Geopolymeric concretes based on fly ash with high unburned content

Valencia-Saavedra, William; Gutiérrez, Ruby Mejía de; Gordillo, M. C.

doi:10.1016/j.conbuildmat.2018.01.071

Cited by 18 publications

(10 citation statements)

References 52 publications

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“…Taking into account the results of isothermal calorimetry, setting time and compressive strength, the hybrid cement could be classified, according to ASTM C1157 and NTC 121, as a low heat of hydration cement (LH type) as can be corroborated in Table 5. In accordance with the results reported by Robayo et al [24] and Valencia-Saavedra et al [19], using other precursors, the hybrid concrete showed a high level of workability, associated with a high fluidity (24 cm settlement) (Figure 10a), without the presence of segregation phenomena (Figure 10b) due to the adequate cohesiveness of the mixture, mainly promoted by the presence of sodium silicate. Additionally, the modulus of rupture (MR) of the material was determined by means of the flexural strength test.…”

Section: Reaction Kinetics Of the Hybrid Cementsupporting

confidence: 90%

“…In the setting time evaluation, three alkaline-activated hybrid cements were used, in which the percentage of OPC was varied at 5, 10, and 20% with respect to the total weight of the precursor (FA In the setting time evaluation, three alkaline-activated hybrid cements were used, in which the percentage of OPC was varied at 5, 10, and 20% with respect to the total weight of the precursor (FA + OPC), keeping the content of activator constant. Chindaprasit et al [17], Robayo-Salazar et al [18], and Valencia-Saavedra et al [19] carried out similar studies. The results obtained showed that the incorporation of calcium sources of a GBFS or OPC type reduces the setting time of alkaline-activated hybrid cements.…”

Section: Reaction Kinetics Of the Hybrid Cementmentioning

confidence: 83%

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Alkali-Activated Hybrid Concrete Based on Fly Ash and Its Application in the Production of High-Class Structural Blocks

et al. 2020

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This article reports the production and characterization of a hybrid concrete based on the alkaline activation of a fly ash (FA) of Colombian origin, which was added with 10% Portland cement (OPC) in order to promote the compressive strength development at room temperature. The alkali-activated hybrid cement FA/OPC 90/10 was classified as a low heat reaction cement (type LH), according to American Society of Testing Materials, ASTM C1157; the compressive strength was of 31.56 MPa and of 22.68 MPa (28 days) at the levels of paste and standard mortar, respectively, with an initial setting time of 93.3 min. From this binder, a hybrid concrete was produced and classified as a structural type, with a compressive strength of 23.16 MPa and a flexural modulus of rupture of 5.32 MPa, at 28 days of curing. The global warming potential index (GWP 100), based on life cycle analysis, was 35% lower than the reference concrete based on 100% OPC. Finally, its use was validated in the manufacture of a solid block-type construction element, which reached a compressive strength of 21.9 MPa at 28 days, exceeding by 40.6% the minimum strength value established by the Colombia Technical Standard, NTC 4026 (13 MPa) to be classified as high class structural blocks.

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Section: Reaction Kinetics Of the Hybrid Cementsupporting

confidence: 90%

Section: Reaction Kinetics Of the Hybrid Cementmentioning

confidence: 83%

Alkali-Activated Hybrid Concrete Based on Fly Ash and Its Application in the Production of High-Class Structural Blocks

et al. 2020

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“…Additionally, recycled aggregates (fine and coarse) from CDW were used. This research has continuity with several studies [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ] previously developed by the Composite Materials Group of the Universidad del Valle (Cali-Colombia) in the alkali activation and geopolymerization line of research [ 40 ]. In these previous studies, the contents of the alkaline activator (NaOH + SS + water) and precursors (NP–GBFS; FA; CDW; RCBW) of each geopolymeric mixture were defined.…”

Section: Introductionsupporting

confidence: 71%

Eco-House Prototype Constructed with Alkali-Activated Blocks: Material Production, Characterization, Design, Construction, and Environmental Impact

et al. 2021

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The interest of the construction industry in alkali-activated materials has increased to the extent that these materials are recognized as alternatives to ordinary Portland cement-based materials in the quest for sustainable construction. This article presents the design and construction of a prototype of an eco-friendly house built from concrete blocks produced using alkali activation technology or geopolymerization. The prototype meets the requirements of the current Colombian Regulations for Earthquake Resistant Buildings (NSR-10) and includes standards related to the performance of the materials, design, and construction method for earthquake-resistant confined masonry of one- or two-story buildings. The alkali-activated blocks were obtained from different precursors (aluminosilicates), including a natural volcanic pozzolan, ground granulated blast furnace slag, fly ash, construction and demolition waste (concrete, ceramic, brick, and mortar), and red clay brick waste. The physical-mechanical characterization of the alkali-activated blocks allowed their classification according to the structural specifications of the Colombian Technical Standard NTC 4026 (equivalent to ASTM C90). The global warming potential (GWP) or “carbon footprint” attributed to the raw materials of alkali-activated blocks was lower (25.4–54.7%) than that of the reference blocks (ordinary Portland cement concrete blocks). These results demonstrate the potential of alkali-activated materials for application in the construction of eco-friendly houses.

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“…In general, the coexistence of C-A-S-H and N-A-S-H gels in FA/GBFS concrete explains the positive behavior of this material. The best characteristics presented by GBFS/OPC and FA/GBFS are related to the greater densification and compactness observed in the SEM test, and due to the lower number of capillaries or permeable pores present in this type of alkaline-activated materials (Valencia-Saavedra et al, 2018;Chotetanorm et al, 2013;Qureshi and Ghosh, 2014;Aydin and Baradan, 2014). Figure 5 shows the results of the rapid chloride permeability test, performed on OPC, GBFS/OPC, and FA/GBFS concretes after 28 days of curing, based on the procedure described in ASTM C1202 (ASTM International, 2019a).…”

Section: Resultsmentioning

confidence: 92%

Alkali-activated concretes based on fly ash and blast furnace slag: Compressive strength, water absorption and chloride permeability

2020

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Concretes based on alkaliactivated binders have attracted considerable attention as new alternative construction materials, which can substitute Portland Cement (OPC) in several applications. These binders are obtained through the chemical reaction between an alkaline activator and reactive aluminosilicate materials, also named precursors. Commonly used precursors are fly ash (FA), blast furnace slag (GBFS), and metakaolin. The present study evaluated properties such as compressive strength, rate of water absorption (sorptivity), and chloride permeability in two types of alkaliactivated concretes (AAC): FA/GBFS 80/20 and GBFS/OPC 80/20. OPC and GBFS/OPC* concretes without alkaliactivation were used as reference materials. The highest compressive strength was observed in the FA/GBFS concrete, which reported 26,1% greater strength compared to OPC concrete after 28 days of curing. The compressive strength of alkaliactivated FA/GBFS 80/20 and GBFS/OPC 80/20 was 61 MPa and 42 MPa at 360 days of curing, respectively. These AAC showed low permeability to the chloride ion and a reduced water absorption. It is concluded that these materials have suitable properties for various applications in the construction sector.

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Geopolymeric concretes based on fly ash with high unburned content

Cited by 18 publications

References 52 publications

Alkali-Activated Hybrid Concrete Based on Fly Ash and Its Application in the Production of High-Class Structural Blocks

Alkali-Activated Hybrid Concrete Based on Fly Ash and Its Application in the Production of High-Class Structural Blocks

Eco-House Prototype Constructed with Alkali-Activated Blocks: Material Production, Characterization, Design, Construction, and Environmental Impact

Alkali-activated concretes based on fly ash and blast furnace slag: Compressive strength, water absorption and chloride permeability

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