The traditional brick-firing process, characterized by high energy consumption and significant pollutant emissions, poses environmental challenges that require innovative solutions. This research addresses these challenges by reducing natural resource usage, energy consumption, and gas emissions through the production of mudbricks in which 5-10 wt% of the clayey soil is replaced by tea grounds. This approach uses waste products and efficient manufacturing techniques aimed at achieving zero carbon emissions. The meticulous selection and processing of organic waste draws inspiration from ancient practices in which plant residues were used to enhance the durability and performance of building materials. This study demonstrates that the inclusion of 10 wt% tea grounds enhances the workability of the clay by 15 %, as the lignin and hydrogen bonds in the tea rearrange the molecules, hardening the material in a similar way to the starch retrogradation process in bread. These mud- bricks provide a 25 % improvement in thermal insulation compared to standard mudbricks, potentially reducing reliance on energy-intensive heating and cooling systems by up to 20 %. It also show a 30 % enhancement in impermeability relative to mudbricks made without tea grounds, with a 10 % increase in compressive strength.

Unpaved roads are essential for transportation infrastructure, particularly for forest industry. Traditionally, unpaved roads are composed of layers using local soils. Poor local soils need to be replaced with gravel, crushed aggregate, or amixture of materials. Due to traffic and weather conditions, unpaved roads require frequent maintenance and repair. To reduce the amount of quality materials and the frequency of maintenance operations, reinforcements can be used (synthetic or natural). This paper focussed on the behaviour of a fine soil reinforced with natural fibres from the forest value chain (pine needles), to assess their use on unpaved forest roads. Cyclic CBR tests were carried out to assess the resilient response of the soil (unreinforced and reinforced); the tests included initial monotonic loading, followed by cyclic loading. The force-penetration response and CBR value improved with the inclusion of pine needles; the best response corresponded to a percentage of incorporation of 1% (mass). For the cyclic loading phase, the permanent displacement decreased with the number of cycles, approaching a resilient response. The reinforcement with pine needles led to an improved elastic response, represented by an equivalent stiffness modulus. The best behaviour was, again, obtained for a percentage of incorporation of 1% (mass). The addition of fibres led to reduced displacements during the test, relatively to the unreinforced soil. The results showed that for unpaved forest roads, where the investment in soil characterisation is often very limited, cyclic CBR tests can be a promising approach in obtaining design parameters.