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- Al-Ayish, Nadia, et al.
(author)
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Safety and sustainability of new admixtures for durable concrete
- 2019
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In: Durable Concrete for Infrastructure Under Severe Conditions.
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Conference paper (other academic/artistic)abstract
- The sustainability of concrete infrastructures is highly dependent on the durability. A longer service life with low repair work reduces the resource use and hence the greenhouse gas emissions. New admixtures based on nanomaterials have the possibility to increase the service life. However, it is also important to consider the embodied impact of the material and safety issues concerning new nanomaterials. Here we present an overview on the latest developments on the safety and sustainability of some novel admixtures.
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Analysis of the Flexural Behavior of Textile Reinforced Reactive Powder Concrete Sandwich Elements Using Optical Measurements
- 2018
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Editorial proceedings (peer-reviewed)abstract
- Prefabricated and non-load bearing sandwich façade elements were developed using Textile Reinforced Reactive Powder Concrete (TRRPC) along with low density Foamed Concrete (FC) and Glass Fiber Reinforced Polymer (GFRP) continuous connecting devices. Four-point bending tests were performed on large-scale TRRPC sandwich element beams to characterize the structural performance, which included the flexural capacity, level of composite action, resulting deformation, crack propagation and failure mechanisms. Optical measurements based on Digital Image Correlation (DIC) were taken simultaneously to enable a detailed analysis of the underlying composite action. The structural behavior of the developed elements was found to be highly dependent on the stiffness and strength of the connectors to ensure composite action between the two TRRPC panels.
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| 8. |
- Baba Ahmadi, Arezou, 1985, et al.
(author)
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Utilization of Bio Ashes in Cement-based Materials: A Case Study in Cooperation with Pulp and Paper and Energy Production Industries in Sweden
- 2020
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In: Nordic Concrete Research. - : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 63:2, s. 63-78
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Journal article (peer-reviewed)abstract
- Worldwide increased concern of the CO2 emissions has led to the replacement of coal by biomass in combustion-based power plants. However, this would cause the scarcity of fly ash, one of the most well-known rest products from coal combustion, which is used as supplementary cementitious materials (SCM) in construction sector to reduce the large environmental footprint of cement production. Seeking to find alternative SCMs, this article aims to demonstrate the viability of using bio ashes in Sweden as SCM, which, due to lack of studies validating their value, are landfilled today. According to the obtained results, bio ashes produced at pulp and paper industries have a considerably consistent chemical composition and exhibit a satisfactory pozzolanic behaviour. Nevertheless, according to the conclusions of this study, the pozzolanicity of these alternative binders is not reflected equally with respect to the most known reactivity tests for common SCMs. The results imply that although “R3” tests method infers the pozzolanic characteristics of the bio ashes in focus of this study, the “activity index test” as well as “calcium consumption test” indicate otherwise.
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- Boubitsas, Dimitiros, et al.
(author)
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Frost Resistance of Concrete – Experience from Long-Term Field Exposure
- 2018
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Reports (other academic/artistic)abstract
- This report presents the results from a research project financed by Trafikverket, the Swedish Transport Administration, co-financed by Cementa AB.The purpose of this project is to investigate concrete specimens exposed to a de-icing salt highway environment at Highway 40 close to Borås after about 20 years. The project work was divided into two parts: Part One for frost resistance of concrete and Part Two for chloride ingress and reinforcement corrosion.In Part One, more than 100 types of concrete mixes with different binder types/combinations, water-binder ratios (w/b) and air contents exposed at three field test sites were examined for external and internal frost damage by measurements of the changes in volume of, and in ultrasonic transmission time through, the specimens. Furthermore, some laboratory tests were carried out to supply necessary data for modelling and identify the possible mechanisms causing frost damage.The results show clearly that the highway environment is the most aggressive with regard to external frost damage. Further, the results from this study show that the existence of entrained air and the water-binder ratio are the main parameters influencing the resistance of concrete to external salt-frost damage. Furthermore, the concrete mixes with CEM I, CEM I + 5 % silica, CEM II/A-LL, CEM II/A-S and CEM I + 30 % slag as binder with entrained air and a water/binder ratio of 0.4 or below, has good resistance to internal and external frost damage. Results show that concrete containing large amounts of slag as part of the binder (CEM III/B) have the severest scaling, irrespective of its content of entrained air.Comparing results from laboratory testing of salt-frost resistance in accordance with SS 13 72 44 (the ‘Slab test’ in CEN/TS 12390-9) with results after nineteen years’ exposure at the highway exposure site shows that the laboratory standard classifies most concrete qualities correctly.However, there is an indication that the laboratory test method may overestimate the scaling resistance of concrete containing a medium to high content of slag as part of the binder. This indicates a need to consider a revision of the slab test procedure so that aging processes is better taken into consideration. A somewhat longer preconditioning time with at least partially an increased carbon dioxide content would for example lead to that the effect of carbonation is better reflected.
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- Chozas, Valle, et al.
(author)
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Synthesis and characterization of reactive powder concrete for its application on thermal insulation panels
- 2015
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In: IOP Conference Series. - : Institute of Physics Publishing (IOPP).
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Conference paper (peer-reviewed)abstract
- This paper describes the synthesis and characterization of a set of textile reinforced reactive powder concrete (RPC) mixes that have been prepared in the framework of the SESBE project which aims to develop facade panels for the building envelope. In order to reduce the environmental impact, high concentration of type I and II mineral additions were added to the mixtures (up to 40% of cement replacement). The mechanical properties of the materials were analysed showing high values of compression strength thus indicating no disadvantages in the compression mechanical performance (∼140 MPa) and modulus of elasticity. In order to enable the use of these materials in building applications, textile reinforcement was introduced by incorporating layers of carbon fibre grids into the RPC matrix. The flexural performance of these samples was analysed showing high strength values and suitability for their further utilization.
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