Improvement in the Carbonation Resistance of Construction Mortar with Cane Bagasse Fiber Added

Abstract

In this work, sugarcane bagasse fiber, a waste product of agroindustry, was added to mortar mixes at different proportions looking to seal porosities so as to improve the resistance of concrete to carbonation and to improve its mechanical properties. To evaluate the behavior of bagasse fibers in the alkaline media typical of mortars, bagasse fibers were subjected to solutions with alkaline pH values, and their chemical structure and morphological behavior was evaluated using FTIR (Fourier transform infrared spectroscopy) and SEM (Scanning Electron Microscopy). Using mortar cylinders in an accelerated carbonation chamber to obtain results in short lapses, the compressive strength and the carbonation were evaluated. The FTIR analysis results indicate that pH values of 11 and 12 causes a delignification, while at pH 9 and 10, a swelling of the molecule occurs because of the addition of hydroxyl ions, behavior that is confirmed with SEM images. A clear effect of the fiber addition on the performance of concrete was observed as the carbonation front of 35 mm for the sample without fibers was reduced to 2 mm for the sample with 2% fiber addition, resulting in an increase of 5 MPa in compressive strength. These results indicate that in the range of mortar pH, chemical changes occured over the sugarcane surface that could cause the growth of fibers and could partially seal the porosity in the mortars, thus enhancing its performance.

Evaluation of the dynamic modulus of elasticity of a pozzolanic mortar of rice husk ash reinforced with sugarcane bagasse

“…For the other mortars it is noticed that the density decreases both with the increase of rice husk ash rate [30,31] and with the increase of sugarcane bagasse rate [13][14][15]. This is related to the introduction of pores in the reference mortar both when using high rates of rice husk ash [32,33], and when using sugarcane bagasse [28] in RHA10.…”

“…For rice husk ash mortars reinforced with sugarcane bagasse, a drop in dynamic modulus of elasticity is observed with increasing sugarcane bagasse in the mortar. This is related to the increase of pores with the increase of sugarcane bagasse in the mortar [28]; which decreases the propagation velocity of sound waves in the mortar [26,34]. The decrease in sound wave propagation velocity directly translates into the decrease in dynamic modulus of elasticity as shown in equation (eq1).…”

“…It is also noted that mortars with 10% rice husk ash reinforced with sugarcane bagasse (R10SB) present a higher porosity than RHA10. This is related to the internal porosity of sugarcane bagasse which accentuates the resulting porosity in R10SB [28].…”

Memorias del X Congreso Nacional de Alconpat México 2022

“…La obtención y preparación de las muestras de fibras de bagazo de caña de azúcar se llevaron a cabo mediante el procedimiento descrito en un trabajo previo que se llevó a cabo en laboratorios del Centro de Investigación en Corrosión (Talavera-Pech et al, 2021). Una vez concluido el proceso de limpieza de las fibras, fueron inmersas en disoluciones con pH desde 13 hasta 9, que son los valores posibles en un concreto expuesto a condiciones de carbonatación, y una muestra de referencia (pH=7) durante 60, 90 y 120 días de exposición.…”

“…Con la finalidad de acelerar el proceso de carbonatación en el concreto, y luego de cumplidos los 28 días de curado, se colocaron en la cámara adaptada en el laboratorio de concreto del Centro de Investigación en Corrosión de la Universidad Autónoma de Campeche, con la capacidad de mantener las condiciones experimentales en 25 ± 2 °C de temperatura y 65 ± 5 % de humedad relativa. A un costado se instaló un tanque comercial de CO2 de 25 kg con un medidor de flujo, que permitió mantener dentro de la cámara una concentración constante de 3 %, ambiente con mayor concentración de CO2 que en el ambiente normal (Talavera-Pech et al, 2021). Dentro de la cámara se colocaron un medidor de humedad relativa y un medidor de CO2.…”