Appraisal of Anchor Arrangement and Size On Sand-Geogrid Interaction In Direct Shear

Soil – reinforcement interaction is a major factor in the analysis and design of reinforced earth structures. In current research the effects of attaching elements of different size and numbers as anchors on enhancement of interaction at soil - geogrid interface under direct shear conditions were studied. Poorly and well graded sands (SC & Sf), a high density polyethylene geogrid, anchors with three different size and numbers (layouts) and clamping length of 2cm from shear surface were used. Samples were prepared dry at a relative density of 80% in a 30×30cm direct shear box and subjected to normal pressures of 12.5, 25 and 50kPa with the shear load applied at a rate of 1mm/min. Results of the assessment show that anchored geogrids improve shear resistance at interface mainly due to mobilization of passive soil resistance that is significantly influenced by the magnitude of the normal pressure and the number and size of anchors. Interaction enhancements achieved varied between a minimum of 8% and a maximum of 42%.

Hygro-Thermal, Hydric, and Mechanical Properties of Fibre and Aggregate-Reinforced Earth Plasters

Earth plasters have been used as a protective coating for buildings but, due to their low strength and low resistance to weather conditions, they have been abandoned for more resistant materials which in return lack vapour permeability. Earth plasters have usually a high moisture sorption rate, and their water vapour permeability is high, allowing the transfer of humidity through the material. These properties make them an interesting material for controlling vapour movement in humid rooms. Improving their strength can be done by adding aggregates and/or fibres, but the real impact of using one type or another of fibres or aggregate is unknown. This research aims to understand the consequence of the choice of fibre or sand in the improvement of strength of plasters and the conservation of the plaster hygro-thermal properties. Properties of plasters using alternative fibres or aggregates such as wool, cow hair, pine needles, sand aimed for concrete mixes, or not properly graded sand have been compared to plasters made more traditionally with chaff fibres and mason sand.