Change search
Link to record
Permanent link

Direct link
Publications (10 of 35) Show all publications
Blomqvist, L., Sterley, M. & Ormarsson, S. (2019). Impact of surface pressure on the shape stability of laminated veneer products. In: Maria Fredriksson (Ed.), Proceedings of the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering WSE 2019: . Paper presented at Northern European network for wood science and engineering (WSE), 9-10 October, 2019, Lund, Sweden (pp. 164-166). Lund: Lund University
Open this publication in new window or tab >>Impact of surface pressure on the shape stability of laminated veneer products
2019 (English)In: Proceedings of the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering WSE 2019 / [ed] Maria Fredriksson, Lund: Lund University , 2019, p. 164-166Conference paper, Oral presentation with published abstract (Other academic)
Place, publisher, year, edition, pages
Lund: Lund University, 2019
National Category
Wood Science
Identifiers
urn:nbn:se:ri:diva-40519 (URN)
Conference
Northern European network for wood science and engineering (WSE), 9-10 October, 2019, Lund, Sweden
Funder
Vinnova, 2019-00780Swedish Energy Agency, 2019-00780Swedish Research Council Formas, 2019-00780
Note

Vinnova 2019-00780. Energimyndigheten 2019-00780. Forskningsrådet Formas 2019-00780.

Available from: 2019-10-11 Created: 2019-10-11 Last updated: 2023-03-13Bibliographically approved
Ong, C. B., Chang, W. S., Ansell, M. P., Brandon, D., Sterley, M. & Walker, P. (2018). Bench-scale fire tests of Dark Red Meranti and Spruce finger joints in tension. Construction and Building Materials, 168, 257-265
Open this publication in new window or tab >>Bench-scale fire tests of Dark Red Meranti and Spruce finger joints in tension
Show others...
2018 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 168, p. 257-265Article in journal (Refereed) Published
Abstract [en]

This study investigates the secondary failure of Malaysian Dark Red Meranti (Shorea spp.) and Spruce (Picea abies) finger joints in a glulam beam in a fire test using a bench-scale test set-up. Secondary failure is the occurrence of failure of the bond lines due to fire and the falling off of the outermost tension layers, exposing the uncharred inner layers to a sudden increase of fire intensity. The lack of published work and the difficulties in describing the behaviour of the finger joints after the secondary failure in a full-scale fire test has identified the need for a simple bench-scale method, incorporating the conditions of the standard fire test. This paper focusses on the performance of the finger joints which together with other defects such as knots and splits are generally the weakest component in the glulam beam. The finger joints were bonded with structural adhesives, specifically phenol resorcinol formaldehyde (PRF) and polyurethane (PUR). They were tested in tension to imitate the failure of finger joints on the tension side of a standard fire test of a glulam beam. Constant heat flux was introduced to the finger-jointed specimens to replicate the secondary failure of a glulam beam in the standard fire test. The results of this study indicate a relationship between the charring rate and density of the specimens, with higher density Dark Red Meranti showing lower charring rate compared to the lower density Spruce specimens. Factors such as constant heat flux as opposed to the time-increasing heat flux exposure and specimen size influenced the charring rate of the specimens. The char rate was measured at the early stages of the fire test, which is known to have higher values since the build-up of the charred layers was not sufficiently substantial to protect the inner unburnt wood. Overall, the bench-scale fire test set-up was able to differentiate the fire performance of the adhesives, with PRF showing better fire performance compared to the specimens finger-jointed with PUR adhesive. In addition, tensile tests at ambient temperature showed no significant difference in tensile strength between finger joints bonded with different adhesives for the same wood species. The tensile strengths of the finger joints bonded with different adhesives were influenced by the temperature profile through the joint. The proposed bench-scale fire test was used to compare the quality of the adhesives in a fire situation, specifically with respect to secondary failure. The PRF was selected as the reference adhesive.

Keywords
Bench-scale fire test, Charring rate, Dark Red Meranti (Shoreaspp.), Finger joints, Heat flux, Phenol resorcinol formaldehyde, Polyurethane adhesive, Secondary failure, Spruce (Picea abies), Tensile strength, Adhesives, Fires, Flammability testing, Formaldehyde, Phenols, Plants (botany), Polyurethanes, Tensile testing, Wooden beams and girders, Charring rates, Fire tests, Phenol resorcinol formaldehydes, Picea abies, Polyurethane adhesives
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33426 (URN)10.1016/j.conbuildmat.2018.02.041 (DOI)2-s2.0-85042515822 (Scopus ID)
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2023-05-16Bibliographically approved
Sterley, M., Noren, J., Liblik, J., Brandon, D. & Just, A. (2018). Small-scale test method for the fire behaviour of woodadhesive bonds in CLT. In: Book of abstracts of the final conference COST FP1404”Fire Safe Use of Bio-Based Building Products”: . Paper presented at COST FP 1404 Final Conference.
Open this publication in new window or tab >>Small-scale test method for the fire behaviour of woodadhesive bonds in CLT
Show others...
2018 (English)In: Book of abstracts of the final conference COST FP1404”Fire Safe Use of Bio-Based Building Products”, 2018Conference paper, Published paper (Other academic)
Abstract [en]

There is an increasing use of cross laminated timber (CLT) in the building sector. CLT is a wood panel product made from layers of solid lumber boards. Each layer of boards is oriented perpendicular to adjacent layers and glued on the wide faces of each board. It has been recognised that different adhesive systems have different behaviour in fire; especially that delamination behaviour of CLT can be avoided by choosing a suitable adhesive system. The best method for evaluation of the delamination is a full‐scale fire test, but considering the high costs of such tests, it is of the utmost importance to develop small‐scale methods for evaluating the adhesive bond properties in fire. The intention is that such small‐scale methods should provide the same results as full‐scale tests. A new, smaller scale method for classifying adhesives with respect to  fire properties would also simplify  the planning of  full scale  tests. Previous  tested small‐scale method for evaluation of finger joints is presented in (1).  In this study, a small‐scale fire test methodology for evaluation of CLT adhesive bond performance in  fire  is  introduced  (2).  The  aim  was  to  demonstrate  an  easy  tool  to  distinguish  between  fire resistant adhesive bonds and non‐fire‐resistant bonds, especially with respect to delamination. The cone heater of a cone calorimeter was used to carry out the tests. Cone calorimeter in accordance with ISO 5660 is one of the most widely used bench‐scale instrument in fire research. This small‐scale  device  has  several  advantages  over  larger‐scale  tests  thanks  to  its  fast,  simple  and  cost‐efficient manner to investigate basic material properties.  

Keywords
cross laminated timber, adhesives, delamination, fire performance, small‐scale test
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36538 (URN)
Conference
COST FP 1404 Final Conference
Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2023-05-16Bibliographically approved
Blomqvist, L., Sterley, M., Sandberg, D. & Johansson, J. (2015). The effect of veneer modification on the bond-line strength in laminated veneer products (ed.). Pro Ligno, 11(4), 43-49
Open this publication in new window or tab >>The effect of veneer modification on the bond-line strength in laminated veneer products
2015 (English)In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 43-49Article in journal (Refereed) Published
Abstract [en]

A major problem in the manufacture of three-dimensional laminated veneer products (LVP) is damage due to stretching and/or buckling of the veneer. To reduce or eliminate this problem, veneer densification or adding a strengthening layer to the veneer can be an alternative. To study how veneer modification influences the veneer-to-adhesive bond strength, three methods of modification were studied in relation to an unmodified reference veneer: (1) densified veneer, (2) veneer pre-bonded with paper and hot melt adhesive (HMA), (3) veneer pre-bonded with non-woven polypropylene (NW) fabric glued to the veneer (a) with a urea formaldehyde (UF) adhesive, (b) with a mixture of UF and polyvinyl acetate (PVAc) adhesive, and (c) with a PVAc adhesive. Densification, pre-bonding with paper, and NW with UF/PVAc adhesive mixture resulted in no or only a slight decrease in strength of the bond-line compared to the reference. NW glued with UF or PVAc adhesive showed a considerable reduction in the strength of the bond-line. The climatic cycling had no significant influence on the bond strength.

Keywords
densification, HMA, pre-bonding, PVAc, strengthening, THM processing, UF, wood
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-6920 (URN)30861 (Local ID)30861 (Archive number)30861 (OAI)
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2023-03-31Bibliographically approved
Blomqvist, L., Sterley, M., Sandberg, D. & Johansson, J. (2014). The influence of veneer modification on adhesive bond strength (ed.). In: Proceedings of 10th Meeting of the Northern European Network for Wood Science & Engineering (WSE 2014).: . Paper presented at Proceedings of 10th Meeting of the Northern European Network for Wood Science & Engineering (WSE 2014). Edited by Peter Wilson. Edinburgh Napier University
Open this publication in new window or tab >>The influence of veneer modification on adhesive bond strength
2014 (English)In: Proceedings of 10th Meeting of the Northern European Network for Wood Science & Engineering (WSE 2014)., Edinburgh Napier University , 2014, , p. 150-155Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Edinburgh Napier University, 2014. p. 150-155
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-12378 (URN)16701 (Local ID)16701 (Archive number)16701 (OAI)
Conference
Proceedings of 10th Meeting of the Northern European Network for Wood Science & Engineering (WSE 2014). Edited by Peter Wilson
Available from: 2016-09-13 Created: 2016-09-13 Last updated: 2023-03-31Bibliographically approved
Sterley, M., Serrano, E. & Enquist, B. (2013). Fracture characterisation of green-glued polyurethane adhesive bonds in Mode I (ed.). Materials and Structures, 46(3), 421-434
Open this publication in new window or tab >>Fracture characterisation of green-glued polyurethane adhesive bonds in Mode I
2013 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 3, p. 421-434Article in journal (Refereed) Published
Abstract [en]

Unseasoned (green) spruce timber side boards of size 25 × 120 × 600 mm were flatwiseglued with a one-component PUR adhesive. Glued pairs of boards were then kiln-dried to 12 % moisture content. A special small-scale specimen for testing the fracture properties of the adhesive bond in Mode I was developed in order to evaluate the adhesive bond properties. The complete force versus deformation curve, including both the ascending and the descending parts, could be obtained with these small-scale specimens, enabling the strength and fracture energy of the bond line to be calculated. In addition, the fractured specimens were examined by scanning electron microscope. Results show that both the tensile strength and the fracture energy of the green glued PUR adhesive bonds were equal to those of the dry glued bonds. The methodology developed and used in the present study gives new possibilities for analysis of the mechanical behaviour of wood adhesive bonds, and particularly of their brittleness and its correlation with the type of fracture path. This is in sharp contrast to the use of standardised test methods (e.g. EN 302, ASTM D905) with specimens having relatively large glued areas. Using such types of specimens, it is not possible to obtain the complete force versus deformation response of the bond. In addition, when using such test methods, failure takes place in the wood or in the fibres near the bond, thus making it impossible to obtain detailed information about the bond line characteristics.

Keywords
Bond line, Ductility, Fracture, Green gluing, Polyurethane, Wood adhesive
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-6444 (URN)10.1617/s11527-012-9911-5 (DOI)2-s2.0-84893644705 (Scopus ID)14541 (Local ID)14541 (Archive number)14541 (OAI)
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2020-12-01Bibliographically approved
Blyberg, L., Serrano, E., Enquist, B. & Sterley, M. (2012). Adhesive joints for structural timber/glass applications: Experimental testing and evaluation methods (ed.). International Journal of Adhesion and Adhesives, 35, 76-87
Open this publication in new window or tab >>Adhesive joints for structural timber/glass applications: Experimental testing and evaluation methods
2012 (English)In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 35, p. 76-87Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-6364 (URN)14542 (Local ID)14542 (Archive number)14542 (OAI)
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2020-12-01Bibliographically approved
Sterley, M., Trey, S., Lundevall, Å. & Olsson, S. (2012). Influence of cure conditions on the properties of a one-compenent moisture-cured polyurethane adhesive in the context of green gluing of wood (ed.). Journal of Applied Polymer Science, 126(S1), E297-E304
Open this publication in new window or tab >>Influence of cure conditions on the properties of a one-compenent moisture-cured polyurethane adhesive in the context of green gluing of wood
2012 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 126, no S1, p. E297-E304Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-6340 (URN)13967 (Local ID)13967 (Archive number)13967 (OAI)
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2023-06-08Bibliographically approved
Vikberg, T., Hansson, L. & Sterley, M. (2012). Moisture movements during drying of green glued glulam beams from Norway spruce sideboards. In: : . Paper presented at International IUFRO Wood Drying Conference : 30/07/2012 - 03/08/2012.
Open this publication in new window or tab >>Moisture movements during drying of green glued glulam beams from Norway spruce sideboards
2012 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Form defects such as cup, crook, twist and bow, often causes low volumetric and economical yield in dried sideboards of Norway spruce. The high stiffness and density of sideboards, however, make them attractive to use as structural timber. The green gluing process i.e. gluing of unseasoned timber (with the subsequent drying) can make gluing of side boards efficient and can overcome the difficulties in utilization of side boards for structural applications.In present work, a study where computed tomography was used to monitor the drying process of a green glued glulam beam is presented. The beam had a dimension in cross-section of approximately 105×235 mm2 and consisted of eleven sideboards, planed and flat wise glued together with a 1-component polyurethane adhesive. After curing, and prior to drying, the beam was split into two halves, of approximate size of 50×235 mm2.The drying took place in a small drying kiln and computed tomography scanning was done every second hour throughout the drying process to get the density distribution in the beam. When the drying was finished the temperature in the kiln was increased to 103°C and kept for 24 hours, as to get a dry density reference. By use of an algorithm for subtracting the dry density, the moisture evaporation throughout the drying process could be estimated. Despite the harsh drying conditions, with a wet bulb depression of 10°C already from the start of the drying process, no formation of cracks or other quality problems could be seen in the process. Neither could any moisture gradient from the outer to the inner boards be detected.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ri:diva-37852 (URN)98ca122c-372e-4b78-8970-cb7865dfa381 (Local ID)98ca122c-372e-4b78-8970-cb7865dfa381 (Archive number)98ca122c-372e-4b78-8970-cb7865dfa381 (OAI)
Conference
International IUFRO Wood Drying Conference : 30/07/2012 - 03/08/2012
Available from: 2016-09-30 Created: 2019-02-28 Last updated: 2023-06-08Bibliographically approved
Sterley, M. & Gustafsson, P. J. (2012). Shear fracture characterization of green-glued polyurethane wood adhesive bonds at various moisture and gluing conditions (ed.). Wood Material Science & Engineering, 7(2), 93-100
Open this publication in new window or tab >>Shear fracture characterization of green-glued polyurethane wood adhesive bonds at various moisture and gluing conditions
2012 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 7, no 2, p. 93-100Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-6366 (URN)14565 (Local ID)14565 (Archive number)14565 (OAI)
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2020-12-01Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7432-2550

Search in DiVA

Show all publications