Vandens įgertį mažinančių cheminių priedų įtaka smulkiagrūdžių betonų savybėms

The article accurately describes the influence of water repellent and silane based concrete admixtures on the technological, physical, mechanical and porosity properties of fine - concrete specimens. To obtain the expected results by changing the amount and type of the silane based chemical admixture, six compositions of concrete slurries were designed using six cube shaped (70,7 × 70,7 × 70,7 mm) and six plate shaped (250 × 250 × 30 mm) specimens. In order to get technological, physical and mechanical properties of concrete (concrete slurry), tests on the rigidity of concrete slurries, compression, bending and splitting strength were performed. In addition, experiments on porosity, frost resistance and water penetration were conducted. On the basis of the obtained results and using different amounts and types of silane based chemical admixtures, the rigidity of concrete (Vebe test) decreased up to 1.78 times in respect to the control specimen. On the other hand, when applying the above introduced silane based chemical admixtures, the results show that the density of concrete specimens (70,7 × 70,7 × 70,7 mm and 250 × 250 × 30 mm) varies accordingly (in respect to control specimen) from −1.69% (using WACKER BS 1001 0.1% in respect to the amount of cement used) to 0.84% (using SILRES BS 290 0.2%) and from −2.03% (using WACKER BS 1001 0.1%) to 0.71% (using SILRES BS 290 0.2%). Bending strength (testing plate shaped specimens) has decreased by 27.4% (using SILRES BS 209 0.2%), compression strength (testing cube shaped specimens) - by 34.6% (using WACKER BS 1701 0.2%) and finally, splitting strength - by 34.7% (by using SILRES BS 290 0.2%) in respect to the control specimen. Water absorption of concrete specimens (cube and plate shaped) without chemical silane based admixtures makes accordingly 2.61% and 4.09%. On the other hand, water absorption of concrete specimens (cube and plate shaped) with chemical silane based admixtures varies from 1.49% (using WACKER BS SMK 2101 0.1%) to 3.71% (using WACKER BS 1001 0.1%) and from 2.03% (using SILRES BS 3003 0.4%) to 4.14% (using WACKER BS 1001 0.1%) in respect to control specimens. The results achieved when conducting the water penetration test show that only the specimens without chemical silane based admixtures have failed the experiment. The results obtained following 100 cycles of freezing-thaw show that all specimens have passed the test and heir surfaces do not contain any cracks.