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- Resumen es exacto "Latin America is one of the leading fiber producers in the world; and those fibers are used to manufacture: bags to packing agro-industries products, ropes, threads and handicrafts. It is important to find new applications for this natural resource, because it will influence the social and economical developments of the region. Therefore, develop further research to extend the use of these fibers in the construction sector is a great importance worldwide theme, because the construction industry uses large quantities of raw materials. This thesis studied the use of Fique fibers to develop new materials for construction applications, in three hierarchical size orders: macro, micro and nano. In case of macro-fibers, epoxy/fique profiles were developed (PRFN) and compared with wood commonly used in construction industry in Latin America. The effect of fibers chemical modification on bending properties and durability in alkaline environments of PRFN was studied. Additionally, barrier properties of epoxy/fique composites, in moist and alkaline environments, were modified by dispersing clay in the matrix. Results showed that fibers treatment with NaOH 18 w/v% increased significantly the flexural properties and the durability of composite. However, addition of clays incorporated air in the epoxy matrix and therefore did not have an effect on composites, but generated a tortuous path to calcium ions. From comparison our material with timber commonly used in Latin America construction industry, it was found that our material is similar to bamboo and oriented strand board (OSB), but with superior properties even after 28 days exposed to moisture and pH~13.
Respect to use of micro and nano fibers; it was studied the effect of the content of microparticles of crystalline cellulose (MCC) and micro and nano cellulose fibers (MNFC) on properties of cement paste in fresh and hardened state. The content of MCC was varied as follows: 0, 1, 2 and 3 wt.%. The content of MNFC was varied as follows: 0, 0.1, 0.2, 0.3 and 0.4 wt.%. Both types of cellulose were compatible with cement hydration products. However MNFC had greater compatibility with hydration products because its greater surface area. The addition of 3 wt.% MCC increased cement paste workability by 25%, while adding a 0.4 wt% of the MNFC increased it by 570%. Moreover, hydration reaction and maximum adiabatic temperature were modified by presence of MCC, while cellulose nanofibers did not had any effect on these variables because MNFC was used in lower proportions.Results obtained from thermogravimetrical analysis showed that, under appropriate curing conditions, both MCC and MNFC increased hydration degree of cement paste. That occurred due to a controlled release of cementitious material's water content that contributed with hydration process. The increment in hydration generated higher modulus and better retention of mechanical properties with temperature. However, the addition of MCC generated micro-cracks (3 – 4 μm) on cement paste; while addition of MNFC did not."
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