Construction and demolition waste generation and properties of recycled aggregate concrete: A global perspective

Environmental concerns related to the disposal of various waste materials have escalated to a worrying level. Depending on the local industries, different types of waste are generated in huge quantities every year. Hence, the demand for more sustainable development has further increased the importance of green construction. In recent years, extensive study efforts have been made to recycle wastes for possible use in the production of concrete products. This is because concrete blocks seem to be the most popular option for the incorporation of recycled waste materials due to the lower quality requirements of materials. This paper reviews published research works on the use of various kinds of wastes (i.e. recycled concrete, crushed brick, soda lime glass, cathode ray tube glass, crumb rubber, ceramic and tile waste, etc.) in the production of concrete blocks. The common concrete block properties as well as the value-added properties of concrete blocks with incorporated waste materials are highlighted and discussed in this paper. Several unique characteristics of recycled crumb rubber, plastic waste and crushed brick enhance the fire resistance, toughness, functional and insulation properties of concrete blocks. Also, the quantity of these materials incorporated into concrete blocks can be maximized up to 100% as natural aggregate replacements, while their usage can also be limited to below 30% in certain applications in order to meet the standard requirements of concrete blocks. The compliance of concrete blocks with standard requirements and the value-added properties have demonstrated good potential for incorporating wastes as aggregate in concrete blocks.

Recycling of wastes for value-added applications in concrete blocks: An overview

http://repositorium.sdum.uminho.pt/bitstream/1822/34111/1/DURABILITY%20OF%20SFRSCC.pdf

Durability of steel fiber reinforced self-compacting concrete

This paper concerns comprehensive experimental study to evaluate properties and environmental suitability of Electric Arc Furnace (EAF) steel slag as well as mechanical behaviour of concrete designed with 100% of EAF slag as aggregate. Several tests were carried out on samples of fresh and aged slag, as required by standard specifications. In addition, the leaching behaviour and the volumetric stability were investigated. Concrete mixtures were designed with aged slag as aggregate having a diameter up to 31.5 mm. The concrete mechanical properties were then compared with the properties of reference mixtures having only natural aggregates. The concrete with EAF slag showed mechanical properties compatible with their use in civil constructions (compressive strength 35–45 MPa and modulus of elasticity up to 46 GPa).

Concrete with EAF steel slag as aggregate: A comprehensive technical and environmental characterisation

http://publications.lib.chalmers.se/records/fulltext/231578/local_231578.pdf

Corrosion of steel bars embedded in fibre reinforced concrete under chloride attack: State of the art

Using waste materials and by-products to produce concrete paving blocks

In the production of conventional paving blocks, it is usual to use a minimum of 210  kg/m3 of cement. However, when portland cement is produced, it impacts negatively on the environment due to carbon dioxide emissions. Therefore, this paper investigates the use of waste and by-product materials, such as run-of-station ash (ROSA), basic oxygen slag (BOS), ground granulated blast-furnace slag (GGBS), plasterboard gypsum (PG), and cement bypass dust (BPD) to reduce the amount of cement in paving blocks. The combinations of binary and ternary blends in different mixes are considered. Tensile strength, skid/slip and freeze/thaw resistance of paving blocks, verified that a cementitious mix containing ROSA up to 60%, GGBS up to 55%, BPD up to 25%, and plasterboard gypsum PG up to 5% by weight can replace portland cement without having any substantial impact on the strength or durability of the blocks. XRD and XRF tests of selected mixes have been presented and discussed. Concrete blocks prepared with OP...

Reducing Cement Contents of Paving Blocks by Using Mineral Waste and By-product Materials

High performance concrete containing steel fibre has gained popularity in recent decades for use in aggressive environments such as coastal and marine structures. It is generally acknowledged that steel fibres are added to improve the toughness, abrasion resistance, flexural behaviour and impact strength of concrete. However, little information is available about the rate of corrosion of fibres in concrete with pozzolanic cementitious matrix and its effects on ductility and flexural capacity of reinforced concrete, which play an important role in long-term serviceability of concrete structures. This paper presents the results of an experimental study that was carried out by accelerating corrosion process to evaluate the effect of corrosion of steel fibres on residual compressive and flexural strength concrete. The mechanical properties of fibre reinforced concrete containing PFA and GGBS subjected to accelerated corrosion were measured and results were correlated to the estimated rate of corrosion. INTRODUCTION Corrosion of steel is an electrochemical process with different reactions occurring at the anodic and cathodic sites. A supply of water and oxygen is required to maintain the reaction. In new concrete the pores solution pH is about 12.5. In these conditions a stable oxide “passive” layer is formed on the surface of the steel which provides protection from corrosion. If the concrete carbonates to the depth of the steel and/or chlorides are present at above critical threshold the protection can be compromised. Products of corrosion generally occupy a larger volume than the uncorroded steel. Unhydrated ferric oxide is about twice the volume, once hydrated it may be up to 6 to 10 times the volume. (Broomfield, 1996).

Corrosion durability of high performance steel fibre reinforced concrete

Use of recycled gypsum in road foundation construction

Disposing of waste is an environmental issue. Using waste will help reduce land filling. The successful research and development of a new building material, or component using waste as raw material, is a very complex and multidisciplinary task having technical, environmental, financial, marketing, legal and social aspects. In this paper it has been tried to find a low compressive strength mix with using only waste material include: Red Gypsum, Plaster board Gypsum, Basic Oxygen Slag, and Cement By Pass Dust. The amount of compressive strength and the flow of mixes had measured. The effect of water amount on compressive strength of some mixes has also measured.

Homayoon Sadeghi-Pouya

Papers

Using waste materials and by-products to produce concrete paving blocks

Reducing Cement Contents of Paving Blocks by Using Mineral Waste and By-product Materials

Corrosion durability of high performance steel fibre reinforced concrete

Use of recycled gypsum in road foundation construction

Use of waste gypsum as construction low strength materials