Drying, cracks and shrinkage evolution of a natural silt intended for a new earth building material. Impact of reinforcement

Shrinkage cracking of unsaturated fine soils: New experimental device and measurement techniques

“…Each image taken by the camera is divided into subsets, which form a virtual grid of measuring points. For more details, DIC method in clayey soils is described in Wei et al, [ 20 ] Eid et al [ 21 ] and Kanema et al [ 22 ] Using this method requires to define some parameters according to iDIC Society Good Practices Guide. [ 54 ]…”

“…The tests aim to understand the shrinkage mechanisms, to study the conditions that lead to the appearance of drying cracks, as well as to follow the cracked network in the soil from different parameters such as: the water content, the total crack area, the average crack width, the number of segments and crack rate. [ 8–23 ] In these studies, various laboratory techniques have been used to describe the soil strains variations during the drying process, from shrinkage to initiation and propagation of cracking. Let us mention below the digital image correlation (DIC) technique and the extensometry technique.…”

“…They showed for all cases that critical strain was reached when the stress reaches the maximum tensile strength of the beam, itself depending on the initial suction. Eid et al [21] used image processing to highlight the drying behaviour of a natural silt without binders. They found that the drying of the soil on a smooth support, which is in contact with the clay sample, induces a homogeneous shrinkage until crack appearance; however, the local deformation appears as heterogeneous.…”

Hydromechanical behavior of a quasi-saturated compacted soils on drying-wetting paths-experimental and numerical approaches

“…Drying tests were performed under controlled relative humidity (30% ± 5%) and temperature (22°C ± 1°C) conditions. The experimental device (Figure 1) consists of a sample support placed on a precision balance and a camera taking photos at regular time intervals during the free drying test [12,13]. The water content measured via the precision balance is an average value in the sample over the total dry mass.…”

“…The water content measured via the precision balance is an average value in the sample over the total dry mass. Two approaches were used for the measurements [13,14]: -Before failure (cracking), measurement of surface strains and identification of the ultimate stress before the formation of the first crack, using VIC-2D software for digital image correlation. At regular time intervals during the free drying tests, photos of the soil surface are taken and analyzed to provide two-dimensional strain maps of the complete planar specimen.…”