The first of a group of five experimental houses has been erected on the campus of the Technical University of Kaiserslautern. Various high-performance building materials are being subjected to a practical test as part of the so-called Small House Village Project.
Small House I is intended to test out the practical possibilities for the use of infra-lightweight concrete, and is a co-operative inter-disciplinary
project, directed by the Kaiserslautern Professors Wolfgang Breit, Jürgen Schnell and Joachim Schulze. Infra-lightweight concrete is understood as
being concrete with a specific weight below that of lightweight concrete. The concrete used in Small House 1 has a dry bulk density of less than
700 kg per cubic metre and uses hot dip galvanized reinforcing steel. The aim of the project is to find a new type of concrete mix and put it to practical use in making high-insulation concrete usable as exposed concrete in external areas subjected to weathering.
In contrast to the conventional multi-layer construction consisting of a load-bearing structure, a fill layer such as rendering or other wall finishes, Small House 1 was constructed as a single shell. The monolithic walls of the experimental building, with integrated core insulation, offer advantages in relation to a reduction in the construction period, the possibility of thermal storage capacity, and an uncomplicated structure open to vapour diffusion. As well as outstanding heat insulation properties at low external temperatures, high-insulation lightweight concrete can also provide very good protection from summer heat. Moreover, if they take the form of exposed concrete, solid walls made from lightweight concrete can provide new design options. Their surfaces differ from typical rendered facades, which are usually made up of composite thermal insulation systems.
The technical specifications for the infra-lightweight concrete used were demanding. The bulk density must be as low as possible, but nevertheless there are demanding requirements to be fulfilled with regard to the strength, the water penetration behaviour and the corrosion prevention. So when it came to the reinforcing steel, it was decided to utilise hot dip galvanized reinforcing steel. Even at low pH values, up to pH 5, hot dip galvanizing ensures adequate corrosion protection for the reinforcement. The onset of reinforcement corrosion can thus be excluded for long periods of time.