The Use of Waste in Clay Materials

Abstract

This thesis aims to recreate a material similar to lightweight concrete with poured earth instead of concrete. Poured earth has a lower carbon dioxide footprint thus it is more sustainable. In the beginning, the beads replace 10 % of the sand. The coagulant, ratio of the dispersant and the coagulant and the mixing time are chosen based on the results from mixing the material and the slump tests. The final mixture needs to be pourable and allow a homogeneous distribution of the EPS beads. Calcium hydroxide at ratio 1:1.75 and a mixing time of three minutes are chosen.

In an attempt to increase the compressive strength of this material (0.85 MPa), the beads are coated with non-ionic surfactants. Unfortunately, the opposite happens and the compressive strength is reduced by half. Thus, for the following tests, no coating is used. The volume fraction of the expanded polystyrene is further increased to check if the recipe chosen in the beginning still works. The thermal conductivity is measured on the samples with increasing EPS values to document the changes. The thermal conductivity of poured earth without any expanded polystyrene is 1.48 W/(m·K) and it is reduced to 0.50 W/(m·K) when 50 % are added. At the end, the CO2 impact of the mixture is calculated and compared to poured earth with various amounts of EPS and conventional concrete.