TESTING OF FOAM CONCRETE FOR DEFINITION OF LAYER INTERACTING WITH SUBSOIL IN GEOTECHNICAL APPLICATIONS

Abstract

Today’s production of foam concrete (FC) has become more suitable for various types of applications due to the usage of new additives and improved technology. One typical application of foam concrete in Europe is the creation of a sub-base layer of the floor of multi-storey buildings, where thermal and noise insulation functions are required. The main advantage of foam concrete production is its unlimited variety of desired properties, which must be properly balanced for a specific application and its interacting structure. Produced FC can have unit weight from 300 to 900 kg.m-3, compression strength from 0.4 to 12 MPa, elasticity modulus from 1200 to 2500 MPa and coefficient of thermal conductivity from 0.15 to 0.30 W.m-1K-1. Thanks to these properties, FC can be used for the construction of foundation slabs of passive houses, as a sub-base layer of industrial floors and as a filling material of narrow excavated shafts. As for concrete, reinforcement can improve tensile properties, but due to corrosion, iron bars or nets must be replaced by special material bars, nets, geogrids or geotextiles. For the mentioned type of structures and loading of FC layers, the importance of laboratory and in-situ testing is crucial. This article presents laboratory tests of one of the selected parameters, which is flexural strength of FC in various unit weights, and demonstrates a significant improvement of strength when non-woven geotextile and mesh type reinforcement was used. Use of geotextile at the bottom part of samples increased flexural strength from 30 to 60%, mesh reinforcement can have doubled basic flexural strength. Crack propagation with respect to time was also observed during tests in order to compare the results of reinforced FC with no reinforced layer.