Class C fly ash-based alkali activated cement as a potential alternative cement for CO2 storage applications

This paper presents a study of parameters affecting the fibre pull out capacity and strain-hardening behaviour of fibre-reinforced alkali-activated cement composite (AAC). Fly ash is a common aluminosilicate source in AAC and was used in this study to create fly ash based AAC. Based on a numerical study using Taguchi’s design of experiment (DOE) approach, the effect of parameters on the fibre pull out capacity was identified. The fibre pull out force between the AAC matrix and the fibre depends greatly on the fibre diameter and embedded length. The fibre pull out test was conducted on alkali-activated cement with a capacity in a range of 0.8 to 1.0 MPa. The strain-hardening behaviour of alkali-activated cement was determined based on its compressive and flexural strengths. While achieving the strain-hardening behaviour of the AAC composite, the compressive strength decreases, and fine materials in the composite contribute to decreasing in the flexural strength and strain capacity. The composite critical energy release rate in AAC matrix was determined to be approximately 0.01 kJ/m 2 based on a nanoindentation approach. The results of the flexural performance indicate that the critical energy release rate of alkali-activated cement matrix should be less than 0.01 kJ/m 2 to achieve the strain-hardening behaviour.

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MECHANICAL PROPERTIES OF FLY ASH-BASED ALKALI-ACTIVATED CEMENT USING A STATISTICAL ANALYSIS TECHNIQUE

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2014.38 ◽

2014 ◽

Vol 1 (1) ◽

Author(s):

Hyuk Lee ◽

Vanissorn Vimonsatit

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Statistical Analysis ◽

Fly Ash ◽

Silica Fume ◽

Dry Density ◽

Analysis Method ◽

Solid Ratio ◽

Alkali Activated ◽

Alkali Activated Cement

This paper presents the mechanical properties of fly ash-based alkali-activated cement (AAC). A statistical analysis method was used to determine the effect of mix proportion parameters on the dry density and compressive strength of fly ash-based AAC pastes and mortars. For that purpose, sample mixtures were designed according to Taguchi’s experimental design method, i.e., in a L9 orthogonal array. Four factors were selected: “silica fume content” (SF), “sand to solid ratio” (s/c), “liquid to solid ratio” (l/s), and “superplasticiser content” (SP). The experimental results were analysed by using signal to noise for quality control of each mixture, and analysis of variance (ANOVA) was used to determine the significant effect on the compressive strength of fly ash-based AAC. Furthermore, a regression-analysis method was used to predict the compressive strength according to the variation of the four factors. Results indicated that silica fume is the most influencing parameter on compressive strength, which could be decreased by superplasticiser and l/s ratio. There is no significant effect of sand-to-cementitious ratio on compressive strength of fly ash-based AAC. The dry density decreases as the sand-to-cementitious ratio is decreased. The increasing l/s ratio and superplasticiser dosage could further decrease the dry density of fly ash-based AAC.

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Research on Mechanism of Architectural Wastes Solidified by Alkali-Activated Cement and Fly Ash

Advanced Materials Research ◽

10.4028/scientific5/amr.446-449.2708 ◽

2012 ◽

Vol 446-449 ◽

pp. 2708-2713

Author(s):

Qin Li ◽

Xiao Jun Zhou ◽

Zhuo Yin Jiang ◽

Ke Wei Sun

Keyword(s):

Fly Ash ◽

Alkali Activated ◽

Alkali Activated Cement

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Alkali-activated complex binders from class C fly ash and Ca-containing admixtures

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2009.08.110 ◽

2010 ◽

Vol 173 (1-3) ◽

pp. 480-486 ◽

Cited By ~ 86

Author(s):

Xiaolu Guo ◽

Huisheng Shi ◽

Liming Chen ◽

Warren A. Dick

Keyword(s):

Fly Ash ◽

Class C ◽

Activated Complex ◽

Alkali Activated

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Adiabatically cured, alkali-activated cement-based wasteforms containing high levels of fly ash

Cement and Concrete Research ◽

10.1016/s0008-8846(01)00589-0 ◽

2001 ◽

Vol 31 (10) ◽

pp. 1437-1447 ◽

Cited By ~ 24

Author(s):

A.R Brough ◽

A Katz ◽

G.-K Sun ◽

L.J Struble ◽

R.J Kirkpatrick ◽

...

Keyword(s):

Fly Ash ◽

Alkali Activated ◽

Alkali Activated Cement

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Investigation of the Effect of Mixing Time on the Mechanical Properties of Alkali-Activated Cement Mixed with Fly Ash and Slag

Materials ◽

10.3390/ma14092301 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2301

Author(s):

Taewan Kim ◽

Choonghyun Kang

Keyword(s):

Mechanical Properties ◽

Fly Ash ◽

Mixing Time ◽

Blending Method ◽

Mixing Method ◽

The Difference ◽

High Alkali ◽

Mixed Water ◽

Alkali Activated ◽

Alkali Activated Cement

This is an experiment on the effect of mixing time for alkali-activated cement (AAC) using a binder mixed with ground granulated blast furnace slag (slag) and fly ash (FA) in a ratio of 1:1 on the mechanical properties. The mixing method of ASTM C305 was used as the basic mixing method, and the following mixing method was changed. Simply adding the same mixing time and procedure, the difference in the order of mixing slag and FA, and controlling the amount of activator and mixed water were considered. As a result of the experiment, the addition of the same mixing time and procedure, pre-injection of slag, and high-alkali mixed water in which half of the activator and mixing water were mixed showed the highest mechanical properties and a dense pore structure. As a result, the design of a blending method that can promote the activation action of slag rather than FA at room temperature was effective in improving the mechanical properties of AAC. In addition, these blending factors showed a clearer effect as the concentration of the activator increased. Through the results of this experiment, it was shown that high-temperature curing, high fineness of the binder, or even changing the setting of the mixing method without the use of excessive activators can lead to an improvement of mechanical properties.

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Developing Mix Proportions for Class C Fly Ash-Based Alkali-Activated 3D-Printed Concrete Mixtures

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/03611981211039167 ◽

2021 ◽

pp. 036119812110391

Author(s):

Fareh Abudawaba ◽

Eslam Gomaa ◽

Ahmed Gheni ◽

Mohamed ElGawady

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Element Concentration ◽

Limit State ◽

Sem Images ◽

Structural Applications ◽

3D Printed ◽

Class C ◽

Alkali Activated ◽

Full Height

This study investigated the use of class C fly ash (FA) as a precursor for alkali-activated mortar (AAM) for 3D-printed concrete (3DPC). AAMs with different water-to-FA (W/FA), alkaline activator-to-FA (Alk/FA), and sodium silicate-to-sodium hydroxide (SS/SH) ratios were examined to develop mixtures that can be tailored for different structural applications of 3DPC. The fresh properties, including extrudability and buildability, were evaluated through the open time (OT) and immediate deformation tests, respectively. Different cycle times (CTs) were applied to achieve a strain limit state necessary to maintain the printed shape. The strength of AAMs in different directions at different CTs was examined. Scanning electron microscopy (SEM) was carried out on AAM specimens having different CTs for a better understanding of the bond area. OTs ranging from 2.5 min to 31 min and axial strains ranging from 0.17% to 11.2% were achieved depending on the proportions of the AAMs and CT, which offers flexibility in optimizing the speed of printing and strength of concrete for different projects. The 3DPC specimens displayed anisotropic behavior compared with full-height specimens, where the compressive strength of full-height specimens was higher by 0.2% to 18% and 0.9% to 28% than 3DPC specimens when tested parallel and normal to the printing directions, respectively. SEM images and line scan indicated an approximately even intensity of the element concentration at the interfacial zones of AAMs having short CTs, which explained the relatively high compressive strength of those specimens. For AAMs having long CTs, there was a significant change in the intensity of the element concentration at the interfacial bond zone, and voids were observed resulting in low compressive strength of those specimens.

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