Internal transport and corrosion behaviors of sulfate corrosion media carried by recycled aggregate in concrete

Tian, Ye; Yan, Xiaohui; Zhang, Mengyuan; Lu, Dong; Yang, Tingting; Wang, Zhenjun; Li, Weiguang

doi:10.1016/j.conbuildmat.2020.120480

Cited by 24 publications

(13 citation statements)

References 23 publications

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“…The high concentration of ettringite in materials attacked by sulfates has also been confirmed in other studies, justifying the expansion tensions caused by the attack [17], [18], [42], [47].…”

Section: Xrdsupporting

confidence: 73%

Influence of internal sulfate attack on cement paste properties: contamination by pyrite

Capraro

Filho

Medeiros

2021

Rev. IBRACON Estrut. Mater.

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The objective of this work was to evaluate the influence of the presence of sulfate in the microstructure and compressive strength of cement pastes. The lack of availability of more suitable aggregates, for reasons of distance or costs, sometimes leads to the use of materials that contain sulfate in their composition, which is harmful to cement mixtures. Currently, there are normative recommendations that limit the content of contaminants in the aggregates. However, there are still divergences as to the content that does not damage the concrete. In order to discuss the levels presented in the standards and the values above those allowed by them, tests were carried out on cementitious compounds contaminated by pyrite in different levels of sulfates (0.0%, 0.5%, 1.0% and 5.0% of SO3). SEM, XRD, compressive strength, ultrasonic pulse velocity and porosity analyses were performed in samples at different ages until 720 days of age. During early ages until the first year, the most contaminated samples presented an increase in their strength (1.0% and 5.0% of SO3). This behavior was explained by SEM, XRD and porosity analyses by filling the pores with products of sulfate attack, such as ettringite. At the end of the tests (720 days) the series that presented the lowest compressive strength, the presence of cracks and large amounts of ettringite was the one that had 5.0% SO3 contamination, proving the importance of a normative limit content.

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Section: Xrdsupporting

confidence: 73%

Influence of internal sulfate attack on cement paste properties: contamination by pyrite

Capraro

Filho

Medeiros

2021

Rev. IBRACON Estrut. Mater.

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“…The method of solution preparation was as follows: the distillate with a temperature of 20 ± 1 • C was poured into a measuring cylinder; the powder of Na 2 SO 4 × 10H 2 O was poured into water and mixed in a laboratory vessel for 3-5 min until the salt was completely dissolved in the water. Further, the cubes of 20 × 20 × 20 mm and 70 × 70 × 70 mm were placed in the resulting solution in the desiccator, and the percentage of Na 2 SO 4 was defined due to the short-term exposure of the samples to sulphate attack [46,47]. The samples were kept in solution for 28 days with control measurements on the 7th, 14th, and 28th day of exposure.…”

Section: Solution Preparationmentioning

confidence: 99%

Influence of Sulphate Attack on Properties of Modified Cement Composites

et al. 2021

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Monitoring the condition of building structures based on composite materials in aggressive environments shows that the deterioration of basic properties occurs under the influence of various factors such as temperature and humidity changes,in addition to changes in the chemical composition of air environment. In addition, the composite materials during the operation must retain not only the mechanical properties laid down at the design stage, but also the electro-physical characteristics, regardless of the type of destructive effects. In the current study, the quantitative assessment of the result of the interaction of an aggressive sulphate-containing medium with composites modified with conductive and dielectric additives was carried out. The effect of sulphateattack on the specific electrical conductivity of cement composites was studied. The nature of the interaction was evaluated by changing the properties of the samples of the developed compositions under the influence of a single-normal solution of sodium sulphate. The analysis was carried out by means of potentiometric titration using the exchange interaction method by fixing the degree of absorption of sulphate ions and determining the concentration of calcium ions in the solution. The measurement of the solution potential allowed determination of the quantitative indicators of the rate of calcium hydroxide leaching from the sample structure,which is necessary to assess the intensity of the destruction process and determine the nature of the change in strength properties.Measurements of the electrical resistivity of samples under the constant influence of sulphate aggression were taken during 28 days of observation. A method for quantifying the effect of a sulphate medium on a cement matrix was proposed that enables the material durability to be predicted. The features of changes in the morphology of structural components after exposure to aggressive solution were determined by physical and chemical methods.

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“…To address this urgent issue, several researchers have attempted to replace Portland cement (PC) with supplementary cementitious materials (SCMs) in UHPC production [ 7 ]. Traditional SCMs have a pozzolanic potential [ 8 ], micro-filler effect [ 9 ], and nucleation effect [ 10 ], contribute to the strength formation, while the ordinary early-age strength, energy consumption, and high-cost [ 3 , 11 ], hindering their applications in some fields [ 3 ]. Therefore, low energy consumption, environment friendly, and low-cost UHPC will be highly desired in future generations in civil engineering.…”

Section: Introductionmentioning

confidence: 99%

Effects of Curing Conditions on the MECHANICAL and Microstructural Properties of Ultra-High-Performance Concrete (UHPC) Incorporating Iron Tailing Powder

Zhong

Yan

et al. 2021

Materials

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It has been reported that iron tailing powder (ITP) has the potential to partially replace cement to prepare ultra-high-performance concrete (UHPC). However, the reactivity of ITP particles in concrete largely depends on the curing method. This study investigates the effects of curing conditions on the mechanical and microstructural properties of UHPC containing ITP. To achieve this objective, three research tasks are conducted, including (1) preparing seven concrete formulations by introducing ITP; (2) characterizing their mechanical performance under different curing regimes; and (3) analyzing their microstructure by XRD patterns, FTIR analysis, and SEM observation. The experimental results show that there is an optimum ITP dosage (15%) for their application. The concrete with 15% ITP under standard curing obtains 94.3 MPa at 7 days, their early-age strength could be even further increased by ~30% (warm-water curing) and ~35% (steamed curing). The steam curing regime stimulates the activity of ITP and refines the microstructure. This study demonstrates the potential of replacing Portland cement with ITP in UHPC production.

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Internal transport and corrosion behaviors of sulfate corrosion media carried by recycled aggregate in concrete

Cited by 24 publications

References 23 publications

Influence of internal sulfate attack on cement paste properties: contamination by pyrite

Influence of internal sulfate attack on cement paste properties: contamination by pyrite

Influence of Sulphate Attack on Properties of Modified Cement Composites

Effects of Curing Conditions on the MECHANICAL and Microstructural Properties of Ultra-High-Performance Concrete (UHPC) Incorporating Iron Tailing Powder

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