Potential of cactos xique-xique mucilage as a surface treatment for compressed earth blocks

Abstract

Buildings with earth walls have outstanding hygrothermal properties, which contribute to a desirable regulation between temperature and humidity of environments. However, this type of masonry is vulnerable to pathologies due to the action of rainwater. This paper evaluates the efficiency of using the mucilage of the xique-xique cactus (Pilosocereus gounellei) as a surface treatment for walls made of compressed earth blocks (CEB). The aim is to obtain a protective film against rainwater, but which is permeable to water vapour. The tests performed with cubic specimens, extracted from CEBs, allowed comparisons between the proposed treatment (TX), using different mucilage concentrations, and a commercial acrylic waterproofing resin (TR), using as control samples without any surface treatment (TC). The results of the water absorption by capillarity tests showed that the TX sample with 1:1 concentration had a similar behaviour to the TR sample, since after 60 minutes of testing, TR, TX1:1 and TC had a mass increase of 0.3 g/cm², 0.5 g/cm² and 1.4 g/cm² respectively. Water vapour permeability for TX1:1 was 5% higher than TR and 6% lower than TC. After heat and thermal shock tests on small walls, the TX1:1 samples performed satisfactorily.

Keywords:
CEB; Film; Watervapour; Permeability