Waste Materials and Composites Research Papers (original) (raw)

Development of asbestos-free brake pad using sawdust was study with a view to replace the use of asbestos whose dust is carcinogenic.
The sawdust was sieve into sieve grades of 100,280,355μm and 1mm. The sieve sawdust was used in production of brake pad in ratio of 20% resin, 10%
graphite, 15% steel, 35-55% sawdust and 0-20% SiC using compression moulding. The properties examined are microstructure analysis, hardness,
compressive strength, density, flame resistance, water absorption. The microstructure reveals uniform distribution of resin in sawdust. The results obtained
showed that the finer the sieve size the better the properties. The results obtained in this work were compared with that of commercial brake pad (asbestos
based and optimum formulation laboratory brake pad sawdust based; the results are in close agreement. Hence sawdust can be used in production of
asbestos-free brake pad.

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- Waste Materials and Composites

In recent years the use of composite materials in structural components has become increasingly common in a wide range of engineering applications. Composite materials offer numerous advantages over more conventional materials because of their superior specific properties, but a serious obstacle to a more widespread use of these materials is their high sensitivity to localized impact loading. This paper presents an experimental study to assess the impact response of drop weight impact tests on fiber reinforced polymer composites with different load and damage identification of composite using Non-destructive testing techniques ultrasonic testing (UT) C scan. In the study includes checking the strength of the specimen, plotting of graphs between the height and the impact energy obtained and tabulating the results after conducting the various functional tests.

Geopolymers are amorphous to semi crystalline polymeric products formed by the alkali activation of alumino-silicate materials with alkaline silicate solution at ambient or slightly elevated temperatures, which can be used as alternative to ordinary cement. In this paper, the feasibility of geopolymer binder from terracotta roof tile waste was investigated by varying different parameters like concentration of sodium hydroxide, proportion of sodium silicate to sodium hydroxide solution, alkaline activator to binder ratio and elevated temperature curing. Strength characteristics of geopolymer mortars at 7 and 28 days were investigated and SEM analysis was conducted for establishing the feasibility of roof tile powder waste as a potential source of geopolymer.

- by Deepa G Nair
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- Waste Materials and Composites, Geopolymer Cement

a b s t r a c t
Morphology and mechanical properties of coconut shell particles reinforced epoxy composites were
evaluated to assess the possibility of using it as a new material in engineering applications. Coconut
shell filled composites were prepared from epoxy polymer matrix containing up to 30 wt% coconut shell
fillers. The effects of coconut shell particle content on the mechanical properties of the composites were
investigated. Scanning electron microscopy (SEM) of the composite surfaces indicates that there are
fairly good interfacial interaction between coconut shell particles and epoxy matrix. It was shown that
the value of tensile modulus and tensile strength values increases with the increase of coconut shell
particles content, while the impact strength slightly decreased, compared to pure epoxy resin. This work
has shown that coconut shell particles can be used to improve properties of epoxy polymer composite
to be used in eco-buildings.

- by Deepa G Nair
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- Materials Science, Waste Materials and Composites, Geopolymer Cement

Production and optimisation of an economic medium to high strength Eco-efficient SCC. RSM and multi-objectives optimisation used to maximise flow and compressive strength. Models for both flow and compressive strength have been developed and verified. g r a p h i c a l a b s t r a c t a b s t r a c t This study aims to produce and optimize Eco-efficient self-compacting concrete (SCC) mixes using multi-waste substitutions. The main input parameters of mixes were total binder, fine aggregate and water contents whereas slump flow and compressive strength were the two main operational responses of produced concrete. Limestone powder (LP) and waste Polyethylene Terephthalate (PET) were used in concrete as parts of cement and fine aggregate respectively with high range water reducing admixture (SP) as part of water. Response Surface Methodology (RSM) and multi-objectives optimization using Minitab 17 statistical software were employed for this purpose. Twenty SCC mixes were designed and checked experimentally using Central Composite Design (CCD) concept in RSM. Mathematical models were established and evaluated using analysis of variance test (ANOVA) according to the experimental results. This is in order to define the effectiveness degree of design parameters on the properties required and to adjust the derived mathematical models. Multi-objectives optimization process was adopted to determine the optimum values of the input parameters. The optimization revealed that the optimum values of the input factors, LP, PET and SP were 20.1%, 2.4% and 1.16% by weight respectively. These theoretical values were checked experimentally and the achieved responses were quiet similar or higher than the best proposed mix. It was deduced that the developed models can be used to ensure a speedy mix design process by achieving maximum tested properties of eco-efficient SCC.

Hexagonal ferrites can be employed in a multitude of applications, the most common hexaferrites are the M ferrites such as BaFe12O19 (barium hexaferrite, BaM). It is known that if Fe3+ is substituted with a combination of Ti4+/Co2+ the coercivity of BaM can be reduced to produce soft M ferrites with easily switchable magnetisation. They can be utilised as powders, films or bulk ceramics, and can be manufactured from a wide variety of synthesis methods. The production of hexaferrites usually requires commercial raw materials, but if an industrial waste can be utilised, this will help to ease waste disposal and storage costs, valorise a waste material and encourage circular economy. In this study, bauxite residue (red mud) from the production of alumina was used to synthesise M-type hexaferrites, using a simple ceramic process. BaCO3, or BaCO3+Co3O4, were added to the red mud, blended and heated at 1000 °C to produce the M-type hexaferrites. Without cobalt addition up to 81.1 wt% M ferrite was produced, and with Co addition up to 74.3 wt% M ferrite was formed. Without cobalt, the M ferrite phase closely resembled BaFe9Al3O19, and was a hard ferrite with a magnetisation of 12–19 A m2/kg for the whole powder (up to 23.6 A m2/kg for the M ferrite phase) and a coercivity of ~290 kA/m. When cobalt was added, secondary titanate phases vanished, and Ti4+/Co2+ partially substituted very soft M ferrite was formed with a low coercivity of ~16 kA/m but a higher magnetisation of 24.5 A m2/kg for the whole powder (up to 34.9 A m2/kg for the M ferrite phase). Therefore, not only can good quality magnetic materials be easily produced from this common waste material, but its magnetic properties can be tuned by varying the 2 + ions added during the process.

- by Robert C Pullar
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- Magnetic Materials, Waste Materials and Composites, Bauxite, Red Mud
- by Grzegorz Rzepa
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- Waste Materials and Composites, Hematite, Magnetite, Iron Oxides

Neem materials are used in the recyclable material field when the manufacturer needs to increase the strength and decrease the weight of a structure. It offers both mechanical and thermal properties. Moreover, an epoxy recycled Neem composite made with epoxy and hardener exhibited greater impact toughness, with a maximum value of 12.32 J/m. The present research has been conducted in an attempt to develop materials incorporating recycled Neem composites that have improved thermal stability for commercial use for essential purposes. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) were the techniques used to determine recycled Neem composites’ thermal properties, such as energy loss, weight loss, etc. X-ray diffraction (XRD) analysis determined that the crystallinity was 58.67%, and the average grain size was 5.34 nm. Scanning electron microscopy with Energy-dispersive X-ray spectroscopy (SEM + EDS) was used for elemental analysis yielding, for example, C 54.30% and Ca 5.99%. FTIR spectroscopy was used for the structural study and morphology of Epoxy Neem Recyclable Composite (ENRC) reinforced materials. The peak in the spectrum at 1750 cm-1 was assigned to the nitrile groups. The different significant effects of recycled Neem waste composite properties were studied to stimulate the recycling of materials and to determine the potential of using recycled waste in composites.

Recent research developments and applications of CLSM for trench backfilling are overviewed. CLSM specifications, practical applications and materials used by different countries are discussed. Long-term site experiences and technical limitations of using CLSM are highlighted. CLSM could be a beneficial way for recycling waste materials and industrial by-products. a b s t r a c t Controlled low-strength material (CLSM) is known as a self-leveling and self-compacting cementitious backfill material used for backfilling. The aim of this paper is to give an overview of the research development and practical application of CLSM for trench backfilling. Widespread application of CLSM is found around the world including in the United States of America (USA) as well as in other developed and developing countries. The main specifications and guidelines used in the USA and referenced by most of the other countries are highlighted in this paper. In addition, long-term site performance and technical limitations to be considered before application of CLSM are also discussed. Based on 115 globally sourced literature articles, it is suggested that the materials used for the production of CLSM are varied from country to country which in turn could have a significant influence on the resulting properties and its application in the field. It is also demonstrated that use of high volume by-products or/and waste materials is an effective way to control the low strength requirement of CLSM and minimize the environmental concerns related to the disposal of these waste materials.

In this experimental study, the impact of using waste materials such as ground granulated blast furnace slag (GGBFS), waste rubber powder (WRP), and recycled concrete aggregate (RCA) were evaluated on the compressive, tensile and, flexural strengths and durability test of rapid chloride migration test (RCMT) of concrete. It was observed that the mechanical properties of concrete decreased by raising the proportions of recycled materials in all replacement ratios. Because of the adverse effects of the WRP and RCA on the cement matrix and the interfacial transition zone, the reduction of the mechanical properties is higher for the concrete specimens with both recycled materials. In the case of durability, the migration rate of chloride ions in concrete is reduced by increasing the WRP rates due to the blockage of micro-pores connections. However, adding the RCA has a negative effect on the durability performance of concrete. Regarding the simultaneous effect of slag, rubber powder, and recycled aggregate on the migration of chloride ions, it can be derived that durability of samples containing 20% slag, 2.5% rubber powder, and 25% recycled aggregate at the age of 7 days on average is 14.8% higher compared to the reference sample. As the age of the samples increases to 28 days, the migration of chloride ions in the samples reduced 9.5% compared to 7 days.

It is difficult to compare the biogas yield of solid substrates from findings in literature because the substrate composition is rarely defined. This complicates not only the calculation of the potential biogas yield of a specific plant, but also the transferability of results to other sites and other countries (including municipal solid waste, source-segregated biowaste, agricultural residues). Based on a case example, an approach to solve this problem is presented and discussed. The studied anaerobic digestion plant is an innovative continuous two-phase two-stage prototype biogas plant operated with a mixture of excreta, straw and oat husks. The dry digestion concept, which is already widely applied to treat municipal solid waste, has demonstrated to also be suitable for this substrate type. Data obtained by this approach with looking at the individual fractions are potentially transferable to other sites. However, in substrate mixtures several factors may enhance both total methane yield and biogas production kinetics compared to digestion of single fractions.