Quantification of moisture content in earth block masonry under natural climatic conditions

The aim of this study is to accurately predict the moisture content in earth block masonry exposed to natural climatic conditions, which is a key factor in assessing its load-bearing capacity. Nuclear magnetic resonance relaxometry and humidity sensor measurements were carried out to quantify the moisture content. In addition, a customised test setup was developed to determine the capillary water absorption of earth blocks. This approach takes into account the deceleration of water absorption due to the swelling of clay minerals and organic additives, which leads to realistic transport coefficients in the hygroscopic range. This allows the moisture content of earth block masonry to be predicted accurately. With regard to the moisture behaviour of typical exterior wall constructions in living spaces, it was found that the equilibrium moisture content in earth block masonry is always lower than 65% relative humidity, which corresponds to the permissible limit of the recently published German design standard for load-bearing earth block masonry. • Sorption behaviour and moisture profiles of earth masonry quantified by NMR relaxometry measurements. • Moisture monitoring of earth masonry for 18 months using embedded humidity sensors. • Prediction of maximum moisture content using transport coefficients derived from capillary water absorption. • Water absorption coefficients can be determined according to EN ISO 15148 with slight adjustments. • Deduction of liquid transport coefficients from capillary water absorption accounts for the material composition.