Deterioration process of high belite cement paste exposed to sulfate attack, calcium leaching and the dual actions

Jiang, Chunmeng; Lin, Yuanhua; Tang, Xinjun; Chu, Huaqiang; Jiang, Linhua

doi:10.1016/j.jmrt.2021.09.125

Cited by 14 publications

(5 citation statements)

References 36 publications

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“…Comparing the XRD patterns of pure cement and the chlorella composites at different concentrations (Figure d), we observe that peaks at 18.1°, 28.7°, 47.1°, and 50.8° are gradually decreased as the biomatter content increases, and at 5 wt %, they are absent from the collected patterns. These peaks correspond to Ca(OH) 2 , − and therefore, their absence in the 5 wt % chlorella composite corroborates the TGA findings that indeed this hydration product is either never formed or entirely depleted in the presence of 5 wt % biomatter. On the other hand, the peaks at 32.3°, 32.6°, 41.3°, and 52°, attributed to anhydrated cement silicates (alite and belite), − are prominent and even found to be increasing with increasing chlorella content, indicating the existence of unhydrated reactants.…”

Section: Resultssupporting

confidence: 84%

“…On the other hand, the peaks at 32.3°, 32.6°, 41.3°, and 52°, attributed to anhydrated cement silicates (alite and belite), 56−58 are prominent and even found to be increasing with increasing chlorella content, indicating the existence of unhydrated reactants. Although the peaks associated with anhydrated cement were observed even at the composites with 10 wt % chlorella, we note that ettringite peaks (located at 15.8°and 22.9°) appear, 53,55 albeit at low intensity, in the XRD patterns of chlorella composites with up to 5 wt % biomatter. As ettringite is the earlier-formed product of cement hydration, the detection of these peaks suggests that the hydration reactions, where tricalcium aluminate (Ca 3 Al 2 O 6 ) reacts with gypsum and water, were activated when the mixture was in contact with water.…”

Section: ■ Results and Discussionmentioning

confidence: 53%

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Long-Term Hindrance Effects of Algal Biomatter on the Hydration Reactions of Ordinary Portland Cement

Lin

Grandgeorge

Jimenez

et al. 2023

ACS Sustainable Chem. Eng.

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The incorporation of carbon-fixing materials such as photosynthetic algae in concrete formulations offers a promising strategy toward mitigating the concerningly high carbon footprint of cement. Prior literature suggests that the introduction of up to 0.5 wt % chlorella biological matter (biomatter) in ordinary Portland cement induces a retardation of the composite cement’s strength evolution while enabling a long-term compressive strength comparable to pure cement at a lower carbon footprint. In this work, we provide insights into the fundamental mechanisms governing this retardation effect and reveal a concentration threshold above which the presence of biomatter completely hinders the hydration reactions. We incorporate Chlorella or Spirulina, two algal species with different morphology and composition, in ordinary Portland cement at concentrations ranging between 0.5 and 15 wt % and study the evolution of mechanical properties of the resulting biocomposites over a period of 91 days. The compressive strength in both sets of biocomposites exhibits a concentration-dependent long-term drastic reduction, which plateaus at 5 wt % biomatter content. At and above 5 wt %, all biocomposites show a strength reduction of more than 80% after 91 days of curing compared to pure cement, indicating a permanent hindrance effect on hardening. Characterization of the hydration kinetics and the cured materials shows that both algal biomatters hinder the hydration reactions of calcium silicates, preventing the formation of calcium hydroxide and calcium silicate hydrate, while the secondary reactions of tricalcium aluminate that form ettringite are not affected. We propose that the alkaline conditions during cement hydration lead to the formation of charged glucose-based carbohydrates, which subsequently create a hydrogen bonding network that ultimately encapsulates calcium silicates. This encapsulation prevents the formation of primary hydrate products and thus blocks the hardening of cement. Furthermore, we observe new hydration products with composition and micromorphology deviating from the expected hardened cement compounds. Our analysis provides fundamental insights into the mechanisms that govern the introduction of two carbon-negative algal species as fillers in cement, which are crucial for enabling strategies to overcome the detrimental effects that those fillers have on the mechanical properties of cement.

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Section: Resultssupporting

confidence: 84%

Section: ■ Results and Discussionmentioning

confidence: 53%

Long-Term Hindrance Effects of Algal Biomatter on the Hydration Reactions of Ordinary Portland Cement

Lin

Grandgeorge

Jimenez

et al. 2023

ACS Sustainable Chem. Eng.

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“…This is mainly due to the diffusion of sulfate ions (SO 4 2-) into the concrete by combining with magnesium (Mg 2+ ), sodium (Na + ) and potassium (K + ) ions, which can react with calcium hydroxide (CH) and alumina to form gypsum (CaSO 4 -2H 2 O), magnesium hydroxide (Mg(OH) 2 ), and hydrate Sulphate Aluminate of Calcium (AFt) (Santhanam et al, 2003;Wu et al, 2024a;Wu et al, 2024b). These chemical changes disrupt the original chemical equilibrium in the hydrated cement system, which in turn triggers the swelling of the material as well as the deterioration of the C-S-H gel, which may ultimately lead to cracking and inevitable structural degradation (Jiang et al, 2021). Therefore, it is crucial to adopt effective methods to improve the resistance of cementitious materials to sulphate attack in.…”

Section: Introductionmentioning

confidence: 99%

Research on the resistance of cement-based materials to sulfate attack based on MICP technology

Zhang,

Peng,

et al. 2024

Front. Mater.

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To evaluate the effect of Microbial Induced Calcium Carbonate Precipitation (MICP) on the enhancement of early resistance to sulfate attack of cementitious materials. In this paper, firstly, the effect of Bacillus subtilis (BM) on the carbonation depth as well as the carbonation rate of standard as well as carbonation-conditioned cementitious sand specimens was investigated. Secondly, the compressive strength and volumetric deformation of the specimens at different ages of immersion in sulfate solution were investigated. Finally, the changes of hydration products before and after the addition of BM were analyzed by X-ray diffraction analysis (XRD), and the microscopic pore structure of the specimens after erosion was analyzed by low-field nuclear magnetic resonance (LF-NMR) and scanning electron microscope (SEM), which revealed the mechanism of the improvement of BM on the resistance to sulfate erosion of the cementitious materials. The results showed that the initial compressive strength of BM carbonised curing specimens, ordinary carbonised curing specimens and BM standard curing specimens were increased by 42.0%, 34.0% and 4.0%, respectively, compared with the ordinary standard curing specimens, respectively, compared with the control group, and the loss of the final compressive strength was reduced by 37.4%, 25.4%, and 14.5%, and the expansion rate was reduced by 31.3%, 22.0%, after sulfate erosion for 6 months, 5.2%, and porosity decreased by 24.2%, 13.6%, and 9.9%. Microbial mineralization accelerated the reaction between Ca2+ in the pore solution and atmospheric CO2, and the calcite formed filled the pores to make the structure denser, increasing the initial compressive strength of the specimens and reducing the loss of properties when exposed to sulfate solution. Therefore, the application of MICP technology in cementitious materials provides a new direction for the development of durable and sustainable cementitious materials.

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“…Low-heat PC, hereafter denoted PLH, contains a high belite content [7], i.e. : C 2 S is the main mineral component of PLH, with a content of >40% [8]. The theoretical energy consumption in preparing 1 kg C 2 S is 1350 kJ, which is 460 kJ lower than that of 1 kg C 3 S [9,10].…”

Section: Introductionmentioning

confidence: 99%

Physical Properties and Hydration Characteristics of Low-Heat Portland Cement at High-Altitude

Wang

Liu²,

Xia

et al. 2023

Materials

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High-altitude environments are characterized by low air pressures and temperature variations. Low-heat Portland cement (PLH) is a more energy-efficient alternative to ordinary Portland cement (OPC); however, the hydration properties of PLH at high altitudes have not been previously investigated. Therefore, in this study, the mechanical strengths and levels of the drying shrinkage of PLH mortars under standard, low-air-pressure (LP), and low-air-pressure and variable-temperature (LPT) conditions were evaluated and compared. In addition, the hydration characteristics, pore size distributions, and C-S-H Ca/Si ratio of the PLH pastes under different curing conditions were explored using X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). Compared with that of the PLH mortar cured under the standard conditions, the compressive strength of the PLH mortar cured under the LPT conditions was higher at an early curing stage but lower at a later curing stage. In addition, drying shrinkage under the LPT conditions developed rapidly at an early stage but slowly at a later stage. Moreover, the characteristic peaks of ettringite (AFt) were not observed in the XRD pattern after curing for 28 d, and AFt transformed into AFm under the LPT conditions. The pore size distribution characteristics of the specimens cured under the LPT conditions deteriorated, which was related to water evaporation and micro-crack formation at low air pressures. The low pressure hindered the reaction between belite and water, which contributed to a significant change in the C-S-H Ca/Si ratio in the early curing stage in the LPT environment.

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Deterioration process of high belite cement paste exposed to sulfate attack, calcium leaching and the dual actions

Cited by 14 publications

References 36 publications

Long-Term Hindrance Effects of Algal Biomatter on the Hydration Reactions of Ordinary Portland Cement

Long-Term Hindrance Effects of Algal Biomatter on the Hydration Reactions of Ordinary Portland Cement

Research on the resistance of cement-based materials to sulfate attack based on MICP technology

Physical Properties and Hydration Characteristics of Low-Heat Portland Cement at High-Altitude

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