Effect of wood/binder ratio, slag/binder ratio, and alkaline dosage on the compressive strength of wood-geopolymer composites
- Authors: Gigar, Firensenay , Khennane, Amar , Liow, Jong-leng , Tekle, Biruk
- Date: 2023
- Type: Text , Conference paper
- Relation: International Symposium of the International Federation for Structural Concrete, fib Symposium 2023, Istanbul, 5-7 June 2023, Building for the Future: Durable, Sustainable, Resilient: Vol. 349 LNCE, p. 658-667
- Full Text: false
- Reviewed:
- Description: The impact of building construction on the environment is significant. Occupying large land areas (urban footprint), buildings are one of the most important consumers of resources and raw materials. They are responsible for 38% of greenhouse gas (GHG) emissions in both developed and developing countries. Therefore, incorporating sustainability and resilience into all aspects of urban infrastructure has become necessary. To curb emissions, part of the answer lies in the use of construction and building materials made from recycled materials. Bio-sourced materials, like wood chips, combined with a cementitious matrix, offer an alternative to conventional materials. They are sustainable, lightweight, and have good thermal insulation. However, because of their inferior mechanical strength, they have limited use as load-bearing structural parts. Furthermore, the use of Portland cement as a binder still poses some challenges due to its high carbon footprint. This study investigates the potential of wood-geopolymer composites for better mechanical performance and environmental sustainability. A 6x2x2x2 fractional factorial-based experimental design was used to simultaneously study the effect of slag content, wood binder ratio, and alkaline on the compressive strength of the wood-geopolymer composite. The experiments showed encouraging results for developing ambient cured wood geopolymer composites. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.
Recycling timber waste into geopolymer cement bonded wood composites
- Authors: Gigar, Firesenay , Khennane, Amar , Liow, Jong-leng , Tekle, Biruk , Katoozi, Elmira
- Date: 2023
- Type: Text , Journal article
- Relation: Construction and Building Materials Vol. 400, no. (2023), p.
- Full Text:
- Reviewed:
- Description: Addressing critical societal challenges, such as climate change, resource depletion, and environmental protection, requires sustainable management of resources. This study reports on the results of an experimental program using waste wood, including chromium copper arsenic (CCA) treated wood, to produce ambiently cured geopolymer cement bonded wood composites (WGC), and the results are very encouraging. The composite exhibited a reasonable compressive strength, which ranged between 7 and 27 MPa inversely corresponding to the amount of wood per binder ratio ranging between 0.1 and 0.4, conferring it the possibility of being used as a building material. The compressive strength of the composite with 40% wood chips showed the lowest compressive strength with values of 9.79, 7.29, and 7.92 MPa for decontaminated, CCA-treated, and non-CCA-treated wood chips, respectively. The results indicated that for all the wood per binder ratios, the use of decontaminated wood chips significantly improves the compressive, flexural, and specific strength of the composites, as well as their ductility, compared to non-decontaminated CCA-treated and non-CCA-treated wood chips. This paves the way for using wood waste in sustainability oriented product development and manufacturing. © 2023 The Author(s)
Parametric study on bond of GFRP bars in alkali-activated cement concrete
- Authors: Tekle, Biruk , Khennane, Amar
- Date: 2020
- Type: Text , Journal article
- Relation: Magazine of Concrete Research Vol. 72, no. 13 (2020), p. 670-680
- Full Text: false
- Reviewed:
- Description: Bond behaviour plays an important role in the design and performance of reinforced-concrete structures. In this study, finite-element modelling is used to perform a parametric study. The bond between the glass fibre-reinforced polymer (GFRP) bar and alkali-activated cement concrete is modelled by surface-based cohesive behaviour. The accuracy of the model is validated by comparing model predictions with experimental results. The effect of concrete cover, bar diameter, compressive strength, lead length, embedment length and GFRP elastic modulus on bond behaviour is investigated. Each of these parameters are varied based on a range of applicable values to study their influence on bond behaviour. The parametric study showed that bond behaviour is mainly affected by concrete cover, bar diameter, embedment length and the compressive strength of the concrete. The effect of the elastic modulus of the GFRP bar is not as pronounced as that of the other parameters, while the influence of lead length can be avoided by providing enough unbonded length at the loaded end. The parametric study is further used to calibrate a well-known bond equation and develop a new regression equation for predicting the maximum bond stress. The predicted results from these equations showed a good agreement with the experimental results as well as those of the finite-element model.
Bond properties of sand-coated gfrp bars with fly ash–based geopolymer concrete
- Authors: Tekle, Biruk , Khennane, Amar , Kayali, Obada
- Date: 2016
- Type: Text , Journal article
- Relation: Journal of composites for construction Vol. 20, no. 5 (2016), p.
- Full Text: false
- Reviewed:
- Description: AbstractBond behavior is an important subject in the design and performance of reinforced concrete structures. In this research, the bond property between sand-coated glass fiber–reinforced polymer (GFRP) bars, a corrosion-resistant substitute to steel bars, and fly ash–based geopolymer cement (GPC) concrete, a more environmental friendly alternative to ordinary portland cement (OPC) concrete, is investigated. Pullout test specimens containing GFRP bars embedded in GPC and OPC concrete cylinders with 100-mm diameter and 170-mm height were prepared. Three different embedment lengths were tested: three, six, and nine times the bar diameter. Average concrete compressive strengths of approximately 25 and 45 MPa and GFRP bar diameters of 12.7 and 15.9 mm were the other test parameters. For each specimen, the test results include the bond failure mode, the average bond strength, the slip at the loaded and free end, and the bond-slip relationship curves. The test results showed that GFRP-reinforced GPC concrete has similar bond strength as that of GFRP-reinforced OPC concrete. The increase in embedment length resulted in the decrease of the bond strength as well as a change in the failure mode of the specimens. Furthermore, the experimental results were used to generate a constitutive bond-slip law. Finally, finite-element modeling is performed by using the constitutive bond-slip law to investigate strain and bond distribution along the embedment length of the bar.