Summary:

Forest communication network consists mainly of dirt roads. Technical problems with forest roads transport occur especially for these dirt roads which are constructed on cohesive topsoil. Lignite fly-ash may be utilized for successful stabilization of cohesive topsoil dirt roads. The pavements stabilized with fly-ash often perform unsatisfactorily under heavy loads and failures are noted as a result. The research described in this paper aimed at developing technical solution for reconstruction of road pavements constructed with admixture of fly-ash and fly-ashslug respectively. Bearing strength variability of fly-ash-soil and fly-ash-slag-soil mixes after failure and application of repair method were considered. Crushed then re-compacted with addition of stabilizer soil mixes as influenced by period and conditions of binding were tested. The stabilizers utilized for testing were both active fly-ash of lignite group IIIC and coke blast furnace slag. Two varieties of mixes were tested. These varieties were sandy clay mixed with addition of 14 % lignite fly-ash and the mixture of 10 % lignite fly-ash and 10% furnace slag respectively. The samples were crashed and re-compacted after 14- and 42-day period of curing in optimal and air-dump conditions. After sample curing deformation modules were measured with the utilization of VSS press. The deformation module measurement procedure was the basis for assessment of the mixtures suitability for reconstruction of forest road pavements after failure. Higher bearing performance especially after air-dump curing occurred for sole fly-ash addition mix varieties. The technical guidelines for reconstruction of road pavements with utilization of re-used crashed pavement materials were developed as well. The clayey pavements after failure may be stabilized again in fortnight period after construction. The repair procedure includes re-compaction and watering to achieve optimum moisture content. In addition, the optimum doses of stabilizer content for the reconstruction after longer than forthright period since the road construction were identified.