Repair of ordinary Portland cement concrete using ambient-cured alkali-activated concrete: Interfacial behavior

Gomaa, Eslam; Gheni, Ahmed; ElGawady, Mohamed A.

doi:10.1016/j.cemconres.2019.105968

Cited by 69 publications

(27 citation statements)

References 38 publications

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“…The developed mixtures displayed compressive strengths exceeding 25.1 MPa; therefore, all developed mixtures can be used for structural applications in transportation infrastructure including bridge decks. Earlier study by the authors showed that the developed mixtures also displayed compatibility for being used as a repair material (5,17). The following conclusions can be drawn from the current investigation:…”

Section: Discussionsupporting

confidence: 67%

“…Both classes were used, however, as precursors for AAC. The chemical reactions of a high calcium content-based AAC are divided into the following two reactions: 1) Geopolymerization which takes place between the aluminosilicate and alkaline solution resulting in an inorganic amorphous three-dimensional polymeric chain and ring structure consisting of Si-O-Al-O bonds ( 1 , 2 ); 2) Hydration process which takes place between the alkali solution and calcium, aluminum, or both, forming calcium silicate hydrate (CSH), calcium aluminate silicate hydrate (CASH), calcium sodium aluminate silicate hydrate (CNASH), or any combination of these ( 2 , 4 , 5 ). Class C FA is readily available in the State of Missouri, US, as the state generates about 82% of its electricity using coal-fired power plants.…”

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confidence: 99%

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Mechanical Properties of High Early Strength Class C Fly Ash-Based Alkali Activated Concrete

Gomaa

Sargon

Kashosi

et al. 2020

Transportation Research Record: Journal of the Transportation R

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This paper presents the mechanical properties of alkali activated concrete (AAC) cured at 70°C for 24 h. The AAC mixtures were synthesized using five class C fly ashes (FAs) having different chemical and physical properties. Sodium hydroxide (SS) and sodium silicate (SH) were used as the alkali activators in this study. A conventional concrete (CC) mixture, having a compressive strength of 34.5 MPa, was synthesized using ordinary Portland cement (OPC) mixture for comparison purposes. The slump, as well as the compressive, tensile splitting, and flexural strengths were investigated at different concrete ages up to 28 days. The results revealed that with increasing the calcium content in an FA used to synthesized AAC mixture, the slump value and the mechanical properties decreased. All AAC mixtures reached approximately 92% of their 28-day compressive strength after 1 day compared with only 29% in the case of CC. Therefore, AAC can be used in applications where rapid strength gain is required, such as urgent repair, precast industry, and so forth. The measured data was also used to develop a set of equations to accurately predict the splitting tensile and flexural strengths.

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Section: Discussionsupporting

confidence: 67%

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confidence: 99%

Mechanical Properties of High Early Strength Class C Fly Ash-Based Alkali Activated Concrete

Gomaa

Sargon

Kashosi

et al. 2020

Transportation Research Record: Journal of the Transportation R

Self Cite

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“…The HSW has significantly effect on the property of pastes, the highest increase in compressive strength was found at 3 days. As some literature have reported that increasing activator concentration leads to an increase in mechanical strength of alkali-activated cementitious materials [9]. The XRD analysis of samples ))and the calcium silicate hydrates (C-S-H(I)) gels were detected in the Mix C1.…”

Section: Analysis Of Sample Compressive Strengthmentioning

confidence: 81%

Effects of high salinity wastewater on the properties of coal gasification residue-based cementitious material

2021

Therm sci

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High salinity wastewater and coal gasification residue are the by-products which need to be utilized as resources for the sustainable development of coal-to-chemicals technology. Using coal gasification residue as the main raw material, supplemented with 10% Portland cement, and high salinity wastewater as the mixing water instead of tap water to prepare cementitious materials. The XRD, TG-DTG, FTIR, SEM, and MIP were used to analyze the influence mechanism of high salinity wastewater on the properties of cementitious materials. The results show that high salinity wastewater was beneficial to the strength development of the cementitious material. When 25% high salinity mastewater was used instead of tap water, the enhancing rates of compressive strength was 294%, 177%, and 186% curing at 3, 7, and 28 days. This is main due to the sulfate and chloride in the high salinity wastewater can promote the formation of C-S-H gels, Friedel?s, salts and C-A-S-H gels in the hydration process of pastes, which can promote the densification of structure. The pores distribution and structure were optimized, increasing the proportion of capillary pores and decreasing macropore to promote the micro-structure more dense. This study can provide a new idea for the comprehensive utilization of industrial waste and achieve the purpose of ?waste control by waste?.

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“…Drawing upon the previous research reported in the literature on utilizing wastewater in concrete, at the same time, considering the potential pozzolanic property of CGR and the alkalinity of CCW (pH>9), alkali-activated materials (AAMs), formulated with alkaline activator and industrial by-products as an aluminosilicate precursor (Izquierdo et al, 2009;Provis et al, 2018), could provide an effective approach to the possible full recycling of CGR and CCW. Previous researches show that, in addition to their low energy consumption, AAMs also have some properties superior to Portland cement (PC), making it more suited for use in the repairing work (Gomaa et al, 2020;Zhang et al, 2020), nuclear waste immobilisation (Gijbels et al, 2018), high-temperature exposure (Çelikten et al, 2019) and multifunctional materials (Tang et al, 2019). Preliminary work carried out by Chen et al (2019) proved that CGR can be blended with steel slag and incorporated into AAMs owing to its amorphous content.…”

Section: Coal Chemical Wastewater(ccw)mentioning

confidence: 99%

Combined effect of coal chemical wastewater and PC on preparing of coal-to-liquids residue-based alkali activated materials

Zhu

et al. 2021

Journal of Hazardous Materials

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Aimed to achieve "waste control by waste" of coal-to-liquids (CTL) industry, coal gasification residue (CGR), the most typical CTL residue, and coal chemical wastewater (CCW) were used as aluminosilicate precursor and auxiliary activator respectively to prepare alkali activated materials (AAMs). CGR-based AAMs using a less concentrated NaOH solution than conventional, with CCW as mixing water were synthesized. The results showed that CCW benefited the compressive strength of CGR-based AAMs significantly, but demonstrating slight reduction over time. The combined effect of CCW and Portland cement (PC) supplied continuous increase of strength and eliminated the strength reduction with age. The mechanisms behind the improved performance of the AAMs due to the introduction of CCW and PC were discussed by XRD, FTIR, TG-DSC, MIP and ESEM. It was found that the increased alkali content due to the introduction of the CCW, supplied more extensive dissolution of active aluminosilicate and progressive geopolymerization of CGR. The coexistence of both N-A-S-H gel and C-A-S-H gel (originated from the introduced PC) in hardened AAM pastes reduced the proportion of pores larger than 100 nm to less than 30%, and provided denser structure.

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Repair of ordinary Portland cement concrete using ambient-cured alkali-activated concrete: Interfacial behavior

Cited by 69 publications

References 38 publications

Mechanical Properties of High Early Strength Class C Fly Ash-Based Alkali Activated Concrete

Mechanical Properties of High Early Strength Class C Fly Ash-Based Alkali Activated Concrete

Effects of high salinity wastewater on the properties of coal gasification residue-based cementitious material

Combined effect of coal chemical wastewater and PC on preparing of coal-to-liquids residue-based alkali activated materials

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