Incorporation of micro and nanoparticles of silica in cementitious composites (original) (raw)
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CHEMICAL AND PHYSICO-MECHANICAL PROPERTIES OF COMPOSITE CEMENTS CONTAINING MICRO- AND NANO-SILICA
Portland cement is one of the most used materials in the world. Due the environmental problems related to its use, such as CO 2 emission and use of non-renewable raw materials, new materials are being researched. In the recent years, there is a great interest in replacing a long time used materials in concrete structure by nanomaterials (NMs) to produce concrete with novel function and better performance at unprecedented levels. NMs are used either to replace part of cement, producing ecological profile concrete or as admixtures in cement pastes. The great reactivity of NMs is attributed to their high purity and specific surface area. A number of NMs been explored and among of them nanosilica has been used most extensively. This work aims to study, the chemical and physico-mechanical properties of composite cements containing silica fume (SF) and nanosilica (NS). Different cement blends were made from OPC, SF and NS. OPC was substituted with SF up to 15.0 mass, %, then the SF portion was partially replaced by NS (2.0, 4.0 and 6.0 mass, %). The hydration behavior was followed by determination of free lime (FL) and combined water (Wn) contents at different curing ages. The required water for standard consistency (W/C), setting times (IST&FST), bulk density (BD) and compressive strength were also estimated. The hydration products were analyzed using XRD, DTA and SEM techniques. The results showed that, both of SF and NS improve the hydration behavior and physico-mechanical properties of composite cements. But, NS possesses higher improvement level than SF. This is due to that, both of them behave not only as filler to improve the microstructure, but also as activator to promote pozzolanic reaction, which enhances the formation of excessive hydration products. The higher beneficial role of NS is mainly due to its higher surface area, filling effect and pozzolanic activity in comparison with SF. The composite cement containing 85.0 % OPC, 11.0 % SF and 4.0 % NS gave the optimum mechanical properties at all ages of hydration.
2020
The durability of cementitious composites continues to be an issue that receives the attention of practitioners and researchers around the world, which has led to the design of high-performance cementitious composites such as engineered cementitious composites (ECC). ECCs have high ductility capacity that makes them more durable, however, further, improvement isdesirable.This paper, therefore,sought to evaluate the mechanical properties and sorptivity capabilities of ECCs produced with dosages of nano-silica.The 28 th -day test results showed improvements in the compressive strength of the specimens with increasing dosage of nanosilica. Nonetheless, the 28 th -day flexural strength of the specimens slightly reduced with an increasing amount of nano-silica dosage. Concerning the 28 th -day sorptivity measurements,it was observed that the sorptivity coefficients reducedwith increased dosages of nano-silica. There were significant reductions in the sorptivity values of the various spec...
Superior-mechanical, microstructure properties of composite cement incorporating SiO2-nano-particles
Egyptian Journal of Chemistry, 2020
T HE impact of silica-nano-particles (SNP) on the hydration characteristics of composite cement containing fly ash (FA) and/or fine granulated slag (FGS) was investigated. The physico-chemical characteristics of different composite-pastes are studied in the presence of 4mass% SNP and 40% FA and/or FGS with the existence of 1mass% polycarboxylate superplasticizer (SP). The physicomechanical characteristics are studied by determination of the water of consistency, setting times (STs), compressive strength (CS), total porosity, (TP), bulk density (BD), chemically combined water (Wn), free lime (FL) contents and gel/ space ratio (X). The phase composition of the formed hydrates is investigated using XRD, DTA∕TGA, and SEM techniques. The represented data shown that 4% SNP improved the hydration process of the composite cement pastes and exhibited superior-compressive strength than neat-cement without SNP, this is due to nano-sized-particles and higher-efficiency of good pozzolanic-action of SNP in the comparison with FA and FGS. The composite cement containing OPC-40%FGS-4%NS in presence of 1%SP possess the highest improvement of mechanical-properties, hydration-kinetics, and microstructure of hardened cement pastes.
Infrastructures
The incorporation of nanotechnology has led to significant strides in the concrete industry, ushering in innovative construction methodologies. Various nanomaterials, including nano-silica (NS), have undergone comprehensive scrutiny as potential partial substitutes for cement in concrete formulations. This article aims to provide a comprehensive overview of the impacts of NS on several mechanical properties of concrete, encompassing compressive, split tensile, and flexural strengths. Additionally, the review delves into the influence of NS on the concrete’s durability, including microstructural characterization and the eradication of structural micropores. NS has demonstrated the capacity to bolster both strength and durability while concurrently diminishing structural micropores. Moreover, this review explores the contemporary status of NS application in cement concrete and presents avenues for prospective research. The assessment of engineering attributes becomes imperative for co...
Ceramics - Silikaty, 2020
The impact of silica-nano-particles (SNP) onto the physicochemical and microscopic characteristics of composite-cements containing 40-60 mass% fly-ash (FA), and/or granulated-slag (GS) were studied. The physico-mechanical and microscopiccharacteristics of the composite cement-pastes were enhanced by the replacement of 4 mass% SNP, especially the early-strength enhancement. The behaviour of the hydration-kinetics was studied from one day up to 360 days. The consistency (W/C) ratio, setting times (STs), compressive strength (CS), total porosity, (TP), bulk density (BD), chemically combined water (Wn), free lime (FL) and gel/space ratio (X) were determined. The behaviour of SNP was proven by XRD, DTA, and SEM techniques. The 4 mass% SNP improves the characteristics and microscopic hydration behaviour of the inspected blended and composite cements matrices in the existence of FA and GS. SNP have a positive effect on the behaviour of composite cement pastes, it diminished the setting times and gives higher compressive strength and gel/space ratio. The SEM micrographs showed the formation of a denser and finer structure of a CSH hydrated gel with a marked reduction in the total porosity of the hardened
IJERT-Physico-Mechanical Properties and Microstructure of Blended Cement Incorporating Nano-Silica
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/physico-mechanical-properties-and-microstructure-of-blended-cement-incorporating-nano-silica https://www.ijert.org/research/physico-mechanical-properties-and-microstructure-of-blended-cement-incorporating-nano-silica-IJERTV3IS070002.pdf In the recent years, the application of nanotechnology in the field of construction and building materials has exponentially increased to produce new materials with novel function and better performance at unprecedented levels. Actually, nano-materials (NMs) can change the concrete world, due to their unique properties, which different from those of the conventional materials. NMs were used either to replace part of cement, producing ecological profile concrete or as admixtures in cement pastes. One of the most commonly used NMs is nano-silica (NS). In this study, the physico-mechanical properties of Portland cement (Type 1) containing NS up to 6.0 mass, % was studied with curing time up to 90-days. The results show that, NS increases the water of consistency as well as setting times, due to its higher specific surface area than OPC. The results of chemically combined water (Wn), free lime (FL), bulk density (BD), and compressive strength (CS) prove that, NS up to 2.0-4.0, mass % seems to be an effective substituent for blending with OPC to improve its physico-mechanical properties. This mainly due to that; NS-particles behave not only as nano-fillers to improve the microstructure of cement paste, but also as activators to promote the hydration of cement phases. The formation of more amounts of CSH in presence of NS was confirmed by XRD and SEM techniques. At higher substitution of OPC with NS (>4.0 mass, %), the values of BD and CS are reduced but still higher than those of the control sample. OPC could be advantageously replaced by 2.0-4.0 mass, % NS, which is the most effective level of NS for producing high-performance blended cement mortars.
Materials
The findings of an extensive experimental research study on the usage of nano-sized cement powder and other additives combined to form cement–fine-aggregate matrices are discussed in this work. In the laboratory, dry and wet methods were used to create nano-sized cements. The influence of these nano-sized cements, nano-silica fumes, and nano-fly ash in different proportions was studied to the evaluate the engineering properties of the cement–fine-aggregate matrices concerning normal-sized, commercially available cement. The composites produced with modified cement–fine-aggregate matrices were subjected to microscopic-scale analyses using a petrographic microscope, a Scanning Electron Microscope (SEM), and a Transmission Electron Microscope (TEM). These studies unravelled the placement and behaviour of additives in controlling the engineering properties of the mix. The test results indicated that nano-cement and nano-sized particles improved the engineering properties of the hardened...
Use of nano-silica in cement based materials—A review
The research nowadays is mainly focusing on the basic science of cementitious material at nano/atomic level. Further, researchers are continuing to improve the durability and sustainability of concrete and have realized significant increment in mechanical properties of cementitious materials by incorporating nano-silica. The review paper summarizes the effect of nano-silica addition on mechanical, durability and microstructure characteristics of paste, mortar and concrete. It provides the current development of application of nano-silica in paste, mortar and concrete. Finally, the future trend/potential and implication of nanosilica in cement-based materials is discussed. Their areas of interest include use of nanosilica in concrete, its study of mechanical and durability properties. High-performance concrete, self-compacting concrete, their performance and durability aspects incorporating industrial by-products. Cement is one of the most energyconsuming materials widely used globally. Efforts are being made mainly to use supplementary cementitious materials in mortars and concrete directed towards the reduction of carbon footprint. The present research work is one such effort towards attaining the above goal.
Construction and Building Materials, 2012
Mineralogical analysis done on Spanish Portland cement Type I pastes, blended with nanosilica was carried out by conventional and high-resolution thermogravimetric analysis (TG-HRTG) and X-ray diffraction (XRD) in order to determine the quantity of the different mineralogical phases obtained during the hydration process. Simultaneously, mortars with the same materials and replacement ratio were made in order to assess their compressive strength for up to 28 days of curing time. In this paper, the rate and quantity of each one of the main constituent phases of the cement during its hydration process (C-S-H, ettringite, portlandite, stratlingite, etc.) were determined. A correlation between the quantity of C-S-H and the development of compressive strength was established. Additionally, the pozzolanic activity of nanosilica was evaluated by quantifying the fixation of calcium hydroxide and its impact on the development of the compressive strength.
Individual and Combined Effect of Nano- and Microsilica on Cement-Based Product
2020
In the cement concrete industry, everybody is concerned about high-strength and high-performance behavior of concrete. These properties were improved using micro- and nano-sized pozzolanic mineral admixtures as stated by various authors. In this paper, author has emphasized mostly on using micro- and nanosilica materials with cement. Literature survey revealed that the most suited mineral admixtures for getting highest behaviors are micro- and nanosilica. Nanotechnology is nowadays a buzzword in everyone’s tips. Nanotechnology in concrete means the addition of nano-sized materials in the range of 1 and 100 nm to improve the behavior of cement and concrete. Micro- and nano-sized silica particles improve the porous behavior of concrete and also produce more calcium silicate hydrate resulting from chemical reaction of nanoparticles and calcium hydroxide. On the other hand, it makes concrete more compact in microstructure point of view, which improves density, strength, and also durabil...