Rapid hydraulic binder comprising a calcium salt

Abstract

A hydraulic binder includes a Portland clinker having a Blaine specific surface of 4000 to 5500 cm.sup.2/g, from 2.5 to 8% of sulphate expressed by mass of SO.sub.3 relative to the mass of clinker, from 1.5 to 10% of calcium nitrite and/or calcium nitrate expressed as anhydrous mass relative to the mass of clinker and from 15 to 50% of a mineral addition including calcium carbonate by mass relative to the total mass of binder.

Claims

1. A hydraulic composition comprising a hydraulic binder comprising a Portland cement clinker having a Blaine specific surface area of 4000 to 5500 cm.sup.2/g, from 2.5 to 8% of sulphate expressed by mass of SO.sub.3 relative to the mass of clinker, from 1.5 to 10% of calcium nitrite and/or calcium nitrate expressed as anhydrous mass relative to the mass of clinker and from 15 to 50% of a mineral addition comprising calcium carbonate by mass relative to the total mass of binder, and water, wherein the quantity of clinker is from 220 to 450 kg/m.sup.3.

2. The composition according to claim 1, wherein the quantity of hydraulic binder is greater than or equal to 300 kg/m.sup.3.

3. A process for production of a hydraulic composition according to claim 1, comprising mixing the binder with water, wherein the temperature at the time of mixing of the various components with water and the temperature at the time of the setting of the composition is from 5 to 35° C.

4. A shaped article for the construction field comprising the hydraulic composition according to claim 1.

5. The hydraulic composition according to claim 1, wherein the hydraulic binder comprises from 2 to 7% of calcium nitrite and/or calcium nitrate expressed as anhydrous mass relative to the mass of clinker.

6. The hydraulic composition according to claim 1, wherein the hydraulic binder only comprises calcium nitrite.

7. The hydraulic composition according to claim 1, wherein the hydraulic binder comprises from 25 to 45% of the mineral addition comprising calcium carbonate by mass relative to the total mass of binder.

8. The hydraulic composition according to claim 1, wherein, in the hydraulic binder, the quantity of clinker is from 40 to 80% by mass relative to the total mass of binder.

9. The hydraulic composition according to claim 1, wherein the hydraulic binder further comprises a mineral addition other than a mineral addition comprising calcium carbonate.

10. The hydraulic composition according to claim 9, wherein the mineral addition other than a mineral addition comprising calcium carbonate is selected from the group consisting of pozzolan, fly ash, and any mixture thereof.

11. The hydraulic composition according to claim 1, wherein, in the hydraulic binder, the quantity of sulphate is at most 4%, expressed by mass of SO.sub.3 relative to the hydraulic binder, the hydraulic binder comprising the clinker, the mineral addition comprising calcium carbonate, the sulphate and optionally a mineral addition other than a mineral addition comprising calcium carbonate.

12. A concrete or mortar having mechanical strength greater than 3 MPa at 6 hours, obtained by hardening the hydraulic composition according to claim 1.

Description

EXAMPLES

(1) Raw Materials

(2) The clinker used in the examples came from the Lafarge cement plant of Le Havre (France). The composition of the clinker is given in the table below:

(3) TABLE-US-00001 SiO.sub.2 Al.sub.2O.sub.3 Fe.sub.2O.sub.3 CaO MgO K.sub.2O Na.sub.2O SO.sub.3 P.sub.2O.sub.5 Mass % 20.98 5.85 2.5 64.7 1.1 0.31 0.14 1.16 0.7

(4) The mineral addition comprising calcium carbonate was limestone commercialised under the brand name of BL200 (supplier: Omya).

(5) Aggregates: each aggregate is characterised by two numbers: the first corresponds to <<d>> as defined in the XPP 18-545 Standard of February 2004 and the second corresponds to <<D>> as defined in the XPP 18-545 Standard of February 2004: the sand was a 0/4 rolled silica-calcareous sand from the Lafarge quarry of Mauzac; the coarse aggregates were the 4/14 rolled alluvial silica-calcareous aggregates from the Lafarge quarry of Mauzac.

(6) The superplasticizers were the following products: SP1: polycarboxylate superplasticizer in solution having 20% of dry extract (supplier: BASF; commercial brand name: Glenium 27); and SP2: superplasticizer (supplier: BASF; commercial brand name: Rheotec).

(7) The calcium nitrite was a calcium nitrite in liquid form having a density of 1.25 +/−0.01 and a dry extract of 32% +/−2% (supplier: Chryso; commercial brand name: SET02).

(8) The sulphate was the anhydrite from eastern France.

(9) Measurement of the Spread and Rheoloqy Monitoring

(10) The spread of the concretes and mortars was measured at 20° C. using an Abrams mini-cone with a volume of 800 mL. The cone dimensions were as follows: Top diameter: 50+/−0.5 mm; Bottom diameter: 100+/−0.5 mm; and Height: 150+/−0.5 mm.

(11) The cone was placed on a dried glass plate and filled with fresh concrete or mortar. It was then leveled. The concrete or mortar slumped onto the glass plate when the cone was removed. The diameter of the disk of concrete or mortar obtained was measured in millimeters +/−5 mm. This is the spread of the concrete or mortar.

(12) These operations were repeated at several time periods (for example at 5, 15 and 30 minutes), and made it possible to monitor the evolution of the rheology for the concrete or the mortar over a given period of time (for example 30 minutes).

(13) Measurement of the Compressive Strength

(14) The measurements of the mechanical compressive strengths were done on samples of hardened concrete or mortar with the following dimensions: 40 mm×40 mm×160 mm.

(15) The samples of concrete or mortar were immediately moulded after the preparation of the concrete or mortar. The mould was attached to a shock table. The concrete or mortar was introduced into the mould in two layers (each layer of concrete or mortar weighing approximately 300 g). The first layer of concrete or mortar, then the second layer was placed by 60 shocks on the shock table. The mould was removed from the shock table and levelled to remove excess concrete or mortar. A plate of glass of 210 mm×185 mm and 6 mm thickness was placed on the mould. The mould covered by the glass plate was placed in a humid enclosure at 10° C. (for Example 1) or at 20° C. (for Example 2). The mould was removed from the enclosure and the sample of hardened concrete or mortar was demoulded at the time period selected for the mechanical compressive test, up to 24 hours after the mixing, then it was submerged in water at 20° C.±1° C.

(16) For the time periods longer than 24 hours after the mixing, the samples were demoulded 24 hours after the mixing, then immersed in water at 20° C.±1° C. (for Example 2). The samples of hardened concrete or mortar were removed from the water 15 minutes maximum, before the measurement of the mechanical compressive strength. The samples of hardened concrete or mortar were dried, then covered with a damp cloth whilst waiting for the measurement

(17) An increasing load was applied on the lateral sides of the samples of hardened mortar at a speed of 2 400 N/s±200 N/s for the measurement of the mechanical compressive strength, until breaking of the sample.

(18) The quantity of carbon dioxide emitted during the production of the clinker was theoretically determined.

Example 1

Spread, Compressive Strength and Emitted Carbon Dioxide

(19) The hydraulic compositions according to the invention (Compositions 1 to 4) were compared to a control composition (Control). Table 1 herein below describes the tested compositions, given that each composition further comprised: 172 kg/m.sup.3 of water; 0.20% of SP2 by percentage of dry mass relative to the clinker; and 3% by mass of SO.sub.3 (provided by the anhydrite) relative to the binding phase (clinker+limestone+anhydrite).

(20) The clinker of the control composition had a Blaine specific surface area of 3500 cm2/g. The clinker of the compositions according to the present invention had a Blaine specific surface area of 4500 cm.sup.2/g.

(21) The unit in Table 1 unless otherwise specified is kg/m.sup.3.

(22) TABLE-US-00002 TABLE 1 Compositions of the concretes tested for Example 1 Binding Coarse SO.sub.3/Clinker Ca(NO.sub.2).sub.2/Clinker phase Clinker Limestone Anhydrite Sand aggregates SP1 (mass %) (mass %) Control 400 329 50 21 780 1108 0.36 3.5 5.3 Comp. 1 400 251 120 29 780 1108 0.23 4.2 7.0 Comp. 2 450 283 135 32 761 1091 0.23 4.2 6.2 Comp. 3 500 314 150 36 739 1066 0.23 4.2 5.6 Comp. 4 600 377 180 43 670 1040 0.23 4.2 4.7

(23) The formulae were defined for 1 cubic meter of concrete.

(24) The concrete was produced according to the procedure described herein below: 1) introduction of the sand and coarse aggregates in the vessel of a Perrier mixer; 2) from 0 to 30 seconds: begin mixing at low speed (140 rpm) and add the pre-wetting water in 30 seconds; 3) from 30 seconds to 1 minute, mix the aggregates and the pre-wetting; 4) from 1 minute to 5 minutes, leave to rest; 5) from 5 minutes to 6 minutes, add the clinker, the limestone and anhydrite; 6) from 6 minutes to 7 minutes, mix at low speed; 7) from 7 minutes to 7 minutes and 30 seconds, add the mixing water, SP1 and nitrite whilst mixing at low speed; 8) from 7 minutes and 30 seconds to 9 minutes and 30 seconds, mix at high speed (280 rpm).

(25) The spread and the compressive strength were measured according to the procedures described herein above. Table 2 below gives the obtained results.

(26) TABLE-US-00003 TABLE 2 Results for the spread, compressive strength and emitted CO.sub.2 measurements for compositions of Example 1 Emitted CO.sub.2 Spread (mm) Compressive (kg/m.sup.3 of 5 15 30 60 90 120 strengths (MPa) concrete) min min min min min min 4 h 5 h 6 h Control 265 285 335 335 300 260 205 0.4 1.2 2.3 Comp. 1 230 285 305 285 265 235 280 1.3 2.1 3.0 Comp. 2 260 310 320 320 300 310 335 1.6 3.0 6.2 Comp. 3 290 240 295 310 300 340 320 2.5 5.1 7.2 Comp. 4 345 205 245 260 265 270 290 5.7 9.8 13.0

(27) According to Table 2 above, when the Control composition and Composition 1 are compared, for a same quantity of binding phase (400 kg/m.sup.3) but a less quantity of clinker in Composition 1 (respectively 350 kg/m.sup.3 of clinker in the Control composition and 280 kg/m.sup.3 of clinker in Composition 1), better compressive strengths were obtained. Likewise, the quantity of emitted CO.sub.2 decreased, and the spread remained within the same order of magnitude.

(28) When the Control composition and Composition 3 are compared, for a same quantity of clinker (350 kg/m.sup.3), better compressive strengths were obtained.

(29) Generally, all the compositions according to the invention made it possible to obtain a compressive strength greater than or equal to 1 MPa 4 hours after the mixing and greater than or equal to 3 MPa 6 hours after the mixing.

(30) It should be noted that the results above were obtained at 10° C. The compositions according to the present invention therefore made it possible to obtain a hydraulic binder having good early mechanical strengths, even at a temperature as low as 10° C.

Example 2

Standardisation

(31) Before being launched on the market, all new hydraulic compositions may be classified in terms of standards, for example according to the EN 197-1 Standard of February 2001. With this aim, the compressive strength of the hydraulic composition is determined according to the EN196-1 Standard of April 2006, on a formulation of standardised mortar.

(32) The hydraulic compositions according to the invention (Compositions 5 and 6) had the composition as described in Table 3 below, given that each composition further comprised: 450 g±2 g of binding phase (clinker+limestone); 1350 g±5 g of standardised sand (siliceous sand according to the EN 196-1 Standard of April 2006; supplier: Société Nouvelle du Littoral); 225 g±1 g of water; and 3% by mass of SO.sub.3 relative to the binding phase.

(33) The clinker had a Blaine specific surface area of 4500 cm.sup.2/g.

(34) The unit in Table 3 unless otherwise specified is kg/m.sup.3.

(35) TABLE-US-00004 TABLE 3 Compositions of the mortars tested for Example 2 SO.sub.3/ Ca(NO.sub.2).sub.2/ Clinker Clinker Clinker Limestone (mass %) (mass %) Comp. 5 315 135 4.2 5.6 Comp. 6 247.5 202.5 5.5 7.1

(36) The mortar was produced according to the procedure described below: Introduce the water, clinker, limestone, sulphate and nitrite into the vessel of a mixer; Mix at 140±5 rpm for 30 seconds; Regularly introduce the sand during 30 seconds; Mix at 285±10 rpm for 30 seconds; Interrupt the mixer for 90 seconds; and Mix at 285±10 rpm for 60 seconds.

(37) The compressive strength was measured according to the procedure described herein above.

(38) Table 4 herein below presents the obtained results.

(39) TABLE-US-00005 TABLE 4 Results of the standardisation test Classification Compressive strength according to (MPa) the EN 197-1 2 days 7 days 28 days Standard Comp. 5 26.0 40.1 53.0 42.5 R Comp. 6 18.9 35.2 45.3 32.5 R

(40) According to Table 4 herein above, the hydraulic compositions according to the invention respected the compressive strength specifications of the EN 197-1 Standard of February 2001 (see paragraph 7, table 2 of the Standard).