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Construction industry is one of the biggest sectors globally and a wide variety of materials are used to carry out various works. Particularly, cement is a material that is used in the construction of various structures and it is also the major source of emission of CO 2 gas into the atmosphere which results in global warming. Many researchers have...
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ICNST 2019 focuses on the fascinating nano-world, mesoscopic physics, analysis with atomic resolution, nano and quantum-effect devices, nanomechanics and atomic-scale processes and so on. ICNST 2019 is aiming to convene experts around the world to present their research works and discuss the present hot topics in the field of nano science and techn...
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... UPV and other conventional procedures are used for comparison with the proposed new procedure. Mixing concrete with nanosilica has received more attention due of its ability to enhance the main characteristics of concrete mixtures including compressive strength, durability, and decrease the effect of the F-T cycles [24,25]. Therefore, the concrete specimens were mixed with different amounts of a nanosilica (0 %, 1 %, 3 %) to investigate the changes in P-wave characteristics that may occur under F-T cycles using UPV and two conventional procedures for comparison with the proposed new technique. ...
Concrete is widely used as construction material in civil infrastructures. Generally, this type of material can deteriorate due to several reasons, such as temperature variations. It is essential to monitor the changes inside the concrete medium using a suitable technique. In this study, six concrete specimens (three prisms and three cylinders) with different nanosilica contents were made and tested using the ultrasonic pulse velocity (UPV) method. These specimens were evaluated under the effect of daily freeze-thaw (F-T) cycle (71 cycles) under controlled laboratory conditions. A new evaluation approach based on selected frequency bands is proposed to analyze the signal spectra to monitor the damage development inside the concrete medium under temperature variations and compared with other conventional procedures. The results obtained show that the proposed approach could capture the damage progress better than other procedures used to evaluate damage propagation in concrete medium. It is shown that the band with high frequencies (42-65 kHz) is more robust to capture damage in all concrete specimens tested in this study in comparison with the UPV methods. In conclusion, the findings of this study indicate that the proposed new approach can be applied to monitor damage propagation in concrete medium under laboratory and field conditions.
... UPV and other conventional procedures are used for comparison with the proposed new procedure. Mixing concrete with nanosilica has received more attention due of its ability to enhance the main characteristics of concrete mixtures including compressive strength, durability, and decrease the effect of the F-T cycles [24,25]. Therefore, the concrete specimens were mixed with different amounts of a nanosilica (0 %, 1 %, 3 %) to investigate the changes in P-wave characteristics that may occur under F-T cycles using UPV and two conventional procedures for comparison with the proposed new technique. ...
... The tests on workability, morphology and mechanical properties on concrete were conducted by three, seven, twenty eight and fifty six days duration of tests. From the test results, the carbon Nano tubes and fibers should increases the flexural strength up to 40% and Nano silica enhances the pozzolanic activity up to 40% [17]. This research work was concentrated on the study of Nano silica utilization to make the special and normal concrete. ...
Researchers are working towards achieving the good strength, finding sustainable material, high performance; improve the structural & durability behaviour etc., of the concrete. This study focuses on the analysis and benefits of addition of raw (RFAC), ultra fine (UFFAC) and nano fly ash (NFAC) on its optimum level in the concrete. The optimum content of raw, ultra fine and nano fly ash is 19%, 22% & 23% are obtained through mechanical properties tests. To find the flexural performance of reinforced concrete beam, the specimen of 2000 mm*100 mm*150 mm has been designed to with stand the load of 35kN. Under the static load, the parameters of load vs. mid span deflection, moment vs. rotation, ductility, energy absorption are calculated and all the results were compared with conventional (CC) specimen. Among all the specimens, NFAC specimens have performed well and the minor cracks are developed due to its high bond between the ingredients. The load carrying capacity of the NFAC specimen has been improved about 9.23%, 8.64% and 5.20%, the deflection has been reduced by 12.32%, 9.70% and 1.63%, also the moment carrying capacity of the NFAC specimen has been improved by 19.66%, 12.90% and 5.26% with respect to CC, RFAC and UFFAC specimens.
Keywords:
Raw flay ash; Ultra fine fly ash; Nano fly ash; Scanning Electron Microscope (SEM); Static load; ductility; Energy absorption
... These best compressive strength improvement percentages are (26, 39, and 35) % at 7, 14, and 28 days when compared to 4 % Sp. mixtures and the same is shown in Figure 2b. This is in agreement with researchers [10][11][12][13][14][15][16][17] . With the addition of 0.2 % nano SiO 2 , the percentage increase in compressive strengths has been (3, 4, and 4) % at 7, 14, and 28 days as compared to 4 % Sp. mixture. ...
... However, nanomaterials still have limitations such as susceptibility to crack formation and brittle behaviour [12]. To overcome these limitations, notable nanomaterials have been used in cement concrete including nano-silica (SiO 2 ) [13], nano-titanium dioxide (TiO 2 ) [14], nano-alumina (Al 2 O 3 ) [15], and nano-iron oxide (Fe 2 O 3 ) [16,17]. Among these nanomaterials, carbon nanotubes (CNTs) have shown remarkable potential in the development of crack-free and durable cementitious composites [18][19][20][21][22]. CNTs are manufactured into two classes: single-walled carbon nanotubes (CNTs) and multi-walled carbon nanotubes (MWCNTs) [23]. ...
... The replacement dosages of nano silica were 1%, 2%, 3%, and 5%. Due to nano silica's (relatively) high cost and water demand, most previous studies limited the maximum dosage of nano silica replacement to 5% [40][41][42][43][44][45]. Hence, a similar limit was employed in the current study (i.e., SF0NS5). ...
... Nanomaterials have their dimensions in the 1 to 100nm range with 10 3 time's higher specific areas when compared to SCMs or micro range materials. Nano silica is also the most economical nanomaterials, the most desirable in performance [3][4][5][6][7][8][9][10][11][12], the most consumed in cement composites, and has proven helpful in promoting the use of salvaged materials in cement matrices worldwide [13][14][15][16][17]. Also, India is blessed with huge agricultural production and the novelty of Nanosilica is that it can be produced from agricultural wastes [18]. Last but not the least, the cost economics of nanoenabled composites are much better than their SCM counterparts [19,20]. ...
This study concerns the application of a water-saving cement additive that can appreciably better the hardened properties of a cured product of a cementitious composition over a long time period. This advanced cement additive is a Nanotechnology based advanced material also known as Nano Materials at varying dosages by weight of ordinary Portland cement (1 part by weight) in a dry mix with river sand constituting 3 parts by weight of cement. Nanomaterials are insoluble in water so it's dissolved in a polymeric compound of Polycarboxylate Ether through ultrasonication.7.07cm cubes are cast with this mixture with water adjoined as per IS:4031 Standards under the fixed water/cement(w/c) at 0.4. After casting the cubes are cured at room temperature and they are tested for 3 Days, 7 Days, 28 Days, & 365 Days for compressive strength. Not only the results when compared are found to be superior to that of the ordinary cement composite cubes but also were found to be much more economical when compared to Silica Fumed cement compositions.
... The contact of Nano-silica in freshly mixed concrete depicts their effect on various characteristics of concrete, for instance, time for setting, consistency, slump value, etc. Zhang et al. [58,59] revealed that 2 % Nano-silica in slag and fly-ash-based concrete decreased the early and final setting time. Jalal et al. [60] and Ghafari et al. [61] also noted an identical impact of Nano-silica on initial and final setting time for self-compacting concrete (SCC) and ultra-high-performance concrete, correspondingly [62]. Various authors observed a reduction in a slump in Nano-silica modified concrete [61,63,64]. ...
Concrete significantly impacts the atmosphere as its primary raw material, Portland cement, determines a considerable proportion of carbon dioxide in its production process. Improving the strength and durability properties of concrete buildings could decrease their influence on the atmosphere. Adding a small proportion of Nano-silica (NS) to concrete could change concrete's configuration at the Nano level. Compared to other nano-materials, Nano-silica has riveted a lot of consideration due to its pozzolan reaction with calcium-hydroxide to make a gel of calcium-silicate-hydrate. Nano-silica can promote the adhesion between the concrete's binder and aggregate by coupling and efficiently enhancing and densifying the concrete's matrix. The present review article focuses on studying the influence of different types and proportions of nano-silica on the hydration, strength, durability, and microstructural characteristics of different cement-based concrete. This review article shows that around 2-4 % of Nano-silica in various types of concrete is suitable to improve the influence of NS on the physical, durability, and mechanical properties and densify concrete microstructure. Also, the present challenges that the concrete industry is facing in the commercial utilization of nano-silica in concrete are discussed in this review article. It is established that this review article will produce novel concepts to endorse the practical utilization of Nano-silica in the construction sector and offer some productive designs for similar research studies in the future.
... Modernization and industrial enterprise pose a serious threat to the environment, which has led to air pollution. For 5-8% of the CO 2 released globally, which contributes to global warming, the carbon dioxide (CO 2 ) emission from the manufacturing of cement [1] is responsible. To reduce the impact of CO 2 emissions caused by cement manufacturing activities in concrete, several compounds have been identified and used to substitute cement [2]. ...
... To minimize environmental pollution, materials with these characteristics have been utilized to partially replace cement in the manufacturing of concrete, including micro-or nano-silica and silica fume [2]. Numerous studies have examined and supported the usage of nano-silica as a cement replacement [1,16]. ...
Cement is utilized extensively in the manufacturing of concrete, which makes it the most common material used in building construction. However, the usage of a great deal of cement results in a great deal of CO2 emissions, which leads to the greenhouse effect. Numerous studies have developed the use of nano-SiO2 in concrete materials to lower the cement content of concrete mixtures while improving mechanical properties. Additionally, a number of studies have demonstrated that silica NPs trigger an inflammatory response in pulmonary fibroblasts. The main cells that produce and maintain the extracellular matrix (ECM) in the connection of the tissue are fibroblasts. Fibroblasts are involved in processes including tissue regeneration and wound healing. Similar to angiogenesis, inflammation, cancer, and pathological and physiological tissue fibrosis, fibroblasts act as intermediaries. The effect of silica nanoparticles on the mechanical properties of concrete (compressive strength, split tensile strength, and flexural strength) was succinctly presented in this paper. Likewise, a number of studies on the reaction of human fibroblasts to silica nanoparticles were evaluated. Numerous research on the addition of silica nanoparticles to concrete revealed that doing so significantly enhanced the material's mechanical properties. The controlled interaction of silica nanoparticles with human fibroblast cells was demonstrated to have potential in a number of applications, including aesthetics, intracellular drug release systems, improving scar tissue, determining the fate of biomaterials in vivo, and designing potential prosthetics and implant surfaces to reduce bacterial adhesion.
... In light of recent advances in nanoscience, the use of nanoadditives in the construction field has opened up new possibilities in cementitious systems [19][20][21][22][23]. Nanosilica (NS) has attracted increased interest and extensive application in cement-based materials due to its nanoscale particle size, high specific surface area, and pozzolanic activity. ...
The impact of nanosilica on the properties and microstructure of cement-based products has lately attracted a lot of attention. The effects of colloidal nanosilica (CNS) at different concentrations on the hydration process and performance of cement-based composites reinforced with coconut coir were examined in this study. CNS was applied at concentrations of 0%, 2%, 4%, and 6% by weight of cement, respectively. The samples were evaluated in terms of flexural test, scanning electron microscopy (SEM), thermogravimetric analysis (TG-DTG), and X-ray Diffraction (XRD) after 7, 28, and 60 days of curing. Flexural strength improved by 13%, 11%, and 23% in the presence of CNS after 7, 28, and 60 days of hydration, respectively, as compared to the samples without CNS addition. The highest flexural strength was reported in samples containing 4% CNS. Beyond this, flexural strength decreases noticeably owing to the presence of too much nanosilica, which repressed the hydration process. The predominant causes of sample failure appear to be fiber breakage and fiber pull-out. In the sample containing 4% CNS, a dense structure was seen. The fibers had a strong bond with the matrix, showing that fiber/matrix bonding was improved. CNS served as a pozzolanic reaction promoter, converting CH to C-S-H, and a filler to improve cement microstructure. The CH content decreased when CNS was added, while the C-S-H gels increased.
