Beneficial role of nanosilica in cement based materials – A review

https://estudogeral.sib.uc.pt/bitstream/10316/80382/1/1-s2.0-S0261306914001691-main.pdf

The effect of nanosilica addition on flowability, strength and transport properties of ultra high performance concrete

Sol-Gel processing of silica nanoparticles and their applications.

An experimental survey on combined effects of fibers and nanosilica on the mechanical, rheological, and durability properties of self-compacting concrete

The effect of Colloidal Nano-silica on workability, mechanical and durability properties of High Performance Concrete with Copper slag as partial fine aggregate

Effect of colloidal nano-silica on the mechanical and physical behaviour of waste-glass cement mortar

Worldwide, around 2.6 billion tons of cement is produced annually. This huge size of production consumes large amounts of energy and is one of the largest contributors to carbon dioxide (CO 2 ) release. Accordingly, there is a pressing demand to minimise the quantity of cement used in the concrete industry. The main challenge to this is to get durable concrete with less cement and within reasonable cost. The economic, environmental and engineering benefits of reusing ground waste-glass powder (WGP) as a partial cement replacement has been established, but low glass reactivity and the possible alkali–silica reaction (ASR) are a drawback. Recent advances in nano-technology have revealed that nano-sized particles such as nano clay (NC) have a high surface area to volume ratio that provides the potential for tremendous chemical reactivity, accelerating pozzolanic activity and hindering ASR. This paper presents a laboratory study of the properties of NC/WGP cement composites. The microstructure, ASR, fracture energy, compressive and flexural properties of cement mortars containing WGP as a cement replacement with and without NC are investigated and compared with plain matrix. In addition, the hydration of cement compounds was followed by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and also X-ray diffraction (XRD). The results showed that incorporation of glass powder has a positive effect on the mechanical properties of cement mortars after 28 days of hydration. Also, the results revealed that the mechanical properties of the cement mortars with a hybrid combination of glass powder and NC were all higher than those of plain mortar and with glass powder after 28 days of hydration. In addition, the DTA/TGA results and XRD analysis showed a reduction in the calcium hydroxide (CH) content in mortars with glass powder and with a hybrid combination of glass powder and NC, which confirms the improvements of mechanical properties and occurrence of pozzolanic reaction after 28 days of hydration.

Effect of nano clay particles on mechanical, thermal and physical behaviours of waste-glass cement mortars

Flax fibers, along with a number of other plant fibers, are rich in cellulose, are relatively cheap, have low density, are highly biodegradable, and are easily renewable with the potential for many composites' reinforcement. However, natural fibers are hydrophilic in nature and covered with waxy substances and pectin, which obstruct the hydroxyl groups from reacting with most binder materials, making it less attractive for reinforcement in polymer composites. Natural fibers are, therefore, usually subjected to alkaline treatment to bleach the fiber surface, swell the cell wall to enable large chemical molecules to penetrate the crystalline region, stop the moisture absorption, and increase the surface roughness. The main goal of this work is to study the effect of the alkaline treatment conditions on the mechanical properties of flax fiber. The effect of treatment parameters such as NaOH concentration, soaking time, and treatment temperature on single fiber tensile strength (TS) and Youn's Modulus (YM) wa...

Optimization of Alkaline Treatment Conditions of Flax Fiber Using Box–Behnken Method

The main concern for natural fibres reinforced cement composites (NFRC) is the durability of the fibres. The alkalinity of the cement matrix is the main causes of the loss of resistance of NFRC. The aim of this work was to determine the effect of partial replacement of Ordinary Portland cement (OPC) by finely ground waste glass powder (WG) and nano clay particles (NC) on the mechanical performance and durability of flax fibre reinforced cement composites (FRC). Tests were designed to study the alkali-silica reaction (ASR), X-ray diffraction analysis (XRD), differential thermal analysis (DTA) and the mechanical performance of the composites. Additionally, the durability of the composites aged under wetting and drying cycles are presented. The results show that incorporation of WG has a positive effect on the mechanical properties and durability of FRC especially when NC is presented. In addition, the DTA results and XRD analysis show a reduction in the calcium hydroxide (CH) content in mortars with both WG and a hybrid combination of WG and NC. This confirms the improvement of mechanical properties and the occurrence of the pozzolanic reaction after 28 days of hydration.

Effect of nano-clay and waste glass powder on the properties of flax fibre reinforced mortar

Pyrolysis has been demonstrated to be a highly effective thermochemical process for converting complex biomaterials into biochar and syngas rich in hydrogen. The pyrolysis of mixed date palm seeds from Saudi Arabia was conducted using a fixed-bed pyrolyzer that was custom made for the purpose. The influence of the pyrolysis temperature (200–1000 °C) on the various physicochemical parameters of the date seed biochar generated through the pyrolysis process and the hydrogen-rich syngas was investigated. Proximate and ultimate analyses indicated a high carbon content in the lignocellulosic constituents such as cellulose, hemicellulose, and lignin. Using energy-dispersive X-ray (EDX) analysis, it was discovered that the elemental composition of biochar changes with the pyrolysis temperature. The date seeds pyrolyzed at 800 °C were found to have the maximum carbon concentration, with 97.99% of the total carbon content. The analysis of the biochar indicated a high concentration of carbon, as well as magnesium and potassium. There was a potential for the production of hydrogen-rich syngas, which increased with the pyrolysis temperature. At 1000 °C, the highest hydrogen and carbon monoxide compositions of 40 mol% and 32 mol%, respectively, were obtained. The kinetic data of the date seed pyrolysis were fitted using linearized model-free methods, such as Friedman, Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS), as well as non-linear methods such as Vyazovkin and advanced Vyazovkin. The activation energies obtained from Friedman, FWO, and KAS varied in the range of 30–75 kJ/mol, 30–65 kJ/mol, and 30–40 kJ/mol, respectively, while those of Vyazovkin and advanced Vyazovkin were found in the range of 25–30 kJ/mol, and 30–70 kJ/mol, respectively. The analysis showed that the FWO and KAS models show smaller variation compared to Friedman.

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A. I. Hussain

Papers

Effect of colloidal nano-silica on the mechanical and physical behaviour of waste-glass cement mortar

Effect of nano clay particles on mechanical, thermal and physical behaviours of waste-glass cement mortars

Optimization of Alkaline Treatment Conditions of Flax Fiber Using Box–Behnken Method

Effect of nano-clay and waste glass powder on the properties of flax fibre reinforced mortar

Hydrogen-Rich Syngas and Biochar Production by Non-Catalytic Valorization of Date Palm Seeds