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American Society for Testing and Materials

Properties and applications of foamed concrete; a review

This review examines the detailed chemical insights that have been generated through 150 years of work worldwide on magnesium-based inorganic cements, with a focus on both scientific and patent literature. Magnesium carbonate, phosphate, silicate-hydrate, and oxysalt (both chloride and sulfate) cements are all assessed. Many such cements are ideally suited to specialist applications in precast construction, road repair, and other fields including nuclear waste immobilization. The majority of MgO-based cements are more costly to produce than Portland cement because of the relatively high cost of reactive sources of MgO and do not have a sufficiently high internal pH to passivate mild steel reinforcing bars. This precludes MgO-based cements from providing a large-scale replacement for Portland cement in the production of steel-reinforced concretes for civil engineering applications, despite the potential for CO2 emissions reductions offered by some such systems. Nonetheless, in uses that do not require steel reinforcement, and in locations where the MgO can be sourced at a competitive price, a detailed understanding of these systems enables their specification, design, and selection as advanced engineering materials with a strongly defined chemical basis.

Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future?

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

The abundant availability and accessibility of plant fibres are the major reasons for an emerging new interest in sustainable technology. While focusing on the composite materials, the main points to be considered are environment friendliness and light weight, with high specific properties. This century has witnessed remarkable achievements in green technology in the field of materials science through the development of high-performance materials made from natural resources is increasing worldwide. Plant fibres are a kind of renewable resources, which have been renewed by nature and human ingenuity for thousands of years. The greatest challenge in working with plant fibre reinforced composites (PFRCs) is their large variation in properties and characteristics. A PFRCs properties are influenced by a number of variables, including the fibre type, environmental conditions, processing methods, and modification of the fibre. A detailed systematic review on these sustainable and renewable green materials is presented in this paper. The overall characteristics of plant fibres used in bio-composites, including source, type, structure, composition, as well as properties, will be reviewed. Finally, the review will conclude with recent developments and future trends of PFRCs as well as key issues that need to be addressed and resolved.

Plant fibre based bio-composites: Sustainable and renewable green materials

Hardened properties of concrete mixtures containing pre-coated crumb rubber and silica fume

Cellular concrete properties and the effect of synthetic and protein foaming agents

Effects of accelerated carbonation on the microstructure of Portland cement pastes containing reactive MgO

Compressive strength, ultrasonic pulse velocity (UPV), non-evaporable water content and the interplay between them were investigated at 1, 3, 7 and 28 days to determine the effects of using ground granulated blast furnace slag (GGBFS) as cement replacement. The variables considered include percentage of GGBFS as cement replacement (0–60%), total binder content (270–450 kg/m3), water-to-binder ratio (0.31, 0.38) and curing period. The dilution effect was observed at day 3, at which point, increasing the amount of GGBFS as cement replacement yielded lower compressive strengths. The results show that the evolution of mechanical properties is affected by the amount of water, percent of GGBFS added and curing regime. By 28 days, the benefit of using GGBFS as cement replacement owing to its effect on the concrete’s packing density and hydration processes was reflected in the compressive strength and UPV measurements when used up to 50% cement replacement. Compressive strength of concrete containing GGBFS is found to increase on average by 10% from 28 days to 120 days. Measurements of non-evaporable water content and mass loss due to scaling revealed that the scaling resistance test for concrete at 28 days is more favorable towards OPC concrete and discriminates against concrete containing high percentages of GGBFS as cement replacement.

Daman K. Panesar

Papers

Hardened properties of concrete mixtures containing pre-coated crumb rubber and silica fume

Cellular concrete properties and the effect of synthetic and protein foaming agents

Effects of accelerated carbonation on the microstructure of Portland cement pastes containing reactive MgO

Evolution of mechanical properties of concrete containing ground granulated blast furnace slag and effects on the scaling resistance test at 28 days

Impact of graphene oxide and highly reduced graphene oxide on cement based composites