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- Hydric behavior of earth materials and the effects of their stabilization with cement or lime: Study on repair mortars for historical rammed earth structuresPublication . Gomes, Maria; Diaz Gonçalves, Teresa; Faria, PaulinaEarthen building materials bear interesting environmental advantages and are the most appropriate to conserve historical earth constructions. To improve mechanical properties, these materials are often stabilized with cement or lime, but the impact of the stabilizers on the water transport properties, which are also critical, has been very rarely evaluated. The researchers have tested four earth-based repair mortars applied on three distinct and representative rammed earth surfaces. Three mortars are based on earth collected from rammed earth buildings in south of Portugal and the fourth mortar is based on a commercial clayish earth. The main objective of the work was over the commercial earth mortar, applied stabilized and not stabilized on the three rammed earth surfaces to repair, to assess the influence of the stabilizers. The other three earth mortars (not stabilized) were applied on each type of rammed earth, representing the repair only made with local materials. The four unstabilized earth materials depicted nonlinear dependence on t1/2 during capillary suction. This behavior was probably caused by clay swelling. Stabilization with any of the four tested binders enabled the linear dependence of t1/2 expected from Washburn's equation, probably because the swelling did not take place in this case. However, the stabilizers also significantly increased the capillary suction and the capillary porosity of the materials. This means that, in addition to increasing the carbon footprint, stabilizers, like cement and lime, have functional disadvantages that discourage their use in repair mortars for raw earth construction.
- Seismic resistance of earth construction in PortugalPublication . Gomes, Maria Idália; Lopes, Mário; Brito, Jorge deThis paper presents an assessment of the potential seismic performance of new earth construction in Portugal. Results of a parametric study on a properly designed rammed earth construction, considering several strengthening solutions, are presented and discussed. It is concluded that single storey houses can have acceptable seismic performance even in high seismicity areas, provided that the structure is adequately strengthened by reinforced concrete columns and beams. Improvement of the characteristics of the structural material (earth) may be necessary to reduce damage.