FR3127942A1 - USE OF NON-HAZARDOUS WASTE INCINERATION BOTTLES IN CONCRETE USES - Google Patents

Abstract

The present disclosure relates to a concrete composition comprising:- a hydraulic binder;- aggregates;- water; and- optionally one or more adjuvants; in which the aggregates comprise MIDND aggregates whose size varies from 4 to 20 mm, said MIDND aggregates having a maximum content by weight of non-ferrous metals not exceeding 0.2% and a maximum content by weight of ferrous metals not exceeding 5%.

Description

USE OF NON-HAZARDOUS WASTE INCINERATION BOTTLES IN CONCRETE USES

FIELD OF THE INVENTION

The present invention relates to the field of concrete compositions, in particular concrete compositions comprising non-hazardous waste incineration bottom ash aggregates.

TECHNOLOGICAL BACKGROUND

Bottom ash from the incineration of non-hazardous waste (MIDND) is raw waste from the extraction of solid materials at the furnace outlet of non-hazardous waste incineration units. They are alkaline materials composed mainly of silicates and aluminas, limestone and lime, water (resulting from the water cooling of MIDNDs), unburned matter and ferrous and non-ferrous metals. In many countries, the use of this mass-produced waste is strictly regulated in order to meet technical and environmental requirements. Thus, before being able to be recovered, the MIDND must go through stages of treatment (extraction of ferrous metals, extractions of non-ferrous metals) and maturation of a few months to reduce their polluting potential.

To date, the main way of recovering MIDNDs is their use in road engineering, for example as sub-base layers or shoulders of paved road structures or even in technical backfill. Their use as aggregate for concrete in partial or total substitution of natural aggregates has also been considered for many years. However, their use in this type of application has been hampered by cement/aggregate compatibility problems reducing the physical integrity and mechanical properties of the materials formed. Indeed, it has been observed that concretes prepared from MIDND are subject to swelling and cracking phenomena. The metallic particles present in MIDNDs, in particular aluminum, have been identified as the main culprits of these phenomena. In fact, aluminum oxidizes in a basic medium leading to the release of hydrogen but also to the formation of aluminum hydroxides likely to cause swelling leading to the cracking of concretes and leading to a reduction in their mechanical properties. Reducing the content of non-ferrous metals in MIDNDs therefore appears to be a challenge to be overcome in order to envisage a broader valuation of MIDNDs in concrete uses.

A need therefore exists for the provision of concrete compositions comprising MIDND aggregates in which the cement/aggregate compatibility problems are reduced and also for the provision of a method for treating MIDND leading to MIDND aggregates that can be used in concrete applications, that is to say without generating the drawbacks observed with conventional MIDNDs.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a concrete composition comprising:

- a hydraulic binder;

- aggregates;

- some water ; And

- optionally one or more adjuvants;

in which the aggregates comprise MIDND aggregates whose size varies from 4 to 20 mm, said MIDND aggregates having a maximum content by weight of non-ferrous metals not exceeding 0.2% and a maximum content by weight of ferrous metals not exceeding 5%.

The present invention also relates to a method for preparing MIDND aggregates comprising the following steps:

(a) supply of MIDND aggregates whose size is less than 20 mm, preferably supply of MIDND aggregates of particle size fraction 0/4, 4/10 and 10/20;

(b) elimination of the non-ferrous elements in the MIDND aggregates by at least one pass, typically at least two passes, of said aggregates in an eddy current separator machine with application of a magnetic field whose power varies from 0, 01 to 1 Tesla.

Finally, the present invention relates to the use of the MIDND aggregates obtained according to the process of the invention for the preparation of concrete and to the use of the concrete composition to trap the heavy metals contained in the MIDND aggregates.

Other aspects of the invention are as described below and in the claims.

FIGURE

illustration of a process for preparing MIDND aggregates according to the invention

Claims (12)

Concrete composition comprising:
- a hydraulic binder;
- aggregates;
- some water ; And
- optionally one or more adjuvants;
in which the aggregates comprise non-hazardous waste incineration bottom ash (MIDND) aggregates whose size varies from 4 to 20 mm, said MIDND aggregates having a maximum content by weight of non-ferrous metals not exceeding 0.2 % and a maximum content by weight of ferrous metals not exceeding 5%. Concrete composition according to Claim 1, in which the MIDND aggregates comprise 4/10 and 10/20 aggregates:
- said 4/10 MIDND aggregates having a maximum content by weight of non-ferrous metals not exceeding 0.2% and a maximum content by weight of ferrous metals not exceeding 5%, and
- said 10/20 MIDND aggregates having a maximum content by weight of non-ferrous metals not exceeding 0.1% and a maximum content by weight of ferrous metals not exceeding 5%. Concrete composition according to claim 1 or 2 corresponding to the following particle size range: Mass % of passers-by at indicated cut-offs minimum mass % maximum mass % Cut 40mm 100 100 20mm 90 100 8mm 40 90 4mm 25 75 2mm 20 60 0.5mm 15 45 0.063mm 10 30 Composition according to one of the preceding claims, in which the hydraulic binder is a Portland CEM I cement, a Portland CEM II compound cement, a CEM III blast furnace cement, a CEM IV pozzolanic cement, a CEM IV compound cement, a granulated slag ground blast furnace or mixtures thereof. Composition according to one of the preceding claims comprising from 70 to 95% by weight of aggregates relative to the total weight of the composition. Composition according to one of the preceding claims, in which the aggregates comprise, relative to the total weight of the aggregates:
- from 0 to 60% by weight of 4/10 MIDND aggregates;
- from 0 to 60% by weight of 10/20 MIDND aggregates; And
- from 10 to 60% by weight of sand,
the sum of the percentages by weight being equal to 100%. Composition according to one of the preceding claims, in which the effective water/hydraulic binder mass ratio is from 0.2 to 0.8. Composition according to one of the preceding claims, in which the adjuvant is chosen from setting accelerators, hardening accelerators, setting retarders, plasticizers, water reducers, superplasticizers, air entrainers, water repellents, pigments and mixtures thereof. Process for preparing MIDND aggregates comprising the following steps:
(a) supply of MIDND aggregates whose size is less than 20 mm, preferably supply of MIDND aggregates of particle size fraction 0/4, 4/10 and 10/20;
(b) elimination of the non-ferrous elements in the MIDND aggregates by at least one pass, typically at least two passes, of said aggregates in an eddy current separator machine with application of a magnetic field whose power varies from 0, 01 to 1 Tesla. A method according to claim 9 wherein step (a) comprises the following steps:
(a') provide matured MIDNDs;
(b′) removing the matured MIDNDs from elements whose size is greater than 300 mm to obtain a particle size fraction of 0/300;
(c′) optionally removing ferrous metals from the 0/300 particle size fraction;
(d') subjecting the 0/300 particle size fraction obtained at the end of step (b') or (c') to screening with at least one cut-off at 20 mm, preferably with a cut-off at 20 mm and a cut at 80 mm;
(e′) optionally removing ferrous metals from the 0/20 particle size fraction obtained in step (d′);
(f') subjecting the 0/20 particle size fraction obtained in step (d') or (e') to a double cut-off screening with a cut-off at 4 mm and a cut-off at 10 mm to obtain the particle size fractions 0/ 4, 4/10 and 10/20;
(g') optionally subjecting the 20/300 particle size fraction, preferably the 20/80 particle size fraction, obtained in step (d') to grinding and repeating steps (d') to (f'). Use of MIDND aggregates obtained according to the process of claim 9 or 10 for the preparation of concrete. Use of the concrete composition according to one of Claims 1 to 8 for trapping the heavy metals contained in the aggregates of MIDND.