Repair mortars for rammed earth constructions

Rammed earth buildings, with resistant and monolithic walls, often have constructive pathology. A survey on more than thirty rammed earth buildings, mainly in Alentejo region (South Portugal), was conducted. As a result, it was found that surface deterioration of the walls seemed to be an usual problem. Many rammed earth buildings are deteriorating due to lack of maintenance and rehabilitation, but also due to incorrect repairs. Several of them were repaired by applying cement-based mortars in the attempt to overcome the general decay, of the walls that could or not be deep. This paper presents the most common pathology: problems due to water ingress and low drying capacity; salt transport and contamination; construction technology like voids left from the formworks; biological attack; different mechanical behaviour between the walls and the repair mortars - mechanical incompatibility. An intervention methodology for repair the degradation of exterior surface, including anomalies diagnosis and application of these repair mortars, is proposed. The support samples preparation - laboratorial rammed earth blocks with surface deterioration - is also described. Finally, an experimental campaign foreseen for the development and application of earth-based mortars for repair rammed earth walls is presented.