Strength and Durability of Hybrid Fibre Reinforced Binary Blend Geopolymer Concrete

This paper deals with an investigation on the influence of hybrid fibres on the strength and durability of binary blend geopolymer concrete. Geopolymer concrete was prepared using Fly ash and GGBS as source material and mix design was carried out as per the guidelines of Professor Rangan of Curtin University, Australia. Different fly ash-GGBS proportions namely 50-50%, 60-40%, 70-30%, 80-20% and 90-10% were considered. The tests on Geopolymer concrete reveal that the compressive strength increases as the percentage of GGBS increases up to 30%. Hence the combination of 70% fly ash and 30% GGBS was considered as a base material. In order to improve the engineering properties of the Geopolymer concrete, hybrid fibres which consist of metallic and non-metallic fibres were introduced in the base material. Metallic fibres considered was crimped steel fibres with different percentages of volume fraction viz. 0.5% and 1.0% and non-metallic fibres considered was basalt fibres with different percentages of volume fraction viz. 0.1%, 0.2% and 0.3%. Strength parameters such as compressive strength, split tensile strength, modulus of rupture and modulus of elasticity were obtained for various combinations of steel and basalt fibres. Similarly durability parameters which include permeability, water absorption, marine attack and sulphuric acid attack were also evaluated. The combination of fibres having 0.5% steel and 0.3% basalt gave better results with regard to both strength and durability of binary blend Geopolymer concrete

"Mother-weights" and lost fathers: parents in South Asian American literature

That parent-child relationships should play a significant role within South Asian American literature is perhaps no surprise, since this is crucial material for any writer. But the particular forms they so often take – a dysfunctional mother-daughter dynamic, leading to the search for maternal surrogates; and the figure of the prematurely deceased father – are more perplexing. Why do families adhere to these patterns in so many South Asian American texts and what does that tell us about this œuvre? More precisely, why are mothers subjected to a harsher critique than fathers and what purpose does this critique serve? How might we interpret the trope of the untimely paternal death? In this article I will seek to answer these questions – arguably key to an understanding of this growing body of writing – by considering works produced between the 1990s and the early twenty-first century by a range of South Asian American writers

Multimodality imaging of transient perivascular inflammation of carotid artery (TIPIC) syndrome: a case report

Abstract Background Transient Perivascular Inflammation of Carotid artery syndrome is a rare clinicoradiological entity characterized by inflammation of the carotid artery wall with surrounding perivascular inflammatory changes. This is a self-limiting condition and necessitates awareness and high degree of suspicion to differentiate from other serious pathologies involving the carotid artery. Case presentation A middle aged asian male patient presented with acute onset of intense pain in the right lateral aspect of neck. Ultrasonography and Magnetic Resonance Imaging showed wall thickening of the common carotid artery and carotid bulb with surrounding inflammation in the perivascular soft tissues. He was treated with brief course of oral anti-inflammatory medications. The patient’s symptoms improved and imaging findings resolved in 2 weeks. Conclusions Being infrequently encountered in clinical practice, recognition of transient perivascular inflammation of carotid artery syndrome by the physician is of prime importance. Prompt radiological investigation and follow-up imaging are crucial for accurate diagnosis, thereby leading to appropriate treatment

Engineering Properties of Hybrid Fibre Reinforced Ternary Blend Geopolymer Concrete

The primary aim of this research is to find an alternative for Portland cement using inorganic geopolymers. This study investigated the effect of steel and polypropylene fibres hybridisation on ternary blend geopolymer concrete (TGPC) engineering properties using fly ash, ground granulated blast furnace slag (GGBS) and metakaolin as the source materials. The properties like compressive strength, splitting tensile strength, flexural strength and modulus of elasticity of ternary blend geopolymer concrete. The standard tests were conducted on TGPC with steel fibres, polypropylene fibres and a combination of steel and polypropylene fibres in hybrid form. A total number of 45 specimens were tested and compared to determine each property. The grade of concrete considered was M55. The variables studied were the volume fraction of fibres, viz. steel fibres (0%, 0.5% and 1%) and polypropylene fibres (0%, 0.1%, 0.15%, 0.2% and 0.25%). The experimental results reveal that the addition of fibres in a hybrid form enhances the mechanical properties of TGPC. The increase in the compressive strength was nominal, and a significant improvement was observed in splitting tensile strength, flexural strength, and modulus of elasticity. Also, an attempt to obtain the relation between the different engineering properties was made with different volume fractions of fibre

Behaviour of Hybrid Fibre-Reinforced Ternary Blend Geopolymer Concrete Beam-Column Joints under Reverse Cyclic Loading

Beam–column joints are extremely vulnerable to lateral and vertical loads in reinforced concrete (RC) structures. This insufficiency in joint performance can lead to the failure of the whole structure in the event of unforeseen seismic and wind loads. This experimental work was conducted to study the behaviour of ternary blend geopolymer concrete (TGPC) beam-column joints with the addition of hybrid fibres, viz., steel and polypropylene fibres, under reverse cyclic loads. Nine RC beam-column joints were prepared and tested under reverse cyclic loading to recreate the conditions during an earthquake. M55 grade TGPC was designed and used in this present study. The primary parameters studied in this experimental investigation were the volume fractions of steel fibres (0.5% and 1.0%) and polypropylene fibres, viz., 0.1 to 0.25%, with an increment of 0.05%. In this study, the properties of hybrid fibre-reinforced ternary blend geopolymer concrete (HTGPC) beam-column joints, such as their ductility, energy absorption capacity, initial crack load and peak load carrying capacity, were investigated. The test results imply that the hybridisation of fibres effectively enhances the joint performance of TGPC. Also, an effort was made to compare the shear strength of HTGPC beam-column connections with existing equations from the literature. As the available models did not match the actual test results, a method was performed to obtain the shear strength of HTGPC beam-column connections. The developed equation was found to compare convincingly with the experimental test results

Influence of Steel Fibers on the Interfacial Shear Strength of Ternary Blend Geopolymer Concrete Composite

Sustainable development is a major issue confronting society today. Cement, a major constituent of concrete, is a key component of any infrastructure development. The major drawback of cement production is that it involves the emission of CO2, the predominant greenhouse gas causing global warming. The development of geopolymers has resulted in a decrease in cement production, as well as a reduction in CO2 emissions. During mass concrete production in the construction of very large structures, interfaces/joints are formed, which are potential failure sites of crack formation. Concrete may interface with other concrete of different strengths, or other construction materials, such as steel. To ensure the monolithic behavior of composite concrete structures, bond strength at the interface should be established. The monolithic behavior can be ensured by the usage of shear ties across the interface. However, an increase in the number of shear ties at the interface may reduce the construction efficiency. The present study aims to determine the interfacial shear strength of geopolymer concrete as a substrate, and high-strength concrete as an overlay, by adding 0.50%, 0.75%, and 1% crimped steel fibers, and two and three shear ties, at the interface of push-off specimens. It was found that three shear ties at the interface can be replaced by two shear ties and 0.75% crimped steel fibers. In addition, a method was proposed to predict the interface shear strength of the concrete composite, which was found to be comparable to the test results

Influence of Steel Fibers on the Interfacial Shear Strength of Ternary Blend Geopolymer Concrete Composite

Sustainable development is a major issue confronting society today. Cement, a major constituent of concrete, is a key component of any infrastructure development. The major drawback of cement production is that it involves the emission of CO2, the predominant greenhouse gas causing global warming. The development of geopolymers has resulted in a decrease in cement production, as well as a reduction in CO2 emissions. During mass concrete production in the construction of very large structures, interfaces/joints are formed, which are potential failure sites of crack formation. Concrete may interface with other concrete of different strengths, or other construction materials, such as steel. To ensure the monolithic behavior of composite concrete structures, bond strength at the interface should be established. The monolithic behavior can be ensured by the usage of shear ties across the interface. However, an increase in the number of shear ties at the interface may reduce the construction efficiency. The present study aims to determine the interfacial shear strength of geopolymer concrete as a substrate, and high-strength concrete as an overlay, by adding 0.50%, 0.75%, and 1% crimped steel fibers, and two and three shear ties, at the interface of push-off specimens. It was found that three shear ties at the interface can be replaced by two shear ties and 0.75% crimped steel fibers. In addition, a method was proposed to predict the interface shear strength of the concrete composite, which was found to be comparable to the test results

Tribological Analysis of Jute/Coir Polyester Composites Filled with Eggshell Powder (ESP) or Nanoclay (NC) Using Grey Rational Method

The wear performance of jute/coir unsaturated polyester composites, filled with eggshell powder (ESP) and nanoclay (NC), were examined, concentrating on two measured parameters, coefficient of friction (COF) and wear rate (WR). To assess the possibilities of this material, a Taguchi study, based on grey relational analysis (GRA), was carried out, based on three testing parameters of the wear performance, load (10, 20, and 30 N), speed (100, 150, and 200 rpm), and sliding distance (30, 40, and 50 m). The material showed promising characteristics especially at high load, low speed, and high sliding distance. When comparing the respective influence of the three different parameters, the speed proved to be the most critical, this suggested the possible application of the biocomposite only for very low values of it. On the other hand, it was also elucidated that the presence and interfacial adhesion of the two fillers considerably hindered the formation of ploughing during wear test, despite the fact that degradation might be continuous and critical as far as loading progresses

Thermodynamic study of the cerium–cadmium system

Cadmium vapor pressures were determined over Ce–Cd samples by an isopiestic method. The measurements were carried out in the temperature range from 690 to 1080 K and over a composition range of 48–85 at% Cd. From the vapor pressures thermodynamic activities of Cd were derived for all samples at their respective sample temperatures, and partial molar enthalpies of Cd were obtained from the temperature dependence of the activities. With these partial molar enthalpies the Cd activities were converted to a common temperature of 823 K. By means of a Gibbs–Duhem integration Ce activities were calculated, using a corresponding literature value for the two-phase field (CeCd₁₁+L) as integration constant. Finally integral Gibbs energies were calculated for the composition range 48–100 at% Cd with a minimum value of −37 kJ g-atom⁻¹ at 823 K in the phase CeCd. Phase boundaries of the intermetallic compounds CeCd, CeCd₂, Ce₁₃Cd₅₈, and CeCd₁₁ were estimated from the vapor pressure measurements and from SEM analyses