Johan Van Ackeren

Tensile behaviour of different high performance fibre reinforced cements

ABSTRACT This paper aims to get insight into the physical significance of the results obtained from curve fitting of a stochastic cracking model on experimental tensile stress-strain data of cementitious composites which are uniaxially reinforced with continuous fibre bundles of different kinds, such as glass, basalt, carbon, polyethylene and polyvinyl alcohol fibres. An experimental test program is performed on the different composites containing typically 20% in volume of fibres, as well on the fibre bundles themselves. A short introduction is given to the theory behind the stochastic cracking model, based on a Weibull distribution of the matrix cracking stress, which is used for modelling the experimental results. The obtained tensile stress–strain curves are analysed by means of curve fitting and an attempt is made to draw conclusions on the physical meaning of these results. The experimental results of tensile tests on specimens with an inorganic phosphate cement matrix containing the different fibre types, revealed a wide range of mechanical behaviour: carbon fibres result in a very stiff material, PE fibres in a very strong material, while the use of PVA fibres results in a very flexible and ductile composite. Curve fitting of the stochastic cracking model on the experimental data was successfully performed, leading to the identification of the Weibull model parameters. The reference cracking strength was found to be much higher than the mean matrix cracking strength. An interpretation, based on the phenomenon of crack suppression, is given for these high values compared to those found in literature for cement composites.

Performance of Sacrificial Cladding Structure Made of Empty Recyclable Metal Beverage Cans under Large-Scale Air Blast Load

This paper demonstrates the use of recyclable waste products such as typical empty metal beverage cans available in the market for the protection of civil engineering structures from an explosive load. The sacrificial cladding structure was made of empty recyclable beverage cans and sandwich composite skin plates. To measure the protection efficiency of these structures large-scale air blast experiments have been conducted. To create a perfect plane shock wave the concept of shock tube was used using concrete sewage pipes. The experimental and numerical crushing performance of the empty beverage cans is studied in detail. Finally, this study concludes that the waste empty metal cans can be considered as a potential member to protect civil engineering structures from the air blast load.

Impact Study of Textile Reinforced Cementitious Materials: Test Method and Preliminary Results

In building engineering, impact loading and other accidental loads are mostly taken into consideration by measures on the structural level rather than on the material level, the latter one is even seldom explored. Textile reinforced Cements (TRCs) is a composite material group which is still in full development. Its potential to dissipate a significant amount of energy under low velocity impact loading was already indicated in a preliminary study. In the present study, the low velocity impact behaviour of TRC laminates is investigated more closely and this by means of an instrumented drop weight test. This study has shown the ability of the used test method to identify damage mechanisms underlying the energy absorption under low velocity impact loading in TRC composite laminates.