Engineering Properties of Alkali-Activated Fly Ash Concrete

Fernández-Jiménez, Ana; Palomo, A.; Hombrados, Cecilio López

doi:10.14359/15261

Cited by 62 publications

(31 citation statements)

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“…The results show that at the same strength class R3 OPC and R3 CSA obtain E d values 35% higher than that of R3 GEO. The low stiffness of the geopolymeric mortar is in accordance with the literature [58][59][60][61][62][63][64]. A lower stiffness means lower induced tensions at a certain deformation and, therefore, a lower probability of cracking caused by tensile (or shear) stresses or expansive reactions.…”

Section: Microstructural Analyses Of Mortarssupporting

confidence: 85%

Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

et al. 2017

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This paper deals with the study of calcium sulfoaluminate (CSA) and geopolymeric (GEO) binders as alternatives to ordinary Portland cement (OPC) for the production of more environmentally-friendly construction materials. For this reason, three types of mortar with the same mechanical strength class (R3 ≥ 25 MPa, according to EN 1504-3) were tested and compared; they were based on CSA cement, an alkaline activated coal fly ash, and OPC. Firstly, binder pastes were prepared and their hydration was studied by means of X-ray diffraction (XRD) and differential thermal-thermogravimetric (DT-TG) analyses. Afterwards, mortars were compared in terms of workability, dynamic modulus of elasticity, adhesion to red clay bricks, free and restrained drying shrinkage, water vapor permeability, capillary water absorption, and resistance to sulfate attack. DT-TG and XRD analyses evidenced the main reactive phases of the investigated binders involved in the hydration reactions. Moreover, the sulfoaluminate mortar showed the smallest free shrinkage and the highest restrained shrinkage, mainly due to its high dynamic modulus of elasticity. The pore size distribution of geopolymeric mortar was responsible for the lowest capillary water absorption at short times and for the highest permeability to water vapor and the greatest resistance to sulfate attack.

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Section: Microstructural Analyses Of Mortarssupporting

confidence: 85%

Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

et al. 2017

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“…The value of Young's modulus of elasticity of GPC was shown about 90% of that OPC concrete of same compressive strength and stress-strain relation in compression was similar to that of OPC concrete using the same aggregate type. Fernandez-Jimenez et al [23] tested some engineering properties of heat cured fly ash geopolymer concrete activated with different activators. According to their study, silicate ions present in the activator solutions improved strength and modulus of elasticity substantially, but caused a slight adverse effect on bond and shrinkage properties.…”

Section: Introductionmentioning

confidence: 99%

Flexural strength and elastic modulus of ambient-cured blended low-calcium fly ash geopolymer concrete

Nath

Sarker

2017

Construction and Building Materials

379

128

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Fly ash geopolymer is an emerging alternative binder with low environmental impact and potential to enhance sustainability of concrete construction. Most previous works examined the properties of fly ash-based geopolymer concrete (GPC) subjected to curing at elevated temperature. To extend the use of GPC in cast-in-situ applications, this paper investigated the properties of blended low-calcium fly ash geopolymer concrete cured in ambient condition. Geopolymer concretes were produced using low-calcium fly ash with a small percentage of additive such as ground granulated blast furnace slag (GGBFS), ordinary Portland cement (OPC) or hydrated lime to enhance early age properties. Samples were cured in room environment (18-23 o C and 70±10% relative humidity) until tested. The results show that, density of hardened GPC mixtures is similar to that of normal-weight OPC concrete. Inclusion of additives enhanced the mechanical strengths significantly as compared to control concrete. For similar compressive strength, flexural strength of ambient cured GPC was higher than that of OPC concrete. Modulus of elasticity of ambient cured GPC tend to be lower than that of OPC concrete of similar grade. Prediction of elastic modulus by Standards and empirical equations for OPC concrete were found not conservative for GPC. Thus, an equation for conservative prediction of elastic modulus of GPC is proposed. *Manuscript Click here to view linked References

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“…Similar trends were observed at the ages of 28 days and 90 days, as shown in Figure 2. Geopolymer concretes cured in elevated temperature generally reported to have low modulus of elasticity as compared to that of OPC concrete of the same compressive strength (Fernandez-Jimenez et al 2006;Sofi et al 2007).…”

Section: Modulus Of Elasticitymentioning

confidence: 99%

Fracture properties of GGBFS-blended fly ash geopolymer concrete cured in ambient temperature

Nath

Sarker

2016

Mater Struct

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Fracture characteristics are important part of concrete design against brittle failure. Recently, fly ash geopolymer binder is gaining significant interest as a greener alternative to traditional ordinary Portland cement (OPC). Hence it is important to understand the failure behaviour of fly ash based geopolymers for safe design of structures built with such materials. This paper presents the fracture properties of ambient-cured geopolymer concrete (GPC). Notched beam specimens of GPC mixtures based mainly on fly ash and a small percentage of ground granulated blast furnace slag (GGBFS) were subjected to three-point bending test to evaluate fracture behaviour. The effect of mixture proportions on the fracture properties were compared with control as well as OPC concrete. The results show that fracture properties are influenced by the mixture compositions. Presence of additional water affected fracture properties adversely. Fracture energy is generally governed by tensile strength which correlates with compressive strength. Critical stress intensity factor varies with the variation of flexural strength. Geopolymer concrete specimens showed similar load-deflection behaviour as OPC concrete specimens. The ambient cured GPC showed relatively more ductility than the previously reported heat cured GPC, which is comparable to the OPC specimens. Fly ash based GPC achieved relatively higher fracture energy and similar values of KIC as compared to those of OPC concrete of similar compressive strength. Thus, fly ash based GPC designed for curing in ambient condition can achieve fracture properties comparable to normal OPC concrete.

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Engineering Properties of Alkali-Activated Fly Ash Concrete

Cited by 62 publications

References 0 publications

Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

Flexural strength and elastic modulus of ambient-cured blended low-calcium fly ash geopolymer concrete

Fracture properties of GGBFS-blended fly ash geopolymer concrete cured in ambient temperature

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