The Use of Air Jigging to Recycle Construction and Demolition Waste



Abstract

The recycling of Inert CDW in new concretes remains problematic. Only a part of this material can be used to substitute coarse aggregates in new concretes, mainly the liberated coarse aggregates from demolished concretes. This paper presents the processing of Inert CDW in air jigs aiming at concentrates with high concrete particle contents. The paper compares different studies carried out with laboratory air jigs aiming at a concentration of concrete particles, which can partially substitute coarse aggregates in new concretes.

Introduction

Nowadays, large quantities of CDW (Construction and Demolition Waste) are produced worldwide: European Union between 310 and 700 million tons [1], United States 145 million tons [2], China about 1 billion tons [3], etc. In Europe, this waste represents over 30% of all solid waste generated [1]. Current CDW processing plants only separate light materials (such as plastics, paper, wood, etc.) and metal parts (ferrous and non-ferrous) after their comminution [4-6]. The remaining material is known as Inert CDW and basically contains bricks, tiles, plaster, concrete, mortar and coarse aggregate [7-9]. The main uses of Inert CDW in terms of quantities are sub-base material for road works, drainage layers, concrete production as a paving block, etc. [10]. It is estimated that around 20% of Inert CDW can be used as coarse aggregate in the formulation of structural concretes [11] They are basically coarse aggregates from demolished concretes liberated by comminution, which can be separated and concentrated by gravity concentration processes. Thus, between 60 and 150 million tons can be generated in Europe alone each year. In Europe, more than 2,800 million tons of aggregates of all types [12] are produced annually, which could be partially replaced by concentrated Inert CDW. With this partial replacement, 2 major problems can be tackled: the use of part of the generated CDW and the production decrease of new aggregates [11,13]. Several publications present the use and characterization of coarse aggregates in construction engineering [14-17]. Knowledge of the physical properties of different demolished concretes is extremely important to enable their recycling [6]. Features such as particle liberation of different components by comminution, liberation of coarse aggregates from cement paste, density and porosity of individual particles, etc., allow the use of techniques for the separation and concentration of species that can be used as coarse aggregate in new concretes. One of these techniques derived from mineral processing is Air Jigging, also known as Pneumatic Jigging.

 

Read more about this article : https://lupinepublishers.com/mining-mechanical-engineerning/fulltext/the-use-of-air-jigging-to-recycle-construction-and-demolition-waste.ID.000102.php


Read more Lupine Publishers Google Scholar Articles : https://scholar.google.com/citations?view_op=view_citation&hl=en&user=dtO2BpUAAAAJ&citation_for_view=dtO2BpUAAAAJ:W7OEmFMy1HYC

 

 

Comments

Post a Comment

Popular posts from this blog

Overview of Known Alkaliphilic Bacteria from Bauxite Residue

Abstract Alkaliphilic bacteria usually grow well at pH 9, and the most extremophilic strains can grow up to values as high as pH 12-13. This group of bacteria has the ability to metabolically reduce alkalinity and are tolerant of high concentrations of ions and metals. Interest in extreme alkaliphiles has been shown as they are sources of useful, stable enzymes, and the cells themselves can be used for biotechnological and other applications at high pH values. Many industrial processes produce highly alkaline waste that is contaminated with toxic trace metals/metalloid. Thus, using alkaliphilic microorganisms is considered an attractive alternative method for treating industrial alkaline residues. Bauxite refining is one of the activities that most produces highly alkaline waste. Alumina extraction from bauxite using concentrated sodium hydroxide in the Bayer process generates a slurry and an extremely alkaline (pH of 9 to 13) by-product known as bauxite residue or r
Read more

Syngas Compositions, Cold Gas and Carbon Conversion Efficiencies for Different Coal Gasification Processes and all Coal Ranks

  Abstract This Paper presents comparison of syngas compositions, for all coal ranks, as produced from different types of coal gasification processes currently in use, namely entrained flow, fluidized bed, and fixed bed gasifiers. Cold gas and carbon conversion efficiencies were investigated. The syngas composition varies with the applied gasification process. The importance of this research arises from the fact that gasifiers produce the environmentally clean fuel required to run any Integrated Gasification Combined Cycle power system. A procedure was conducted to get estimates for bituminous coal. It is important to have knowledge of the chemical reactions which take place in each gasifier and the raw syngas produced from the specific reaction involved to develop an Integrated Coal Gasification Combined Power Generation plant with CO 2 recovery in order to increase the cycle efficiency and mitigate CO 2 emission and other pollutants. The results indicate that the e
Read more

Effect of Annealing Process on Microstructure of SiC-Mg Mixture Powder

Abstract SiC particles with 8wt.% magnesium alloy powders as additives were mixed followed by annealing at 280 and 400 ℃ for 1 and 4 h. The particle size, phase condition, morphology and compositions distribution were analyzed using laser diffraction analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM). It was found that particles mixed homogeneously before annealing. Annealing processes have a positive effect on the decrease of magnesium alloy particle size. It has almost no effect on magnesium alloy particle size with increasing the annealing duration at 280 ℃. However, the diameter of magnesium particle decreased obviously with increasing the annealing duration at 400 ℃. Magnesium alloy particles annealed at 400 ℃ is smaller than that of the 280 ℃ ones under the same annealing duration. Si component was observed in powder annealed at both temperatures. Grain size of SiC was reduced and microstrain was improved with increase of annealing temperatu
Read more