“…Figure 14, SEM image of the failed surface of UHPCM reinforced with GNP, provides indications that GNP interact with micro-cracks. Previous studies also confirm a crack filling effect of GNPs in cement matrices [97,100].…”
Concrete is the most widely used construction material. It offers a desirable balance of cost, strength, moisture barrier qualities, and dimensional and chemical stability. The rising costs of aging infrastructure systems, however, point to the need for further improvements in concrete properties. Carbon-based nanomaterials (CBNs) are predicted to have excellent mechanical properties, and so are attractive candidates for addressing these issues. However, the relatively high cost of CBNs, means that only low weight fractions in cement matrices will be economically viable, which presents a significant challenge. The research presented here investigated various surface functionalization techniques for improving the compatibility of carbon nanomaterials (multi-walled carbon nanotubes, carbon nanofiber and graphene nanoplatelets) with cementitious materials in fresh and hardened state. The effects of surface functionalization on the contributions of CBNs to the performance characteristics of ultra-high-performance cementitious matrices (UHPCM) were evaluated. Functionalized multi-walled carbon nanotubes at 0.03% weight fraction increased the flexural strength by 30%, doubled the energy absorption capacity, and tripled the ductility of UHPCM. The moisture barrier qualities, abrasion resistance and toughness characteristics of UHPCM benefited significantly from introduction of CBNs at less than 0.1% weight fraction. This study demonstrates that the low weight fraction of CBNs can effectively enhance the key engineering properties of UHPCM at a viable cost. Thus, this approach has both performance advantages and economic benefits.
Article highlights
Surface functionalization of multiwalled CNTs improved dispersion in cementitious matrices at low weight fractions.
0.03 wt.% multiwalled CNT addition increased the flexural strength and the flexural toughness of UHPCM.
Abrasion resistance and moisture barrier qualities improved.
These improvements are achieved at viable cost.
“…Figure 14, SEM image of the failed surface of UHPCM reinforced with GNP, provides indications that GNP interact with micro-cracks. Previous studies also confirm a crack filling effect of GNPs in cement matrices [97,100].…”
Concrete is the most widely used construction material. It offers a desirable balance of cost, strength, moisture barrier qualities, and dimensional and chemical stability. The rising costs of aging infrastructure systems, however, point to the need for further improvements in concrete properties. Carbon-based nanomaterials (CBNs) are predicted to have excellent mechanical properties, and so are attractive candidates for addressing these issues. However, the relatively high cost of CBNs, means that only low weight fractions in cement matrices will be economically viable, which presents a significant challenge. The research presented here investigated various surface functionalization techniques for improving the compatibility of carbon nanomaterials (multi-walled carbon nanotubes, carbon nanofiber and graphene nanoplatelets) with cementitious materials in fresh and hardened state. The effects of surface functionalization on the contributions of CBNs to the performance characteristics of ultra-high-performance cementitious matrices (UHPCM) were evaluated. Functionalized multi-walled carbon nanotubes at 0.03% weight fraction increased the flexural strength by 30%, doubled the energy absorption capacity, and tripled the ductility of UHPCM. The moisture barrier qualities, abrasion resistance and toughness characteristics of UHPCM benefited significantly from introduction of CBNs at less than 0.1% weight fraction. This study demonstrates that the low weight fraction of CBNs can effectively enhance the key engineering properties of UHPCM at a viable cost. Thus, this approach has both performance advantages and economic benefits.
Article highlights
Surface functionalization of multiwalled CNTs improved dispersion in cementitious matrices at low weight fractions.
0.03 wt.% multiwalled CNT addition increased the flexural strength and the flexural toughness of UHPCM.
Abrasion resistance and moisture barrier qualities improved.
These improvements are achieved at viable cost.
“…As given in Figure 13, borophene-based nanobelts had dimensions of 80 nm thickness and 220 nm width and a 1–5 µm in length and such a large length-diameter ratio played a significant reinforcing role in the cement matrix. 72 It is assumed that borophene-based nanobelts formed due to the rolled structure of borophene sheets in which atoms of pure boron were arranged.Figure 13.Microbridging in mortar matrix with β borophene nanosheet additive.…”
This study is the first investigation focused on the preparation of novel synthesized borophene nanosheets and their use in cementitious composites. The two-dimensional β borophene was prepared by a facile and low-cost sonication process including ultrasonic cavitations. To understand the effect of the novel synthesized borophene nanosheets, varying ratios of 0, 0.5, 1, 2, 3, and 5 wt% of cement were incorporated in cement composites and improvements on the mechanical strength, workability, and toughness were identified. Also, for the microstructure evaluation, several advanced characterization techniques including SEM, EDS, XRD, and TGA were presented and the relationship between the microstructure and mechanical properties of cementitious composites modified with borophene nanosheets was discussed. As a result of this study, with the incorporation of the borophene nanosheets, clear improvements were achieved for the 28 day compressive and flexural strengths of the specimens within a range of 5–19% and 4–13%, respectively. The findings also indicated that borophene nanosheets contributed to the formation of a denser microstructure of the corresponding cement composites. Thus, within this study, the utility of as-prepared borophene nanosheets in cementitious composites is proved and proposed as a two-dimensional potential nanomaterial candidate to be used in cementitious composites.
“…Surface modifications can be conducted with low-cost graphite materials to improve their dispersion and interfacial interactions in cementitious matrixes. Acid functionalization (a chemical modification) on the surface of graphite can introduce carboxyl and hydroxyl groups (-COOH and -OH), which creates uniform dispersion of graphite in the cement matrix and forms active sites for the initiation of cement hydration [106].…”
Section: Methods To Improve Graphite-based Eccc Propertiesmentioning
Electrically conductive cementitious composites (ECCCs) have been widely used to complete functional and smart construction projects. Graphite, due to its low cost and wide availability, is a promising electrically conductive filler to generate electrically conductive networks in cement matrixes. Cement-based materials provide an ideal balance of safety, environmental protection, strength, durability, and economy. Today, graphite is commonly applied in traditional cementitious materials. This paper reviews previous studies regarding the effects and correlations of the use of graphite-based materials as conductive fillers on the properties of traditional cementitious materials. The dispersion, workability, cement hydration, mechanical strength, durability, and electrically conductive mechanisms of cementitious composites modified with graphite are summarized. Graphite composite modification methods and testing methods for the electrical conductivity of ECCCs are also summarized.
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