The test is to determine two important physical characteristics of cementitious mortars: shrinkage and swelling. These quantities are considered relative changes in length; the measurement result is expressed in millimeters per meter (mm/m). If not otherwise specified, not less than 3 prisms must be tested, each of size 40 mm x 40 mm x 160 mm: 3 samples are used to determine the shrinkage (after drying) and 3 samples are used for swelling (after immersion in water). The samples are obtained by mixing the binder, sand, water and additives in an apparatus according to a typical standard mixing procedure. So it is necessary to preserve the samples for the first 24 h in molds coated with a glass plate in a chamber with (20 ± 5)°C and at least 90% relative humidity. After taking them out, and after covering the heads of the measuring pins with lubricant, samples are stored at (20 ± 5)°C and (65 ± 5)% relative humidity. The measurements are performed after 24 hours (initial measurement) and after 3, 7, 14, 28 and 56 days. After disarmament, samples are stored at temperature of (21 ± 2)°C and (60 ± 10)% RH. In the case of immersion (to determine the swelling) samples must be kept immersed in the drinking water at temperature of (21 ± 2)°C. It is important that the position of the sample in the measuring device is always the same for each measurement. To ensure this, the samples must be marked. Control measures on the reference samples must be taken before and after measurements. For measurement, the sample or reference sample must be accurately positioned vertically into the support on the base measurement apparatus. The change in length must be calculated in relation to the initial value (Lo) detected after 24 h. The deformation due to the movement must be expressed as the change in length (ΔL) compared to length (Lg), in mm/m units, expressed to the nearest 0.01 mm/m of water for 56 days to one of (21 ± 2)°C. Once the retention period is terminated the samples muset be inspected for any signs of cracking or delamination, and the presence of such defects must be recorded. It is recommended to take pictures to document defects. The samples shall be then subjected to adhesion test by pull-off.

 

Material type Standard Test method
finishing plasters EN 998-1
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gypsum-based plasters EN 13279-1
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screeds EN 13454-2 EN 13454-2
restoring mortars EN 1504-3
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grouting mortars EN 13888 EN 12808-4
self-levelings EN 13813 EN 13454-2
cements EN 197-1
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surface protection
mortars
EN 1504-2 EN 12617-1

 

Instruments used to perform the test: Shrinkage linear comparator

 

The test consists to determine the shrinkage (after drying) and the swelling (after water immersion).The test consists to determine the shrinkage (after drying) and the swelling (after water immersion).