The influence of compaction pores on sorptivity and carbonation of concrete

Gönen, Tahir; Yazıcıoğlu, Salih

doi:10.1016/j.conbuildmat.2006.02.010

Cited by 130 publications

(54 citation statements)

References 15 publications

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Section: Microstructural Analysismentioning

confidence: 99%

“…For porosity measurements cylindrical specimens with 20 mm diameter and 50 mm height were used. Two specimens for each of the examined mixes were tested at 28 days after casting following the procedure described in previously published studies [38,39].For SEM analysis, geopolymer mortar samples were coated with carbon after 7 and 28 days curing and imaged using a Leo S420 stereoscan scanning electron microscope with an accelerating voltage range of 1-30 kV. FTIR analysis was carried out on fine powder generated by grinding the 28 days geopolymer paste sample to reduce its particle size.…”

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confidence: 99%

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Development of geopolymer mortar under ambient temperature for in situ applications

Al-Majidi

Λαμπρόπουλος

Cundy

et al. 2016

Construction and Building Materials

293

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Geopolymer concrete technology involves production of more environmentally friendly waste material-based concrete which could be a viable solution for conventional concrete replacement. Typical fly ash-based geopolymer concrete however requires high temperature curing treatment in order to develop sufficient early strength properties, which is considered a severe limitation for cast-in-place concrete applications. Most previous studies on geopolymer concrete have focused on the properties of concretes pre-hardened by heat curing and/ or by aggressive chemical treatment (e.g. alkali activation using concentrated sodium hydroxide (NaOH)). The current study presents an extensive experimental investigation on the mechanical and microstructural properties of geopolymer concrete mixes prepared with a combination of fly ash and slag cured under ambient temperature. 'User friendly' geopolymer mixes were produced using fly ash (FA) and Ground Granulated Blast furnace Slag (GGBS) mixed together with potassium silicate with molar ratio equal to 1.2 (as the activator) and water. The results indicated that heat curing treatment can be avoided by partial replacement of fly ash with slag. The compressive strength of the examined mixes was found to be in the range of 40-50MPa for 40 % and 50 % GGBS replacement mixtures respectively. Moreover, the flexural and direct tensile strengths of geopolymer mixes are considerably improved as the GGBS content is increased.Based on FTIR and SEM/EDS analysis, the inclusion of a higher content of GGBS resulted in a denser structure by formation of more hydration products.Keywords: Fly ash, slag, ambient temperature, user friendly geopolymer mortar *Manuscript Click here to view linked References 2 IntroductionThere are many environmental issues associated with the production of Ordinary Portland cement (OPC), such as consumption of 5% of natural resources, and generation of 5-7 % of total global anthropogenic carbon dioxide emissions [1][2][3][4]. This has led to an urgent need for the development of alternative materials that may provide technically viable alternative solutions to conventional cementitious concrete, with more favourable environmental credentials. Geopolymer concrete manufacture is one of the most promising techniques which has been developed in the last few years. Utilization of geopolymer materials can reduce 80% of greenhouse gas emissions associated with material production, and overcome issues related to cement production and unregulated disposal of industrial materials by recycling these materials in geopolymer manufacture [5][6][7].Geopolymers are inorganic by-product materials, rich in silicon (Si) and aluminium Five different mixtures of geopolymer mortar proportions were examined with various ratios of GGBS to total binder (10%, 20%, 30%, 40% and 50 %, Table 2). Based on preliminary experimental studies undertaken during the current project, the optimum mix design (in terms of mechanical strength and workability) was achieved using water, alkaline activator...

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Section: Microstructural Analysismentioning

confidence: 99%

mentioning

confidence: 99%

Development of geopolymer mortar under ambient temperature for in situ applications

Al-Majidi

Λαμπρόπουλος

Cundy

et al. 2016

Construction and Building Materials

293

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“…Concrete is typical anisotropic porous composites and its sub-microstructures, such as porous system, ITZs between aggregate and paste matrix, volume fraction of unhydrated cement gains, are related to the engineering properties of concrete, i e, strength, permeability and volume stability of concrete [1][2][3] . As mineral admixtures can alleviate the burden of environment, there exist a large number of literatures on effects of mineral admixtures on the microscopic characteristics of concrete [4,5] .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of sub-microstructure in concrete with low water-binder ratio by SEM-BSE image analysis

Qian

Guo³

et al. 2010

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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The coarse pore system, interfacial transition zone (ITZ) between aggregate and paste matrix and volume fraction of unhydrated cement in concrete (w/c＝0.3) containing mineral admixtures were quantitatively characterized by the scanning electron microscope-backscattered electron (SEM-BSE) image analysis technique. The experimental results show that compound addition of slag and fly ash decreases the coarse porosity from 10.17% to 3.74% and the threshold diameter of coarse pore size from 345 µm to 105 µm compared with concrete (w/c＝0.30) without mineral admixtures; Moreover with compound addition of fly ash and slag, the volume proportion of unhydrated cement in paste matrix is reduced by 30%, the maximum amount of coarse pores in the ITZ between aggregate and paste decreases from 13.11% to 5.57% and the thickness of ITZ is reduced by 37% , compared with concrete without mineral admixtures.

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“…This is probably due to the complex internal porosity of a cement-based material (Gonen and Yazicioglu 2007) and the significant dependence of the absorption rate on the properties of fluid and its interactions with the porous medium (Li and Firoozabadi 2000).…”

Section: Introductionmentioning

confidence: 99%

Hygro-Gradient Model for Permeability of Unsaturated Cementitious Composites

Han

Maekawa

2017

ACT

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A new method for predicting the water absorption process of unsaturated cementitious composites is proposed, and its functionality is experimentally verified. The mechanism of the capillarity on water absorption process is mathematically termed by a slip boundary condition of micro-flow of pore water, and employed to an unsaturated water permeation on the scheme of multi-scale modeling. The rapid sorption just after the exposure to condensed water is fairly simulated owing to the non-local formulation of hygro-gradient, which simply represents the thermodynamics of non-equilibrated states in dry pores. The proposed model of complexity of micro-pore connection is examined in terms of the initial water content, porosity and saturation of micro-pore structure and volume ratio of aggregate. It is further examined in terms of the intrinsic hydraulic profile by using the Boltzmann's transform.

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The influence of compaction pores on sorptivity and carbonation of concrete

Cited by 130 publications

References 15 publications

Development of geopolymer mortar under ambient temperature for in situ applications

Development of geopolymer mortar under ambient temperature for in situ applications

Evaluation of sub-microstructure in concrete with low water-binder ratio by SEM-BSE image analysis

Hygro-Gradient Model for Permeability of Unsaturated Cementitious Composites

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