Formulation and method for producing ultra-high-performance concretes

Abstract

A formulation and method for obtaining ultra-high performance concretes, which provide a concrete with good mechanical properties of, inter alia, traction, compression, deformation, durability, ductility and toughness, with reduced related costs.

Claims

1. An ultra high performance concrete formulation comprising: Portland Cement in an amount between 24% to 29% v/v; calcium carbonate in an amount between 11.5% to 16.5% v/v; silica fume in an amount between 10.5% to 15.5% v/v; silica sand in an amount between 27% to 35% v/v; water in an amount between 22.5% to 25% v/v; high range water regulating additives in an amount between 2.5% to 3.0% v/v; and metallic fibers in an amount between 2% to 2.5% v/v.

2. The ultra high performance concrete formulation of claim 1, wherein said water regulating additive is a high range water reducing super plasticizer additive.

3. The ultra high performance concrete formulation of claim 1, comprising: Portland Cement in an amount of 24% v/v; calcium carbonate in an amount of 11.5% v/v; silica fume in an amount of 10.5% v/v; silica sand in an amount of 27% v/v; water in an amount between of 22.5% v/v; high range water regulating additives in an amount of 2.5% v/v; and metallic fibers in an amount of 2% v/v.

4. The ultra high performance concrete formulation of claim 1, comprising: Portland Cement in an amount of 24.02% v/v; calcium carbonate in an amount of 11.48% v/v; silica fume in an amount of 10.44% v/v; silica sand in an amount of 29% v/v; water in an amount between of 21.15% v/v; high range water regulating additives in an amount of 1.9% v/v; and metallic fibers in an amount of 2% v/v.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Referring now to the invention, it consists of a formulation and method of obtaining ultra high performance concretes that achieves a concrete with good mechanical properties of traction, compression, deformation, ductility, toughness, and durability among many other characteristics. Likewise, the formulation of the present invention uses elements that allow the reduction of the related costs. Thus, the ultra high performance concrete formulation of the present invention may comprise:

(2) Portland Cement in an amount between 19% to 29%; calcium carbonate in an amount between 6.5% to 16.5%; silica fume in an amount between 4.5% to 15.5%; silica sand in an amount between 22% to 35%; water in an amount between 15% to 25%; high range water regulating additives in an amount between 1.5% to 2.5%; and metallic fibers in an amount between 1.5% to 2.5%, with the fibers having lengths between 13 mm to 60 mm and diameters between 0.3 mm to 0.75 mm. Depending on the application, mixtures of fibers with different lengths are employed, wherein mixtures of short fibers and long fibers can be used.

(3) Wherein, said water regulating additive can be a high-range water-reducing superplasticizer additive which can be selected from the group consisting of Master Glenium 7920, Glenium 356, UHF 7350-2 Sikaviscocrete and Sika viscocrete 5e-c3, this being not limiting for the invention, but the other materials can also be considered and used for the present invention. It is noted that, although silica sand is used in the present invention, this does not imply that the invention is limited thereto, but that other types of sands well known in the art can be considered and used in the present invention, being for example silica sands, quartz sands, quartz powder, etc.

(4) Thus, among the advantages of the present formulation we find that adding calcium carbonate favors the resistance gain at later ages, in addition to the increase in manageability favoring transport times. The high levels of material handling allow for self-compacting and self-leveling behavior.

(5) On the other hand, several formulations have been prepared according to the present invention that have proved to be effective and on which the following non-limiting examples of the invention will be provided. Such examples comprise the components and their test percentages that fall within the ranges indicated above.

Example 1

(6) In a first preferred embodiment, the ultra high performance concrete formulation of the present invention has been prepared with the following components and percentages:

(7) Portland Cement in an amount of 20%;

(8) calcium carbonate in an amount of 16.5%;

(9) silica fume in an amount of 10%;

(10) silica sand in an amount of 24.5%;

(11) water in an amount between of 25%;

(12) high range water regulating additives in an amount of 2.5%; and

(13) metallic fibers in an amount of 1.5%.

(14) Under this formulation, we have surprisingly obtained a concrete with mechanical compression properties fc=100-110 MPa, tensile stress=1-3 MPa, and deformation d=0.8%. Likewise, the concrete obtained has demonstrated a remarkable ductility (micro-cracking), with high durability and toughness.

Example 2

(15) In a second preferred embodiment, the product of the ultra high performance concrete formulation of the present invention has been prepared with the following components and percentages:

(16) Portland Cement in an amount of 24%;

(17) calcium carbonate in an amount of 11.5%;

(18) silica fume in an amount of 10.5%;

(19) silica sand in an amount of 27%;

(20) water in an amount between of 22.5%;

(21) high range water regulating additives in an amount of 2.5%; and

(22) metallic fibers in an amount of 2%.

(23) Under this formulation, surprisingly a concrete has been obtained with mechanical properties of fc=140-170 MPa for compression, of ft=7-10 MPa for traction, and of d=1% for deformation. Likewise, the obtained concrete has shown a remarkable ductility (micro-cracking), with high durability and toughness.

Example 3

(24) In a third preferred embodiment, the product of the ultra high performance concrete formulation of the present invention has been prepared with the following components and percentages:

(25) Portland Cement in an amount of 24.02%;

(26) calcium carbonate in an amount of 11.48%;

(27) silica fume in an amount of 10.44%;

(28) silica sand in an amount of 29%;

(29) water in an amount between of 21.15%;

(30) high range water regulating additives in an amount of 1.9%; and

(31) metallic fibers in an amount of 2%.

(32) Under this formulation, surprisingly a concrete has been obtained with mechanical properties of fc=165-175 MPa for compression, of ft=9-10 MPa for tensile stress, and d=1.1% for deformation. Likewise, the obtained concrete has demonstrated a remarkable ductility (micro-cracking), with high durability and toughness.

(33) On the other hand, the present invention aims to provide a method for obtaining ultra-high performance concrete, which comprises a first stage of pre-mixing an amount of between 19% to 29% of Portland Cement with an amount of between 6.5% to 16.5% of calcium carbonate and an amount of between 4.5% to 15.5% of silica fume to form a premix. Then, an amount of 15% to 25% of water with an amount of between 1.5% to 3.0% of high-range water reducing additives is charged in a mixer and mixed at a speed of between 100 to 3000 RPM for 1 to 2 minutes. After that time, we proceed to add the premix of Portland cementcalcium carbonatesilica fume in the mixer.

(34) Then, mixing of the premix is carried out in conjunction with the water-additive mixture until the flow time is reached. Once the fluidity is reached, it must be mixed for 1.5 to 2.5 minutes at maximum speed.

(35) Likewise, a quantity of sand is loaded in a skip or loader which transports the sand to the mixer. When sufficient height is reached, the sand is added to the mixer, adding an amount of between 22% to 35% sand for 0.5 to 1.5 minutes and then mixing for 2 to 4 minutes at maximum speed. Then, the mixer is stopped and the inside of the mixer is scraped until the mixture of sand is mixed with the fluid mixture. Once the removal stage is finished, we proceed to restart the mixing process, mixing at maximum speed for 2 to 3 minutes until a final semi-material is obtained, then the mixer is stopped, and properties in this fresh material are evaluated. Once the evaluation is completed and the properties are correct, an amount of 1.0 to 3.0% of metallic fibers is added during 0.5 to 1.5 minutes. Next, the process of mixing the final semi-material together with the metal fibers at maximum speed for 1 to 3 minutes is continued until obtaining a desired consistency, and the obtained material is discharged.

(36) During the stage of unloading of the concrete material, the concrete properties measurement in fresh state is carried out.

(37) In a preferred embodiment, the step of mixing an amount of water with a high-range water reducing additive can be carried out for 1.5 minutes. The stage of mixing the mixture, once fluidity is achieved, can be carried out for 2 minutes. The step of adding sand in the mixer can be carried out for 1 minute, and mixed for 3 minutes. The step of adding the metal fiber can be carried out for 1 minute, while the step of mixing the mixture of the final semi-material with the metal fibers can be carried out for 2 minutes.

(38) In this way, the formulation and method of obtaining ultra-high performance concretes of the present invention are constituted, which allow a concrete of good mechanical properties with low related costs. Likewise, it is emphasized that the method of the invention is of utmost importance because the times and the order of how the materials are mixed must be controlled in order to achieve an ultra-high performance concrete with the aforementioned mechanical properties. At the same time, depending on the mixer used and its mixing energy, it has been decided to shorten the mixing times and it has been considered a wet process, based on activities. Furthermore, among the advantages of the invention it is the low cost of the supplementary cementing materials used and the use of seven (7) low cost components for its manufacture. This concrete will allow to direct the constructions and the designs towards a more sustainable environment since it allows lower material consumption and lower maintenance of the structures.

(39) All the percentages employed in the present application, related to the components of the formulation, are volume percentage concentrations. All the fc values mentioned in the Examples were measured after 28 days.