Rotafix Ltd.

Swansea, United Kingdom

Rotafix Ltd.

Swansea, United Kingdom
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Alam P.,Åbo Akademi University | Smedley D.,Rotafix Ltd.
International Wood Products Journal | Year: 2013

In this paper, are described a series of tests that have been undertaken to elucidate the effects of geometry, material properties and reinforcement location on the flexural properties of laminated veneer lumber. The fracture modes are found to be a function of the properties and location of the reinforcement and ultimately the strength of bonding between the components. The use of high modulus reinforcements is beneficial to enhancing the stiffness of laminated veneer lumber, whereas lower stiffness reinforcements are beneficial for the enhancement of strength. Lowered fractions of rod and plate reinforcement are as beneficial as higher fractions of rod and plate reinforcement in reinforcing timber, provided they are judiciously positioned in the timber and have a stable bond. © 2013 IWSc, the Wood Technology Society of the Institute of Materials, Minerals and Mining.


Roseley A.S.M.,University of Bath | Rojo E.,Complutense University of Madrid | Ansell M.P.,University of Bath | Smedley D.,Rotafix Ltd.
International Journal of Adhesion and Adhesives | Year: 2011

The technology for bonding in rods into timber structures for repair, reinforcement and forming primary connections is now well established. An ambient temperature cure adhesive is required for bonding on site and for overhead application thixotropic (shear thinning) characteristics are essential. At the same time bonded-in components may experience service temperatures of 50 °C or more, especially in roof spaces. It is commonly supposed that an adhesive with a glass transition temperature (Tg) below the in-service temperature will suffer from potential creep unless it is tightly cross-linked. In this paper the creep properties of three epoxy-based, thixotropic adhesives are investigated, which are less heavily cross-linked and possess Tg values between 30 and 60 °C. The adhesives are subjected to a creep load in tension within a Dynamic Mechanical Thermal Analyser used in static mode with a step-wise increase in temperature and a range of stress levels. A unique laminated shear specimen has been developed comprising an adhesive layer sandwiched by two thin wood veneers so that the adhesive layer can be stressed in shear. The results demonstrate that in the temperature range between Tg and Tg15 °C the thixotropic adhesives creep to a limit, behaving as classic viscoelastic polymers and above Tg15 °C they behave like rubbers with no creep. At high stresses and temperatures the adhesives eventually fail by rupture of the adhesive bonds. In conclusion, thixotropic adhesives are seen to possess a unique combination of physical and chemical properties, which enable them to function above Tg under creep load. © 2011 Elsevier Ltd. All rights reserved.


Ahmad Z.,University Technology of MARA | Ansell M.P.,University of Bath | Smedley D.,Rotafix Ltd
IOP Conference Series: Materials Science and Engineering | Year: 2011

This research work is concerned with in situ bonded-in timber connection using pultruded rod; where the manufacturing of such joint requires adhesive which can produce thick glue-lines and does not allow any use of pressure and heat. Four types of thixotropic (for ease application) and room temperature cured epoxy based were used namely CB10TSS (regarded as standards adhesive), Nanopox (modification of CB10TSS with addition of nanosilica), Albipox (modification of CB10TSS with addition of liquid rubber) and Timberset (an epoxy-based adhesive with addition of micro-size ceramic particles). The quality of the adhesive bonds was accessed using block shear test in accordance with ASTM D905. The bond strength depends on how good the adhesive wet the timber surface. Therefore the viscosity and contact angle was also measured. The nano- and microfiller additions increased the bond strength significantly. The viscosity correlates well with contact angle measurements where lower viscosities are associated with lower contact angles. However contact angle contradicts with measured strength and wettability.


Smedley D.,Rotafix Ltd. | Tiew J.,Business Development | Roseley A.,University of Bath | Ahmad Z.,University Technology of MARA | Ansell M.P.,University of Bath
World Conference on Timber Engineering 2012, WCTE 2012 | Year: 2012

In order to promote the use of indigenous hardwoods in construction in Malaysia the Malaysian Timber Industry Board (MTIB) commissioned a large-scale timber structure in Johor, designed by a local architect. The building is an exhibition hall with a floor area of 4, 686m2 and the form of the building is defined by three shell-shaped halls each comprised of 39 glue-laminated arches. Each arch is constructed from seven glue-laminated Keruing (Diptercarpaceae) elements connected by bonded-in steel rods using Rotafix thixotropic epoxy adhesive. The structure is supported on a raised concrete foundation and the moment-resisting framework is clad in 12mm Malaysian marine ply attached to rolled zinc sheet onto which is fixed Belian (Eusideroxylon zwageri) shingles from Sarawak. Glue-laminated timber (glulam) was manufactured close to the construction site using PRF adhesive and the glulam elements were assembled partially in the factory and partially on site using double-ended galvanised steel rods with 15mm solid steel plate separators. The bonded-in construction technique allowed connections to be hidden and assembly to proceed rapidly on site. The paper describes all aspects of the construction process in conditions of high humidity and rainfall and temperatures reaching 37°C. The structure has been instrumented at the joints in order to continuously assess temperature and any movement in the completed building and initial results of this assessment are reported.


Roseley A.,University of Bath | Ansell M.P.,University of Bath | Smedley D.,Rotafix Ltd. | Porter S.,University of Bath
World Conference on Timber Engineering 2012, WCTE 2012 | Year: 2012

Thixotropic, shear-thinning epoxy adhesives are the optimum choice for in situ assembly of timber structural joints under ambient conditions. These adhesives are suitable for injection into roof members and under bridge decks where gravity is a problem for conventional adhesives. However these ambient cure adhesives possess relatively low glass transition temperatures (Tg) and there are concerns associated with their stability under creep loads in conditions of high temperature and humidity. These concerns have been addressed in a paper presented at WCTE 2010 and in a subsequent journal publication where creep data generated in a dynamic mechanical thermal analyser (DMTA) has demonstrated the stability of these adhesives above Tg. In this paper results of creep tests on bonded-in connections, at a design shear stress of 2N/mm2 at the rod to adhesive interface, arc presented at temperatures of 20,30, 40 and SOX with levels of relative humidity (RH) of 65,75,85 and 95%. Creep experiments were conducted in a walk- in environmental chamber and creep was followed with laser displacement sensors. At intermediate combinations of temperature and RH level (e.g. 30°C, 75%RH), secondary creep was observed up to a limit. Under extreme conditions of high temperature and RH tertiary creep to failure occurred. Copyright © (2012) by WCTE 2012 Committee.


Ahmad Z.,University Technology of MARA | Ansell M.P.,University of Bath | Smedley D.,Rotafix Ltd | Md Tahir P.,University Putra Malaysia
Indian Journal of Engineering and Materials Sciences | Year: 2012

This paper reports the investigation made on the effect of nano and micro-particles additions on the thermal properties of epoxy based adhesives when exposed to different environmental conditions. The thermal behaviors of the adhesives are measured using dynamic mechanical thermal analysis (DMTA) following exposure to different temperatures and humidities which include temperatures of 20, 30 and 50°C, relative humidities of 65, 75 and 95% RH and soaking in water at 20°C and placed in the oven at 50°C. The dynamic thermal properties reported include storage modulus and loss modulus, the loss tangent and the glass transition temperature, Tg. For nano-and micro-particles filled adhesives, the glass transition temperature increases with increase in temperature even though the adhesives are subjected to high humidity and this is due to further cross-linking. The results show that room temperature cured epoxies are only partially cured at room temperature.


Ahmad Z.,University Technology of MARA | Ansell M.,University of Bath | Smedley D.,Rotafix Ltd | Tahir P.M.,University Putra Malaysia
Advanced Materials Research | Year: 2012

The mechanical properties of adhesive materials change over time, especially when they are subjected to long-term loading regimes. The significance of this is often overlooked at the design stage. When adhesives are subjected to a constant load, they may deform continuously, depending on temperature, humidity and cross-link density. This progressive deformation is called creep and will continue until rupture or yielding causes failure. It is imperative that reliable accelerated tests be developed to determine the long-term time-dependent performance of adhesives under different environmental conditions. The long-term creep behaviors of thixotropic and room temperature cure epoxy based adhesives reinforced with nano-particles specially formulated for insitu bonding of pultruded rod into timber for repair and strengthening of timber structures were investigated. In this study two epoxy-based adhesives with nano-particles (silica fume and rubber) addition were subjected to bending creep tests, in accelerated environments. Experimental data showed that the adhesives reinforced with nano-rubber particles showed less creep deformation than the unreinforced adhesives. © (2012) Trans Tech Publications, Switzerland.


Ahmad Z.,University Technology of MARA | Ansell M.,University of Bath | Smedley D.,Rotafix Ltd. | Tahir P.M.,University Putra Malaysia
Journal of Materials in Civil Engineering | Year: 2012

The mechanical properties of adhesive materials change over time, especially when they are subjected to long-term loadings. The significance of this is often overlooked at the design stage. When adhesives are subjected to a constant load, they may deform continuously, depending on temperature, humidity, and cross-link density. This progressive deformation is called creep. It is imperative that reliable accelerated tests be developed to determine the long-term time-dependent performance of adhesives under different environmental conditions. The long-term creep behavior of thixotropic and room temperature cure epoxy-based adhesives reinforced with nano particles were investigated. The adhesives in this investigation are formulated with the target of application for in situ bonding of pultruded rod into timber for the repair and strengthening of timber structures. In this study, two epoxy-based adhesives with added nano particles (silica fume and rubber) were subjected to bending creep tests in accelerated environments. Experimental data showed that the adhesives reinforced with nano rubber particles exhibited less creep deformation than the unreinforced ones. © 2012 American Society of Civil Engineers.


Pizzo B.,CNR Tree and Timber Institute | Smedley D.,Rotafix Ltd.
Construction and Building Materials | Year: 2015

The manuscript deals with the main characteristics of those adhesives normally used for the reinforcement of timber structures, achieved through site-applied bonding. The characteristics relate to a combination of chemical composition and product formulation. A section describes testing procedures for products to be used on site, as this aspect does not exist in current European standards. The principal issues associated with the use of those products, mainly relating to long-term duration, are considered, focusing more on the adhesive characteristics rather than to the wood substrate properties. Finally, possible challenges are introduced in order to stimulate research in this field. © 2015 Elsevier Ltd. All rights reserved.

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