DRY CEMENTITIOUS MATERIAL MIXTURE FOR 3D-PRINTING

Abstract

A dry cementitious material mixture for 3D-printing, includes a hydraulic cement, at least one viscosity enhancing admixture, at least one accelerator and aggregates, wherein the at least one viscosity enhancing admixture is present in an amount of 0.05-1.5% by weight based on the hydraulic cement and the at least one accelerator is present in an amount of 0.5-6.0% by weight based on the hydraulic cement.

Claims

1. A dry cementitious material mixture for 3D-printing, comprising a hydraulic cement, at least one viscosity enhancing admixture, at least one accelerator and aggregates, wherein the at least one viscosity enhancing admixture is present in an amount of 0.05-1.5% by weight based on the hydraulic cement and the at least one accelerator is present in an amount of 0.5-6.0% by weight based on the hydraulic cement.

2. The dry cementitious material mixture according to claim 1, wherein the hydraulic cement consists of Portland cement.

3. The dry cementitious material mixture according to claim 1, wherein the at least one accelerator comprises calcium formate, calcium chloride and/or calcium nitrite.

4. The dry cementitious material mixture according to claim 1, wherein the at least one accelerator is an organic accelerator.

5. The dry cementitious material mixture according to claim 1, wherein the hydraulic cement comprises Portland cement and an aluminate cement, wherein said at least aluminate cement is present in an amount of <1.5% by weight based on the total amount of hydraulic cement.

6. The dry cementitious material mixture according to claim 5, wherein the at least one accelerator comprises sodium carbonate.

7. The dry cementitious material mixture according to claim 5, wherein the dry cementitious material mixture further comprises a setting retarder.

8. The dry cementitious material mixture according to claim 1, wherein the at least one viscosity enhancing admixture comprises unmodified polysaccharides or modified polysaccharides, acrylic polymers, and/or an inorganic material.

9. The dry cementitious material mixture according to claim 1, wherein the dry cementitious material mixture further comprises fibers.

10. The dry cementitious material mixture according to claim 1, wherein the dry cementitious material mixture further comprises a superplasticizer.

11. The dry cementitious material mixture according to claim 1, wherein the aggregates consist of particles having a maximum particle size of 16 mm.

12. The dry cementitious material mixture according to claim 11, wherein the aggregates comprise fine aggregates having a maximum particle size of 4 mm, and optionally coarse aggregates having a maximum particle size of 10 mm.

13. The dry cementitious material mixture according to claim 1, wherein the hydraulic cement is present in an amount of 25-45% by weight based on the dry cementitious material mixture.

14. A method of placing a flowable construction material for building structural components layer-by-layer, said method comprising: providing a dry cementitious material mixture according to claim 1, mixing the dry cementitious material mixture with water to obtain a flowable construction material, conveying the flowable construction material to a deposition head, placing the construction material through an outlet of the deposition head in order to form a layer of construction material, wherein no admixtures are added to the flowable construction material in or at the deposition head.

15. The method according to claim 14, wherein the amount of water mixed with the dry cementitious material mixture is selected to obtain a water/dry cementitious material mixture weight ratio of 0.09-0.23.

16. The method according to claim 14, wherein the flowable construction material has a yield strength of 0.25-8 kPa when being placed.

17. A method comprising providing a dry cementitious material mixture according to claim 1 for 3D-concrete-printing through a deposition head, with no addition of any admixture in or at the deposition head, after having been mixed with water.

18. The dry cementitious material mixture according to claim 1, wherein the at least one viscosity enhancing admixture is present in an amount of 0.2-0.6% by weight based on the hydraulic cement and the at least one accelerator is present in an amount of 1.5-4.0% by weight based on the hydraulic cement.

19. The dry cementitious material mixture according to claim 4, wherein the organic accelerator is calcium formate.

20. The dry cementitious material mixture according to claim 5, wherein said at least aluminate cement is present in an amount of <1.0% by weight based on the total amount of hydraulic cement.

Description

[0070] The invention will now be described in more detail by reference to the following examples.

[0071] In the following examples various dry cementitious material mixtures where provided, which were used for preparing mortar. The mortar was prepared according to the following procedure: [0072] using a standard Perrier mortar mixer [0073] add all powder components into the mixer mixing the powder with low speed (140 r/min) for 2 minutes [0074] adding water within 15 seconds while keeping on mixing for 2 minutes

[0075] The following components were used in the dry cementitious material mixtures described below. All components are in powder form:

TABLE-US-00001 Supplier/ Component Abbreviation Type Origin CEM I 52, 5R CEM I Ordinary Portland LafargeHolcim SR3 Cement Spain - Carboneras plant Limestone Limestone sand, LafargeHolcim crushed 0/2 maximum size 2 mm Spain Limestone Limestone sand, LafargeHolcim crushed 0/4 maximum size 4 mm Spain Saint Bonnet Aggregate, size LafargeHolcim 5/10 R from 5 to 10 mm France Viscocrete SP Superplasticizer Sika 225 P Mecellose VEA1 Viscosity enhancing Lotte Fine Hiend 2001 admixture Chemical Cimsil A55 VEA2 Viscosity enhancing TOLSA S.A. admixture Arbocel FI Fiber1 Cellulose G-Biosciences 540 CA microfiber Neuflex AC 6 Fiber2 Fiber Neuvendis mm Calcium ACC1 Accelerator Sigma Aldrich formate DENKA SC1 CA Blend of calcium Kerneos aluminate cement and calcium sulphate Sodium ACC2 Accelerator for Sigma Aldrich carbonate DENKA SC1 Citric acid Ret Retarder for DENKA Sigma Aldrich SC1 Ciment Fondu CF Aluminate cement Kerneos Calcium ACC3 OPC Accelerator Sigma Aldrich chloride (CaCl.sub.2) Calcium ACC4 OPC Accelerator Sigma Aldrich nitrite Ca (NO.sub.2).sub.2

[0076] Examples nos. 1-18 (Table 1 and 2) refer to mortars that have been prepared based on a dry cementitious material mixture according to the invention.

[0077] Reference examples nos. 1-5 (Table 3 and 4) refer to mortars that have been prepared based on a dry cementitious material mixture that does not correspond to the invention.

TABLE-US-00002 TABLE 1 Effective Ex CEM I Sand Sand AGG SP VEA1 VEA2 Fiber 1 Fiber 2 ACC1 ACC4 ACC3 water 1 weight for 559.58 .sup. 606.2 .sup.1  .sup. 682.68 .sup.2 0   0.744 1.119 1.511 0.56 0.47 13.055 0.00 0.00 308.96 1 m.sup.3 [kg] wt-% of dry 30.0 32.5 36.6 0.0  0.040 0.060 0.081 0.030 0.025 0.70 0.000 0.000 17 mix wt-% of 100.00 108.33 122.00 0.00 0.13 0.20 0.27 0.10 0.08 2.33 0.00 0.00 55 cement 2 weight for 559.58 .sup. 606.2 .sup.1 .sup. 682.7 .sup.2 0   0.67 1.49 0 0 0.47 13.06 0.00 0.00 308.96 1 m.sup.3 [kg] wt-% of dry 30.02  32.52  36.62 0.00 0.040 0.08 0.00 0.00 0.03 0.70 0.000 0.000 17 mix wt-% of 100.00 108.33 122.00 0.00 0.12 0.27 0.00 0.00 0.08 2.33 0.00 0.00 55 cement 3 weight for 559.58 .sup. 605.3 .sup.1 681 .sup.2  0   0.671 1.494 1.511 0 0.47 13.055 0.00 0.00 308.96 1 m.sup.3 [kg] wt-% of dry 30.0 32.5 36.6 0.00 0.036 0.08 0.08 0.0 0.03 0.7 0.000 0.000 17 mix wt-% of 100.00 108.17 121.70 0.00 0.12 0.27 0.27 0.00 0.08 2.33 0.00 0.00 55 cement 4 weight for 559.58 .sup. 606.2 .sup.1 .sup. 682.7 .sup.2 0   0.671 1.494 0 0 0.47 0 0.00 11.192 308.96 1 m3 [kg] wt-% of dry 30.05  32.55  36.66 0.00 0.036 0.08 0.00 0.00 0.03 0.00 0.000 0.60 17 mix wt-% of 100.00 108.33 122.00 0.00 0.12 0.27 0.00 0.00 0.08 0.00 0.00 2.00 55 cement 5 weight for 559.58 .sup. 606.2 .sup.1 .sup. 682.7 .sup.2 0   0.671 1.494 0 0 0.47 0 9.792 0.00 308.96 1 m.sup.3 [kg] wt-% of dry 30.07  32.58  36.69 0.00 0.036 0.08 0.00 0.00 0.03 0.00 0.53 0.000 17 mix wt-% of 100.00 108.33 122.00 0.00 0.12 0.27 0.00 0.00 0.08 0.00 1.75 0.00 55 cement 6 weight for 318.00  .sup. 149.05 .sup.3  .sup. 781.20 .sup.5 858.29 .sup.7  0.42 0.64 0.85 0.32 0.27 7.42 0.00 0.00 185.50 1 m.sup.3 [kg] wt-% of dry 15.0  7.0 36.9 40.6  0.020 0.030 0.040 0.015 0.013 0.351 0.000 0.000 9 mix wt-% of 100.0 46.9 245.7  269.9   0.133 0.200 0.267 0.100 0.083 2.333 0.00 0.00 58 cement 7 weight for 352.00  .sup. 142.08 .sup.3  .sup. 744.72 .sup.5 818.21 .sup.7  0.47 0.70 0.94 0.35 0.29 8.21 0.00 0.00 205.33 1 m.sup.3 [kg] wt-% of dry 17.0  6.9 36.0 39.6  0.023 0.034 0.045 0.017 0.014 0.397 0.000 0.000 10 mix wt-% of 100.0 −40.4  211.6  232.4   0.133 0.200 0.267 0.100 0.083 2.333 0.00 0.00 58 cement 8 weight for 393.00  .sup. 133.82 .sup.3  .sup. 701.42 .sup.5 770.64 .sup.7  0.52 0.79 1.05 0.39 0.33 9.17 0.00 0.00 229.25 1 m.sup.3 [kg] wt-% of dry 19.5  6.7 34.9 38.3  0.026 0.039 0.052 0.020 0.016 0.456 0.000 0.000 11 mix wt-% of 100.0 34.1 178.5  196.1   0.133 0.200 0.267 0.100 0.083 2.333 0.00 0.00 58 cement 9 weight for 364.00  .sup. 605.95 .sup.4  .sup. 581.21 .sup.6 524.58 .sup.8  0.49 0.73 0.97 0.36 0.30 8.49 0.00 0.00 212.33 1 m.sup.3 [kg] wt-% of dry 17.4 29.0 27.8 25.1  0.023 0.035 0.047 0.017 0.015 0.407 0.000 0.000 10 mix wt-% of 100.0 166.5  159.7  144.1   0.133 0.200 0.267 0.100 0.083 2.333 0.00 0.00 58 cement 10 weight for 416.00  .sup. 560.46 .sup.4  .sup. 537.57 .sup.6 485.19 .sup.8  0.55 0.83 1.11 0.42 0.35 9.71 0.00 0.00 242.67 1 m.sup.3 [kg] wt-% of dry 20.7 27.9 26.7 24.1  0.028 0.041 0.055 0.021 0.017 0.482 0.000 0.000 12 mix wt-% of 100.0 134.7  129.2  116.6   0.133 0.200 0.267 0.100 0.083 2.333 0.00 0.00 58 cement 11 weight for 450.00  .sup. 530.20 .sup.4  .sup. 508.54 .sup.6 458.99 .sup.8  0.60 0.90 1.20 0.45 0.38 10.50 0.00 0.00 262.50 1 m.sup.3 [kg] wt-% of dry 22.9 27.0 25.9 23.4  0.031 0.046 0.061 0.023 0.019 0.535 0.000 0.000 13 mix wt-% of 100.0 117.8  113.0  102.0   0.133 0.200 0.267 0.100 0.083 2.333 0.00 0.00 58 cement .sup.1 Limestone sand having a maximum particle size of 2 mm (LafargeHolcim Spain) .sup.2 Limestone sand having a maximum particle size of 4 mm (LafargeHolcim Spain) .sup.3 Siliceous sand from La sabliére CCSH having a maximum particle size of 1 mm. .sup.4 Limestone sand from Cassis having a maximum particle size of 1.6 mm .sup.5 Siliceous sand from PUMP-Saint Bonnet having a maximum particle size of 5 mm .sup.6 Limestone sand from Cassis having a particle size of between 1.6 mm and 6 mm .sup.7 Siliceous aggregates from PUMP-Saint Bonnet having a particle size of between 5 mm and 10 mm .sup.8 Limestone aggregates from Cassis having a particle size of between 6 mm and 10 mm

TABLE-US-00003 TABLE 2 Fiber Fiber Ex CEM I Sand Sand AGG SP VEA1 VEA2 1 2 ACC1 CA ACC2 Ret Water 12 weight for 588.4 594.3 .sup.1  .sup. 735.5 .sup.2   .sup. 0.0 .sup.7 0.8 0.6 1.0 2.0 1.0 7.9 7.9 19.6 2.0 266.0 1 m.sup.3 [kg] wt-% of 30.01  30.31  37.51   0.00 0.04 0.03 0.05 0.10 0.05 0.4 0.40 1.00 0.10 14 dry mix wt-% of 100.0 47.5.sup.  248.8 0 0.1 0.1 0.2 0.3 0.2 1.3 1.3 3.3 0.3 45 cement 13 weight for 314.0 149.0 .sup.3  .sup. 781.2 .sup.5  .sup. 858.3 .sup.7 0.4 0.3 0.5 1.0 0.5 4.2 4.2 10.5 1.0 183.2 1 m.sup.3 [kg] wt-% of 14.84 .sup. 7.04  36.91  40.55 0.02 0.01 0.02 0.05 0.02 0.20 0.20 0.49 0.05 9 dry mix wt-% of 100.0 47.5.sup.  248.8 273.3 0.1 0.1 0.2 0.3 0.2 1.3 1.3 3.3 0.3 58 cement 14 weight for 348  142.08 .sup.3  .sup. 744.71 .sup.5  .sup. 818.20 .sup.7 0.464 0.348 0.58 1.16 0.58 4.64 4.64 11.6 1.16 203 1 m.sup.3 [kg] wt-% of 16.8  6.9  36.0  39.6 0.025 0.018 0.031 0.1 0.0 0.2 0.2 0.6 0.1 10 dry mix wt-% of 100.0 40.8.sup.  214.0 235.1 0.1 0.1 0.2 0.3 0.2 1.3 1.3 3.3 0.3 58 cement 15 weight for 388.0 133.8 .sup.3  .sup. 701.4 .sup.5  .sup. 770.6 .sup.7 0.5 0.4 0.6 1.3 0.6 5.2 5.2 12.9 1.3 226.3 1 m.sup.3 [kg] wt-% of 19.29 .sup. 6.65  34.88  38.32 0.03 0.02 0.03 0.06 0.03 0.26 0.26 0.64 0.06 11 dry mix wt-% of 100  34.48 180.8 198.6 0.13 0.1 0.15 0.3 0.2 1.3 1.3 3.3 0.36 58 cement 16 weight for 360.0 606.0 .sup.4  .sup. 581.2 .sup.6  .sup. 524.6 .sup.8 0.5 0.4 0.6 1.2 0.6 4.8 4.8 12.0 1.2 210.0 1 m.sup.3 [kg] wt-% of 17.25  29.03  27.85  25.13 0.02 0.02 0.03 0.06 0.03 0.23 0.23 0.57 0.06 10 dry mix wt-% of 100 168.3 .sup.  161.4 145.7 0.14 0.11 0.16 0.3 0.2 1.33 1.33 3.33 0.33 58 cement 17 weight for 411.0 560.5 .sup.4  .sup. 537.6 .sup.6  .sup. 485.2 .sup.8 0.5 0.4 0.7 1.4 0.7 5.5 5.5 13.7 1.4 239.8 1 m.sup.3 [kg] wt-% of 20.4 27.9.sup.   26.7  24.1 0.02 0.02 0.03 0.07 0.03 0.3 0.3 0.7 0.07 12 dry mix wt-% of 100.0 136.4 .sup.  130.8 118.1 0.1 0.1 0.2 0.3 0.2 1.3 1.3 3.3 0.3 58 cement 18 weight for 445.0  530.20 .sup.4  .sup. 508.54 .sup.6  .sup. 458.99 .sup.8 0.59 0.45 0.74 1.48 0.74 5.93 5.93 14.83 1.48 259.58 1 m.sup.3 [kg] wt-% of 22.68  27.03  25.92  23.40 0.03 0.02 0.04 0.08 0.04 0.30 0.30 0.76 0.08 13 dry mix wt-% of 100.0 119.1 .sup.  114.3 103.1 0.1 0.1 0.2 0.3 0.2 1.3 1.3 3.3 0.3 58 cement .sup.1 Limestone sand having a maximum particle size of 2 mm (LafargeHolcim Spain) .sup.2 Limestone sand having a maximum particle size of 4 mm (LafargeHolcim Spain) .sup.3 Siliceous sand from La sabliére CCSH having a maximum particle size of 1 mm .sup.4 Limestone sand from Cassis having a maximum particle size of 1.6 mm .sup.5 Siliceous sand from PUMP-Saint Bonnet having a maximum particle size of 5 mm .sup.6 Limestone sand from Cassis having a particle size of between 1.6 mm and 6 mm .sup.7 Siliceous aggregates from PUMP-Saint Bonnet having a particle size of between 5 mm and 10mm .sup.8 Limestone aggregates from Cassis having a particle size of between 6 mm and 10 mm

TABLE-US-00004 TABLE 3 CEM I Sand 1 Sand 2 AGG SP VEA1 VEA2 Fiber1 Fiber2 ACC1 CA ACC2 Ret Water Ref 1 weight for 514.8 606.2 682.7 0 0.34 1.96 0 0 0.47 0 44.7 5.395 1.063 280 1 m.sup.3 [kg] wt-% of 27.7 32.6 36.8 0.0 0.02 0.1 0.0 00 0.03 0.0 2.4 0.3 0.1 15 dry mix wt-% of 100 117.75 132.61 0.00 0.07 0.38 0.00 0.00 0.09 0.00 8.68 1.05 0.21 54 cement Ref 2 weight for 537.2 606.2 682.7 0 0.34 1.49 0 0 0.47 0 22.4 5.595 1.063 280 1 m.sup.3 [kg] wt-% of 28.9 32.6 36.8 0.0 0.02 0.1 0.0 0.0 0.03 0.0 1.2 0.3 0.1 15 dry mix wt-% of 100 112.84 127.08 0.00 0.06 0.28 0.00 0.00 0.09 0.00 4.17 1.04 0.20 54 cement Ref 3 weight for 537.2 666.2 682.7 0 0.34 1.49 0 0 0.47 0 22.4 0 0 280 1 m.sup.3 [kg] wt-% of 28.9 32.6 36.8 0.0 0.02 0.1 0.0 0.0 0.03 0.0 1.2 0.0 0.0 15 dry mix wt-% of 100 112.84 127.08 0.00 0.06 0.28 0.00 0.00 0.09 0.00 4.17 0.00 0.00 54 cement Ref 4 weight for 559.58 610 693 0 0.671 1.679 0 0 0.47 0 0 0 0 308.96 1 m.sup.3 [kg] wt-% of 30.0 32.7 37.2 0.0 0.04 0.1 0.0 0.0 0.03 0.0 0.0 0.0 0.0 17 dry mix wt-% of 100 109.01 123.84 0.00 0.12 0.30 0.00 0.00 0.08 0.00 0.00 0.00 0.00 55 cement Sand 1 . . . Limestone sand having a maximum particle size of 2 mm (LafargeHolcim Spain) Sand 2 . . . Limestone sand having a maximum particle size of 4 mm (LafargeHolcim Spain)

TABLE-US-00005 TABLE 4 CEM I Sand 1 Sand 2 AGG SP VEA1 VEA2 Fiber1 Fiber2 ACC1 CF ACC2 Ret Water Ref 5 weight for 514.8 606.2 682.7 0 0.336 1.958 0 0 0.47 0 44.7 0 0 308.96 1 m.sup.3 [kg] wt-% of 27.81 32.75 36.88 0.00 0.02 0.11 0.00 0.00 0.03 0.00 2.41 0.00 0.00 17 dry mix wt-% of 100.00 117.75 132.61 0.00 0.07 0.38 0.00 0.00 0.09 0.00 8.68 0.00 0.00 55 cement Sand 1 . . . Limestone sand having a maximum particle size of 2 mm (LafargeHolcim Spain) Sand 2 . . . Limestone sand having a maximum particle size of 4 mm (LafargeHolcim Spain)

TABLE-US-00006 TABLE 5 Bonding strength, Yield stress development by Stress at 10% deformation or strength MPa Temperature hand vane test. kPa development by compression, kPa 5 min (° C.) 0 min 2 min 5 min 10 min 20 min 30 min 30 min 60 min 90 min 120 min inter-layer Ex 1 10 0.6 1.6 2.0 3.0 4.6 5.2 N.M. N.M. N.M. N.M. N.M. 20 1.5 2.0 3.0 3.5 4.6 5.8 10.1  16.1 23.6 35.2 0.4 Ex 12 10 0.5 2.0 4.5 5.6 14.2 29.5 N.M. N.M. N.M. N.M. N.M. 20 1.3 2.9 5.1 6.5 17 34.8 30.3  179.3  502.2  1127.7  — Ex 2 10 0.2 0.6 2.0 3.8 6.6 8.2 N.M. N.M. N.M. N.M. N.M. 20 0.2 0.8 1.0 2.2 3.2 4.1 6.3 12.4 22.5 44.6 1.1 Ex 3 10 N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. 20 0.2 1.2 2.2 3.2 4.5 5.8 8.9 17.6 27.9 51.3 N.M. Ex 4 10 N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. 20 0.1 0.6 0.8 1.2 2 2.8 N.M. N.M. N.M. N.M. N.M. Ex. 5 10 N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. 20 0.2 0.6 1.2 1.3 2 2.7 N.M. N.M. N.M. N.M. N.M. Ref 1 10 0.2 0.5 1.0 4.2 16.3 >34 N.M. N.M. N.M. N.M. 0.5 20 0.5 1.0 2.7 10.0 >34 N.M. N.M. N.M. N.M. N.M. Ref 2 10 0.2 1.0 2.0 4.2 8.8 18.6 N.M. N.M. N.M. N.M. 0.5 20 0.2 0.8 1.5 3.9 17.6 NM N.M. N.M. N.M. N.M. N.M. Ref 3 10 0.5 1.2 2.0 3.0 3.6 3.8 N.M. N.M. N.M. N.M. 0.4 20 1.6 2.4 2.8 3.0 4.3 5.1 N.M. N.M. N.M. N.M. N.M. Ref 5 10 3.6 5.0 7.0 13.5 16.8 22.5 N.M. N.M. N.M. N.M. N.M. 20 0.6 1.0 1.8 2.8 3.7 4.9 7.4 14.3 27.9 51.3 1.0 Ref 4 10 N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. N.M. 20 0.4 0.9 1.2 1.8 2.2 2.6 5.3  8.7 13.4 44.6 N.M. N.M.: not measured.

TABLE-US-00007 TABLE 6 Tempera- Setting time (Vicat), Strength at 24 hour, ture minute Density, MPa (° C.) start end g/cm.sup.3 flexural Compressive Ex 1 10 650 720 2.17 2.3  7.7 20 270 435 2.16 5.1 20.6 Ex 12 10 87 119 2.22 1.7  3.2 20 70 108 2.21 6.9 24.4 Ex 2 10 N.M. N.M. 2.13 3   10.1 20 205 295 2.08 5.3 21.2 Ex 3 10 N.M. N.M. N.M. N.M. N.M. 20 210 260 N.M. N.M. N.M. Ex 4 10 N.M. N.M. N.M. N.M. N.M. 20 180 260 2.10 N.M. N.M. Ex. 5 10 N.M. N.M. N.M. N.M. N.M. 20 230 300 2.13 N.M. N.M. Ref 1 10 34 37 2.14 4.0 11.4 20 20 32 2.03  6.92 23.6 Ref 2 10 >1440 >1440 N.M. N.M. N.M. 20 34 40 2.06 5.9 20.1 Ref 3 10 557 627 2.12 3.7 11.0 20 275 405 2.13 6.1 21.1 Ref 5 10 N.M. N.M. N.M. N.M. N.M. 20 200 300 N.M. N.M. N.M. Ref 4 10 N.M. N.M. N.M. N.M. N.M. 20 315 390 N.M. N.M. N.M. N.M.: not measured.

[0078] The mortars prepared according to Examples nos. 1-18 and the mortars prepared according to Reference Examples nos. 1-5 have been tested according to the following testing procedures, in order to obtain the results indicated in Tables 5 and 6.

[0079] The strength at 24 hours after placing and the setting time were determined using the Vicat needle test according to EN 196-3 of September 2017.

[0080] The yield stress is measured with a scissometer. A scissometer consists of a pale vane that has a diameter of 33 mm and a height of 50 mm. The pale is plunged into the material to be tested and to which an increasing torque is applied. When a failure occurs in the material, the vane starts to rotate, generally as the torque reaches its maximum value, which is considered as the characteristic value that is representative of the yield stress of the material. The yield stress measurement is preferably carried out within 30-60 sec after the material has been placed.

[0081] The yield stress at 10% of deformation/strength of cubic samples at very early age was obtained from cubic samples prepared and tested by a compression test at 30 minutes, 60 minutes, 90 minutes and 120 minutes after mixing. The testing method is the following: [0082] Cubic samples of dimension 5×50×50 cm are molded after mixing powder with water. [0083] 20 minutes after mixing, cubic samples are unmolded with care and placed in a lab at 20° C.+/−0.5° C. at 50%+/−5% relative humidity before testing. [0084] Unmolded samples are then tested by compression test at 30 minutes, 60 minutes, 90 minutes and 120 minutes after mixing.

[0085] The stress-deformation curve is obtained from the compression test for each sample. If the curve presents a lean drop of yield stress after reaching a maximum value, the maximum yield stress just before the drop is considered as the compressive strength of the tested sample. Otherwise, the yield stress that corresponds to a deformation of 10% is taken as an equivalent of compressive strength.

[0086] The adhesion (bonding strength) between material layers was measured according to the following method. A fresh mortar is prepared and deposited as a first layer on a surface. After a duration of 5 minutes, a second layer of the same mortar is deposited and the specimen is left to harden for a duration of 7 days at 20° C. The surface of the top layer is prepared and polished for it be to perfectly horizontal and smooth, before the tensile test is carried out to measure the strength of adhesion between the two layers. This measurement is made using standard laboratory methods.

[0087] The very early age deformation change was tested according to the following protocol. After mixing, the fresh mortar or concrete material is poured into a U shape mold, 60 cm in length, 7 cm in width and 5 cm in average depth. The two end faces of the mold in contact with the material are mobile. They move apart or closer according to the expansion or shrinkage of the material. The length change of the material is measured up to 2 days in 20° C.+/−1° C., 50% HR+/−5%. It gives an indication on the deformational change, of the material at an early age, combining the effect of chemical shrinkage, autogenous shrinkage and drying shrinkage.

[0088] The strength development of the embodiments of Examples 1, 2, 3 and 12 are shown in FIG. 1. The results show that Example 12 has the highest strength development, which is due to the presence of a small amount (0.40 wt.-% based on the dry mix) of calcium aluminate cement together with an accelerator (sodium carbonate) that accelerates the setting of the calcium aluminate cement.

[0089] The strength development of Examples 1, 2 and 3 compared to the strength development of reference examples Ref. 4 and 5 is shown in FIG. 2. The results show that the strength development is not sufficient with reference example Ref. 4, which is due to the absence of an accelerator.

[0090] FIG. 3 illustrates the effect of the presence of cellulose microfibers in the dry mix when comparing Example 1 (with cellulose fibers) with Example 3 (without cellulose fibers). The strength development is improved when no cellulose microfibers are present in the dry mix.

[0091] FIG. 4 illustrates the effect of the presence of calcium formate in the dry mix when comparing Example 2 (with calcium formate) with reference example Ref. 4 (without calcium formate). The strength development is significantly improved when calcium formate is present in the dry mix.

[0092] FIG. 5 illustrates the effect of the presence of a second viscosity enhancing admixture, namely Cimsil A55 in the dry mix when comparing Example 2 (without Cimsil A55) with example 3 (with Cimsil A55). The strength development is improved when the dry mix comprises Cimsil A55 as a second viscosity enhancing admixture.

[0093] FIG. 6 compares the strength development of Example 1 to the strength development of reference example Ref. 5. Ref. 5 contains a considerable amount of aluminate cement, whereas Example 1 does not contain any (calcium) aluminate cement.

[0094] FIG. 7 illustrates the interlayer adhesion (bonding strength between layers) of Examples 1, 2 and 3 and of reference examples Ref. 1, 2, 3 and 5. The interlayer time for the different mixes was fixed at 5 minutes, which means that a second layer was printed 5 minutes after a first layer had been printed. When interlayer time increases, the bonding between layers will decrease. When comparing Examples 1, 2 and 3 in FIG. 7, it can be seen that adding Cimsil A55 to the dry mix reduces the interlayer bonding. However, Cimsil A55 facilitates the extrusion of material. Further, when comparing Example 2 with reference examples Ref. 1 and Ref. 2 it can be seen that the use of a calcium aluminate cement (in combination with sodium carbonate and citric acid) can accelerate the hydration of the cement for a better yield strength development, but reduces the interlayer bonding.

[0095] FIG. 8 illustrates the dimensional change of Example 1 and of Example 12 after mixing up to 48 hours. It can be seen that by adding a calcium aluminate cement (in combination with sodium carbonate and citric acid) as for Example 12, the very early age shrinkage (mainly chemical) can be significantly reduced. This gives a better dimensional stability, which is beneficial. On the other hand, an over-dosage of calcium aluminate cement can lead to expansion, as shown with reference example Ref. 1 and reference example Ref. 2. For the reference example Ref. 3, the dimension change is slightly higher than with Example 2, which is due to the fact that the calcium aluminate cement alone does not contribute to any properties as it acts as inert material.

[0096] FIG. 9 illustrates the temperature robustness of the yield stress evolution by comparing tests carried out at 10° C. and at 20° C. It can be seen that with Examples 1 and 12 the yield stress evolution is essentially independent of the temperature. The temperature robustness of the yield stress development is decreased with Example 2, which is due to the absence of the viscosity enhancing admixture Cimsil A55 and of the cellulose fibers Arbocel. Further, the temperature robustness of reference examples Ref. 1 and 2 are also decreased when compared to Example 12, which is due to the absence of the viscosity enhancing admixture Cimsil A55 and of the cellulose fibers Arbocel.

[0097] FIG. 10 illustrates the yield stress evolution at different W/C ratios in Examples 1 and 2. The W/C ratio represents the weight ratio of the effective water to the cement present in the dry mix. Example 1 shows a better water robustness compared with Example 2, which is due to the presence of Arbocel (modified cellulose fibers).

EXAMPLE 19

[0098]

TABLE-US-00008 Component Amount (grams) CEM I 52, 5R 275.0 Calcium carbonate 100M 55.0 AF-T 0/1-C (sand) 450.0 AF-T 1/2-C (sand) 200.0 Mecellose 21010 0.60 Berolan LP-W1 0.10 Cimsil A55 3.00 Calcium Formate 15.00 Arbocel FI 540 CA 4.00 Citric acid 0.25 Fibers 6mm 0.50 Optibent 987 3.00

EXAMPLE 20

[0099] The following example illustrates the effect of different accelerators on yield stress development.

[0100] The mixes in the table below are compared to the mix of example 1 (Ex 1), which contains calcium formate (ACC1) as an accelerator.

TABLE-US-00009 TABLE 7 Composition Composition accelerated with ACC3 accelerated with ACC4 weight for wt-% of wt-% of weight for Wt-% of wt-% of 1 m.sup.3 dry mix cement 1 m.sup.3 dry mix cement CEM I 52.5R 559.58 30.05 100 559.58 30.07 100 Limestone crushed 0/2 606.2 32.55 108.33 606.2 32.58 108.33 Limestone crushed 0/4 682.7 36.66 122 682.7 36.69 122 PUMP-Saint Bonnet 5/10 R 0 0 0 0 0 0 SP 0.671 0.04 0.12 0.671 0.04 0.12 VEA1 1.49 0.08 0.27 1.494 0.08 0.27 VEA2 0 0 0 0 0 0 Fiber1 0 0 0 0 0 0 Fiber2 0.47 0.03 0.08 0.47 0.03 0.08 ACC1 0 0 0 0 0 0 ACC3 11.19 0.6 2 0 0 0 ACC4 0 0 0 9.792 0.53 1.75

[0101] The development of yield stress was measured over a duration of 30 minutes, and the results are summarised in table 8 below. The measurement show that calcium formate has a strong positive effect related on the yield stress development, compared to the two inorganic accelerators (calcium chloride and calcium nitrite). In the case of the use of calcium formate, this translates into an increased capacity for the deposited materials to withstand their own weight and to support the weight of additional layers deposited on top.

TABLE-US-00010 TABLE 8 Yield stress development (kPa) Mixture 0 min 2 min 5 min 10 min 20 min 30 min Ex 1 1.5 2.0 3.0 3.5 4.6 5.8 Composition 0.1 0.6 0.8 1.2 2 2.8 accelerated with ACC3 Composition 0.2 0.6 1.2 1.3 2 2.7 accelerated with ACC4

EXAMPLES 21 AND 22

[0102] The following examples describe a high strength mono-mortar premix, where the super-plasticizing admixture CHRYSO®Optima 100 is pre-diluted in the water. The other admixtures components are all in the dry premix.

[0103] In examples 21 and 22, Foxcrete S200, a starch ether viscosity modifier agent provided by Avebe, is used.

[0104] The compressive strength of this mixture, measured in 4×4×16, measured according to the protocol described in the standard NF EN 196-1 of September 2016, is of 96.2 MPa.

[0105] Although the overall performance of examples 21 and 22 was acceptable, as shown by the overall yield stress development, it was observed here that the viscosity and the flowing behavior of the wet mixture was negatively affected by the mixing step of the premix with water. More specifically, during the mixing and the pumping of the wet mixture, the apparent viscosity decreased, rendering the system less suitable for 3d printing purposes, as the deposited ribbons would be less capable of withstanding their own weight and that of the ribbons deposited immediately on top.

[0106] It then appears that the use of Foxcrete S200 is less preferable for the preparation of a premix for 3D printing.

TABLE-US-00011 TABLE 9 wt.-% of wt.-% of kg/m.sup.3 dry mix cement PREMIX Cement CEM I 52, 5 R - 681.80 33.9 100 21 Le Teil plant Limestone fine filler 340.90 17.0 50 (Durcal 1) Siliceous micro-sand 975.38 48.5 143.06 (0.2-0.6 mm) Foxcrete S200 (powder) 0.60 0.0 0.09 Calcium formate 11.59 0.6 1.70 Added Water 253.99 12.6 37.25 water CHRYSO ® Optrma 100 8.98 0.4 1.32 (liquide) Yield stress development of Example 21 (kPa) 2 min 5 min 10 min 20 min 30 min 0.8 1.8 2.8 4.2 6.1

TABLE-US-00012 TABLE 10 wt.-% of wt.-% of kg/m.sup.3 drymix cement PREMIX Cement CEM I 52, 5 R - 681.80 33.9 100 22 Le Teil plant Limestone fine filler 340.90 17.0 50 (Durcal 1) Siliceous micro-sand 975.38 48.5 143.06 (0.2-0.6 mm) Foxcrete S200 (powder) 0.60 0.0 0.09 Calcium formate 11.59 0.6 1.70 Added Water 253.99 12.6 37.25 water CHRYSO ® Optima 100 8.98 0.4 1.32 (liquide)

TABLE-US-00013 TABLE 11 Yield stress development of Example 22 (kPa) 2 min 5 min 10 min 20 min 30 min 0.8 1.8 2.8 4.2 6.1