Method for the kinetic regulation of cementitious binders

Abstract

A method for the kinetic regulation of cementitious binders and/or cementitious binder compositions, the method including the steps of providing a cementitious binder, admixing at least one borate mineral to said cementitious binder, and optionally admixing an activator selected from the group consisting of CaO, Ca(OH).sub.2, and/or CaSO.sub.4.

Claims

1. A method for the kinetic regulation of cementitious binders and/or cementitious binder compositions, the method comprising 1) providing a cementitious binder, 2) providing at least one borate mineral, 3) mixing the cementitious binder and the at least one borate mineral in any given order, and 4) optionally admixing an activator selected from the group consisting of CaO, Ca(OH).sub.2, CaSO.sub.4,and combinations thereof, the method further comprising 5) grinding the at least one borate mineral, wherein a dosage and/or a specific surface area of every borate mineral is chosen in a way that a product P as defined by the equation P=D.Math.(SSA).sup.1/2, wherein D is the dosage of the respective borate mineral in weight % relative to the cementitious binder and SSA is the specific surface area of the respective borate mineral in m.sup.2/g, is from 0.01-75.

2. The method according to claim 1, wherein the cementitious binder comprises at least one calcium aluminate cement and/or at least one calcium sulphoaluminate cement.

3. The method according to claim 2, wherein the cementitious binder additionally comprises at least one Ordinary Portland Cement.

4. The method according to claim 3, wherein a weight ratio of the at least one Ordinary Portland Cement to the at least one calcium aluminate cement and/or the at least one calcium sulphoaluminate cement is from 200:1-1:1000.

5. The method according to claim 1, wherein the at least one borate mineral is of natural origin.

6. The method according to claim 1, wherein the at least one borate mineral is selected from the group consisting of calcium borate, calcium metaborate, takedaite, kotoite, frolovite, hexahydroborite, suanite, sussexite, szaibelyite, wiserite, pinnoite, pentahydroborite, calciborite, meyerhofferite, inyoite, colemanite, hydroboracite, howlite, jarandolite, johachidolite, kernite, sborgite, ulexite, larderellite, probertite, tertschite, nasinite, gowerite, tuzlaite, hilgardite, aksaite, admontite, kaliborite, fabianite, nobleite and combinations thereof.

7. The method according to claim 1, wherein the specific surface area of the at least one borate mineral is between 0.1-200 m.sup.2/g.

8. The method according to claim 1, wherein the method additionally comprises at least one 1) drying the at least one borate mineral, 2) admixing aggregates, 3) admixing other additives, 4) admixing water.

9. The method according to claim 1, wherein the activator is admixed to a cementitious binder composition to immediately start a setting and curing reaction.

10. The method according to claim 1, wherein the grinding comprises in-situ grinding of the at least one borate mineral in the presence of the cementitious binder.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 shows an exemplary cumulative heat flow curve. The open time, final setting time, and plateau height are marked.

(2) FIG. 2 shows an exemplary heat flow curve. The open time and final setting time are marked.

WORKING EXAMPLES

(3) Heat flow curves were measured in an isothermal process as described in standard ASTM C1702-17. Examples were measured using an instrument i-CAL 8000 from Calmetrix. Cumulative heat flow curves were calculated from heat flow curves by integration using software default parameters.

(4) The open time is the time at the point of inflection of the cumulative heat flow curve. It was measured on the heat flow curve as the time where the heat flow curve starts to increase. The final setting time was derived from the heat flow curve as the time when the increase in energy measured per 1 min becomes less than 0.1 J/g.

(5) The plateau height is the total energy released from the time of mixing with mixing water until the final setting time is reached.

(6) BET surfaces were determined in accordance with standard ISO 9277 by the adsorption of nitrogen. The measurement was done as a three point measurement at 196 C. using a Horiba SA-9600 instrument with Helium as a carrier gas. Samples were dried at 70 C. for 5 days prior to measurement.

(7) The following Table 1 gives an overview of borate minerals used. All chemicals were used as supplied unless otherwise noted.

(8) TABLE-US-00001 TABLE 1 Borate minerals used Specific surface Particle size D1- Borate mineral Purity area [m.sup.2/g] D99 [m] boric acid 99.5% n.r. n.r. calcium borate >98% 11.5 0.6-69 ulexite 89% 2.6 0.7-130 colemanite 80% 1 0.5-113 gerstley borate* 26.8% B.sub.2O.sub.3 2.4 0.6-87 *Gerstley borate used from US Borax Inc n.r.: not relevant

(9) The following Tables 2a to 2c give an overview of the various cementitious binders used. All cements were used as supplied.

(10) TABLE-US-00002 TABLE 2a Commercial cementitious binders used Cement Type Supplier Alpenat CSA cement Vicat SA Alicem CSA cement Heidelberg Zement AG Isidac 40 CAC Cimsa Cimento AS

(11) TABLE-US-00003 TABLE 2b BYF cement composition (XRD, Rietveld refinement) Phase wt % Ye'elimite 29 2 Belite 46 3 Ferrite 4 1 Calcium sulfate 6 1 Others 15 2

(12) TABLE-US-00004 TABLE 2c Ternary blend composition Supplier Ternal white 60 w % Imerys CEM I 52.5R 25 w % Heidelberg Zement AG CaSO.sub.4 (alpha- 15 w % Casea hemihydrate)

Examples E1-E19

(13) The respective cementitious binder and the respective borate mineral as indicated in below tables 3-5 were mixed in dosages as indicated in below tables 3-5 in a dry state by vigorously shaking the powders until visually homogeneous. Then water was added in an amount to realize a water/cement ratio of 0.5. Mixing was then continued on a Heidolph propeller mixer for 1 min at 1000 rpm. All mixing procedures were done at 23 C. and 50% r.h.

(14) The following table 3 shows mixes and results with the cementitious binder BYF.

(15) TABLE-US-00005 TABLE 3 Retardation of BYF cement with various borate minerals Borate Open Final Borate mineral time setting Plateau mineral dosage ** P [min] time [h] height [J/g] C-1* None (ref.) 0 n.r. 72 27.6 214 C-2* None 0.2 n.r. 168 28.2 222 (boric acid) E-1 ulexite 0.5 0.8 190 24.2 208 E-2 ulexite 1.0 1.6 448 28.6 196 E-3 colemanite 1.0 1 126 25.3 200 E-4 colemanite 2.0 2 194 32.4 205 E-5 calcium 1.0 3.4 958 45.5 204 borate E-6 gerstley 1.0 1.6 221 29.6 192 borate E-7 gerstley 2.0 3.1 331 35.8 201 borate E-8 gerstley 3.0 4.7 550 40.3 207 borate *comparative example not according to the invention ** in w % based on cementitious binder P = D .Math. (SSA).sup.1/2 (product of dosage and square root of the specific surface area of the borate mineral) n.r.: not relevant n.m.: not measured

(16) The following table 4 shows mixes and results with the cementitious binder Alpenat.

(17) TABLE-US-00006 TABLE 4 Retardation of Alpenat cement with various borate minerals Borate Open Final Borate mineral time setting Plateau mineral dosage ** P [min] time [h] height [J/g] C-3* None (ref.) none n.r. 90 20.2 251 E-9 ulexite 0.5 0.8 281 27.3 266 E-10 ulexite 1 1.6 967 49.8 261 E-10a ulexite 2 3.2 4440 105 241 E-10b ulexite 7.5 12.1 >10000 n.m. n.m. E-11 colemanite 2 2.0 134 22.0 244 E-12 colemanite 4 4.0 195 n.m. n.m. E-12a colemanite 3.5 3.5 208 15.4 256 E-13 calcium 1 3.4 1069 41.6 247 borate E-13a calcium 2 6.8 2512 63.6 267 borate E-13b calcium 7.5 25 >10000 n.m. n.m. borate E-14 gerstley 2 3.1 792 30.6 237 borate *comparative example not according to the invention ** in w % based on cementitious binder P = D .Math. (SSA).sup.1/2 (product of dosage and square root of the specific surface area of the borate mineral) n.r.: not relevant n.m.: not measured

(18) The following table 5 shows mixes and results with the cementitious binders Isidac 40, Alicem, and the ternary blend.

(19) TABLE-US-00007 TABLE 5 Retardation of cements Alicem, Isidac 40, and the ternary blend with various borate minerals Cementitious Borate Open Final Plateau binder/ mineral time setting height Borate mineral dosage ** P [min] time [h] [J/g] C-4* Alicem/ 0 n.r. 30 19.8 273 None (ref.) E-15 Alicem/ 1.0 3.4 88 32.5 258 calciumborate E-16 Alicem/ 2.0 6.8 607 40.4 241 calciumborate C-5* Isidac 40/ 0 n.r. 483 48.2 360 None (ref.) E-17 Isidac 40/ 0.5 0.8 561 40.6 350 ulexite C-6* Ternary blend/ 0 n.r. 0 18.5 270 None (ref.) E-18 Ternary blend/ 1.0 3.4 32 19.7 268 calciumborate Ternary blend/ 2.0 6.8 1081 70.6 275 calciumborate Ternary blend/ 3.5 11.9 12000 300 295 calciumborate Ternary blend/ 7.5 25.5 >18000 n.m. 91 calciumborate *comparative example not according to the invention ** in w % based on cementitious binder P = D .Math. (SSA).sup.1/2 (product of dosage and square root of the specific surface area of the borate mineral) n.r.: not relevant n.m.: not measured

(20) From the results presented in above Tables 3-5 it becomes clear that efficient set-retardation, expressed by prolonged open times, is achieved by a method of the present invention as compared to the references which are not prepared according to a method of the present invention and which do not comprise any borate minerals. The borate minerals used in a method of the present invention are even more efficient as compared to boric acid because they lead to a higher increase in open time but at the same time a lower increase in the final setting time.

(21) It becomes further clear that a higher product P as defined by equation (I) above leads to a longer open time and normally also to a longer final setting time.

Examples E19-E20

(22) BYF cement and ulexite (0.5 w % based on cement weight) were mixed in a dry state by vigorously shaking the powders until visually homogeneous. Water was added in an amount to realize a water/cement ratio of 0.5. Mixing was then continued on a Heidolph propeller mixer for 1 min at 1000 rpm. For examples E-19 and E-20, a suspension of Ca(OH).sub.2 and CaSO.sub.4 hemihydrate (2:1 by weight, 25% solids content) was admixed on a Heidolph propeller mixer for 1 min at 1000 rpm. The suspension was added in 10 w % related to the cement weight after the time indicated in below table 6. All mixing procedures were done at 23 C. and 50% r.h.

(23) TABLE-US-00008 TABLE 6 Kinetic regulation with ulexite and additional activator added ulexite Time*** Open time Final setting Plateau dosage ** P [min] [min] time [h] height [J/g] E-19 0.5 0.8 1 1 14.6 154 E-20 0.5 0.8 60 60 13.9 138 * comparative example not according to the invention ** in w % based on cementitious binder ***time elapsed after addition of water and until addition of activator P = D .Math. (SSA).sup.1/2 (product of dosage and square root of the specific surface area of the borate mineral) n.r.: not relevant

(24) As can be seen from the above table 6, the addition of the activator to a cementitious binder composition comprising ulexite is an efficient mean for the reactivation. The hydration reaction starts immediately after the addition of the activator and proceeds quickly thereafter. This is in particular obvious if compared with the examples C-1 and E-1 of the above table 3.