CEC input to evaluate the butyl diammonium dichloride as a swelling reducer in clay rich material

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Previous research suggest that repeated swelling of the clay minerals involve differential strain during wetting and drying cycles which may induce decay under a fatigue of the clay rich material. Scaling due to this process has been observed on some stone binding clay but also on earthen material used in architecture. Since recent years, research on the conservation of clay-rich sandstones lead to the development of bifunctional cationic surfactants as swelling reducers for sandstones with high hygric and hydric dilatation. In this paper, the butyl diammonium dichloride surfactant was experimented on earthen material to reduce important hygric dilatation which leads to fast and important decay of earthen material. It has been directly added into the clay mixture of molded adobe brick that was to be physically and mechanically tested. The aim is to further investigate the interaction of the surfactant with clay minerals. Series of experiments showed great impact on various physical-mechanical properties of the molded earthen mixtures. Some could have been expected according to the function of the surfactant, which is to block the micropores within the clay mineral structures, responsible for the swelling. Thus, the decrease of the specific surface area as well as the hygric dilatation is understandable. However, according to the concentration of surfactant used within the adobe mixture, other properties are also affected such as the ultrasonic velocity, the water uptake coefficient, the hydric shrinkage and the compressive strength. Therefore this paper underlines important influences in changes of properties of molded adobe according to the concentration of surfactant used, and the cation exchange capacity of the material. The paper will show a new approach consisting in adapting the concentration of surfactant as a function of cation exchange capacity (CEC) of the material.