Strengthening the very early-age structure of cementitious composites with coal fly ash via incorporating a novel nanoadmixture based on C-S-H phase activators

Golewski, Grzegorz Ludwik; Szóstak, Bartosz

doi:10.1016/j.conbuildmat.2021.125426

Cited by 70 publications

(13 citation statements)

References 82 publications

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“…The specimens at room temperature ( Figure 12 a) mainly consist of poorly crystallized and fibrous particles of C–S–H gels, amorphous and well-crystallized Ca(OH) 2 , and a large number of unhydrated FA particles. The dense structure in Figure 12 a resulted in excellent mechanical properties of the specimens [ 2 , 44 ]. Compared to the microstructures of the unheated specimens, the specimens exposed to 200 °C did not change significantly.…”

Section: Resultsmentioning

confidence: 99%

“…Cementitious composites with cement as the primary material are extensively used in the construction of infrastructure, such as highways, bridges, dams, and houses [ 1 ]. They have become the most commonly used building material worldwide [ 2 ]. They possess the advantages of easy acquisition, high strength, convenient construction, and low cost, which make them popular in the engineering field.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Properties of Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites after High-Temperature Exposure

Zhang

et al. 2022

Gels

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The mechanical properties of cementitious composites before and after exposure to high temperature are affected by calcium–silicate–hydrate (C–S–H) gels. To evaluate the effects of high temperature, plyvinyl alcohol (PVA) fiber content, and the cooling method on properties of cementitious composites, physical, mechanical, and microscopic tests were performed in this study. The target temperatures were 25, 100, 200, 300, 400, 600, and 800 °C. The PVA fiber contents were 0.0, 0.3, 0.6, 0.9, 1.2, and 1.5 vol%. The high-temperature resistance of PVA fiber-reinforced cementitious composite (PVA-FRCC) specimens was investigated through changes in their appearance, mass loss, compressive strength, splitting tensile strength, flexural strength, and microstructure. The results showed that PVA fibers reduced the probability of explosion spalling in the PVA-FRCC specimens exposed to high temperatures. The mass loss rate of samples exposed to temperatures below 200 °C was small and lower than 5%, whereas a significant mass loss was observed at 200 °C to 800 °C. A small rise in the cubic compressive and splitting tensile strengths of samples was found at 400 °C and 300 °C, respectively. Below 400 °C, the fibers were beneficial to the mechanical strength of the PVA-FRCC specimens. Nevertheless, when the temperature was heated above 400 °C, melted fibers created many pores and channels, which caused a decrease in the strength of the specimens. The method of cooling with water could aggravate the damage to the cementitious composites exposed to temperatures above 200 °C. High temperature could lead to the decomposition of the C–S–H gels of the PVA-FRCC samples, which makes C–S–H gels lose their bonding ability. From the perspective of the microstructure, the structure of PVA-FRCC samples exposed to 600 °C and 800 °C became loose and the number of microcracks increased, which confirmed the reduction in macro-mechanical properties.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites after High-Temperature Exposure

Zhang

et al. 2022

Gels

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“…For these reasons, the development of multi-component cements with a diversified composition is justified from an economical and ecological point of view. In addition, the synergistic effect of the interaction of several mineral additives can have a favorable effect on the properties of multi-component cements, compared to cements containing only one mineral additive [ 43 , 44 , 45 ]. This allows, among others, for preparing concrete composites that are resistant to significant static, impact, and dynamic and fatigue loads [ 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ].…”

Section: Introductionmentioning

confidence: 99%

Fracture Performance of Cementitious Composites Based on Quaternary Blended Cements

Golewski

2022

Materials

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This study presents test results and in-depth discussion regarding the measurement of the fracture mechanics parameters of new concrete composites based on quaternary blended cements (QBC). A composition of the two most commonly used mineral additives, i.e., fly ash (FA) and silica fume (SF), in combination with nanosilica (nS), has been proposed as a partial replacement for ordinary Portland cement (OPC) binder. Four series of concrete were made, one of which was the reference concrete (REF) and the remaining three were QBC. During the research, the main mechanical parameters of compressive strength (fcm) and splitting tensile strength (fctm), as well as fracture mechanics parameters and the critical stress intensity factor (KIcS), along with critical crack-tip opening displacements (CTODc) were investigated. Based on the tests, it was found that the total addition of siliceous materials, i.e., SF + nS without FA, increases the strength and fracture parameters of concrete by approximately 40%. On the other hand, supplementing the composition of the binder with SF and nS with 5% of FA additive causes an increase in all mechanical parameters by approximately 10%, whereas an increase by another 10% in the FA content in the concrete mix causes a significant decrease in all the analyzed factors by 10%, compared to the composite with the addition of silica modifiers only.

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“…There have been some attempts to study the transport behaviors of chloride ions by considering various concrete material factors. Golewski and Szostak [21][22][23] indicated that the nano-admixtures in the form of the active C-S-H seeds is an innovative form for accelerating the curing of concrete with fly ash (FA) at a very early stage, which can lead to the formation of a more homogeneous and compact cement matrix structure. By this token, the chloride penetration resistance for the aforementioned concrete materials can be greatly increased.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Chloride Concentration Profiles in Concrete by the Consideration of Concrete Material Factors under Marine Tidal Environment

Liu

et al. 2022

JMSE

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The corrosion of reinforcement induced by chloride ions is one of the most significant causes of durability deterioration for reinforced concrete (RC) buildings. The concrete material factors, including the water-to-cement ratio (w/c) of concrete, as well as the content, shape, particle grading, and random distribution of coarse aggregate embedded in mortar, have a marked effect on chloride transport performance within concrete. However, comprehensive consideration for the effects of both w/c and coarse aggregate performances on chloride diffusion characteristics in concrete is scarce, especially regarding the chloride diffusion model of concrete. In this paper, an indoor exposure experiment exploring chloride ions intruding into mortar and concrete specimens with w/c = 0.4, 0.5 and 0.6 was carried out, in order to acquire the chloride diffusion parameters for concrete three-phases composites. Based on the numerical algorithm of random generation and placement of two-dimensional random convex polygon coarse aggregate, mesoscopic numerical models for concrete, considering various coarse aggregate contents as well as grading, were established. Using the numerical simulation method of finite element analysis for chloride transport in cement-based materials, which can replace some of the exposure tests, the influences of w/c, coarse aggregate content and grading on chloride diffusion performance in concrete mesoscopic models were systematically probed. According to the Fick’s second law, a chloride diffusion model by the consideration of w/c, volume fraction of coarse aggregate (VFCA), and maximum size of coarse aggregate (MSCA) was developed to assess the chloride concentration profiles in concrete under arbitrary w/c, coarse aggregate content, and coarse aggregate grading conditions. Certainly, the precision accuracy for this proposed chloride diffusion model was validated. The research results can provide theoretical support for chloride erosion behavior and structural durability assessment of concrete with different mix proportions.

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Strengthening the very early-age structure of cementitious composites with coal fly ash via incorporating a novel nanoadmixture based on C-S-H phase activators

Cited by 70 publications

References 82 publications

Mechanical Properties of Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites after High-Temperature Exposure

Mechanical Properties of Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites after High-Temperature Exposure

Fracture Performance of Cementitious Composites Based on Quaternary Blended Cements

Modelling of Chloride Concentration Profiles in Concrete by the Consideration of Concrete Material Factors under Marine Tidal Environment

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