. The effect of temperature on the modulus of elasticity of concrete was considered in the ACI 318-14 equation by using the compressive strength affected by temperature and the results showed good agreement with the experimental data.

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Portland Cement Hydration Behavior at Low Temperatures: Views from Calculation and Experimental Study

Cited by 16 publications

References 18 publications

The Effect of Exposure on the Autogenous Self-Healing of Ordinary Portland Cement Mortars

The Effect of Exposure on the Autogenous Self-Healing of Ordinary Portland Cement Mortars

A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Temperature Effect on the Compressive Behavior and Constitutive Model of Plain Hardened Concrete

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