Recycling of waste concrete has become an important issue worldwide due to the continued increase of construction wastes. Also, the growing global construction activities urge to find sustainable resources to replace natural materials for the production of concrete. In the past few decades, many researches have been carried out on the use of recycled aggregate (RA) derived from construction and demolition wastes to produce concrete products. This paper reviews the previous findings on the effects of use of RA on durability of concrete. In general, the amount of adhered mortar and the quality of the original concrete have a significant effect on the properties of resulting concrete. The increase of RA content and w/c ratio results in poorer durability of concrete. In comparison, the negative effect of recycled fine aggregate is more obvious than that of recycled coarse aggregate. The use of pozzolanic materials either for surface coating of RA or intermixed within the concrete are effective and feasible to improve the overall durability of concrete. Recent researches on CO2 treatment indicate that it can enhance the properties of RA and durability of concrete significantly.

Durability of recycled aggregate concrete – A review

A critical review and assessment for usage of recycled aggregate as sustainable construction material

This chapter describes the methodology used in EPA’s Waste Reduction Model (WARM) to estimate streamlined life-cycle greenhouse gas (GHG) emission factors for concrete beginning at the point of waste generation. The WARM GHG emission factors are used to compare the net emissions associated with concrete in the following two waste management alternatives: recycling and landfilling. Exhibit 1 shows the general outline of materials management pathways for concrete in WARM. For background information on the general purpose and function of WARM emission factors, see the Introduction & Overview chapter. For more information on Recycling and Landfilling, see the chapters devoted to these processes. WARM also allows users to calculate results in terms of energy, rather than GHGs. The energy results are calculated using the same methodology described here but with slight adjustments, as explained in the Energy Impacts chapter.

나의 Concrete 연구실

Properties of recycled aggregate concrete made with recycled aggregates with different amounts of old adhered mortars

Investigation of coal bottom ash and fly ash in concrete as replacement for sand and cement

Freeze–thaw resistance, mechanical and transport properties of self-consolidating concrete incorporating coarse recycled concrete aggregate

The effect of alkali activator concentration and curing conditions on consistency and strength of waste clay brick powder-based geopolymer composites was investigated. For this purpose, geopolymer mortars with twenty different activator concentrations were produced and those mixtures having optimum alkali activator concentration were subjected to different curing conditions. Test results indicated that the optimum alkali activator concentration corresponded to M s (SiO 2 /Na 2 O) ratio of 1.6 and Na 2 O content of 10% by weight of the binder. A maximum compressive strength of 36.2 MPa was achieved by curing at 90 °C, 40% RH for 5 days. In order to characterise the morphology and the structure of the resultant composites, x-ray powder diffraction analysis, thermogravimetric analysis, fourier transform infrared spectroscopy analysis, scanning electron microscopy analysis and micro computed tomography analysis were performed. It was determined that the microstructure analysis results were consistent with the compressive strength results. Denser structure was observed by microstructure analysis in the mixtures having high compressive strength.

Effect of alkali activator concentration and curing condition on strength and microstructure of waste clay brick powder-based geopolymer

Effect of different types of superplasticizer on fresh, rheological and strength properties of self-consolidating concrete

In this study, the effects of fine recycled concrete and glass aggregate on mechanical and durability performance of concrete were investigated. The waste concrete and glass were crushed, sieved and re-mixed to fulfill the same gradation as the available 0–4 mm crushed limestone aggregate size fraction. The recycled aggregates were substituted for fine aggregate as 0, 15, 30, 45 and 60 % by weight. 28-day mechanical and durability performance of the mixtures were determined. The maximum reduction in strength was observed in the specimens containing 60 % recycled glass aggregate. In addition, increasing the recycled concrete aggregate content caused decrease in UPV value and increase in water absorption, depth of penetration of water under pressure, chloride-ion penetration and water sorptivity of the concrete mixture. However, in recycled glass aggregate-containing mixture, UPV value increased and transport properties were improved with the increasing recycled glass aggregate content.

Mechanical and durability performance of concrete incorporating fine recycled concrete and glass aggregates

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Murat Tuyan

Papers

Freeze–thaw resistance, mechanical and transport properties of self-consolidating concrete incorporating coarse recycled concrete aggregate

Effect of alkali activator concentration and curing condition on strength and microstructure of waste clay brick powder-based geopolymer

Effect of different types of superplasticizer on fresh, rheological and strength properties of self-consolidating concrete

Mechanical and durability performance of concrete incorporating fine recycled concrete and glass aggregates

Optimization of reactive powder concrete by means of barite aggregate for both neutrons and gamma rays