چكيده به لاتين
For many years, Gypsum has been used by humans for construction. One of the recent developments in this field is the use of fiber-reinforced gypsum for the production of durable and strong gypsum composites. This study aimed to investigate the effect of expanded perlite on the lightening of gypsum boards and the effect of strengthening these boards by woven glass fiber. For this purpose, gypsum samples by adding 0, 10, and 20 wt.% of perlite were fabricated. Then, the samples were reinforced with woven fiber of 200, 300, 400, and 600 g/m2. To evaluate the mechanical properties, compressive, flexural, and shear tests were performed according to BS EN 8500, BS EN 15283, and ASTM E519 standards. To measure the strain in the pure shear tests, the digital image correlation (DIC) method and the analysis with Match-ID software were used.
The results showed that adding 10% and 20% expanded perlite reduced the density by 34% and 63%, respectively. The compressive strength tests showed that the specific compressive strength of gypsum decreased by 26% and 60% by adding 10% and 20% expanded perlite. In such a case, the specific flexural strength is reduced by 44% and 60%, respectively, and the specific shear strength is reduced by 36% and 66%, respectively. Although according to the obtained results, the addition of expanded perlite to the gypsum has reduced the specific compressive strength, specific flexural, and specific shear strength, however, the reinforcement of the samples by woven glass fiber has compensated this reduction. For example, a gypsum sample with 20% perlite, reinforced with woven glass fiber of 300 g/m2, has shown a 114% increase in specific flexural strength in comparison with that of the pure gypsum sample. Examination of the mechanical behavior of reinforced specimens showed that the woven glass fiber changed the brittle flexural behavior to ductile.
By reinforcement of the perlite-induced gypsum specimens, the specific shear strength has not reached the specific shear strength of the pure gypsum. However, for example, the specific shear strength of a sample with 20% expanded perlite and reinforced with woven glass fiber of 300 g/m2 has increased by 30% compared to nonreinforced perlite/gypsum composites. Examination of the rupture pattern of shear specimens showed that the reinforcement of the specimens had an effect on the shear behavior so that the unreinforced specimen has an in-plane rupture but the reinforced specimen shows an out-of-plane rupture. The specific shear modulus has also increased with the reinforcement of the samples so that the specific shear modulus of the gypsum sample with 20% perlite reinforced by woven glass fiber of 300 g/m2 has increased 117% in comparison with the perlite-induced gypsum specimens. The use of woven glass fiber has increased the mechanical properties of the perlite/gypsum. Moreover, comparing the results of the present research with other research works shows that the consumption of woven glass fiber is significantly reduced compared to that of the reinforcement by short glass fiber.
