Fracture Properties Evaluation of Cellulose Nanocrystals Cement Paste

Abstract

Due to the need for high-performance and sustainable building materials, the investigation of the determination of fracture toughness of cement paste using new and sustainable materials, such as cellulose nanocrystals (CNCs) is worthwhile. Contrary to other well-known nano-reinforcement particles, such as carbon nanotubes, CNCs are less toxic; therefore, they have less safety and environmental risks. Fracture behavior of cement paste has been studied intensively for a long time. However, the incorporation of new materials in the cement paste, such as cellulose nanocrystal materials (CNCs), has not been fully investigated. In this paper, the fracture behavior, compressive strength, and hydration properties of cement paste reinforced with cellulose nanocrystal particles were studied. At the age of 3, 7, and 28 days, a three-point bending moment test, and a calorimetry and thermogravimetric analysis, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX) analysis were performed on the water-to-binder-weight ratio of 0.35 cement paste, containing 0.0%, 0.2%, and 1.0% volume cellulose nanocrystals. Results indicated that the fracture properties and compressive strength were improved for the sample containing 0.2% CNCs. Preliminary results indicate that CNCs can improve the fracture behavior of cementitious materials and can be considered as a renewable and sustainable material in construction.

Fly-Ash-Based Geopolymers Reinforced by Melamine Fibers

“…Polymer fibers are the most frequently used group of fibers as reinforcing additives [ 25 ]. The main objective of the addition of these types of fibers is improving mechanical properties, in particular bending strength [ 24 , 27 ], and reducing the propagation of microcracks in materials [ 23 , 28 ]. Other benefits that can be achieved as a result of introducing chemical fibers into geopolymers, depending on their type, may include an increase in fire resistance [ 24 , 27 ] or a decrease in the thermal conductivity coefficient.…”

A Review on the Application of Nanocellulose in Cementitious Materials

“…Similar conclusions were obtained by Flores et al who indicated that even if the size of CNCs used is larger than that used by Cao et al [ 50 ], the overall trend in the hydration heat is similar to each other, and CNCs were observed to delay cement hydration at an early age but improve the hydration at a later age [ 24 ]. Besides, Ghahari et al indicated that the use of 0.2% and 1% CNCs by volume of cement paste could extend the dormant period of cement hydration that is indicative of the delayed hydration but increase the hydration heat that is indicative of the increased degree of hydration [ 51 ].…”

“…Several conclusions can be drawn. First, a modest dosage of CNCs (e.g., 0.2% by weight of cement) can improve the mechanical properties, whereas a high dosage of CNCs can result in a negative effect [ 13 , 15 , 49 , 50 , 51 , 53 , 54 ]. The improvement in the mechanical properties of cementitious materials at low dosages of CNCs can be attributed to the increased degree of hydration at a given age.…”

Green Concrete for a Circular Economy: A Review on Sustainability, Durability, and Structural Properties

“…Another approach is by partial substitution of ordinary Portland cement (OPC) with waste supplementary cementitious materials (SCMs), which were categorized according to Liew et al [ 32 ] in three groups: 1—industrial wastes such as ground granulated blast furnace slag (GGBFS), fly ash (FA), and silica fume (SF), 2—agricultural wastes such as RHA, corncob ash (CA), and sawdust ash (SA), and 3—municipal wastes such as glass and plastics. Furthermore, cellulose nanocrystals are other green materials extracted from plants and trees, which when partially substituted by OPC can cause a significant reduction in CO 2 consumption with improved compressive strength and fracture properties of concrete [ 33 ].…”