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Every year, glacial rivers in Greenland transport and deposit vast quantities of fine-grained rock material (GP). In the present study we characterise this raw material (GP) and evaluate whether it is possible to produce adobe bricks for a local production in an Arctic region such as Greenland. The raw material characterization included determination of the grain size distribution and the plastic properties. For enabling the production of adobe bricks, it was, based on these tested parameters, found necessary to add a fraction of a coarser gravel-size material (KG) in addition to the fine-grained rock material (GP). Small-scale prisms and cylinders for determination of the drying shrinkage behaviour and the mechanical performance of the composite material were produced containing 50/50 of GP and KG, respectively. Adobe bricks are often reinforced with fibres of natural or synthetic materials to improve the ductility of the composites, such as for example straw, however, in Arctic regions such materials are often a scares resource due to the existing type of vegetation. Therefore, we instead added fibres from discarded polyethylene fishing nets, which is a local waste material often present in coastal towns in Greenland. The addition of fibres from waste fishing nets to the adobe specimens resulted in enhanced drying shrinkage behaviour, post-crack performance and toughness for prisms when exposed to flexural loads., Academic Journal of Civil Engineering, Vol 37 No 2 (2019): Special Issue - ICBBM 2019

Depositing mine tailings entail major economic costs and negative environmental impacts. Thus finding an alternative to depositing is of interest. This study focused on the use of mine tailings as partial cement replacement, thereby preventing depositing the mine tailings. At the same time, such use would reduce the CO2 emission related to the production of cement. Mine tailings from two different mines Zinkgruvan (Sweden) and Nalunaq (Greenland) were both tested as 5 and 10 % cement replacement. All mortar specimens with mine tailings had lower compressive strength compared to a reference specimen at 7, 14 and 28 days of curing. Both mine tailings showed contributions to the pozzolanic activity. This tendency was more profound for Zinkgruvan. No evidence of either mine tailing containing minerals acting as nucleation sites was, however, seen. The specimens containing mine tailings were compared to a specimen containing a 10 % replacement of cement with coal fly ash, commonly used in Denmark. The compressive strength of specimens containing mine tailings exceeded the compressive strength of the specimen containing coal fly ash, indicating further the amorphous content of volcanic decent contained in the mine tailings to contribute to the pozzolanic activity and thus increase the compressive strength. Mine tailings have a high content of toxic chemical elements, but no significant amount of chemical elements was seen leaching from neither the pure mine tailings nor the mortar specimens containing mine tailings. Overall, the results show that these mine tailings have potential as a mineral admixture for substitution of cement in concrete., Academic Journal of Civil Engineering, Vol 35 No 2 (2017): Special Issue - ICBBM 2017

This work is a preliminary investigation on major properties for lightweight aggregate (LWA) concrete where sewage sludge ash (SSA) partly replaces the cement. To use SSA in LWA concrete production could lower the CO2 footprint (due to use of less cement) and maybe also give better thermal insulating properties, as the SSA particles are porous and might result in a more porous LWA concrete, the thermal conductivity is however not investigated in this preliminary work. Blocks of LWA concrete were cast. The replacement percentage of cement with SSA was varied: 0, 15, 20, 25, 30, 35 or 45%. From each block, test specimens were drilled (75 mm in both diameter and height). Porosity and compressive strength were measured. It was found that up to 30% SSA did not reduce the compressive strength significantly compared to the reference. These replacement percentages without strength loss are high compared to mortar samples in a previous investigation with SSA from the same incineration plant. The compressive strength of the laboratory produced reference LWA concrete was 1.75 MPa, which was lower than an industrial produced LWA concrete (3 MPa) with the same aggregate, fly ash and cement mass ratio. The mass of water to obtain a LWA concrete mix ideal for casting increased with increasing SSA mass. This due to the porosity and irregular shape of the relatively coarse (d50 95 µm) SSA particles. The water demand for mortar with this SSA replacing 20% cement was increased by 16% compared to the reference without SSA. Thus, the increased need for water in the LWA concrete mixture was as expected. The porosity of the LWA concretes with SSA was higher than the reference, which partly might be due to the high porosity of the SSA particles, revealing that the thermal conductivity was lower. Thus all together the results from this investigation are encouraging in order to continue the research topic., Academic Journal of Civil Engineering, Vol 35 No 2 (2017): Special Issue - ICBBM 2017

In this study, the potential of reusing plastic fibres from discarded waste fishing nets of polyethylene (PE) as fibre reinforcement in gypsum-based building materials is investigated. The fishing nets were not reprocessed, but simply washed and cut to monofilament fibres by an industrial operation. The fibre length was ranging from 1 mm (pulp) to 65 mm, and the diameter from 0.25 mm to 0.35 mm. Gypsum-based prisms and cylinders were cast with these fibres (fibre addition of 0.5 – 2.00 wt%). Mechanical properties such as compressive strength and three-point bending strength of fibre reinforced cylinders and prisms were determined by laboratory-scale testing. A decrease in first-crack strength of the prisms was observed. However, the addition of waste PE fibres resulted in improved post-crack behaviour., Academic Journal of Civil Engineering, Vol 35 No 2 (2017): Special Issue - ICBBM 2017

Tema: Wastewater treatment: technologies, operation, control and optimisation, risk assessment and working environment. Experience from new technologies

Chloride ion diffusion coefficient in concrete is estimated very often by using electromigration tests, among which the Rapid Chloride Migration (RCM) test is becoming more and more popular. Nevertheless, this test receives much criticism due to lacks in its scientific background. In this paper the theoretical background of the RCM test is critically evaluated in order to show the weak points. Chloride concentration profiles measured after the migration tests give serious evidence of oversimplification of the chloride transport model adopted in the RCM test as they are substantially different from the theoretical ones. Besides this, foregoing research unveils that the chloride ion diffusion coefficients obtained from the traditional non-steady-state diffusion test and from the RCM test are correlated but not identical. As concluded in this paper, the chloride transport model currently adopted for the RCM test should be modified with the non-linear chloride binding isotherm and nonequilibrium between the concentrations of free and bound chlorides. With these phenomenon included, the diffusivity of chlorides obtained from the RCM test should have a new and correct meaning.