Utilisation of alkaline activated industrial by-products in deep soil mixing
- Yaghoubi, Mohammadjavad, Arulrajah, Ar, Disfani, Mahdi, Horpibulsuk, Suksun, Bo, Myint, Leong, Melvyn
- Authors: Yaghoubi, Mohammadjavad , Arulrajah, Ar , Disfani, Mahdi , Horpibulsuk, Suksun , Bo, Myint , Leong, Melvyn
- Date: 2017
- Type: Text , Conference paper
- Relation: Seventh International Conference on Geotechnique, Construction Materials and Environment, Nov. 21-24, 2017, ISBN: C3051, Mie, Japan p. 96-101
- Full Text:
- Reviewed:
- Description: The use of deep soil mixing (DSM) technique in deep ground improvement projects has increased over the past decade due to being more cost-effective and easier to implement compared to other techniques such as piling, for structures subject to low to medium loads. Currently, Portland cement, lime and their combination are being used as the most common binders in DSM. However, due to the economic and concerning environmental disadvantages of using these binders, there is a need for new environmentally friendly cementing materials. This research attempts to find a way to use stockpiles of industrial by-products, such as fly ash (FA) and slag (S), as new green binders; consequently, reducing the carbon footprint in ground improvement projects. Different contents of FA and S, activated by liquid alkaline activator (L), were added to a soft marine soil to evaluate the changes in its behaviour as well as its microstructure. In addition, mixtures with cement (C), lime (Li) and their combination were prepared and tested for comparison. Binders were added at contents of 10, 20 and 30%, by dry soil mass, and samples were cured for 7 days. The results revealed that these new binders significantly increased the strength and stiffness of the soft soil, and they can be a suitable replacement for C and Li. The optimum mixture was found to be CIS+5% FA+15% S, within the range of binder, L and water content studied in this research. Moreover, recycling FA and S would substantially limit the expansion of landfill sites.
- Authors: Yaghoubi, Mohammadjavad , Arulrajah, Ar , Disfani, Mahdi , Horpibulsuk, Suksun , Bo, Myint , Leong, Melvyn
- Date: 2017
- Type: Text , Conference paper
- Relation: Seventh International Conference on Geotechnique, Construction Materials and Environment, Nov. 21-24, 2017, ISBN: C3051, Mie, Japan p. 96-101
- Full Text:
- Reviewed:
- Description: The use of deep soil mixing (DSM) technique in deep ground improvement projects has increased over the past decade due to being more cost-effective and easier to implement compared to other techniques such as piling, for structures subject to low to medium loads. Currently, Portland cement, lime and their combination are being used as the most common binders in DSM. However, due to the economic and concerning environmental disadvantages of using these binders, there is a need for new environmentally friendly cementing materials. This research attempts to find a way to use stockpiles of industrial by-products, such as fly ash (FA) and slag (S), as new green binders; consequently, reducing the carbon footprint in ground improvement projects. Different contents of FA and S, activated by liquid alkaline activator (L), were added to a soft marine soil to evaluate the changes in its behaviour as well as its microstructure. In addition, mixtures with cement (C), lime (Li) and their combination were prepared and tested for comparison. Binders were added at contents of 10, 20 and 30%, by dry soil mass, and samples were cured for 7 days. The results revealed that these new binders significantly increased the strength and stiffness of the soft soil, and they can be a suitable replacement for C and Li. The optimum mixture was found to be CIS+5% FA+15% S, within the range of binder, L and water content studied in this research. Moreover, recycling FA and S would substantially limit the expansion of landfill sites.
Alkali activated cement mixture at ambient curing : strength, workability, and setting time
- Tekle, Biruk, Holschemacher, Klaus
- Authors: Tekle, Biruk , Holschemacher, Klaus
- Date: 2022
- Type: Text , Journal article
- Relation: Structural Concrete Vol. 23, no. 4 (2022), p. 2496-2509
- Full Text:
- Reviewed:
- Description: The success of ordinary Portland cement (OPC) comes at a risk to the environment because of the large carbon dioxide emissions associated with cement manufacturing. This has led the scientific community to look for alternative cementitious materials with lower environmental impact. Alkali activated cement (AAC) is an excellent alternative to this end. In this study, the effect of binder content, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water content to total solid binder ratio (TW/TB) on the strength, setting time and flowability of ambient cured AAC mixtures are studied using Taguchi method of experimental design. Binder content was varied from 550 to 750 kg/m3, AS/B ratio from 0.14 to 0.22, SS/SH ratio from 1.5 to 2.5, and TW/TB ratio from 0.29 to 0.39. The study results showed that within the investigated range, an increase in binder content has a minor effect on strength but resulted in a considerable increase in setting time and flowability. An increase in the AS/B ratio resulted in increased flowability and setting time and a decrease in strength. Moreover, the study also investigated the relationship between compressive strength and flexural strength. © 2021 The Authors. Structural Concrete published by John Wiley & Sons Ltd on behalf of International Federation for Structural Concrete.
- Authors: Tekle, Biruk , Holschemacher, Klaus
- Date: 2022
- Type: Text , Journal article
- Relation: Structural Concrete Vol. 23, no. 4 (2022), p. 2496-2509
- Full Text:
- Reviewed:
- Description: The success of ordinary Portland cement (OPC) comes at a risk to the environment because of the large carbon dioxide emissions associated with cement manufacturing. This has led the scientific community to look for alternative cementitious materials with lower environmental impact. Alkali activated cement (AAC) is an excellent alternative to this end. In this study, the effect of binder content, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water content to total solid binder ratio (TW/TB) on the strength, setting time and flowability of ambient cured AAC mixtures are studied using Taguchi method of experimental design. Binder content was varied from 550 to 750 kg/m3, AS/B ratio from 0.14 to 0.22, SS/SH ratio from 1.5 to 2.5, and TW/TB ratio from 0.29 to 0.39. The study results showed that within the investigated range, an increase in binder content has a minor effect on strength but resulted in a considerable increase in setting time and flowability. An increase in the AS/B ratio resulted in increased flowability and setting time and a decrease in strength. Moreover, the study also investigated the relationship between compressive strength and flexural strength. © 2021 The Authors. Structural Concrete published by John Wiley & Sons Ltd on behalf of International Federation for Structural Concrete.
Freeze–thaw resistance and sorptivity of fine-grained alkali-activated cement concrete
- Tekle, Biruk, Ly, Tran, Hertwig, Ludwig, Holschemacher, Klaus
- Authors: Tekle, Biruk , Ly, Tran , Hertwig, Ludwig , Holschemacher, Klaus
- Date: 2023
- Type: Text , Journal article
- Relation: Structural Concrete Vol. 24, no. 3 (2023), p. 4286-4296
- Full Text:
- Reviewed:
- Description: The paper investigates the freeze–thaw resistance and sorptivity behavior of fine-grained alkali-activated concrete cured at ambient temperature. A blended binder system containing fly ash, ground granulated blast furnace slag, and silica fume was used. A combination of sodium hydroxide and sodium silicate was used as an activator. The freeze–thaw resistance was evaluated based on mass loss (scaling), and the extent of internal damage was assessed by testing the ultrasonic time at different cycles. Initial and secondary sorptivity coefficients were calculated based on the cumulative water absorption values at different time intervals. Alkali content, sodium silicate to sodium hydroxide ratio, and water to binder ratio were investigated. The experimental results showed that water to binder ratio is the most significant parameter for the scaling; higher ratios result in higher scaling. In terms of internal damage, alkali content is the most significant. The increase of alkali increased the amount of internal damage in the concrete. The initial sorptivity coefficient increased with the water and alkali content and decreased with the silicate content. The secondary sorptivity coefficient showed no significant change with the investigated parameters. © 2022 The Authors. Structural Concrete published by John Wiley & Sons Ltd on behalf of International Federation for Structural Concrete.
- Authors: Tekle, Biruk , Ly, Tran , Hertwig, Ludwig , Holschemacher, Klaus
- Date: 2023
- Type: Text , Journal article
- Relation: Structural Concrete Vol. 24, no. 3 (2023), p. 4286-4296
- Full Text:
- Reviewed:
- Description: The paper investigates the freeze–thaw resistance and sorptivity behavior of fine-grained alkali-activated concrete cured at ambient temperature. A blended binder system containing fly ash, ground granulated blast furnace slag, and silica fume was used. A combination of sodium hydroxide and sodium silicate was used as an activator. The freeze–thaw resistance was evaluated based on mass loss (scaling), and the extent of internal damage was assessed by testing the ultrasonic time at different cycles. Initial and secondary sorptivity coefficients were calculated based on the cumulative water absorption values at different time intervals. Alkali content, sodium silicate to sodium hydroxide ratio, and water to binder ratio were investigated. The experimental results showed that water to binder ratio is the most significant parameter for the scaling; higher ratios result in higher scaling. In terms of internal damage, alkali content is the most significant. The increase of alkali increased the amount of internal damage in the concrete. The initial sorptivity coefficient increased with the water and alkali content and decreased with the silicate content. The secondary sorptivity coefficient showed no significant change with the investigated parameters. © 2022 The Authors. Structural Concrete published by John Wiley & Sons Ltd on behalf of International Federation for Structural Concrete.
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