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Effects of different grain size of expanded perlite aggregate and content of silica aerogel on the characteristics of lightweight cementitious composite

Vashchuk Andrii, Ślosarczyk Agnieszka

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 4

art. no. 174338

EN

In this research, an attempt was made to investigate effects of expanded perlite aggregate grain size on consistency, density, compressive strength, thermal conductivity and microstructure of 15 different composite mixes with silica aerogel. As for the samples preparation, expanded perlite aggregate of 5 different groups based on grain size, were used for sample preparation, then partially replaced by volume for 20% and 40% of hydrophobic silica aerogel particles. The results showed, that density of the samples varied between 0.35 g/cm3 and 1.5 g/cm3, flexural strength varied between 3.4 MPa and 7.4 MPa, compressive strength was in the range between 12.3 MPa and 55 MPa, thermal conductivity coefficient was in the range between 0.130 W/mK and 0.190 W/mK. Scanning electron microscopy showed that expanded perlite aggregates and silica aerogel particles are capable of being mixed and formed homogenous mixture. Nevertheless, microscope images indicated weaker adhesion of silica aerogel particles at interfacial zone as compared with expanded perlite aggregate particles. Results revealed, that both of the factors: grain size of expanded perlite aggregate particles silica aerogel content influenced the density, compressive strength and thermal conductivity. The study also indicated feasibility of expanded perlite aggregate and silica aerogel for achieving homogeneous mixture of the lightweight cementitious composites. Study demonstrated that using different size fractions of expanded perlite aggregate affects differently physical, mechanical and thermal characteristics of the lightweight cementitious composite with silica aerogel.

2

Assessment of eggshell and CaCO3 reinforced recycled aluminium green metal matrix

Hasan L. M., Ali A. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 118, nr 2

57--61

EN

Purpose In this study, an environmentally friendly metal matrix was prepared, and the influence of eggshell powder and CaCO3 particles on the tensile strength and hardness of recycled aluminium were assessed. Design/methodology/approach A matrix made of recycled aluminium was employed. Calcium carbonate and eggshells served as the study's reinforcing materials. Separately, weight percentages of 2, 4, and 8% of eggshell and calcium carbonate were used. The samples were made by sand-casting. Findings The results showed that both eggshell and calcium carbonate positively affect the hardness, yield, and ultimate tensile strength of recycled aluminium. The hardness values were improved as the percentage of the eggshell increased. The maximum hardness was achieved at 2% calcium carbonate. Similarly, the highest improvement of yield strength was for 2% CaCO3 addition, while the highest tensile strength was obtained at 8% eggshell addition. Research limitations/implications To get better results, it would be desirable to use finer eggshells than those utilized in this study. Practical implications Composites made with an aluminium matrix exhibit exceptional mechanical and physical characteristics. The most challenging obstacle to overcome is the cost of metal matrix composites. Eggshells are a by-product that could be employed as a lightweight, affordable form of reinforcement. One way to get rid of this by-product, improve composite characteristics, and lower the cost of aluminium composite is to use eggshells. Originality/value A comparative investigation was carried out to determine the effects of adding agricultural by-product eggshell, and commercial CaCO3 reinforcement material on the characteristics of recycled aluminium matrix integrated 425 µm sized eggshell and CaCO3 separately as a reinforcement material to create a metal matrix that is beneficial to the environment.

3

Influence of alternative binder on the properties of hemp hurds composites

Stevulova N., Schwarzova I.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2017

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z. 64, nr 4/I

59--64

EN

Composites based on natural fibres as organic filler are studied for several years because traditional building materials such as concrete are increasingly being replaced by advanced composite materials (fibre reinforced cement). The current trend in the construction industry is the effort to achieve sustainable development using rapidly renewable material resources instead of limited raw materials as well as using alternative materials. The need for development of promising and environmentally friendly materials is related to the industrial interest in the use of natural plant fibres as reinforcement into lightweight composites. The attention is given to hemp fibres as a substitute for synthetic fibers in lightweight composites due to their unique mechanical, thermal insulation, acoustic and antiseptic properties. Optimizing the adhesion of hemp plant fibre to the inorganic matrix in the composite is related to the modification of hemp fibers and/or the appropriate option and treatment of binder. In this paper, the attention is given to the study properties of composite based on hemp hurds as filler and alternative binder (MgO-cement). The hemp as a building composite component is rapidly renewable, carbon-negative, non-toxic, mildew-resistant and pest-free. Cement based on MgO seems to be a suitable binding agent for composites based on hemp hurds. Experimental work is focused on the study of impact of alternative binder on the selected properties of prepared lightweight composites and variation of mixtures based on hemp hurds and alternative binder focused on the MgO and SiO2 component (silica sand and silica fume in variation). The evaluation of the physical and mechanical properties of hemp hurds composites with alternative binder is given. The results have shown that by incorporating hemp hurds into a magnesium oxide cement matrix it is possible to prepare materials with suitable thermal insulating properties usable in non-load-bearing structures.

PL

Od kilku lat badane są kompozyty na bazie włókien naturalnych jako wypełniacze organiczne, ponieważ tradycyjne materiały budowlane, takie jak beton, są coraz częściej zastępowane zaawansowanymi materiałami kompozytowymi (cement wzmacniany włóknami). Obecną tendencją w branży budowlanej jest dążenie do osiągnięcia zrównoważonego rozwoju przy wykorzystaniu szybko odnawialnych surowców, a nieograniczonych surowców, a także przy użyciu alternatywnych materiałów. Potrzeba opracowania ekologicznych dla środowiska materiałów jest związana z przemysłowym wykorzystaniem naturalnych włókien roślinnych jako zbrojenia do lekkich materiałów kompozytowych oraz włókien konopnych jako substytut włókien syntetycznych w lekkich kompozytach ze względu na ich unikalne własności mechaniczne, termoizolacyjne, akustyczne i antyseptyczne. Optymalizacja przyczepności włókna roślinnego konopi do matrycy nieorganicznej w kompozycie jest związana z modyfikacją włókna konopnego i/lub odpowiednią opcją i obróbką spoiwa. W niniejszym dokumencie zwrócono uwagę na właściwości badawcze kompozytu bazującego na opasach konopnych (w odcieniach drewna konopi) jako wypełniacza i alternatywnego środka wiążącego (MgO-cement). Konopie jako komponent złożony z budynków są szybko odnawialne, są odporne na węgiel, nietoksyczne, odporne na pleśń i wolne od szkodników. Wydaje się, że cement na bazie MgO jest odpowiednim środkiem wiążącym dla kompozytów na bazie konopi. Eksperymentalne prace koncentrują się na badaniu termicznego przetwarzania naturalnego surowego materiału magnezytowego do jego późniejszego wykorzystania jako alternatywnego składnika wiążącego do lekkich materiałów kompozytowych oraz zróżnicowania mieszanek kompozytowych opartych na opaskach konopnych i alternatywnym środku wiążącym skupionym na składniku MgO i SiO2. Ocenę fizycznych i mechanicznych właściwości konopnych prasuje kompozyty z alternatywnym spoiwem. Wyniki wykazały, że poprzez włączenie konopnych włókien do matrycy cementowej tlenku magnezu można przygotować materiały o odpowiednich właściwościach termoizolacyjnych użytych w konstrukcjach nie obciążających.