Deterioration of alkali-activated mortars exposed to natural aggressive sewer environment

Khan, Hammad Anis; Khan, M.S.H.; Castel, Arnaud; Sunarho, Jerry

doi:10.1016/j.conbuildmat.2018.07.137

Cited by 61 publications

(20 citation statements)

References 56 publications

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“…Testing of AAM durability in the field has generally shown results that are consistent with laboratory trials under non-accelerated or minimally-accelerated conditions; the materials that have been put into service under varying conditions have in many cases served very well, including concretes dating back to the 1950s [151,247,248], and more recent demonstration or full-scale infrastructure projects [249][250][251][252] including an airport in Australia that was constructed largely from alkali-activated concretes [253]. Such projects are essential in building stakeholder acceptance of AAM technology, and in using the experience gained to guide standards development, to ensure that the materials selected, specified and used are fully fit for purpose [254].…”

Section: Durabilitymentioning

confidence: 79%

Recent progress in low-carbon binders

Shi

Provis

2019

Cement and Concrete Research

493

131

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The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements.

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Section: Durabilitymentioning

confidence: 79%

Recent progress in low-carbon binders

Shi

Provis

2019

Cement and Concrete Research

493

131

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“…Previous research reports that use SCMs, such as FA and MK, not only contributes to the reduction of environmental pollution, but also makes a positive contribution to the sustainability and durability of concrete and mortars [52][53][54]. Following from that, the purpose of this investigation was to examine the effects of partially replacing OPC with massive-generated materials from different production sources that would create a cementitious composite material with similar properties to the currently marketed binder, but without all of the detrimental effect to the environment.…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Characterization of a Hybrid Cement Based on Fly Ash, Metakaolin and Portland Cement Clinker

2020

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Hybrid cement has become one of the most viable options in the reduction of CO 2 emissions to the environment that are generated by the cement industry. This could be explained by the reduction of the content of clinker in the final mixture and substitution of the remaining percentage with supplementary cementitious materials with the help of an alkaline activation. Following that, properties that are provided by an Ordinary Portland Cement and of a geopolymer are mixed in this type of hybrid material and could be achieved at room temperature. Thereafter, the main objective of this research was to synthesize hybrid cements reducing the clinker content of Portland Cement up to 20% and use metakaolin and fly ash as supplementary cementitious materials in different proportions. The mixtures were alkaline activated with a mixture of sodium silicate and sodium hydroxide, calculating the amounts according to the percentage of Na 2 O that is present in each of the activators. The samples were then characterized using Compressive strength, X-ray diffraction, Fourier Transform Infrared Spectroscopy, and Scanning Electron Microscopy with energy-dispersive X-ray spectroscopy. The results indicated that the hybrid cements have similar mechanical properties than an Ordinary Portland Cement, and they resulted in a dense matrix of hydration products similar to those that are generated by cements and geopolymers.Materials 2020, 13, 1084 2 of 15 that serve as partial or total substitutes are called supplementary cementitious materials (SCMs) [4], of which the best known are ground granulated blast furnace slag (GGBFS), fly ash (FA), silica fume (SF), and calcined clays. The use of these materials can be a viable solution for the reduction of CO 2 emissions [5]. Current cement consumption is projected to be double by 2050, and the use of these materials could highly reduce CO 2 emissions to the environment [4]. Following that, a model of binders is currently being studied, which consists of adding to the mix of supplementary materials a very low portion of CaO in the form of clinker, to obtain a setting at room temperature [1]. During the past decades, alkali-activated and blended cement have attracted strong interest worldwide, due to their advantages of low energy cost, high strength, good durability, and sustainability. A major incentive for the further development of such cements is generated by the great quantity of annual generation of wastes, which cause a need to find new uses for them. The main raw materials used for this proposal are FA, GGBFS, and metakaolin (MK), in which activators, like water glass and sodium hydroxide, are used. Among the alkaline cements, two large groups are known: (a) calcium and silicon-rich activated materials (Me 2 O-MeO-Al 2 O 3 -SiO 2 -H 2 O system); here, the activation of GGBFS (SiO 2 + CaO > 70%) corresponds, under relatively mild alkalinity conditions [6]. A hydrated calcium aluminosilicate gel (C-A-S-H) is the main hydration product generated, similar to the gel generated in the hydrati...

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“…Though there is also formation of similar layer with sulphuric acid, the reaction products are mainly gypsum and calcite ( Fig. 3 (b) and 4 (d)) which were not stable enough to stop the progress of the sulphuric acid in to the core (Koenig and Dehn, 2016;Khan et al, 2018). An attempt was made to further quantify the different layers formed and their effect on the binder matrix in Figure 5.…”

Section: Influence Of Type Of Acidmentioning

confidence: 99%

Performance of Fibre-Reinforced Slag-Based Alkali Activated Mortar in Acidic Environment

Perumal¹,

Tobias²,

Luukkonen³

et al. 2020

XV International Conference on Durability of Building Materials and Components. eBook of Proceedings

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The main aim of the work is to study the effect of different fibres (steel, glass and basalt) on resistance of blast furnace slag-based alkali-activated mortar in acidic environment. The alkaliactivated slag mortars were exposed to 5% sulfuric and acetic acid solutions for 30 days. Mass change, compressive strength and microstructural changes were evaluated. In plain mortar, it was observed that 70% of the strength was retained in acetic acid environment whereas only 20% of residual strength remains in sulphuric acid environment. FTIR spectroscopy shows the degradation of the matrix, which implies the alkali-activated mortar was more vulnerable in sulphuric acid environment due to its aggressive nature compared to acetic acid. Decalcification and formation of calcium acetate also hinders the further progress of damage in acetic acid attack. Fibres helped in improving the performance of the mortar by holding the matrix together when the degradation occurred in acidic environment. Compared to plain mortar, incorporation of steel fibres exhibited a maximum strength retention of 19% in acetic acid and 7% in sulphuric acid, followed by glass and basalt fibres. SEM images clearly show the debonding of fibres and disintegration of matrix in acidic environment, which resulted in strength loss.

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Deterioration of alkali-activated mortars exposed to natural aggressive sewer environment

Cited by 61 publications

References 56 publications

Recent progress in low-carbon binders

Recent progress in low-carbon binders

Synthesis and Characterization of a Hybrid Cement Based on Fly Ash, Metakaolin and Portland Cement Clinker

Performance of Fibre-Reinforced Slag-Based Alkali Activated Mortar in Acidic Environment

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