Page 75 - New Trends in Green Construction

DIFFERENCE BETWEEN TREATED ABACA FIBERS IN CEMENTITIOUS MORTAR
Stefany Alcívar Bastidas, Ma José Martínez-Echevarría Romero
Keywords: natural fibers, abaca, NaOH treatment, cementitious mortar 1. Introduction
This paper has the purpose of analyzing the influence of different treatments of abaca fibers used in cementitious mortars. Three different treatments were made to abaca fibers before applying them to the mortar. The results indicated that these treatments did not increase the results in the mechanical properties; however, they showed a better behavior when trying to split its parts.
2. Materials and methods
The mortar used in this research corresponds to a relation cement - sand of 1:3 with a water flow of 105±5% according to NTE INEN 2518:2010. The cement corresponds to a hydraulic cement M type named GU provided by HOLCIM ECUADOR, the sand accomplishes the granulometric analysis required by ASTM C144-04. The abaca fiber was produced and collected in Santo Domingo-Ecuador by FURUKAWA PLANTATION. The amount of water varies according to the flow test determined for each treatment.
Three different treatments were applied to the abaca fibers: hornification (HR) (Ferreira et al. 2017), sodium hydroxide solution (3%) and water (HS) (Jiang et al. 2018) and finally an adherent solution of natural latex with a coating of silica fume (LS) (Silva et al. 2017). The fiber’s length was determined by previous authors using 25 mm (Zukowski et al., 2018) (Ferreira et al. 2018) with a dosage of 0.2% of the mortar’ solid weight. The amount of water required per each treatment is: HR 362g, HS 380g and LS 355g. These quantities were obtained after applying the flow test per sample.
Different tests were performed, such as: water absorption, setting time through Vicat Needle and bending and compression tests. A total of 34 samples were performed and tested.
3. Results and conclusions
Water absorption was measured drying the samples in a uniform way in a thermal balance (OHAUS). For this test the different treated fibers were immersed water for 8 hours. After this time, the test was performed. Sample with no fiber (NF) showed 70.74%, HS 74.71%, LS 52.59% and HR 73.20%. The results show that the treatment with natural latex and silica fume has the lowest absorption capacity and the two other treatments have almost the same percentage of humidity as the sample without fiber.
In order to measure the setting time, the VICAT Needle test was performed to a cementitious paste performed with 650 g of cement and the leaching water after leaving the fibers immersed for 8 hours in water. Samples with no fiber had an initial setting time of 136 min and a final one of 535min. while HS 148 and 497min; LS 137 and 479 min and HR 156 and 461min respectively. The results show that there is no critical variation between the different treatments.
75
New Trends in Green Construction