Impact of manufacturing imperfections and surface defects on stress–strain behaviour of flexible adhesive joints

Abstract

Precise adherence to the manufacturer’s instructions and requirements plays an important role in various installation processes. The presented paper deals with the evaluation of the effect of manufacturing imperfections and surface defects on the failure behaviour of flexible adhesive intended for façade application. The failure to comply with the accepted procedures is more common in construction practice than in other sectors of the industry, mostly due to the surrounding conditions and lack of trained supervision. Unfortunately, this may lead to premature failure of adhesively bonded joints and a considerable shortening of the service life of the entire construction. To determine the potential of the risk, five types of artificially applied (a) manufacturing imperfections: (1) application on wet adhesion promoter, (2) application after the expiry of the laying-time, (3) curing of samples at +1℃ (b) surface defects: (4) application on a wet substrate and (5) application on a dirty surface, were suggested. Moreover, the Taguchi L32 orthogonal array design was used to arrange the test setup of all possible combinations. The 1 K polyurethane adhesive was applied in tensile butt joints and single-lap shear joints composed of aluminium alloy and thermally modified wood substrates. The obtained results confirmed that non-observance of the required manufacturing techniques and recommended procedures can have a negative impact on the decrease of the adhesively bonded joint strength and deformation behaviour. Surprisingly, the most critical was not the combination of all suggested types of imperfections and defects. The performed one-way ANOVA revealed that the most perilous was the combination of types 2 and 4 in the tensile test with 77% joint strength reduction. In the shear test, the most critical was the combination of all types of imperfection and defects which led also to a 77% drop of shear strength.

The Development of Controlled Orientation of Fibres in SFRC

“…The effect is stronger at a higher flow rate or when the rate may act on the fibre for a longer period of time (i.e., lower viscosity or longer flow time). Thanks to this model, the shape and geometry of the form, the method of filling and the viscosity significantly affect the alignment of the fibres [ 32 , 33 ].…”

Evaluation of Construction Site Noise to Allow the Optimisation of Construction Processes and Construction Machinery Selection

“…In the Czech Republic, noise limit values are compared only for direct operation of work machines and for persons in residential buildings in the vicinity of the construction site, not for construction managers. Future analyses should also focus on the use of soundproof barriers and covers for construction machinery [12,15,24,35,38] and multicriteria optimization of own construction schedules [27,39]. There are existing studies on the layout of the construction site in connection with the main construction machines [3,4,[40][41][42][43], but very little account is taken of machine noise in the optimization [2,5,44].…”

“…There are existing studies on the layout of the construction site in connection with the main construction machines [3,4,[40][41][42][43], but very little account is taken of machine noise in the optimization [2,5,44]. It is possible to continue the research of noise from construction and for the transmission inside the building and the subsequent propagation of noise and vibration in the indoor environment of buildings [23,24,[45][46][47][48].…”

“…However, it is also possible to measure values, for example inside buildings and to evaluate the attenuation by the perimeter cladding and other structures. Field measurements are not covered in this paper, but many studies are available [12,[21][22][23][24][25][26][27][28][29]. Figure 2 presents a graphically processed methodology of the possibility of access of the contractor to solve the noise from construction.…”

“…However, it is also possible to measure values, for example inside buildings and to evaluate the attenuation by the perimeter cladding and other structures. Field measurements are not covered in this paper, but many studies are available [12,[21][22][23][24][25][26][27][28][29].…”