Alkali-activated natural pozzolan/slag mortars: A parametric study

Najimi, Meysam; Ghafoori, Nader; Sharbaf, MohammadReza

doi:10.1016/j.conbuildmat.2017.12.222

Cited by 68 publications

(30 citation statements)

References 56 publications

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“…Najimi et al activated the 30%, 50%, and 70% slagincorporated binder using sodium hydroxide (NaOH) and sodium silicate solutions in their experimental study. In 28-day compressive strength tests, the strength was found to be varying from 20.9 to 43.2 MPa [10].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Thermal Conductivity of Aerogel-Incorporated Alkali-Activated Slag Mortars

Bostancı

Sola

2018

Advances in Civil Engineering

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Compressive strength, thermal conductivity coefficient, and porosimetric properties of alkali-activated slag (AAS) mortars containing silica aerogel were investigated experimentally in this study. For this purpose, slag mortar mixtures at 0.75% and 1.0% aerogel content ratios were prepared, and these mortar mixtures were activated with lithium carbonate (Li 2 CO 3 ) at 0.03% and 1.50% dosage rates. Mortar samples were exposed to curing process in water for 2, 7, and 28 days, and the samples, which completed the curing stage, were subjected to the compressive strength test. e porosimetry test and the thermal conductivity coefficient measurement were carried out following the compressive strength test on 28-day samples. e varying aerogel content rate in the mixtures and the effects of the dosage of Li 2 CO 3 on the gel, capillary, and macropore distributions, and the effect of changing porosimetric properties on compressive strength and thermal conductivity coefficient were analyzed in detail. Experimental studies have shown that AAS mortars including an optimum 0.75% aerogel content rate and 0.03% Li 2 CO 3 activation provided a compressive strength of 34.1 MPa and a thermal conductivity coefficient of 1.32 W/mK. Aerogel addition provides a partial compressive strength increase at 7-and 28-day samples while it also causes maximum strength loss of 5.0% at 2-day samples.

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Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Thermal Conductivity of Aerogel-Incorporated Alkali-Activated Slag Mortars

Bostancı

Sola

2018

Advances in Civil Engineering

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“…The partial replacement of CSW with BFS or FA allowed this ceramic waste to be activated at 20 °C and generated mortars with a wide range of mechanical properties, depending on the percentage of replacement and the curing conditions. 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…”

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

confidence: 99%

“…The partial replacement of CSW with BFS or FA allowed this ceramic waste to be activated at 20 • C and generated mortars with a wide range of mechanical properties, depending on the percentage of replacement and the curing conditions. 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.…”

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

confidence: 99%

“…As explained by Zedan et al [1], alkali-activated binders may be classified into two main types: low-calcium systems, which generally require applying temperature to set; and calcium-based binders, which usually harden at room temperature. While N-A-S-H gel mainly forms in the former, the activation of high-calcium systems principally brings about C-A-S-H gel [2,3]. Both gels may co-exist in the presence of calcium, with calcium silicate hydrate (C-A-S-H) being favored at a high pH (>12) if sufficient calcium is provided [4].…”

Section: Introductionmentioning

confidence: 99%

“…Alkali-activated fly ash (FA) and blast furnace slag (BFS) may be considered the models for lowand high-calcium binders, respectively [3]. FA is obtained by the electro-static separation of dust from These particles homogenized after their particle size was reduced when milled in a jars turner roller (Roller 1 by Gabrielli), for which 5-L volume cylindrical alumina jars were used.…”

Section: Introductionmentioning

confidence: 99%

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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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Enhancement of impact resistance of alkali‐activated slag concrete through biochar supplementation

Egodagamage,

Yapa,

Buddika

et al. 2024

Structural Concrete

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Biochar is a well‐known sustainable and effective additive used in mortar/concrete to improve its mechanical properties. However, its potential to improve the impact resistance of concrete is still unexplored. This paper investigates biochar's effectiveness in improving the strength and impact performance of alkali‐activated slag concrete (AASC). Five AASC samples with 0%, 2%, 4%, 6%, and 8% rice husk biochar (RB) were employed in an experimental program. The strength and the impact resistance were tested, and the latter was assessed over a drop‐weight test conforming to the ACI Committee 544 guidelines. The crack propagation of the impact‐tested samples was examined using micro‐CT images. The results showed that adding RB up to 6% improved, notably the 28‐day compressive strength of AASC. At 6% RB, the strength enhancement was 44.6%, whereas no additional gain was observed at the 8% RB blend. More importantly, except for the 8% RB sample, the impact resistance was considerably augmented with the RB level increment. The increment in the impact number at the first crack and the failure in the 6% RB sample were as high as 185% and 180%, respectively. The reduction in the solution/binder ratio of the mix with the addition of biochar and the internal curing effect of biochar were deemed to be responsible for these improvements. However, possibly due to biochar's brittle characteristics, the increase in RB dosage from 6% to 8% reduced the impact resistance drastically.

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Alkali-activated natural pozzolan/slag mortars: A parametric study

Cited by 68 publications

References 56 publications

Mechanical Properties and Thermal Conductivity of Aerogel-Incorporated Alkali-Activated Slag Mortars

Mechanical Properties and Thermal Conductivity of Aerogel-Incorporated Alkali-Activated Slag Mortars

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

Enhancement of impact resistance of alkali‐activated slag concrete through biochar supplementation

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