| 1. |
- De Bruijn, Paulien, et al.
(författare)
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Mechanical properties of lime-hemp concrete containing shives and fibres
- 2009
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Ingår i: Biosystems Engineering. - : Elsevier BV. - 1537-5110 .- 1537-5129. ; 103:4, s. 474-479
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Tidskriftsartikel (refereegranskat)abstract
- The effect of using different binding agents in combination with hemp shives and fibres in Lime-Hemp Concrete (LHC) building material was examined. LHC is a light composite building material with building lime as binding agents and hemp (Cannabis sativa) as a renewable raw material from agriculture. Contemporary LHC only uses the woody core part of the hemp, the shive. However, using both hemp shives and fibres may improve the mechanical strength, eliminating the need for a fibre separation process. The aim was to elucidate the feasibility of using the entire fragmented hemp stalk in an LHC, and to determine some important material properties such as compressive strength, splitting tensile strength, water sorption and frost resistance. LHC with varying inclusions of the lime-based binders were tested, as were five mixes using the binding agents hydrated lime, hydraulic lime, and cement. Specimens were cured for 12 weeks at room temperature and 40 days in a carbonation room (4.5 vol% CO2), and tested for mechanical properties, water sorption and frost resistance. Using both shives and fibres in LHC may be advantageous for countries such as Sweden where facilities for separating hemp from shives are not commercially available.
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| 2. |
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| 3. |
- Falk, Jörgen, et al.
(författare)
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Ventilated rainscreen cladding: A study of the ventilation drying process
- 2013
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Ingår i: Building and Environment. - : Elsevier BV. - 1873-684X .- 0360-1323. ; 60, s. 173-184
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Tidskriftsartikel (refereegranskat)abstract
- The air exchange in rainscreen walls is expected to provide ventilation drying if excess moisture is absorbed in the wall construction. In an earlier paper, we presented a cavity airflow model and measurement based estimations of air change rates (ACH) in south-facing experimental walls. Here, focus is on the ventilation drying process and its practical implications. ACH in the experimental walls were calculated and converted into drying rates at different stages in the drying process. Furthermore, changes in the drying rates due to changes in the cavity design and in the outdoor climate were investigated. The significance of the drying rates was demonstrated in a case study. Findings showed that the cavity design is of major importance for the drying rate if the material adjacent to the cavity is wet over its entire extension. For such extreme cases, a light facade colour, vented horizontal battens and, in particular, a small cavity depth, are adverse factors for the drying rate. As the drying process proceeds and the moisture transport from the material to the cavity air becomes dependent on vapour diffusion, the drying rates for different cavity designs tend to be evened out. If the resistance to vapour flow in the material reaches high levels, a favourable outdoor climate is significantly more important than the cavity design to promote drying. Also for the case where the material adjacent to the cavity initially is only locally wet, findings showed that the cavity design is of minor importance for the drying time. (c) 2012 Elsevier Ltd. All rights reserved.
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| 4. |
- Falk, Jörgen, et al.
(författare)
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Ventilated rainscreen cladding: Measurements of cavity air velocities, estimation of air change rates and evaluation of driving forces
- 2013
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Ingår i: Building and Environment. - : Elsevier BV. - 1873-684X .- 0360-1323. ; 59, s. 164-176
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Tidskriftsartikel (refereegranskat)abstract
- To analyse the moisture performance of wall systems with a ventilated rainscreen cladding, the air change rate per hour (ACH) is required. However, the average ACH and its variation depend on many factors. This study focuses on performing field measurements of air velocities and temperatures in south oriented wall cavities characterised by either vertical wooden battens or horizontal vented metal battens. A physical cavity airflow model together with laboratory test of loss factors were used to analyse the data and interpret the results. With vertical battens, findings estimated the average ACH during a measurement period to be 230-310 ACH. In the cavities with horizontal battens, the ACH was 60-70% lower. The daily variations were considerable and hours with solar radiation and clear skies resulted in ACH that exceeded the average values 2-3 times. In contrast to airflow induced by thermal buoyancy, wind-induced airflow was irregular with frequent changes in both velocity and direction. This pattern was observed independent of the angle between the wind and the cladding. The frequent changes in flow direction significantly reduced the efficiency of wind-driven airflow to create air exchange. The wind-induced airflow in wall cavities with a pronounced non-linear relationship between the driving force and the air velocity is suppressed in the presence of buoyancy. For rainscreen claddings exposed to many hours of solar radiation, this effect increases the possibility of accurate estimations of ACH.
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| 5. |
- Hassanzadeh, Manouchehr, et al.
(författare)
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Sprickbildning i puts på isolering
- 2005
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Ingår i: Bygg och teknik. - 0281-658X. ; , s. 33-36
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Vid byggnadsmaterial, Lunds tekniska högskola, har problem med sprickbildning i puts på isolering studerats under ett antal år. Projektet startade i större skala 1999 med generella brottmekaniska analyser, laboratoriemätningar av brukets egenskaper och "fullskaleförsök" på provväggar i laboratorium. Resultaten från de första årens studier redovisades översiktligt i Bygg & teknik 8/02. Bland annat visades där sprickutseendet hos den första proväggen. Vidare diskuterades olika mekanismer som kunde ge upphov till sprickbildningen. Brukets krympning i kombination med att stålarmeringen var placerad nära värmeisoleringen bedömdes vara den primära orsaken till sprickbildningen.
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| 6. |
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| 8. |
- Johansson, Sanne, et al.
(författare)
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Biologisk påväxt på mineraliska fasader
- 2005
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Ingår i: Bygg & teknik. - 0281-658X. ; :8, s. 12-14
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- I maj 2004 påbörjades ett nytt projekt vid Lunds Tekniska Högskola som handlar om biologisk påväxt på mineraliska fasader. Projektet finansieras av FORMAS. Bakgrunden till projektet var att flera fall av nybyggda putsade fasader fick kraftig påväxt inom bara några år efter putsningen. Flera pilotförsök blev genomförda för att undersöka problemet i detalj och en sammanfattning av dessa redovisades i Bygg & Teknik 8/2002. Syftet med det nya projektet är att undersöka ovanstående problem genom att kombinera byggnadsteknisk kunskap med biologisk kunskap om de organismer vi finner på fasader.
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| 9. |
- Johansson, Sanne, et al.
(författare)
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Biologisk påväxt på putsade fasader
- 2007
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Ingår i: Bygg & teknik. - 0281-658X. ; :8, s. 42-43
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Vid Byggnadsmaterial LTH studerar vi biologisk påväxt på putsade fasader. Förutom mögel och bakterier som inte gör fotosyntes, så är samtliga andra organismer som växer på fasader fotosyntetiskt aktiva: alger, lavar och mossor. Vårt huvudintresse ligger i att beskriva samspelet mellan klimatet (främst temperatur och fukt) på fasaden, typ av fasad (isolering, putstjocklek, ytskikt, färgtyp etc.) och den biologiska aktiviteten.
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| 10. |
- Johansson, Sanne, et al.
(författare)
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Estimation of mould growth levels on rendered facades based on surface RH and surface temperature measurements
- 2010
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Ingår i: Building and Environment. - : Elsevier BV. - 1873-684X .- 0360-1323. ; 45, s. 1153-1160
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Tidskriftsartikel (refereegranskat)abstract
- Many façades made with thin rendering on thermal insulation have problems with biological growth. In this study surface temperature and surface RH were monitored over a 20 month period on test house façades with different constructions (thermal inertia), surface color and compass directions. This data were used to test three theoretical indices of biological growth with the aim of indicating the potential of mould growth on different types of rendered façades. The result show that thin renderings on thermal insulation have significantly higher surface humidities compared to façade constructions with higher thermal inertia and therefore have a higher potential for mould growth. The color is the most important factor for the surface humidity levels on south facing façades (on the northern hemisphere) as darker surfaces absorb more solar radiation and therefore have a higher average temperature. On a north facing façade the heat storage capability of the façade and its effect on the surface temperature is most import
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