چكيده به لاتين
Abstract:
Nowadays the use of renewable resources to achieve the model of sustainable development for building materials is growing. One of the most effective methods for reducing environmental impact result from the use of petroleum products is the use of plant fibers. Engineered cement composite is a material with high strength and toughness, in which PVA fibers commenly are used as a reinforced. According to the unique characteristics of this material, it is necessary to use it in our country. Unfortunately, PVA fiber is not produced in Iran. To overcome this problem and also as for the importance of replacing the synthetic fibers with natural fibers and producing green composites, natural cellulose fibers is used as reinforcement of ECC in the project. For these purpose pulp kraft fibers with different volume percentages (0.5, 1, 1.5 and 2 percent) was used in cement based matrix. The following samples including of nano and micro pulp kraft use different ratio of individually and hybrid with PVA fibers were produced. All of the samples curing in 28 days in water, under test of three-point bending. Nano- and micro-fibers used in this project are achiaved from chemical methods including alkali treatment and acid hydrolysis with ultrasound mechanical treatment from brown pulp kraft. Dynamic light scattering analysis (DLS) was used to determine the size of nanofibers obtained. As for the result, increase of volume precentage of pulp kraft results to behavier change of composite az brittle from to tension softening. In hybrids composites, replace PVA with micro and nano in different volume precent leads to composites toughness reduction. It is show that in 1.5% volume fiber, hybrid composites are more strenghter incomparison with PVA fiber composite.
Keywords: Engineered cementitious composite, Flexural behavior, cellulose fibers, Chemi-mechanical methods to extract cellulose nanofibers
