Impedance spectroscopy of chemically enhanced clays used for adobe construction

Sun-dried clay or mud bricks were one of the first building materials used by man. The main advantages of these materials are: their availability in dry regions, their low cost and their remarkable insulating properties. However, compared to other materials, the physical properties such as compressive strength and water absorption are very low and very high, respectively. The aim of this work is to develop high performance clay composition with the highest compressive strength and the lowest water absorption using chemically enhanced clay mixtures, which can find applications in the building industry. In the present work the impedance spectroscopy technique is used to study the development of both high compressive strength and low water absorption of different mixtures, namely: a) clay + water, b) clay + acrylic emulsion, and c) clay + asphalt emulsion + acrylic emulsion. Thus, for these mixtures it was shown that impedance spectra consisted of two semicircles: one describes the electrical properties of the clay and the other one represents those of the capillary porosity. In addition, it was found that the mechanical properties such as compressive strength of the mixtures are related to the amount of capillary porosity. The results obtained have shown that the mixture clay + acrylic emulsion + asphalt emulsion has the best combination of reasonable compressive strength and low water absorption, for a clay likely to be used for adobe construction.