Modification and stabilization of road structure unbound layers has extensively been studied both at laboratory and field for decades. The most commonly used binders for soil modification and stabilization are cement and quicklime (CaO), but alternative pozzolans and their mixtures are of economical, technical and environmental interest. This study presents soil stabilization with wood fly ash (WFA) at laboratory. Natural sand (Sa), Sa mixtures with 10% and 20% WFA were compacted at optimal water content according to Standard Proctor test LVS EN 13286-2:2012, and California bearing ratio (CBR) tested according to LVS EN 13286-47:2012 for cured samples after 96 hours immersed in water with 2 kg surcharge and after 7 days sealed simultaneously. At the same time also Immediate bearing index was determined for natural soil and their mixture with 10% WFA. Results showed 3.79 times enhancement in CBR values Sa after 7 days curing, justifying that WFA is valuable material for hydraulically bound mixtures.

No abstract

The paper discusses the EU directive and the rules for disposing of sewage treatment plant (STP) sludge and storage conditions that have been adopted, it does not fully cover possible use of STP sludge for industrial purposes. One of the ways of reducing amount of sludge is treatment of this waste for further application as additive or raw material for producing building materials. Manufacturing of porous ceramic materials from local raw materials (e.g. clay) using water treatment sludge and sawdust as combustible filler is possible. In order to reduce the sludge humidity, freezing method was used, where sludge give away more loose water in the process of thawing. It was proved during the research that sewage treatment plant sludge can be used to make porous ceramic materials.

No abstract