Faiz Shaikh

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Hemp Fabric Reinforced Organoclay–Cement Nanocomposites: Microstructures, Physical, Mechanical and Thermal Properties

SpringerBriefs in Molecular Science, 2017

This chapter presents the micro-structural characterisation, physical, mechanical and thermal pro... more This chapter presents the micro-structural characterisation, physical, mechanical and thermal properties of nanoclay-cement nanocomposites fabricated and tested at 56 days. The influence of nanoclay on properties of hemp fabric-reinforced cement composites is also presented in this chapter. Two layers of hemp fabric (HF) were used and the total amount of hemp fabric in each specimen was about 2.5 wt%.

Dynamic compressive properties of high volume fly ash (HVFA) concrete with nano silica

Construction and Building Materials, 2021

Abstract High Volume Fly Ash (HVFA) concrete enables the utilization of fly ash (FA) to diminish ... more Abstract High Volume Fly Ash (HVFA) concrete enables the utilization of fly ash (FA) to diminish greenhouse gas emission by decreasing the demand of ordinary Portland cement. Structures made of HVFA concrete, such as roadside barriers, tunnel cushions and building walls could be subjected to impact and blast loads during service life. Thus, dynamic performance of HVFA concrete is worthy of investigating for better analysis and design of concrete structures. This paper presents the quasi-static and dynamic properties of HVFA concrete containing FA contents of 40 and 60% (by wt.) as partial replacement of cement. The effect of 2% (by wt.) nano silica (NS) on the quasi-static and dynamic properties of HVFA concrete is also studied. The dynamic compressive tests are carried out by using a split Hopkinson pressure bar (SHPB) with 100 mm diameter. The failure processes and patterns as well as stress–strain curves of plain and HVFA concretes under different strain rates are compared. The strain rate effects on the compressive strength, modulus of elasticity and energy absorption capacities are analysed. The experimental results show that quasi-static and dynamic performances of HVFA concrete are enhanced by the addition of NS. With the increase of FA content, the damage level becomes more severe, and modulus of elasticity and energy absorption capacities of HVFA concretes become lower at the similar strain rate. Dynamic increase factors (DIF) of compressive strength for HVFA concretes are quantified and compared with the empirical formulae recommended by Euro-International Committee for Concrete (CEB) for normal concrete. Adding NS leads to lower DIF for compressive strength of HVFA concrete. Empirical formulae for DIF of compressive strength, modulus of elasticity and energy absorption capacity of HVFA concretes with and without nano silica as a function of strain rate are proposed. It is worth noting that the NS modified HVFA C60F38N2 in this study has higher compressive strength, modulus of elasticity and energy absorption capacity than the plain concrete (PC), which shows the potential to replace the normal concrete as a sustainable construction material.

Correction to: Durability properties of high volume fly ash concrete containing nano-silica

Materials and Structures, 2021

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Experimental and numerical study on structural behaviour of tyre-bale sandwich wall under different loading conditions

Australian Journal of Structural Engineering, 2021

Materials for infrared domes are required to maintain good properties in harsh environments inclu... more Materials for infrared domes are required to maintain good properties in harsh environments including mechanical strength, optical transmittance over a wide range of wavelengths and low emissivity. The purpose of this work is to sputter Y 2 O 3 film onto a sapphire substrate by a radio frequency magnetron sputtering method and investigate the structural and thermal radiation properties of the films. In addition, the apparent emissivity of the coated sapphire is simulated for different film thicknesses at different temperatures. The experimental results show that the surface of the Y 2 O 3 film is homogeneous, has a dense morphology and is totally polycrystalline. After being coated with the Y 2 O 3 film, the transmission of the sapphire substrate is improved and the emissivity is decreased with increasing film thickness, especially at high temperatures. Simulation results show that apparent emissivity of a sapphire substrate at high temperatures can be reduced effectively by the Y 2 O 3 film when the ratio of the thickness of Y 2 O 3 film and sapphire substrate is larger than 0.01.

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Effect of nano SiO2 on mechanical properties of micro-steel fibers reinforced geopolymer composites

Ceramics International, 2021

Abstract This paper presents the mechanical properties of micro steel fiber reinforced fly ash ge... more Abstract This paper presents the mechanical properties of micro steel fiber reinforced fly ash geopolymer composites containing different amounts of nano-silica. Four different fly ash-based geopolymer composites (GPC) are prepared by using a fixed amount of micro-steel fibers (0.5% by weight) and four different amounts of nano silicon dioxide (SiO2) consisting of 0%, 1%, 2%, and 3% amounts by weight. The GPC with 0% nano SiO2 having 0.5% micro-steel fibers is taken as the control mix. Different mechanical and microstructural properties of fabricated GPC are examined by assessing their stress-strain behavior, compressive strength, flexural strength, bending load-deflection behavior, impact strength, fracture toughness, toughness modulus, elastic modulus, toughness indices, hardness, and scanning electron microscopy (SEM). The outcomes of tests depicted that the addition of nano SiO2 significantly enhanced the mechanical properties and microstructure of micro-steel fiber-reinforced GPC by producing a denser matrix and refining the interfacial zones. According to the results of this study, the recommended amount of nano SiO2 to be utilized in GPC for the optimal behavior is 2%.

Flexural behavior of hybrid PVA fibers reinforced ferrocement panels at elevated temperatures

Fire and Materials, 2018

Mine tailings-based geopolymers: Properties, applications and industrial prospects

Ceramics International, 2021

Abstract The use of mine tailings (MTs) as aggregates or precursors of alkali-activated materials... more Abstract The use of mine tailings (MTs) as aggregates or precursors of alkali-activated materials and geopolymers (GPs) seems to be a promising approach for their sustainable utilization since it allows not only reducing the dynamics of MTs accumulation in the environment and the environmental damage they cause but also it combines the advantages geopolymer technology that is associated with reducing the carbon footprint, the ability to utilize other technogenic aluminosilicate waste, the versatility of the properties of GPs as a general construction binder. Taking into account the complex material composition of mine tailings, and relatively little knowledge of the features of the geopolymerization of tailings and the influence of various factors on the properties of MTs-based geopolymers, there is now a need to generalize these aspects and assess the prospects for possible applications. This article is a generalization and a detailed analysis of the relationship between structural, mechanical, and thermal properties, durability, leaching behavior, and other important characteristics of MTs-based geopolymers. Here, in addition to the key fundamental aspects of the formation of properties of MTs based geopolymers, well-known examples of their applications in binder pastes, mortars, and concretes, as well as bricks, backfill materials, adsorbents, porous materials, and other promising applications are considered in detail. In addition, economic and production aspects are also discussed.

Characterization and properties of geopolymer nanocomposites with different contents of nano-CaCO3

Construction and Building Materials, 2020

Abstract This study investigated the impact of calcium carbonate nanoparticles (nano-CaCO3) on th... more Abstract This study investigated the impact of calcium carbonate nanoparticles (nano-CaCO3) on the mechanical properties of geopolymer composites. To that end, varying contents of nano-CaCO3 were mixed with geopolymer paste. On the other hand, mechanical properties were investigated based on three aspects: flexural and compressive strengths, impact strength, and hardness. According to the findings of this study, nano-CaCO3 could be efficacious in improving all the mechanical properties of geopolymer. Microstructures of the geopolymer mixed with nano-CaCO3 were also evaluated by scanning electron microscopy (SEM). According to the findings, nanoparticles could potentially enhance the mechanical performance of the geopolymer nanocomposites. In addition, the SEM micrographs of fractured surfaces were found to exhibit a greater packed structure with a reduced number of pores of the geopolymer that contained nano-CaCO3; this, in turn, enhanced the strength of geopolymer nanocomposite specimens.

Environmental assessment of supplementary cementitious materials and engineered nanomaterials concrete

AIMS Environmental Science, 2020

Concrete has been one of the most common building materials used in construction in the world for... more Concrete has been one of the most common building materials used in construction in the world for many centuries. The manufacturing of concrete plays an important role in the generation of global warming emissions and waste and causes non-renewable resource depletion. This research assesses the environmental impacts of the use of supplementary cementitious materials (SCMs) and engineered nanomaterials (ENMs) (i.e., by-products) as partial replacement of ordinary Portland cement in concrete. It also evaluates the structural performance of the use of construction and demolition waste as partial replacement of natural aggregate in concrete in terms of compressive strength and durability. Results show that the use of SCMs and ENMs reduces the global warming impact (GWI) and the cumulative energy demand (CED) of concrete production without reducing strength and durability. In some cases, it enhances durability and strength. However, there is a tradeoff between durability and strength improvement with the use of reengineered by-products resulting in increased GWI and CED. Although they produce almost the same GWI and CED as those of OPC concrete, improving the use of recycled aggregates as a partial natural aggregate replacement can reduce the use of virgin materials.

Effect of nano silica and fine silica sand on compressive strength of sodium and potassium activators synthesised fly ash geopolymer at elevated temperatures

Fire and Materials, 2017

Influence of Nano Silica Particles on Durability of Flax Fabric Reinforced Geopolymer Composites

Materials, 2019

The durability of natural fibres as reinforcement in geopolymer composites continues to be a matt... more The durability of natural fibres as reinforcement in geopolymer composites continues to be a matter of concern due to the alkalinity of activators of geopolymer matrices. The alkaline environment is the main reason for natural fibres degradation in cementitious matrices. This paper presents the influence of nano silica (NS) on the durability and mechanical performance of geopolymer composites that are reinforced with flax fabric (FF). The durability investigations were conducted after the storage of samples at ambient temperature for 32 weeks. The study revealed that the addition of nano silica has a positive influence on the physical and mechanical properties of these composites. The presence of NS accelerated the geopolymeric reaction and lowered the alkalinity of the system, thus reducing the degradation of flax fibres.

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Behaviour of Carbon and Basalt Fibres Reinforced Fly Ash Geopolymer at Elevated Temperatures

International Journal of Concrete Structures and Materials, 2018

This paper presents the behaviour of potassium activators synthesized fly ash geopolymer containi... more This paper presents the behaviour of potassium activators synthesized fly ash geopolymer containing carbon and basalt fibre at ambient and elevated temperature. Six series of fly ash based geopolymer were cast where carbon and basalt fibre were added as 0.5, 1 and 1.5% by weight of fly ash. One extra control series without any fibre was also cast. Each series of samples were tested at ambient temperature and also heated at 200, 400, 600 and 800°C and thus a total of 35 series of samples were tested in this study. The result shows that the geopolymer containing 1 wt% basalt and 1 wt% carbon fibre exhibited better compressive strength, lower volumetric shrinkage and mass loss than other fibre contents. Among two fibres composites, the carbon fibre geopolymer exhibited better performance than its basalt fibre counterpart regardless of temperature. The microstructure of carbon fibre reinforced geopolymer composite is more compact containing fewer pores/voids than its basalt based counterpart at elevated temperatures. The results also support the fact that carbon fibre is better than basalt fibre at elevated temperature and showed better bonding with geopolymer at elevated temperature.

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Effect of mixing methods of nano silica on properties of recycled aggregate concrete

Structural Concrete, 2017

Effect of micro-silica on mechanical and durability properties of high volume fly ash recycled aggregate concretes (HVFA-RAC)

Advances in concrete construction, 2015

This paper presents the effect of different micro-silica (MS) contents of 5, 10 and 15 wt.% as pa... more This paper presents the effect of different micro-silica (MS) contents of 5, 10 and 15 wt.% as partial replacement of cement on mechanical and durability properties of high volume fly ash-recycled aggregate concretes (HVFA-RAC) containing 50% class F fly ash (FA) and 35% recycled coarse aggregate (RCA) as partial replacement of cement and natural coarse aggregate (NCA), respectively. The measured mechanical and durability properties are compressive strength, indirect tensile strength, elastic modulus, drying shrinkage, water sorptivity and chloride permeability. The effects of different curing ages of 7, 28, 56 and 91 days on above properties are also considered in this study. The results show that the addition of MS up to 10% improved the early age (7 days) strength properties of HVFA-RAC, however, at later ages (e.g. 28-91 days) the above mechanical properties are improved for all MS contents. The 5% MS exhibited the best performance among all MS contents for all mechanical properties of HVFA-RAC. In the case of measured durability properties, mix results are obtained, where 10% and 5% MS exhibited the lowest sorptivity and drying shrinkage, respectively at all ages. However, in the case of chloride ion permeability a decreasing trend is observed with increase in MS contents and curing ages. Strong correlations of indirect tensile strength and modulus of elasticity with square root of compressive strength are also observed in HVFA-RAC. Nevertheless, it is established in this study that MS contributes to the sustainability of HVFA-RAC significantly by improving the mechanical and durability properties of concrete containing 50% less cement and 35% less natural coarse aggregates.

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Comparative study of sodium and potassium based fly ash geopolymer at elevated temperatures

Proceedings of the Second International Conference on Performance-based and Life-cycle Structural Engineering (PLSE 2015), 2015

This paper presents the effects of sodium and potassium based activators on compressive strengths... more This paper presents the effects of sodium and potassium based activators on compressive strengths and physical changes of class F fly ash geopolymer exposed to elevated temperatures. Samples were heated at 200 0 C, 400 0 C, 600 0 C and 800 0 C to evaluate the residual compressive strength after 28 days of curing. The fly ash geopolymer were synthesized with combined sodium silicate and sodium hydroxide solutions and potassium silicate and potassium hydroxide solutions by varying mass ratios of Na2SiO3/NaOH and K2SiO3/KOH of 2, 2.5 and 3. Results show that in the cases of Na2SiO3/NaOH ratios of 2 and 2.5, the compressive strengths of geopolymers are decreased at 400, 600 and 800 o C, with exception at 200 o C. The reduction is significantly high from 32-61% at 800 o C compared to ambient temperature strength. However, significant improvement is noticed in the case of Na2SiO3/NaOH ratio of 3, where the residual compressive strengths are increased upto 600 o C. Better results on the geopolymer synthesized with potassium based activators are obtained where the residual compressive strength up to 600 o C are much higher than their sodium based counterparts. The geopolymer containing K2SiO3/KOH ratio of 3 even gained about 5% strength at 800 o C. It is also found that the fly ash geopolymer synthesized with potassium based activators is more stable at elevated temperatures than its sodium based counterparts in terms of higher residual compressive strengths, lower mass loss, lower volumetric shrinkage and lower cracking damage.

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Corrosion Durability of Reinforcing Steel in Cracked High-Performance Fiber-Reinforced Cementitious Composite Beams

Journal of Materials in Civil Engineering, 2015

AbstractThis paper reports test results on the corrosion durability of reinforcing steel in three... more AbstractThis paper reports test results on the corrosion durability of reinforcing steel in three series of precracked beams of ordinary mortar; a high-performance fiber-reinforced cementitious composite (HPFRCC) containing polyethylene (PE) fibers, referred as mono HPFRCC; and hybrid combinations of steel cord (SC) and PE fibers, referred as hybrid HPFRCC. In each series three precracked beams with a maximum crack width of 0.1–0.5 mm were tested. All beams were subjected to an accelerated corrosion regime consisting of applying constant 3-V DC potential across rebar (anode) and cathode and cyclic wetting and drying cycles. The durability performance of the specimens was examined through regular monitoring of corrosion current—hence, the calculated steel loss, the corrosion-induced damage measured by the longitudinal crack width and through visual inspection. At the end of the corrosion tests, the reinforcing bars in all specimens were exposed to observe the corrosion depth, corroded area, actual amount o...

Influence of the type of activator combinations on the deflection hardening behavior of geopolymer composites

ABSTRACT This paper presents the effects of two different sodium-based (Na-based) and potassium b... more ABSTRACT This paper presents the effects of two different sodium-based (Na-based) and potassium based (K-based) activator combinations on the properties of a recently developed fly ash based ductile fiber reinforced geopolymer composite (DFRGC) exhibiting deflection hardening and multiple cracking behavior in flexure. Experimental results revealed that although the potassium-based DFRGC (DFRGC-K) exhibited superior matrix workability; however, the sodium-based DFRGC (DFRGC-Na) exhibited superior deflection capacity, compressive and flexural strengths with significantly enhanced composite ductility and toughness.

Strain Hardening Behavior of Engineered Geopolymer Composites: Effects of the Activator Combination

Fly ash-based engineered geopolymer composites (EGCs) exhibiting strain hardening behavior under ... more Fly ash-based engineered geopolymer composites (EGCs) exhibiting strain hardening behavior under uni-axial tension were developed employing two different sodium-based (Na-based) and potassium-based (K-based) activator combinations. The relatively brittle low calcium (Class F) fly ash-based geopolymer matrix was reinforced with randomly oriented short poly vinyl alcohol (PVA) fibers (2% v/v). Na-based activator combination was composed of 8.0 M NaOH solution (28.6% w/w) and Na 2 SiO 3 solution (71.4% w/w) with a SiO 2 /Na 2 O ratio of 2.0; whereas, K-based activator combination was composed of 8.0 M KOH solution (28.6% w/w) and K 2 SiO 3 solution (71.4% w/w) with a SiO 2 /K 2 O ratio of 2.23. The matrix and composite properties of the developed fly ash-based EGCs including workability of the fresh matrix, density, compressive strength and uni-axial tensile behavior were evaluated. The experimental results revealed that the sodium-based EGC (EGC-Na) exhibited superior tensile strain capacity, compressive and uni-axial tensile strengths with significantly enhanced ductility.

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Effect of cooling methods on residual compressive strength and cracking behavior of fly ash concretes exposed at elevated temperatures

Fire and Materials, 2014

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Comparative deflection hardening behavior of short fiber reinforced geopolymer composites

Construction and Building Materials, 2014

h i g h l i g h t s Ductile fiber reinforced geopolymer composites (DFRGCs) were demonstrated. Ma... more

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