Use of Greenlandic resources for the production of bricks

Abstract

The housing situation in Greenland is critical. In 2012, approximately 20 % of the housing was dilapidated, and due to an increasing population in the larger towns, there is currently an urgent need for the construction of new homes. Today, materials used in the Greenlandic construction industry are mostly imported, and due to high import costs, it is therefore important to investigate the potential for local construction material production. The aim of this PhD-study was to identify and test suitable raw materials for such local production. Clay-based bricks were chosen due to several reasons: • Bricks, in general, are durable and fire-resistant materials, which possess good thermal and acoustic properties. In the harsh Arctic to sub-arctic climate of Greenland, which places high demands on construction materials, especially the thermal properties and durability of bricks are desirable characteristics. • Bricks are heterogeneous materials, which can accommodate materials of wide ranging compositions without losing their technical properties. For this reason, the ceramic industry has been identified as one of the major recipients for waste in the future. Wastes of different types are becoming an increasing environmental and logistical problem worldwide, and their recycling has therefore received much attention. The protection of the vulnerable Arctic nature is a great concern and waste management by ceramic incorporation should therefore be investigated. • Historically, masonry constructions (including bricks) were dismissed in Greenland in the early 1950’s, due to low frost resistance of the mortar. Although this dismissal might have been technically warranted at the time, the ceramic industry has since experienced extensive development, and today clay-based brick constructions can therefore be designed to withstand the Arctic climate conditions. • In 2006, the Arctic Technology Centre, DTU Civil Engineering in collaboration with the Danish brickworks Petersen Tegl conducted a large scale brick pilot-production from Greenlandic glaciogene marine clay from an occurrence near the town of Kangerlussuaq. The bricks were used for the construction of a house in Sisimiut, Greenland and it was established that the Kangerlussuaq occurrence was suitable as raw material for bricks. Large occurrences of fine-grained glaciogene marine sediments are, however, found throughout Greenland and the knowledge gaps identified and covered by this study are therefore: • to establish the characteristics, similarities and variations of Greenlandic marine sediment occurrences in general, in respect to potential use as brick clays. • to describe how the variations in the sediments influence the properties of produced bricks. • to investigate the link between raw material characteristics, processing details and resulting technical characteristics of bricks produced from a representative sediment occurrence. Furthermore, in relation to the potential for incorporating waste in the produced bricks, the following knowledge gap was identified and covered: • to identify and conduct initial testing on waste types, which could be of interest in Greenlandic brick production. The waste types investigated in this study were municipal solid waste incineration (MSWI) ashes and tailings from the mining industry. The major conclusions obtained from this study were: • The Greenlandic marine sediments have very similar grain size distributions, mineralogy and major element chemistry. Furthermore, these properties are comparable to those of North American and North Scandinavian marine clays. • Bricks with acceptable properties of e.g. compression strength, open porosity and water absorption can be produced from the sediments. However, the properties largely depend on the processing of the sediment, e.g. firing procedure and initial treatments. • Addition of waste materials, such as the investigated bottom ash and mine tailings, generally improve the technical properties of the bricks, e.g. lowers the open porosity and increases the density. However, increased leaching of heavy metals was observed after firing, which could pose an environmental concern and requires further investigation.