Tagungsbeiträge

The refugee crisis has shown that the fast construction of medium-term homes in crisis regions is a major challenge. Particularly in the middle east the lacks of suitable construction sands, energy, water and infrastructure leads to the requirement of novel production methods for building blocks. In the present work, methods for the application of local sands in polymer concrete bricks were developed. The basic conditions and requirements for a concept of a mobile production plant for bricks were analyzed. A layout consisting of standard shipping containers was chosen. A production chain with defined mixtures of cleaned quartz sands, rock flour and polyester resin could be configured to manifacture bricks containing 87 % filling material in an inline-process with a cycle time of less than one hour. The adaption for natural desert sands started with an analysis of variying temperatures and humidity. Sands from multiple countries around the earth were analyzed in rheometer experiments. It could be shown that the curing times depend on the filling sand, preventing a simplified implementation into the established processes. The desert sands were characterized for differences in particle size, particle shape, specific heat capacity and chemical composition. Particle analysis showed that a larger angle of repose leads to fewer void content in the brick. The minor differences of specific heat were not sufficient to inhibit the self-acceleration of the exothermic resin reaction. The divergences of the chemical composition were identified as the most important obstacle. The premise is that available sands should be used. Thus the only possibility was to adapt the mixture of the polyester resin to the filling material. The resin is inhibited to ensure adequate time for wetting the sand. MEKP hardeners were combined with cobalt and cobalt-amine accelerators. The analysis showed that especially cobalt-amine accelerators lead to the pursued cycle time of under 60 minutes. On the other hand a correlation between the metallic elements in the sand and the viscosity increase of the polymer concrete could be obtained. These elements impede the effect of the cobalt complex in the accelerator. Particular ratios of hardener and accelerator for every sand must be applied. A user-friendly fast test was developed that can be performed on site. So the suitability of the resin and the filling material is ensured. The mechanical properties of desert sand and quartz sand polymer concrete were measured in standard devices. The results show that the strength of common polymer concrete can almost be achieved. Desert sand bricks could be used even to build two-storey houses. Based on the examinations a mold concept for the establishment of a series process was derived. The comparatively high shrinkage of the polyester resin and the friction of the sand were taken into account to design a manufacturing mold with a reusable core. It could be shown that the application of desert sands for the production of building blocks is possible. The impacting factors were examined and a concept for a process adapted to the natural resources was established. A mobile production plant can now be built to help diminish the harm of refugees in crisis regions.