Chloride ion penetration performance of recycled concrete with different geopolymers

Alabi, Stephen Adeyemi; Mahachi, Jeffrey

doi:10.1016/j.matpr.2020.04.199

Cited by 13 publications

(9 citation statements)

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“…As illustrated in Figure 11, there are various techniques for mixing RCA in a GPC since there is no standard method for mixing GPC, and it is based on trial and error (Alabi and Mahachi, 2021). Regarding the use of solid alkali activator and NAs, Rahman and Al-Ameri (2021) mixed solid components, including alkali activator (AA), fly ash, slag, micro fly ash and coarse and fine aggregates and mixed them for 4 min (method A in Figure 11).…”

Section: Rca Treatmentmentioning

confidence: 99%

“…The binding materials are added and mixed (Wang et al ., 2020), or in some studies like mixing technique G, aggregates and binder are mixed simultaneously. After that, an alkaline solution is added and mixed (Alabi and Mahachi, 2021; Waqas et al ., 2021). If it is required to add superplasticiser, it can be added at the final stage (Wang et al ., 2020; Waqas et al ., 2021).…”

Section: Rca Treatmentmentioning

confidence: 99%

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A review of the advanced treatment techniques for enriching the recycled concrete aggregates for recycled-based concrete: economic, environmental and technical analysis

Nikmehr

Kafle

Al-Ameri

2023

SASBE

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PurposeThis study aimed to review various existing methods for improving the quality of recycled concrete aggregates (RCAs) as a possible substitution for natural aggregates (NAs) in concrete. It is vital as the old paste attached to the RCA weakens its structure. It is due to the porous structure of the RCA with cracks, weakening the interfacial transition zone (ITZ) between the RCA and binding material, negatively impacting the concrete's properties. To this end, various methods for reinforcement of the RCA, cleaning the RCA's old paste and enhancing the quality of the RCA-based concrete without RCA modification are studied in terms of environmental effects, cost and technical matters. Furthermore, this research sought to identify gaps in knowledge and future research directions.Design/methodology/approachThe review of the relevant journal papers revealed that various methods exist for improving the properties of RCAs and RCA-based concrete. A decision matrix was developed and implemented for ranking these techniques based on environmental, economic and technical criteria.FindingsThe identified methods for reinforcement of the RCA include accelerated carbonation, bio deposition, soaking in polymer emulsions, soaking in waterproofing admixture, soaking in sodium silicate, soaking in nanoparticles and coating with geopolymer slurry. Moreover, cleaning the RCA's old paste is possible using acid, water, heating, thermal and mechanical treatment, thermo-mechanical and electro-dynamic treatment. Added to these treatment techniques, using RCA in saturated surface dry (SSD) mixing approaches and adding fibres or pozzolana enhance the quality of the RCA-based concrete without RCA modification. The study ranked these techniques based on environmental, economic and technical criteria. Ultimately, adding fibres, pozzolana and coating RCA with geopolymer slurry were introduced as the best techniques based on the nominated criteria.Practical implicationsThe study supported the need for better knowledge regarding the existing treatment techniques for RCA improvement. The outcomes of this research offer an understanding of each RCA enrichment technique's importance in environmental, economic and technical criteria.Originality/valueThe practicality of the RCA treatment techniques is based on economic, environmental and technical specifications for rating the existing treatment techniques.

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Section: Rca Treatmentmentioning

confidence: 99%

Section: Rca Treatmentmentioning

confidence: 99%

A review of the advanced treatment techniques for enriching the recycled concrete aggregates for recycled-based concrete: economic, environmental and technical analysis

Nikmehr

Kafle

Al-Ameri

2023

SASBE

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“…The compressive strength and split tensile strength of the geopolymer concrete were reported to increase by 5.8 and 24%, respectively, with a 10% usage of the plastic powder as a partial replacement of sand. Geopolymers blended recycled concrete (OPC, fly ash, rice husk ash, river sand, Cupola furnace slag, and crushed granite) was discovered by Alabi and Mahachi [ 30 ] to have better penetration resistance to chloride ion than other concrete mixes in the study and are therefore more durable. With low chloride ion penetrability, it could be affirmed that the geopolymer-blended recycled concrete offered good protection to steel reinforcement against corrosion.…”

Section: Introductionmentioning

confidence: 99%

Durability Performance of Geopolymer Concrete: A Review

Wong

2022

Polymers

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Geopolymer concrete is produced from the geopolymerization process, in which molecules known as oligomers integrate to form geopolymer networks with covalent bonding. Its production expends less thermal energy and results in a smaller carbon footprint compared to Ordinary Portland Cement (OPC) concrete. It requires only an alkaline activator to catalyze its aluminosilicate sources such as metakaolin and fly ash, to yield geopolymer binder for the geopolymerization to take place. Because of its eco-friendly technology and practical application, current research interest is mainly concentrated on the endurance of geopolymer concrete to resist heat and chemical aggressions. As such, it is pertinent for this review article to provide critical insight into the recent progress in research on the durability of geopolymer concrete. One significant outcome of the review is that the admixture of geopolymer concrete could be blended with additives such as micro-silica and fibers such as polypropylene fibers, to enhance its durability. The review on the durability aspects of geopolymer concrete showed that it had high compressive strength at an optimal elevated temperature, low to medium chloride ion penetrability, and high resistance to acid attack and abrasion. This makes geopolymer concrete a viable candidate to replace OPC concrete in the construction industry.

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“…Disposal of industrial waste materials in open dumpsites leads to detrimental environmental issues consisting of groundwater contamination, bulk storage spillage, and heavy metal leaching [ 26 , 27 , 28 ]. Therefore, the utilization of industrial by-products and waste materials for geopolymer production is considered economically and environmentally beneficial due to the increased need for green building materials [ 29 , 30 , 31 , 32 ]. However, geopolymer is still a new technology with gaps in design standards requiring further research and experiments to standardize it [ 33 , 34 ].…”

Section: Introductionmentioning

confidence: 99%

Geopolymer: A Systematic Review of Methodologies

et al. 2022

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The geopolymer concept has gained wide international attention during the last two decades and is now seen as a potential alternative to ordinary Portland cement; however, before full implementation in the national and international standards, the geopolymer concept requires clarity on the commonly used definitions and mix design methodologies. The lack of a common definition and methodology has led to inconsistency and confusion across disciplines. This review aims to clarify the most existing geopolymer definitions and the diverse procedures on geopolymer methodologies to attain a good understanding of both the unary and binary geopolymer systems. This review puts into perspective the most crucial facets to facilitate the sustainable development and adoption of geopolymer design standards. A systematic review protocol was developed based on the Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist and applied to the Scopus database to retrieve articles. Geopolymer is a product of a polycondensation reaction that yields a three-dimensional tecto-aluminosilicate matrix. Compared to unary geopolymer systems, binary geopolymer systems contain complex hydrated gel structures and polymerized networks that influence workability, strength, and durability. The optimum utilization of high calcium industrial by-products such as ground granulated blast furnace slag, Class-C fly ash, and phosphogypsum in unary or binary geopolymer systems give C-S-H or C-A-S-H gels with dense polymerized networks that enhance strength gains and setting times. As there is no geopolymer mix design standard, most geopolymer mix designs apply the trial-and-error approach, and a few apply the Taguchi approach, particle packing fraction method, and response surface methodology. The adopted mix designs require the optimization of certain mixture variables whilst keeping constant other nominal material factors. The production of NaOH gives less CO2 emission compared to Na2SiO3, which requires higher calcination temperatures for Na2CO3 and SiO2. However, their usage is considered unsustainable due to their caustic nature, high energy demand, and cost. Besides the blending of fly ash with other industrial by-products, phosphogypsum also has the potential for use as an ingredient in blended geopolymer systems. The parameters identified in this review can help foster the robust adoption of geopolymer as a potential “go-to” alternative to ordinary Portland cement for construction. Furthermore, the proposed future research areas will help address the various innovation gaps observed in current literature with a view of the environment and society.

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Chloride ion penetration performance of recycled concrete with different geopolymers

Cited by 13 publications

References 1 publication

A review of the advanced treatment techniques for enriching the recycled concrete aggregates for recycled-based concrete: economic, environmental and technical analysis

A review of the advanced treatment techniques for enriching the recycled concrete aggregates for recycled-based concrete: economic, environmental and technical analysis

Durability Performance of Geopolymer Concrete: A Review

Geopolymer: A Systematic Review of Methodologies

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