PSI - Issue 74

Małgorzata Lenart et al. / Procedia Structural Integrity 74 (2025) 44 – 49 Małgorzata Lenart / Structural Integrity Procedia 00 (2025) 000–000

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Fig. 2. Graph of volumetric changes of the tested mortars over a 90-day period.

The third area (the highest graphs on the 90th day of the test in Fig. 2) includes the course of shrinkage of both polymer-modified mortars, the one with 30% and 50% polymer suspension content cured under the foil. Their shrinkage after 90 days of testing was -0.31 mm/m. Analysing the course of the shrinkage curve of the mortar with 50% polymer suspension content, it can be seen that it has a milder course, which will result in the smallest shrinkage in a longer period of time (in which no measurements were taken). 6. Summary and conclusions In summary, a synergistic effect of both composite care and its modification with polymer on shrinkage determined after 90 days of hardening can be observed. The highest shrinkage, as expected, was shown by unmodified and uncured mortars or those cured by covering them with a curing agent. This shrinkage was -0.89 mm/m. The next level of shrinkage was shown by composites modified with polymer at different levels, cured with the preparation and uncured. Their shrinkage ranged from -0.57 mm/m to -0.62 mm/m, which is from 64% to 70% of the shrinkage of the reference unmodified and uncured mortar. The lowest shrinkage was demonstrated by mortars modified with polymers and cured under foil. Their shrinkage after 90 days was -0.31 mm/m, which is about 35% of the shrinkage of the unmodified and uncured mortar.

Therefore, the following conclusions can be drawn on the basis of the realized research program : 1) The addition of carboxylated stearin-butadiene latex in form of a suspension reduces shrinkage changes of about 30% determined after 90 days of hardening with relation to the unmodified and uncured reference mortar. 2) After 90 days of curing of the composites, no large, significant changes in the level of the marked shrinkage were observed for the mortars modified with 30% and 50% content of carboxylated stearin-butadiene latex suspension.