Enhanced autogenous self-healing of cement-based composites with mechanically activated fluidized-bed combustion fly ash

Tomczak, Kamil; Jakubowski, Jacek; Kotwica, Łukasz

doi:10.1016/j.conbuildmat.2021.124028

Cited by 21 publications

(16 citation statements)

References 31 publications

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“…The characteristics of cement and both mineral additives are presented in Table 2. Details on the phase composition of fly ashes have been given by Tomczak et al [37]. Morphology of grains of both fly ashes was examined with a scanning electron microscope (SEM) FEI Nova NanoSEM 200.…”

Section: Preparation Of Mortar Samplesmentioning

confidence: 99%

“…The developed surface of MAFBC grains, together with high open porosity, contributes to the increased water demand of mixtures with these ashes. However, it has been shown that this type of ash is characterized by significantly higher initial reactivity than siliceous fly ash [37,62]. To ensure comparable workability and air content in fresh mortars, CHRYSO ® Optima 185 superplasticizer was used.…”

Section: Preparation Of Mortar Samplesmentioning

confidence: 99%

“…As cited in Section 1, most commonly, cracks are filled with portlandite, calcium carbonate and C-S-H phase [20,22]. As shown in [37], the use of MAFBC fly ash leads to the formation of new types of self-healing products, such as hydrated calcium aluminates. The formation of such products is stimulated by the high amount of alumina present in MAFBC fly ash [37].…”

Section: Microscopic Observationsmentioning

confidence: 99%

“…These will constitute a reservoir of binding material that can react and hydrate at a later time [29,36]. Thus, cement-based composites with a lower water-to-binder ratio (w/b) can be expected to have a higher potential for self-healing [37]. However, the potential during crack formation may not be completely utilized as indicated in [28] due to too low permeability of composite matrix, as is the case in high strength concretes, among others.…”

Section: Introductionmentioning

confidence: 99%

“…These relationships are presented in the example of mortars and concretes with mineral additives: mechanically activated fly ash from the combustion of brown coal in fluidized bed boilers (MAFBC fly ash) and siliceous fly ash from the combustion of hard coal in pulverized coal boilers. So far, the use of fluidized bed combustion ashes as binders [53][54][55], stabilizers in geotechnical work [56,57] or concrete additives [58][59][60] was described in several works, but rarely in terms of enhancing the efficiency of self-healing [37].…”

Section: Introductionmentioning

confidence: 99%

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Key Factors Determining the Self-Healing Ability of Cement-Based Composites with Mineral Additives

2021

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This paper reveals the relationships between key factors that determine the ability of cementitious composites to self-heal autogenously and specific measures for quantifying the effects of this process. The following material factors: water-to-binder ratio (w/b), uniaxial compressive strength and age of the composite at the time of defect formation were considered, as well as the method and degree of damage to the tested material. The subjects of this study were mortars and concretes in which Portland cement was partially replaced, to varying degrees, with mechanically activated fluidized bed combustion fly ash (MAFBC fly ash) and siliceous fly ash. The samples were subjected to three-point bending or cyclic compression tests after 14 or 28 days of aging, in order to induce defects and then cured in water for 122 days. Microscopic (MO) and high-resolution scanning (HRS) observations along with computer image processing techniques were used to visualize and quantify the changes occurring in the macro-crack region near the outer surface of the material during the self-sealing process. Techniques based on the measurement of the ultrasonic pulse velocity (UPV) allowed the quantification of the changes occurring inside the damaged materials. Mechanical testing of the composites allowed quantification of the effects of the activity of the binder-supplementary cementitious materials (SCMs) systems. The analysis of the results indicates a significant influence of the initial crack width on the ability to completely close the cracks; however, there are repeated deviations from this rule and local variability of the self-sealing process. It has been shown that the compressive strength of a material is an important indicator of binder activity concerning crack width reduction due to self-sealing. Regardless of the crack induction method, the internal material changes caused by self-sealing are dependent on the degree of material damage.

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Section: Preparation Of Mortar Samplesmentioning

confidence: 99%

Section: Preparation Of Mortar Samplesmentioning

confidence: 99%