Perren, Steven (2023) Properties of cement mortar mix containing combined waste plastics and glass. [USQ Project]
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Abstract
As the world’s population increases so does the waste we produce. Global waste will double by 2050 and triple by 2100 unless more sustainable methods are implemented. Construction and demolition activities generate 30 to 40% of the total solid waste generated worldwide, 4.5 bi ton / year. In recent years there has been increasing interest in transitioning from a linear to circular economy; the key principles of which include avoiding waste materials, improving resource recovery, increasing the use and demand of recycled materials and better managing material flows.
In the 2020 to 2021 financial year Australia generated 75,8 Mt of waste. Key contributors to these waste flows were ash (from electricity production), building and demolition waste and organic materials. Glass waste in Australia accounted for approximately 2% of Australia’s total waste flows while plastic waste accounted for 3.4% of total waste flows. There are significant proportions of glass and plastic waste currently going to landfill, which represent a missed economic opportunity. In Australia rubbish collected in the yellow lids is for loose container recyclables that include aluminium and steel cans, glass bottles and jars and is assumed to be sorted and recycled, however this is not always the case. A report in 2020 put Australia’s waste at approximately 74 million tonnes yearly, with 84% of all plastic going straight to landfills. A component of solar panels is glass, and with the lifecycle of these panels is approximately 21 years and recycling options are currently limited, with only 17% of a panel by weight being recycled. The remaining 83% which includes glass, silicon and polymer back sheeting is currently not recyclable in Australia. Other glass that is not able to be recycled are microwave turntables, ovenware, crystal glass, mirrors and light bulbs, due to the items containing chemicals that do not allow the glass to melt at the same temperature as glass bottles and jars.
Traditional concrete structures are made of sand, cement, coarse aggregates, and water. Concrete by volume is the second most used material on the planet. Portland cement is the main binder of concrete and mortar, and large amounts of sand and gravel are extracted to provide the aggregate material for the concrete mix. The global total annual cement consumption in 2016 was 4.13 gigatons (Gt) and is anticipated to grow to 4.68 Gt per year by 2050.
Sand is now the most widely used construction material in the world, and recent studies have called it a ‘declining resource’. Crushed glass is similar in its chemical and physical composition to sand, and studies have demonstrated its applicability when used as a sand replacement in a structural concrete application at a replacement rate of up to 20%. From the literature it has been demonstrated that incorporating glass as a fine aggregate increases the compressive strength of the mortar / concrete, whilst also increasing the workability of the mix. Crushed glass aggregate has also been found to decrease water absorption, decrease thermal conductivity, and increase the electrical resistivity of a concrete mix.
Likewise, the incorporation of PET fibres has been found to increase the tensile strength of a concrete mix. Thereby improving the long-term durability of the structure. While there have been many studies on the use of glass and plastic for structural concrete applications, further studies are required to effectively promote its utilisation in the construction industry. The implications of incorporating both materials and their potential benefits are yet to be investigated.
The current gap in the literature is knowledge on the implications of incorporating both materials, therefore the main objective of the study is to investigate and identify which ratio of glass and plastic is best suited when replacing sand as a fine aggregate in mortar mixes. The purpose is to maximise the amount of recycled material into the mortar mix and to report the findings to create a viable alternative option for the use of mortar in the construction industry. The outcomes of the project may be upscaled and applied to standard structural concrete mixes. It is envisaged that a combination of glass aggregate and PET fibres may provide a synergistic effect enhancing the durability of a concrete mix, whilst reducing waste to landfill, and reducing cost.
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| Item Type: | USQ Project |
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| Item Status: | Live Archive |
| Faculty/School / Institute/Centre: | Current – Faculty of Health, Engineering and Sciences - School of Engineering (1 Jan 2022 -) |
| Supervisors: | Manalo, Allan; Seligmann, Hannah |
| Qualification: | Bachelor of Engineering (Honours) (Civil) |
| Date Deposited: | 01 Oct 2025 01:00 |
| Last Modified: | 01 Oct 2025 01:00 |
| Uncontrolled Keywords: | waste material; glass waste; cement |
| URI: | https://sear.unisq.edu.au/id/eprint/52987 |
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