| 1. |
- Björk, Folke., et al.
(författare)
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Degradation of components in flooring systems in humid and alkaline environments
- 2003
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Ingår i: Construction and Building Materials. - 0950-0618 .- 1879-0526. ; 17:3, s. 213-221
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Tidskriftsartikel (refereegranskat)abstract
- Constituents from products that are used in the flooring on a concrete slab such as carpets of plasticised PVC and water-based adhesives sometimes degrade in an alkaline and humid environment. The concrete itself could be such an environment. In order to examine the effect of different levels of alkalinity and humidity on the mentioned products a specialised procedure was developed. By this procedure it was possible to imitate the effect of an environment of alkalinity and humidity corresponding to a recently produced concrete slab on different substances and also collect volatile degradation products produced. Degradation of some of the constituents was dependent on the levels of alkalinity and humidity, although there were significant differences in the possibility to resist the environmental factors. For some of the components, an increase in alkalinity resulted in a much higher production of degradation products even when the relative humidity was kept on a comparatively low level. The results give basis for a recommendation not to adhere plastic floorings directly to a recently produced slab of high-quality concrete because the alkaline material in the concrete could cause degradation.
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| 2. |
- Björk, Folke., et al.
(författare)
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Measurement of alkalinity in concrete by a simple procedure, to investigate transport of alkaline material from the concrete slab to a self-levelling screed
- 2002
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Ingår i: Construction and Building Materials. - 0950-0618 .- 1879-0526. ; 16:8, s. 535-542
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Tidskriftsartikel (refereegranskat)abstract
- A test procedure for measurement of alkalinity for cementitious materials that is, reliable, simple. and only needs a small amount of sample, was developed and applied to check whether transport of alkaline material from a concrete surface to a covering screed can result in a detectable increase in pH-value. It was found that any transport of alkaline material from a rather humid concrete did not increase the level of alkalinity (or pH-value) of the screed covered with a carpet. It was noted that carbonation Occurred gradually from the surface and inwards when the materials were exposed to ambient air. For the prisms, of 95%, RH pH-value in the concrete surface increased with time. A transport process that allows hydroxide ions solved in the pore water in the concrete to diffuse towards the carbonated surface and thus give an increased pH-value, can explain this.
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| 3. |
- Granne, F., et al.
(författare)
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Joints between roofing felt and sheet metal flashings - short- and long-term tests
- 2000
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Ingår i: Construction and Building Materials. - 0950-0618 .- 1879-0526. ; 14:07-jun, s. 375-383
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Tidskriftsartikel (refereegranskat)abstract
- The adhesion between roofing felt and sheet metal flashings has been measured and analysed and test methods for this have been developed. Both bituminous and polymeric roofing felts have been used. The steel has been PVC-coated galvanised steel sheets and the bituminous roofing felts have been of both SBS and APP modified type. All the joints have been made with heat welding. The tests show that it is possible to obtain joints with sufficient strength using the contractors ordinary welding procedures.
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| 4. |
- Granne, F., et al.
(författare)
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Wind load resistance tests of heat-welded joints between roofing felt and sheet metal flashings
- 2003
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 17:5, s. 319-324
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Tidskriftsartikel (refereegranskat)abstract
- The wind load resistance of joints between roofing felt and sheet metal has been measured in a wind uplift chamber. Both bituminous and polymeric roofing felts have been used. The sheet metal has been PVC-coated galvanised steel sheets and the bituminous roofing felts have been of both SBS and APP modified type. All the joints have been made by heat welding. The tests show that peeling is the dominating process in the failure of joints during wind load.
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| 5. |
- Täljsten, Björn
(författare)
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Strengthening concrete beams for shear with CFRP sheets
- 2003
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Ingår i: Construction and Building Materials. - 0950-0618 .- 1879-0526. ; 17:1, s. 15-26
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Tidskriftsartikel (refereegranskat)abstract
- The method of strengthening concrete structures with FRP composites has existed for over a decade; the most common way to strengthen structures is in bending, but also wrapping of columns is quite common. There are also needs for strengthening concrete structures in shear, for example concrete beams, slabs, columns, etc. A typical structure can be a parking garage. However, strengthening concrete structures for shear is not as common as for bending and confinement. This paper presents examples to strengthen concrete beams for shear. First traditional strengthening methods are presented briefly, then the use of CFRP (Carbon Fibre reinforced Polymers) composites for shear strengthening is presented. Tests on beams strengthened in shear with CFRP sheets are presented and a short presentation on how to design for shear strengthening with CFRP is given. Furthermore, a field application of a parking slab strengthened for shear with CFRP unidirectional fabric is presented. The laboratory tests show the importance of considering the principal directions of the shear crack in relation to the unidirectional fibre. The field application shows that it is easy to strengthen existing structures for shear with CFRP fabrics.
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| 6. |
- Addassi, Mouadh, et al.
(författare)
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Reactive mass transport in concrete including for gaseous constituents using a two-phase moisture transport approach
- 2020
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Ingår i: Construction and Building Materials. - : Elsevier. - 0950-0618 .- 1879-0526. ; 232, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the further development of a tool for multi-phase reactive mass transport modelingfor durability estimation of cement-based materials, by the addition of the gas phase, adopting a trulyseparate two-phase moisture transport approach. The governing system of equations are based on phys-ically sound hybrid mixture based version of the Poisson-Nernst-Planck system of equations includinggaseous transport in the air-filled space, ionic transport in the liquid phase, electro-migration of ionicspecies, a two-phase moisture transport model, and sorption. The addition of the gas phase and thetwo-phase moisture description enables the user of the model to investigate individual and combinedeffects of different degradation processes in unsaturated systems. The altering of hydrated cement underthree different environments were studied representing an accelerated carbonation environment, a sub-merged marine environment and a cyclic drying-wetting zone in a marine environment, to illustratesome of the model’s capabilities.
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| 7. |
- Al-Ayish, Nadia, et al.
(författare)
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The influence of supplementary cementitious materials on climate impact of concrete bridges exposed to chlorides
- 2018
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 188, s. 391-398
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Tidskriftsartikel (refereegranskat)abstract
- In order to reach a specific service life of reinforced concrete structures a certain cover thickness is needed. At present, this is regulated by national standards that also limit the amount and type of supplementary cementitious materials in different exposure environments. The regulations do not, however, consider the actual durability performance of concrete with supplementary cementitious materials. As a consequence, the LCA results might be misleading. This paper shows the environmental impact of concrete with supplementary cementitious materials in chloride environment considering their specific performances. Prescriptive and performance based service life prediction models for chloride ingress are applied and compared.
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| 8. |
- Amiandamhen, Stephen, 1983-, et al.
(författare)
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Recycling sawmilling wood chips, biomass combustion residues, and tyre fibres into cement-bonded composites : Properties of composites and life cycle analysis
- 2021
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Ingår i: Construction and Building Materials. - : Elsevier Ltd. - 0950-0618 .- 1879-0526. ; 297
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the properties and sustainability of cement-bonded composites containing industrial residues such as wood chips, tyre fibres and biomass combustion residues, i.e. bottom ash (BA) and fly ash (FA). The effect of cement-to-raw material (wood/tyre fibre) ratio (C/RM) and the aggregate content (BA and FA) on thermal and mechanical properties of the composites were investigated. Scanning electron microscopy (SEM) and life cycle analysis (LCA) were also conducted. The results revealed that as the aggregate content increased in wood composites, the mechanical properties also increased. The mean thermal conductivity and volumetric heat capacity of tyre composite samples were 0.37 W/mK and 1.2 MJ/m3K respectively, while the respective values for wood composite samples were 0.29 W/mK and 0.81 MJ/m3K. SEM analysis showed adequate bonding between wood/tyre fibres and cement matrix. LCA revealed that the materials share of the total primary energy use was about 60% for all analysed composites. © 2021 The Author(s)
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| 9. |
- André, Alann, 1980, et al.
(författare)
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Application of fracture mechanics to predict the failure load of adhesive joints used to bond CFRP laminates to steel members
- 2012
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 27:1, s. 331-340
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Tidskriftsartikel (refereegranskat)abstract
- The use of bolted or welded elements to upgrade metallic structures has been a common practice for many years. Moreover, the use of adhesively bonded carbon fiber reinforced polymer (CFRP) laminates, as an alternative method, has attracted a great deal of attention in recent years. One important aspect of the design of adhesive joints used to bond CFRP laminates to steel substrates is the determination of the properties of the CFRP/adhesive/steel interfaces, which have not yet been established in codes or standards. The purpose of this paper is experimentally to determine the fracture properties of the adhesive material and to evaluate the accuracy of numerical methods using this information, in order to predict the strength of adhesive joints in steel members bonded with CFRP laminates. The results from four series of experimental tests are compared with numerical results and discussed in terms of load-bearing capacity and failure modes.
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| 10. |
- André, Alann, 1980, et al.
(författare)
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Compression failure mechanism in small scale timber specimens
- 2014
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 50, s. 130-139
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the failure mechanism of wood loaded in compression parallel to the grain has been shown to be an important parameter in the design of timber beams strengthened with fibre-reinforced plastics (FRP). In this paper, a constitutive relationship for wood under uniaxial compression load parallel to the grain was determined experimentally. Several parameters, such as silviculture, moisture content and radial position in the log in relation to the pith from where the specimen was sawn, were considered. Small clear-wood specimens were used. The strain localisation in the failure region (kinkband) was monitored using the digital image correlation method. The results show that silviculture and moisture content are two very important parameters which influence the compression failure mechanism. Furthermore, there is a significant difference in behaviour between specimens from the juvenile region of the log and specimens from mature wood. Based on experimental results, two numerical models were built, considering either a global or a local constitutive relationship. It was demonstrated that both numerical models yield accurate results and that, depending on the experimental equipment available, a constitutive relationship could be extracted and used as input in these numerical models. (C) 2013 Elsevier Ltd. All rights reserved.
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