Performance enhancement of recycled concrete aggregate – A review

Disposal of waste tire rubber has become a major environmental issue in all parts of the world. Every year millions of tires are discarded, thrown away or buried all over the world, representing a very serious threat to the ecology. It was estimated that almost 1000 million tires end their service life every year and out of that, more than 50% are discarded to landfills or garbage without any treatment. By the year 2030, there would be 5000 million tires to be discarded on a regular basis. Tire burning, which was the easiest and cheapest method of disposal, causes serious fire hazards. Temperature in that area rises and the poisonous smoke with uncontrolled emissions of potentially harmful compounds is very dangerous to humans, animals and plants. The residue powder left after burning pollutes the soil. One of the possible solutions for the use of waste tire rubber is to incorporate into cement concrete. This paper presents an overview of some of the research published regarding the fresh and hardened properties of rubberized concrete. Studies show that there is a promising future for the use of waste tire rubber as a partial substitute for aggregate in cement concrete. It was noticed from literatures that workable concrete mixtures can be made with scrap tire rubber and it is possible to make light weight rubber aggregate concrete for some special purposes. Rubberized concrete shows high resistance to freeze-thaw, acid attack and chloride ion penetration. Use of silica fume in rubberized concrete enables to achieve high strength and high resistance to sulfate, acid and chloride environments.

A comprehensive review on the applications of waste tire rubber in cement concrete

Recycling of waste tire rubber as aggregate in concrete: durability-related performance

Waste tyres and their accumulation is a global environmental concern; they are not biodegradable, and, globally, an estimated 1.5 billion are generated annually. Waste tyres in landfill and stockpiles are renowned for leaching toxic chemicals into the surrounding environment, acting as breeding grounds for mosquitoes, and fuelling inextinguishable fires. The properties of waste tyre rubber and engineering applications have been previously reported in a range of publications with respect to the environmental, economic, and technical factors. This study compiles and reviews this research with a focus on geotechnical engineering applications, such as earthworks and infrastructure construction. The applications of waste rubber in construction materials includes cementitious concrete, asphalt concrete, and granular materials for earth structures. Crumb rubber, when used as a sand replacement in flowable concrete fill, improved ductility and strength-to-weight ratio. A 40 MPa concrete mix with 0.6% rubber crumb content exhibited optimal strength and air entrainment capabilities, displaying minimal damage after 56 freeze/thaw cycles. Rubber, as a partial replacement for aggregate in road base and sub-base layers, adversely affected the California Bearing Ratio (CBR) of the graded aggregate base course. Rubber-soil mixtures as the interface of foundation and structure yielded a 60–70 % reduction in vertical and horizontal ground accelerations when subjected to earthquake simulation modelling. There is concern regarding the toxicity of waste rubber incorporated products due to leachates of heavy metals and other chemicals common in tyres. Further comprehensive studies in this area are needed. Leachate studies should be conducted under different pH and liquid to solid ratios.

Recycling waste rubber tyres in construction materials and associated environmental considerations: A review

Effect of waste tyre rubber on mechanical and durability properties of concrete – A review

Effect of mechanical activation on the properties of rice husk ash-based one part geopolymer

This research explores the potential of using municipal solid waste incinerator bottom ash (MSWIBA) as a partial replacement for fine aggregate and ordinary Portland cement (OPC) as a stabilizer in the production of compressed stabilized earth blocks (CSEBs). The study investigates the effect of varying levels of cement content (ranging from 0% to 10%) and MSWIBA content (ranging from 0% to 25%) on the strength and durability of CSEBs. The strength characteristics of CSEBs were evaluated through tests such as wet and dry compressive strength, flexural strength, water absorption, and stress–strain behavior, while durability was tested through wetting–drying cyclic tests. The results indicated that CSEB blocks made with 20% MSWIBA content and 10% cement were able to fulfill strength criteria. Additionally, using these blocks could result in cost savings of 8% during construction when compared to using fired clay bricks (FCB). Furthermore, varying the cement content while maintaining a constant proportion of MSWIBA showed a significant change in the stress–strain behavior and a cost analysis performed for CSEBs stabilized with the optimal quantity of MSWIBA-OPC combination showed that they can be a viable alternative to conventional earth blocks, providing an eco-friendly, sustainable, and cost-effective solution for construction initiatives.

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Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

The disposal of hazardous waste materials in landfills and open areas creates a severe impact on the environment. Silica Fume (SF), a by-product from the ferrosilicon and silicon industry, is generated in high quantities. Recent studies have highlighted the advantages of reusing SF to produce high-strength concrete (HSC) and ultra-high-performance concrete (UHPC) instead of discarding it. This paper herein reviews the current research on SF in concrete and discusses the physical and chemical properties, mechanical properties, durability, and microstructure. Depending on the concentration of the SF, flexural, tensile, and compressive strength was positively influenced. Also, SF improved the pore size to increase drying shrinkage through the pozzolanic reaction. A few studies showed the disadvantages of SF exhibiting the negative impact on workability and shrinkage of concrete. The influence of SF on cement hydration products should be analyzed from the microstructure perspective. 

Blessen Skariah Thomas

Papers

Effect of mechanical activation on the properties of rice husk ash-based one part geopolymer

Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

Effect of silica fume on the properties of sustainable cement concrete

A review on rheological behaviour of alkali activated materials and the influence of composition factors

A comprehensive review on the use of natural fibers in cement/geopolymer concrete: A step towards sustainability