Abstract This research evaluates the behavior of plaster with a water-repellent additive when submitted to a natural aging process. Casting plaster and silane/siloxane-based water-repellent were used as materials. The water/plaster ratio was set at 0.7 and the contents of 0.2% and 0.4% of water-repellent were used, in relation to the plaster mass. Plaster pastes without water-repellent (reference) and containing mass water-repellent were evaluated at ‘zero’ age and after 30, 60, 90, 120, and 150 days of natural aging. After 150 days of natural aging, it was observed that the mechanical properties of the material (compressive strength and hardness) did not undergo significant variations and remained above the minimum required by a standard. The addition of water-repellent resulted in a considerable reduction in water absorption, demonstrating the water repellency capacity of the material, compared to the reference specimen.

Estudou-se os efeitos de auxilias exógenas e ácido bórico, no enraizamento de estacas de lichia (Litchi chinensis Sonn.). As estacas foram uniformizadas, com 25 cm de comprimento e 4 folhas cortadas pela metade. Cerca de 2,5 cm da base das mesmas foi mergulhado nos tratamentos: H2O; Boro 150 µg/ml; IBA 5.000 ppm, IBA 2.000 ppm; IBA 5.000 ppm + Boro 150 µg/ml; IBA 2.000 ppm + Boro 150 µg/ml; NAA 3.000 ppm; NAA 1.500 ppm; NAA 3.000 ppm + Boro 150 µg/ml; NAA 1.500 ppm + Boro 150 µ/g/ml. A estaquia foi realizada no mês de setembro (Hemisfério sul), sendo que as estacas foram colocadas em bandejas de isopor, tendo como substrato vermiculita e mantidas sob nebulização intermitente. Os resultados obtidos permitiram concluir que o IBA 5.000 ppm por 1 minuto foi o tratamento mais efetivo, proporcionando 83,33% de estacas enraizadas em 120 dias, enquanto o tratamento testemunha (H2O), apresentou somente 16,67% de estacas enraizadas.

The effects of exogen auxins and boric add were studied on lychee (Litchi chinensis Sonn.) cuttings. Cuttings were standardized to twenty-five cm length, with four leaves, cut in half. The bases of the cuttings were dipped of 2,5 cm in water solutions, resulting in the following treatments: H2O; Boron 150 µg/ml; IBA 5,000 ppm; IBA 2,000 ppm; IBA 5,000 ppm plus boron 150 µg/ml; IBA 2,000 ppm plus boron 150 µg/ml; NAA 3,000 ppm; NAA 1,500 ppm; NAA 3,000 ppm plus boron 150 µg/ml; NAA 1,500 ppm plus boron 150 µg/ml. Cutting was performed in September (southern hemisphere) and the cuttings were place in styrofoam trays, using vermiculite as substratum and kept under intermittent mist It was concluded that 5,000 ppm IBA for one minute was the best treatment to improve rooting (83,33%), while the control (H2O) showed only 16,67% of rooted cuttings.