Study of synergy between a natural volcanic pozzolan and a granulated blast furnace slag in the production of geopolymeric pastes and mortars

Robayo-Salazar, Rafael; Gutiérrez, Mejía de; Puertas, Francisca

doi:10.1016/j.conbuildmat.2017.09.092

Cited by 49 publications

(25 citation statements)

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“…Therefore, it has been demonstrated that modifiers or secondary sources of calcium (CaO) and reactive Al 2 O 3 can be incorporated into these binders to render the thermal curing process unnecessary. Indeed, adding a small amount (≤ 30%) of granulated blast furnace slag (GBFS) to NPs to obtain alkali-activated binary cements allows these materials to harden at room temperature (25°C) (16,21,(45)(46)(47)(48), thus enabling their use in "on-site" applications. Incorporating GBFS into NPs is advantageous because its dissolution during the alkaline activation process produces many Ca 2+ ions that participate in the formation of calcium silicate hydrate (C-S-H) and calcium aluminosilicate hydrate (C-A-S-H) gels (49)(50)(51).…”

Section: Introductionmentioning

confidence: 99%

Alkali-activated binary concrete based on a natural pozzolan: physical, mechanical and microstructural characterization

2019

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This article presents the physical, mechanical and microstructural characterization of an alkali-activated binary concrete (AABC) based on a natural pozzolan (NP) of volcanic origin (70%) and granulated blast furnace slag (GBFS) (30%) cured at room temperature (25°C). A solution based on the combination of NaOH and waterglass (Na2SiO3·5H2O) was employed as an alkaline activator. The concrete design was obtained using a modified version of the “absolute volume” method (ACI 211.1). The performance of the AABC was similar and even superior to that of the reference concrete (OPC); e.g., it exhibited a compressive strength of up to 43.4 MPa at 360 days. These results demonstrate that the NP has potential for use in the industrial-scale production of these types of materials in the foreseeable future.

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Section: Introductionmentioning

confidence: 99%

Alkali-activated binary concrete based on a natural pozzolan: physical, mechanical and microstructural characterization

2019

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“…Authors like Zedan et al [1] or Najimi et al [3] have attributed the better mechanical properties obtained with increasing amounts of BFS to the amorphous calcium aluminosilicates provided by BFS, which enhance the possibilities of forming hydration products. Robayo-Salazar et al [19] have also observed how the reaction heat increases with higher BFS additions, which not only accelerated the process kinetics, but also favored the activation of a pozzolan at room temperature. The wide range of compressive strength results obtained falls in line with the previous study by Najimi et al [3], who also observed a wide variation in the compressive strength results of natural pozzolan/BFS blended mortars (20 to 47 MPa after 28 days at 20 • C), depending on the BFS content (30,50 or 70 wt %) and the mix proportions of the activating solutions.…”

Section: Strength Of the Csw/bfs And Csw/fa Blended Mortarsmentioning

confidence: 89%

“…The wide range of compressive strength results obtained falls in line with the previous study by Najimi et al [3], who also observed a wide variation in the compressive strength results of natural pozzolan/BFS blended mortars (20 to 47 MPa after 28 days at 20 • C), depending on the BFS content (30,50 or 70 wt %) and the mix proportions of the activating solutions. Robayo-Salazar et al [19] also observed how BFS activated a natural volcanic pozzolan at room temperature, and reported improved strength values with increasing BFS contents (up to 30 wt %, which provided 37.24 MPa in the mortars cured at 20 • C for 28 days). Similarly, Pan et al [20] also found that adding BFS allowed FA to activate at room temperature, and these authors reported strength values of 29 MPa in the 50 wt % FA/BFS mortars cured at room temperature for 28 days.…”

Section: Strength Of the Csw/bfs And Csw/fa Blended Mortarsmentioning

confidence: 91%

“…The 100 wt % BFS pastes ( Figure 12) had the densest microstructure, formed mainly by C-S-H/C-A-S-H gel [19,20,35], and was similar no matter what the curing conditions were (65 • C or 20 • C). These results also fall in line with the compressive strength results reported in Figure 4, and agree with those previously reported by Pan et al [20], who also observed a denser microstructure in the 100 wt % BFS pastes compared with that presented by the alkali-activated 50 wt % FA/BFS blends.…”

Section: Field Emission Scanning Electron Microscopy (Fesem)mentioning

confidence: 99%

“…However, addition of Ca(OH) 2 and applying temperature to cure samples proved essential to successfully activate this ceramic waste material, which limited its use mainly to prefabricated applications. In order to improve the properties of alkali-activated binders developed using a single material as a precursor, several studies have lately combined low-calcium precursors, like CSW, with different sources of calcium and reactive Al 2 O 3 , such as BFS [1,2,[19][20][21][22][23], FA [6], calcium aluminate cement (CAC) or Portland cement (PC) [24,25]. observed that the heat of reaction in an alkali-activated natural pozzolan/BFS binary cement increased with BFS addition, which accelerated the kinetics of the process and, consequently, favored the activation of the pozzolan at room temperature, as well as strength development.…”

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The Compressive Strength and Microstructure of Alkali-Activated Binary Cements Developed by Combining Ceramic Sanitaryware with Fly Ash or Blast Furnace Slag

et al. 2018

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The properties of a binder developed by the alkali-activation of a single waste material can improve when it is blended with different industrial by-products. This research aimed to investigate the influence of blast furnace slag (BFS) and fly ash (FA) (0-50 wt %) on the microstructure and compressive strength of alkali-activated ceramic sanitaryware (CSW). 4 wt % Ca(OH) 2 was added to the CSW/FA blended samples and, given the high calcium content of BFS, the influence of BFS was analyzed with and without adding Ca(OH) 2 . Mortars were used to assess the compressive strength of the blended cements, and their microstructure was investigated in pastes by X-ray diffraction, thermogravimetry, and field emission scanning electron microscopy. All the samples were cured at 20 • C for 28 and 90 days and at 65 • C for 7 days. The results show that the partial replacement of CSW with BFS or FA allowed CSW to be activated at 20 • C. The CSW/BFS systems exhibited better mechanical properties than the CSW/FA blended mortars, so that maximum strength values of 54.3 MPa and 29.4 MPa were obtained in the samples prepared with 50 wt % BFS and FA, respectively, cured at 20 • C for 90 days. fuel gases in coal thermoelectric plants [5] and, according to [6,7], it is estimated that approximately 750-780 million tons are produced yearly. Granulated BFS is formed by rapidly cooling melted slag during iron production [8]. As reported by the World Steel Association [9], 1629.6 million tons of steel were produced worldwide in 2016, of which 74.3% are made in blast furnaces and the remaining 25.7% in electric furnaces. Consequently, approximately 300-360 million tons of iron slag were produced globally in blast furnaces in 2016, and 160-240 million tons of steel slag were generated in electric arc and basic oxygen furnaces [10].In the last few decades, the use of different silico aluminate waste materials as a precursor in alkali-activated binders has been widely investigated [11,12]. Reusing waste materials as a precursor positively contributes to sustainable development because it limits the mining of natural resources, reduces the visual impact caused by accumulated waste, and diminishes the emissions associated with Portland cement manufacture [13,14]. Ceramic materials are a very interesting option to be explored to develop alkali-activated cements as they are chemically inert and present a long biodegradation period (up to 4000 years) [15]. Among them, ceramic sanitaryware waste (CSW) units are expected to present quite a homogeneous chemical and mineralogical composition since they are generally sintered within a narrow range of calcination temperatures (1200-1280 • C [16]). Moreover, CSW units (i.e., washbasins, lavatories, or bidets) can be easily separated from construction and demolition waste (CDW), which implies that they will present fewer impurities, such as gypsum or Portland cement. As reported by Baraldi [17], nearly 349.3 million CSW units were globally produced in 2014, of which almost 12% (41.6 million) was manufacture...

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Effect of Curing Conditions on the Mechanical Properties of Geopolymer Binder Based Natural Moroccan Pozzolan

Doughmi,

Baba

2023

Springer Proceedings in Earth and Environmental Sciences

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Study of synergy between a natural volcanic pozzolan and a granulated blast furnace slag in the production of geopolymeric pastes and mortars

Cited by 49 publications

References 60 publications

Alkali-activated binary concrete based on a natural pozzolan: physical, mechanical and microstructural characterization

Alkali-activated binary concrete based on a natural pozzolan: physical, mechanical and microstructural characterization

The Compressive Strength and Microstructure of Alkali-Activated Binary Cements Developed by Combining Ceramic Sanitaryware with Fly Ash or Blast Furnace Slag

Effect of Curing Conditions on the Mechanical Properties of Geopolymer Binder Based Natural Moroccan Pozzolan

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