SK280498B6 - Mixture for road layer from electrosteel slag and method of its production - Google Patents

Abstract

Composition comprises sand and/or gravel which are prepared from electrical furnace steelworks slag mixed with one or more binder(s) chosen from hydraulic binders, pozzolanic fly ash, derivatives of pozzolanic fly ash and the mixtures thereof, and at least one activator, or else with one or more binder/activator(s).

Description

Technical field

The present invention relates to a mixture obtained on the basis of steel slag from an electric furnace intended for the production of road layers and to a process for the production of this mixture.

BACKGROUND OF THE INVENTION

The steel furnace slag, hereinafter referred to as the LAFE electrical steel slag, is a by-product of steel production. This slag occurs in the form of an artificial basic rock, the main components of which are lime (CaO), iron oxide (Fe ₂ O ₃ ), silica (SiO ₂ ), magnesium oxide (MgO) and alumina (Al ₂ O ₃ ). An important component of this slag is calcium orthosilicate ( ₂ CaO.SiO ₂ ), also called bicalcium silicate. This calcium orthosilicate occurs in two allotropic forms, beta and gamma. The beta form is metastable and tends to transform into a gamma form that is stable at ambient temperature. The transformation of the beta form into the gamma form is accompanied by an increase in the order of magnitude of 15%, causing rock disaggregation. This peculiarity of LAFE slag has hitherto been a major disadvantage in its use for road layers. Until now, the LAFE slag has been of little use or unusable and has been an obstructive and environmentally polluting by-product.

It was therefore necessary to find useful outlets for the LAFE slag. DE 39 15373 describes compositions for the production of road layers which contain a conversion steel-slag and waste products with a small particle size. The compositions according to the present invention comprise a CCT, but not a CCT. The binders used in the solution according to the invention are different from those used in DE 39 15373. The mixtures according to the invention make it possible to obtain road layers which are more stable than the road layers using the mixture according to DE 39 15373.

SUMMARY OF THE INVENTION

It has been found that the disadvantage associated with the use of LAFE slag can be eliminated and that LAFE slag (electro-steel slag) can be used to produce a road layer having good stability by first converting the LAFE slag into a coating composition. paths that include:

(a) sand or a mixture of grit and gravel obtained from electrical slag, hereinafter called LAFE sand or a mixture of grit and gravel LAFE, (b) one or more binders, (c) at least one activator, or (a) sand and a mixture of grit and gravel; a mixture of crumb and gravel prepared from etectro-steel slag (LAFE sand) or (a mixture of crumb and gravel LAFE), (d) one or more binders / activators.

LAFE sand and LAFE grit / gravel mixture are prepared from electro-steel slag by grinding, iron removal and sieving of LAFE slag. Thereby it is possible to obtain LAFE sand with a granulometric value of 0/8 mm or a mixture of crumb and gravel LAFE with a granulometric value of 0 / 31.5 and preferably 0/20 mm or 0/14 mm. The grit / gravel mixture 0 / 31.5 or 0/20 or 0/14 mm is a mixture with continuous granulometry up to 31.5 mm, optionally up to 20 mm or 14 mm.

Removal of iron is understood to mean a process which makes it possible to remove slag from metal particles with magnetic properties.

The iron removal process is important for the stability of the road layer.

The binder (b) may be selected from hydraulic binders, puzzoan ash (volcanic origin), puzzolan ash derivatives and mixtures thereof. Of the hydraulic binders, granulated blast furnace slag, cement standardized on the basis of granulated slag, and special binders used for road construction are preferred. Special binders are mainly products labeled ARC (road activator CEDEST) manufactured by CEDEST, especially products labeled ARC 1, ARC 2 and ARC 3.

ARC 1 contains approximately 85% by weight of blast furnace granulated slag, the rest being lime (CaO).

ARC 2 contains about 75 to 80% of blast furnace granulated slag, the remainder being a sutphatic activator, the major part of which is natural calcium sulfate.

ARC 3 contains about 80% by weight of blast furnace granulated slag, the rest up to 100% being calcium CaO and calcium sulphate CaSO ₄ .

As regards standardized cements, CLK (slag clinker cement) and in particular CLK 45 cement sold by CEDEST, as well as CPJ cements, in particular CPJ 45 cements manufactured by different firms, are performing well.

CLK cements contain approximately 80 parts by weight of blast furnace granulated slag, the remainder being mostly clinkers and less gypsum.

Clinker is an artificial stone made of anhydrous calcium aluminosilicate obtained by burning at a temperature of about 1450 ° C.

CPJ cements belong to the class of composite Portland cements. They contain about 70% clinker, about 23% ash, the remainder being slag and a small amount of natural calcium sulfate.

Lime in the form of quicklime CaO or slaked lime Ca (OH) ₂ is used as activator.

Standardized cements and special binders used in road construction can also act as a binder / activator. In other words, standardized cements and special binders used in road construction can be used either as a hydraulic binder or as a binder / activator. The term binder / activator is understood to mean a product having both a binder and an activator role. It is a binder that does not need the presence of an activator.

The good quality slag blend composition according to the invention comprises 93-98% by weight of the LAFE sand / gravel mixture and 2-7% by weight of the binder / activator selected from products labeled ACR 1, ACR 2 and ACR 3.

Another good composition according to the invention comprises 93 to 96% by weight of a sand and gravel mixture of LAFE and 4 to 7% by weight of a binder / activator selected from CLK cements and CPJ cements.

Good results are also obtained from a mixture containing: LAFE sand or LAFE grit / gravel mixture 74 ± 5% blast furnace slag 25 ± 5% quicklime or slaked lime 1%

Another group of mixtures allowing the production of good quality road debris is as follows:

LAFE sand or a blend of LAFE grit and gravel in an amount equal to or greater than 53% by weight, one or more activators in an amount of 1 to 3% by weight, one or more hydraulic binders supplementing the mixture up to 100% by weight.

Another mixture contains:

LAFE sand or LAFE gravel / gravel mixture 58 ± 5% blast furnace slag 20 ± 5%

SK 280498 Β6 fly ash fly ash 20 ± 5% quicklime or slaked lime 2 ± 1%

The slag mixtures according to the invention harden over time, result in a solid and stable structure and can be classified in class C or class D Sand classification for new roads with heavy and medium traffic, dimensionally differentiated in the new road structure type catalog (DRCR-1977 ) or in the class of said mixtures of chips and gravel.

Class C counts for said slag sands with a tensile strength (Rt), measured after 180 days, higher than 0.4 MPa for said sands-cements with a tensile resistance Rt, measured after 90 days, higher than 0.5 MPa.

Class D counts for said slag sands with an Rt value after 180 days higher than 0.65 MPa and for said sands-cements with an Rt value after 90 days higher than 0.75 MPa.

The term sands-cements refers to mixtures containing normal cement in addition to LAFE sand. Said slag means mixtures containing, in addition to LAFE sand, a binder and an activator or a binder / activator but not containing cement.

The term grit / gravel mixtures means mixtures containing, in addition to the LAFE grit / sand mixture, also cement or a special binder used in road construction or an activator binder or binder / activator.

The granulometric analysis of a composition according to the invention prepared either from sand and a mixture of crumb and sand LAFE or from a mixture of crumb and sand LAFE 0/14 or 0/20 and a hydraulic binder or a binder / activator is shown in Tables I and II below.

Table I

Granulometric analysis of the mixture prepared from the grit / gravel mixture 0/14 and the binder or binder / activator

Particle size mm Sieving of collected substances,% minimum maximum 25 100 14 85 100 10 6a 97 6.3 50 84 4 38 71 2 26 56 0.5 13 32 0.2 9 21 00:08 5 12

Table II

Granulometric analysis of a mixture prepared from 0/20 grit / sand mixture and binder or binder / activator

Particle size mm Sieving of collected substances,% minimum maximum 31.5 100 20 85 100 10 55 88 6.3 42 74 4 32 66 2 23 54 0.5 11 31 0.2 7 21 0.08 4 12

In Tables I and II, the first column shows the particle size and the other two columns give the minimum or maximum sieving of the collected substances in percent.

The average chemical composition of the sand and the LAFE grit / gravel mixture is as follows:

fe 16.57 CD <0.005 WITH <0.05 CaO 40.52 Cr 1,845 F 1.2650 SiO ₂ 11.96 Cu 0.0115 and 0,002 MgO 9.70 Mn 4,085 IN 0.0395 Al2O3 4.30 Ni : 0.0065 Bé 0 On the 0,025 Pb : 0,045 with 0.0010 The 0,015 sn : <0.005 P2O5 0,655 Zn : 0,002 you 0.15 Mo : 0,055

The minimum and maximum quantities of the main components are

following: minimum maximum fe 14 19 CaO 37 43 SiO ₂ 11 13 MgO 8 11 A1 ₂ O ₃ 3 6

The LAFE crumb and gravel mixtures of the invention have a tensile strength measured after 360 days of curing equal to or greater than 0.65 MPa for the grit / LAFE slag mixture equal to or greater than 0.80 MPa for the grit mixture and gravel LAFE-pre-crushed slag equal to or higher than 1.10 MPa for standardized grit-gravel-cement mixtures or for special grit-gravel-binder mixtures.

The term "grit / gravel mixture-pre-crushed slag" means a grit / gravel mixture LAFE 0 / 31.5 or 0/20, or 0/14 mm with pre-crushed granular slag with a granulometric value of 0/2 mm containing 10% by weight of fine average granulates, having a granulometric value equal to or less than 80 microns.

It is also an object of the present invention to provide a composition for making road layers with good dimensional stability and good tensile and compressive strength. The method is characterized in that grinding, iron removal and sieving of the electro-steel slag (LAFE) are carried out to obtain a LAFE sand of a granulometric value of about 0/8 mm or a LAFE grit / gravel mixture of about 0 / 31.5 and preferably about 0 / 20 or 0/14 mm, also allowing the mixing of LAFE sand or a mixture of crumb and gravel LAFE thus obtained with one or more hydraulic binders, with azole ash, with pozzolanic ash derivatives or mixtures thereof, or with at least one activator or at least one activator a binder / activator.

The process variant according to the invention is characterized by crushing, removing iron and sieving LAFE slags to prepare both LAFE sand with a granulometric value of about 0/8 mm, and a LAFE grit / gravel mixture having a granulometric value of about 0 / 31.5 and preferably about 0/20 mm or 0/14 mm. Thereafter, the LAFE sand and the LAFE grit / gravel mixture are mixed with one or more binders selected from the group of hydraulic binders, pozzolanic ashes, pozzolanic ash derivatives and mixtures thereof, and at least one activator or at least one binder / activator.

When the LAFE sand and the LAFE gravel / gravel mixture are mixed, the LAFE sand ratio is 15 to 65% and preferably 20 to 60% by weight and the LAFE gravel / gravel mixture ratio is 15 to 65%, preferably 20 to 60% by weight to the total LAFE sand weight. + LAFE grit and gravel mixtures.

Other objects of the invention are apparent from the following description and examples. The invention is illustrated by the following non-limiting examples, in which percentages are based on dry weight, in which sand LAFE denotes 280498-6 denotes sand with a granulometric value of approximately 0/8 mm and a grit / gravel mixture LAFE denotes granulates with a granulometric value of about 0/31 5 mm, and preferably about 0/20 or 0/14 mm, obtained by the twin removal of iron and sieving of the electro-steel slag.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

LAFE sand or gravel-gravel mixture LAFE 96%

Cement CLK. 45 4%

Example 2

LAFE sand or LAFE grit / gravel mixture 93%

Cement CLK 45 7%

Example 3

LAFE sand or LAFE grit / gravel mixture 93%

Product labeled ARC 1, ARC 2 or ARC 3 7%

Example 4

LAFE sand or LAFE grit / gravel mixture 98%

Product labeled ARC 1, ARC 2 or ARC 3 2%

Example 5

LAFE sand or LAFE grit / gravel mixture 79%

Blast furnace slag 20%

Quicklime 1%

Example 6

LAFE sand or LAFE grit / gravel mixture 69% Blast granulated slag 30%

Quicklime 1%

Example 7

LAFE sand or LAFE grit / gravel mixture 53% Blast granulated slag 22%

Popolček 23%

Slaked lime 2%

Example 8

LAFE sand or gravel / gravel mixture LAFE 57%

Blast furnace slag 20%

Popolček 20%

Slaked lime 3%

Example 9

LAFE sand or LAFE grit / gravel mixture 70% Blast granulated slag 29%

Quicklime 1%

Example 10

LAFE sand or grit / grit LAFE 74%

Blast furnace slag 25%

Non-slaked lime 1% (a) sand or gravel / slag mixture of steel slag from an electric furnace of 53% or more by weight of the total mixture, (b) one or more binders, (c) at least one solidification activator, or (a) sand or a mixture of pulp and gravel from a steel slag from an electric furnace in an amount of 93 to 98% by weight; (d) one or more binders / activators in an amount of 2 to 7% by weight based on the total weight of the mixture.

A composition according to claim 1, characterized in that the binder (b) is selected from the group consisting of blast furnace granulated slags, pozzolanic ashes, pozzolanic ash derivatives and mixtures thereof.

A composition according to claim 1 or 2, wherein the activator is quicklime or slaked lime.

The composition of claim 1, wherein the binder / activator is selected from granulated slag cements and special binders used in road construction.

A composition according to claim 1 or 4, characterized in that it contains 93 to 96% by weight of sand or a mixture of pulp and gravel of electro-steel slag and 4 to 7% by weight of cement.

A composition according to any one of claims 1 to 3, characterized in that it comprises:

sand or a mixture of pulp and gravel of electro-steel slag 74 ± 5%, blast-furnace granulated slag 25 ± 5%, quicklime or slaked lime 1%.

7. A composition according to any one of claims 1 to 3 comprising:

sand or gravel / gravel mixture electro-steel debris 58 ± 5%, blast furnace granulated slag 20 ± 5%, pozzolanic ashes 20 ± 5%, quicklime or slaked lime 2 ± 1%.

A process for producing a road layer composition having good dimensional stability and good tensile and compressive strength according to any one of claims 1 to 7, characterized in that crushing, iron removal and sieving of the steel slag from the electric furnace are carried out, to obtain sand with a granulometry of about 0/8 mm and / or a mixture of grit and gravel with a granulometry of about 0 / 31.5 mm and preferably about 0/20 mm or 0/14 mm, then this sand is mixed with electro-steel slag and / or a mixture of pulp and gravel of electro-steel slag with one or more binders selected from the group consisting of hydraulic binders, pozzolanic ashes, pozzolanic ash derivatives and mixtures thereof, and at least one activator or at least one binder / activator.

A method according to claim 8, characterized in that the products of the electro-steel slag are mixed with sand and a mixture of grit and gravel in a ratio of 15 to 65% by weight of sand and from 15 to 65% by weight of grit and gravel. and gravel.

Claims (1)

End of document PATENT CLAIMS 1. A composition for a road layer comprising: