Author ORCID Identifier

https://orcid.org/0000-0002-4798-2051

https://orcid.org/0000-0001-8087-8232

Document Type

Report

Publication Date

Winter 2024

Abstract

This study evaluated the effects of incorporating cellulose nanocrystals (CNC) into Engineered Cementitious Composites (ECC) and regular concrete materials, focusing on mechanical properties and the use of cost-effective ingredients. CNC, synthesized from rice husk, was characterized by a crystallinity index of 55%. Four concentrations of CNC were investigated: 0.5, 1.0, 1.5, and 2.0 wt.% of cement. Three types of mixtures were developed: M-0, without sugarcane bagasse ash (SCBA) as a sand replacement; M-50, with 50% SCBA as a sand replacement; and regular concrete. The M-0 and M-50 composites underwent compressive strength and uniaxial tensile strength (UTT) testing, with their morphology examined using Scanning Electron Microscopy. The best-performing mixtures were further subjected to flexural strength testing. Regular concrete specimens were evaluated for compressive strength, density, and surface resistivity. The study found that the addition of CNC led to a 51% and 28% improvement in compressive strength for M-0/CNC-1.0 and M-50/CNC-0.5 mixtures, respectively, compared to control samples. All specimens exhibited pseudo-strain-hardening behavior, with the highest tensile strain capacity of 3.24% observed in the M-50/CNC-2.0 mixture. This enhancement in mechanical properties is attributed to two mechanisms: short-circuit diffusion and electrostatic attraction between sulfate esters and cement particles. In regular concrete mixtures, surface resistivity and density measurements indicated a reduction in porosity. Finally, the cracks observed during UTT were tight, with widths less than 200 μm.

Comments

Tran-SET Project 22CLSU14

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