Low-cement-consumption large-flow-state micro-expansion ultra-high-performance concrete

Abstract

The invention discloses high-flow-state micro-expansion ultra-high-performance concrete with low cement consumption, and relates to the technical field of concrete. The ultra-high performance concrete is prepared from the following raw materials in parts by mass: 500 parts of cement, 80 to 160 parts of silica fume, 100 to 260 parts of superfine fly ash, 100 to 260 parts of micron-sized filler, 60 parts of expanding agent, 1180 parts of quartz sand, 15 to 30 parts of polycarboxylic acid high-performance water reducing agent and 160 to 180 parts of water. The steel fiber accounts for 1.5-2.5% of the volume of the steel fiber; the particle sizes of the superfine fly ash and the micron-sized filler are both less than 10 microns. The ultra-high performance concrete provided by the invention is green, carbon-saving, economical, environment-friendly and excellent in performance, and the ultra-high performance concrete has the characteristics of low cement consumption, good fluidity, low viscosity and micro-expansion, and has ultra-high strength.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and particularly to a low-cement-usage, high-fluidity, slightly expanding ultra-high performance concrete. Background Art

[0002] UHPC (Ultra-High Performance Concrete) is a new type of building material with ultra-high strength, ultra-high toughness, and excellent durability. The compressive strength of UHPC usually exceeds 100 MPa, far higher than that of ordinary concrete, and its tensile strength, elastic modulus, durability and other properties are also significantly superior to traditional concrete. With the progress of technology and the increasing growth of engineering requirements, the development prospect of ultra-high performance concrete (UHPC) is very broad. The excellent mechanical properties and durability of UHPC can meet the higher requirements of modern engineering for structural safety and durability, and it is more and more widely used in fields such as bridges, high-rise buildings, water conservancy projects, ocean engineering, rail transit, new energy, etc.

[0003] UHPC usually uses ultra-fine powder materials such as portland cement, quartz sand, silica fume, and finely ground slag, and adds appropriate amounts of reinforcing materials such as steel fibers or polymer fibers. The dosage of single-component cementitious materials in UHPC is large, generally above 1000 kg / m 3 ³, and the cement dosage in the cementitious materials is the largest, accounting for 70% - 80% of the UHPC cementitious material components. A large amount of carbon dioxide emissions will be generated during the cement production process, which is one of the main sources of carbon emissions in the construction industry. By reducing the cement usage, UHPC directly reduces the carbon emissions during the production process, which helps to alleviate the global warming problem. The production of cement requires a large amount of natural resources and energy, including raw materials such as limestone and clay, and energy such as coal and electricity. Reducing the cement usage means saving these precious resources and promoting the sustainable development of the construction industry.

[0004] The high viscosity of UHPC is a significant disadvantage, mainly due to factors such as its low water-binder ratio, high cementitious material dosage, and enhanced intermolecular forces between particles. These factors significantly reduce the fluidity of the UHPC paste, making it difficult to flow and spread freely during the pouring process. Poor fluidity will affect the pouring efficiency and quality of UHPC, especially in complex structures where precise control of shape and size is required, resulting in increased construction difficulty and even affecting the overall performance of the structure. The high viscosity of UHPC will lead to difficulties in pumping and vibrating, causing material waste and extended construction period, and affecting the economy.

[0005] Due to the characteristics of ultra-high performance concrete (UHPC) such as low water-binder ratio, no coarse aggregate, and incorporation of reactive mineral admixtures, its mechanical properties and durability are greatly improved. However, at the same time, it also leads to a generally larger shrinkage of UHPC compared to ordinary concrete. During the hardening process, due to water evaporation and chemical reactions, UHPC may undergo significant shrinkage, which can then cause cracking. The hydration reaction rate of UHPC is relatively fast, resulting in a more concentrated and intense release of hydration heat. Especially for large-volume UHPC, heat dissipation is slower, and the risk of temperature difference cracking in UHPC is greater. Reducing the cement content in UHPC can reduce the total heat release, but currently, there are still problems in ultra-high performance concrete such as a relatively large cement content and easy cracking of concrete materials. Summary of the Invention

[0006] The purpose of the present invention is to provide a low-cement-content, high-fluidity, slightly expanding ultra-high performance concrete to solve the problems existing in the above-mentioned prior art and achieve excellent comprehensive performance of ultra-high performance concrete with low cement content.

[0007] To achieve the above purpose, the present invention provides the following solutions:

[0008] The present invention provides an ultra-high performance concrete, and its raw materials include the following components:

[0009] Cement, silica fume, ultra-fine fly ash, micron-sized filler, expansive agent, quartz sand, polycarboxylate superplasticizer, steel fiber, and water;

[0010] The mass ratio of the cement, silica fume, ultra-fine fly ash, micron-sized filler, expansive agent, quartz sand, polycarboxylate superplasticizer, and water is 500:80 - 160:100 - 260:100 - 260:60:1180:15 - 30:160 - 180;

[0011] The micron-sized filler is ultra-fine limestone powder, ultra-fine slag powder, or ultra-fine quartz powder;

[0012] The volume proportion of the steel fiber in the raw materials is 1.5 - 2.5%;

[0013] The particle size of the ultra-fine fly ash, ultra-fine limestone powder, ultra-fine slag powder, or ultra-fine quartz powder is less than 10 μm.

[0014] Preferably, the cement is Portland cement or ordinary Portland cement.

[0015] Preferably, the strength grade of the cement is ≥52.5.

[0016] Preferably, the silica fume is grade 90 silica fume.

[0017] Preferably, the ultra-fine fly ash is class FⅠ fly ash.

[0018] Preferably, the ultrafine slag powder is granulated blast furnace slag powder of grade S95 or above.

[0019] Preferably, the expansive agent is magnesium oxide expansive agent.

[0020] Preferably, the water reducing rate of the water reducing agent is ≥30%; more preferably, the solid content of the water reducing agent is 40%.

[0021] The present invention also provides a method for preparing the above ultra-high performance concrete, comprising the following steps:

[0022] Mix the raw materials according to the ratio to obtain the ultra-high performance concrete.

[0023] Preferably, the preparation method comprises the following steps:

[0024] (1) Mix and dry blend the cement, silica fume, ultrafine fly ash, micron-sized filler, expansive agent and quartz sand. The dry blending time is not less than 5 min to obtain a dry blend mixture;

[0025] (2) Add the polycarboxylate superplasticizer and water to the dry blend mixture and stir (not less than 10 min) to obtain a colloidal mixture;

[0026] (3) Gradually or in portions add the steel fibers to the colloidal mixture and stir to obtain a UHPC mixture;

[0027] (4) Pour and mold the UHPC mixture, then let it stand and cure to obtain the ultra-high performance concrete.

[0028] More preferably, the curing is steam curing carried out according to the steam curing system specified in GB / T 31387-2015.

[0029] The ultra-high performance concrete of the present invention has low cement consumption, good fluidity, low viscosity, has a micro-expansion property, and high strength, and can reach grade C160 or above (compressive strength > 160 MPa). It is a kind of ultra-high performance concrete that is green, carbon-saving, economical, environmentally friendly and has excellent performance.

[0030] The present invention discloses the following technical effects:

[0031] 1. The ultra-high performance concrete of the present invention has low cement consumption, can save raw material costs, and thus reduce the total heat of hydration of the concrete and reduce the risk of temperature difference cracking of the concrete.

[0032] 2. The ultra-high performance concrete of the present invention has good fluidity and low viscosity. Using ultrafine mineral admixtures, it requires less water, has better fluidity under the same conditions, the slump flow at the time of discharge is more than 700 mm, and the slump flow time is less than 7 s.

[0033] 3. The ultra-high performance concrete of the present invention has a micro-expansion property, which can compensate for the shrinkage of the concrete and reduce the risk of shrinkage cracking of the concrete.

[0034] 4. The ultra-high performance concrete of the present invention has high strength and still has ultra-high mechanical properties under the conditions of low cement consumption and high fluidity. Detailed implementation manners

[0035] The various exemplary implementation manners of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0037] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0038] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are only exemplary.

[0039] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0040] In the following examples of the present invention:

[0041] The cement used is Portland cement or ordinary Portland cement that complies with the national standard GB 175-2023, and the strength grade is 52.5 or above.

[0042] The silica fume used is 90-grade silica fume that complies with the national standard GB / T 27690-2023.

[0043] The ultrafine fly ash used is Class F fly ash conforming to the national standard GB / T 1596-2017, and the average particle size is less than 10 μm.

[0044] The ultrafine limestone powder used is limestone powder conforming to the national standard GB / T 35164-2017, and the average particle size is less than 10 μm.

[0045] The ultrafine slag powder used is granulated blast furnace slag powder of a grade above S95 conforming to the national standard GB / T 18046-2017, and the average particle size is less than 10 μm.

[0046] The ultrafine quartz powder used meets the technical indicators of quartz powder in the national standard GB / T 31387-2015, and the average particle size is less than 10 μm.

[0047] The expansive agent used is a magnesia-based expansive agent for concrete conforming to the standard CBMF 19-2017 of the China Building Materials Association.

[0048] The quartz sand used meets the technical indicators of quartz sand in the national standard GB / T 31387-2015. Single-sized quartz sands such as coarse-sized sand, medium-sized sand, and fine-sized sand are used, and the proportion of each particle size of the quartz sand follows the closest packing theory.

[0049] The polycarboxylate superplasticizer used is a polycarboxylate superplasticizer conforming to the national standard GB 8076-2008, with a solid content of 40% and a water reduction rate of over 30%.

[0050] The steel fiber used meets the performance indicators of steel fiber in the national standard GB / T 31387-2015 and can be straight or profiled.

[0051] The mixing water used meets the requirements of the industry standard JGJ 63-2006.

[0052] Example 1

[0053] A low-cement-usage, high-fluidity, slightly expansive ultra-high-performance concrete, the raw material components are as follows:

[0054] P·O 52.5 cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, mixing water, and straight copper-plated steel fiber;

[0055] Among them, the mass ratio of cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, and mixing water is 500:80:260:100:60:1180:15:160;

[0056] Among them, the volume fraction of the steel fiber is 2%.

[0057] The preparation steps of low cement dosage, high fluidity and micro expansion ultra-high performance concrete are as follows:

[0058] (1) Weigh cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansion agent, and quartz sand according to the test mix ratio for use;

[0059] (2) Dry mixing stage: Pour the materials weighed in step (1) into a concrete forced mixer for dry mixing until the materials are evenly distributed. The dry mixing time is 5 minutes.

[0060] (3) Wet mixing stage: add water and polycarboxylic acid high-performance water reducing agent to the dry mix obtained in step (2) and stir thoroughly. During the stirring process, ensure that all materials are fully mixed to form a uniform mixture. The stirring time is 10 minutes.

[0061] (4) When the mixture changes from granular to colloidal state, add steel fibers and stir. The fibers are added in batches to ensure that they are evenly dispersed in the concrete.

[0062] (5) The UHPC mixture obtained in step (4) is introduced into a mold for casting, and compacted by vibration to expel internal bubbles, with the vibration time being 20 seconds;

[0063] (6) Cover the UHPC test block with plastic wrap, leave it at room temperature for 24 hours, then remove the mold and cure;

[0064] (7) The maintenance system is steam maintenance, which shall be carried out in accordance with the steam maintenance system specified in GB / T 31387-2015.

[0065] Example 2

[0066] A low-cement-dosage, high-fluidity, micro-expansion ultra-high performance concrete, the raw material components are as follows:

[0067] P·O 52.5R cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansion agent, quartz sand, polycarboxylic acid high-performance water reducing agent, mixing water and end hook type copper-coated steel fiber;

[0068] Among them, the mass ratio of cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansion agent, quartz sand, polycarboxylic acid high-performance water reducer and mixing water is 500:100:180:160:60:1180:20:160;

[0069] Among them, the volume content of steel fiber is 2.5%.

[0070] The preparation method is the same as Example 1.

[0071] Example 3

[0072] A low-cement-usage high-fluidity slightly expanding ultra-high performance concrete, the raw material components are as follows:

[0073] P·Ⅱ 52.5 cement, silica fume, ultra-fine fly ash, S95 grade ultra-fine slag powder, expansion agent, quartz sand, polycarboxylate high-performance water reducer, mixing water and straight copper-plated steel fiber;

[0074] Among them, the mass ratio of cement, silica fume, ultra-fine fly ash, ultra-fine slag, expansion agent, quartz sand, polycarboxylate high-performance water reducer, and mixing water is 500:120:180:140:60:1180:20:170;

[0075] Among them, the volume fraction of steel fiber is 2%.

[0076] The preparation method is the same as that of Example 1, the difference is only that in step (1), the ultra-fine limestone powder is replaced by ultra-fine slag powder.

[0077] Example 4

[0078] A low-cement-usage high-fluidity slightly expanding ultra-high performance concrete, the raw material components are as follows:

[0079] P·Ⅱ 52.5R cement, silica fume, ultra-fine fly ash, ultra-fine quartz powder, expansion agent, quartz sand, polycarboxylate high-performance water reducer, mixing water and end-hook copper-plated steel fiber;

[0080] Among them, the mass ratio of cement, silica fume, ultra-fine fly ash, ultra-fine quartz powder, expansion agent, quartz sand, polycarboxylate high-performance water reducer, and mixing water is 500:140:100:200:60:1180:20:170;

[0081] Among them, the volume fraction of steel fiber is 2%.

[0082] The preparation method is the same as that of Example 1, the difference is only that in step (1), the ultra-fine limestone powder is replaced by ultra-fine quartz powder.

[0083] Example 5

[0084] A low-cement-usage high-fluidity slightly expanding ultra-high performance concrete, the raw material components are as follows:

[0085] P·O 52.5R cement, silica fume, ultra-fine fly ash, S105 grade ultra-fine slag powder, expansion agent, quartz sand, polycarboxylate high-performance water reducer, mixing water and straight copper-plated steel fiber;

[0086] Among them, the mass ratio of cement, silica fume, ultra-fine fly ash, ultra-fine slag powder, expansion agent, quartz sand, polycarboxylate high-performance water reducer, and mixing water is 500:160:100:180:60:1180:20:180;

[0087] Among them, the volume fraction of steel fibers is 1.5%.

[0088] The preparation method is the same as that of Example 1, except that in step (1), the ultrafine limestone powder is replaced by ultrafine slag powder.

[0089] Comparative Example 1

[0090] Compared with Example 2, the silica fume content in Comparative Example 1 is less than that in Example 2, and the reduced silica fume is replaced by an equal mass of ultrafine limestone powder.

[0091] A super high performance concrete, the raw material components are as follows:

[0092] P·O 52.5R cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, mixing water and end-hooked copper-plated steel fibers;

[0093] Among them, the mass ratio of cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, and mixing water is 500:50:180:210:60:1180:20:160;

[0094] Among them, the volume fraction of steel fibers is 2.5%.

[0095] The preparation method is the same as that of Example 1.

[0096] Comparative Example 2

[0097] Compared with Example 2, the silica fume content in Comparative Example 2 is greater than that in Example 2, and the increased silica fume is replaced by an equal mass of ultrafine limestone powder.

[0098] A super high performance concrete, the raw material components are as follows:

[0099] P·O 52.5R cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, mixing water and end-hooked copper-plated steel fibers;

[0100] Among them, the mass ratio of cement, silica fume, ultrafine fly ash, ultrafine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, and mixing water is 500:200:180:60:60:1180:20:160;

[0101] Among them, the volume fraction of steel fibers is 2.5%.

[0102] The preparation method is the same as that of Example 1.

[0103] Comparative Example 3

[0104] Compared with Example 2, in Comparative Example 3, the medium sand of manufactured sand is used to replace the quartz sand in Example 2.

[0105] A ultra-high performance concrete, the raw material components are as follows:

[0106] P·O 52.5R cement, silica fume, ultra-fine fly ash, ultra-fine limestone powder, expansive agent, medium sand of manufactured sand, polycarboxylate superplasticizer, mixing water and end-hooked copper-plated steel fiber;

[0107] Among them, the mass ratio of cement, silica fume, ultra-fine fly ash, ultra-fine limestone powder, expansive agent, medium sand of manufactured sand, polycarboxylate superplasticizer, and mixing water is 500:100:180:160:60:1180:20:160;

[0108] Among them, the volume fraction of steel fiber is 2.5%.

[0109] The preparation method is the same as that of Example 1, the only difference is that the quartz sand in step (1) is replaced by medium sand of manufactured sand.

[0110] Comparative Example 4

[0111] Compared with Example 2, in Comparative Example 4, the dosage of polycarboxylate superplasticizer is 1 / 2 of that in Example 2.

[0112] A ultra-high performance concrete, the raw material components are as follows:

[0113] P·O 52.5R cement, silica fume, ultra-fine fly ash, ultra-fine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, mixing water and end-hooked copper-plated steel fiber;

[0114] Among them, the mass ratio of cement, silica fume, ultra-fine fly ash, ultra-fine limestone powder, expansive agent, quartz sand, polycarboxylate superplasticizer, and mixing water is 500:100:180:160:60:1180:10:160;

[0115] Among them, the volume fraction of steel fiber is 2.5%.

[0116] The preparation method is the same as that of Example 1.

[0117] Comparative Example 5

[0118] Compared with Example 2, in this comparative example, the expansive agent is not added, and the expansive agent is replaced by an equal mass of ultra-fine limestone powder.

[0119] A ultra-high performance concrete, the raw material components are as follows:

[0120] P·O 52.5R cement, silica fume, ultra-fine fly ash, ultra-fine limestone powder, quartz sand, polycarboxylate superplasticizer, mixing water and end-hooked copper-plated steel fiber;

[0121] Among them, the mass ratio of cement, silica fume, ultra-fine fly ash, ultra-fine limestone powder, quartz sand, polycarboxylate superplasticizer, and mixing water is 500:100:180:220:1180:20:160;

[0122] Among them, the volume fraction of steel fiber is 2.5%.

[0123] The preparation method is the same as that of Example 1, with the only difference being that no expansive agent is added in step (1).

[0124] The ultra-high performance concrete test blocks prepared in Examples 1-5 and Comparative Examples 1-5 were tested for compressive strength in accordance with GB / T 31387-2015, the slump flow and slump flow time of the ultra-high performance concrete were tested in accordance with GB / T 50080-2016, and the shrinkage rate of the ultra-high performance concrete was tested in accordance with GB / T 50082-2009. The test results are shown in Table 1.

[0125] Table 1 Performance test data of examples and comparative examples

[0126]

[0127]

[0128] As can be seen from Table 1, the slump flow of the ultra-high performance concrete in Examples 1-5 is above 730 mm, the flexural strength is above 17.1 MPa, the compressive strength is above 165.9 MPa, and the 28-day drying shrinkage rate is lower than 78 με.

[0129] For Comparative Example 1 with less silica fume than the silica fume content in Example 2, the slump flow at the time of leaving the mixer increases, the slump flow time shortens, but the strength decreases significantly, and the 28-day drying shrinkage rate is large; for Comparative Example 2 with more silica fume than the silica fume content in Example 2, the slump flow at the time of leaving the mixer decreases significantly, the slump flow time increases significantly, the strength has no obvious change, and the 28-day drying shrinkage rate is also large; compared with Example 2, for Comparative Example 3 where medium sand in manufactured sand replaces quartz sand, the slump flow at the time of leaving the mixer decreases significantly, the slump flow time increases significantly, the strength decreases significantly, and the 28-day drying shrinkage rate increases significantly; for Comparative Example 4 with a lower content of polycarboxylate superplasticizer than the superplasticizer content in Example 2, the slump flow at the time of leaving the mixer decreases significantly, less than 500 mm, the slump flow time cannot be measured, the strength has no obvious change, and the 28-day drying shrinkage rate increases significantly; compared with Example 2, for Comparative Example 5 without adding an expansive agent, the slump flow at the time of leaving the mixer increases, the slump flow time has no obvious change, the strength has no obvious change, but the 28-day drying shrinkage rate increases significantly.

[0130] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An ultra-high performance concrete, characterized in that: The raw materials include the following components: Cement, silica fume, ultrafine fly ash, micron-sized filler, expansion agent, quartz sand, polycarboxylic acid high-performance water-reducing agent, steel fiber and water; The mass ratio of the cement, silica fume, ultrafine fly ash, micron-sized filler, expansion agent, quartz sand, polycarboxylic acid high-performance water-reducing agent and water is 500:80-160:100-260:100-260:60:1180:15-30:160-180; The micron-sized filler is ultrafine limestone powder, ultrafine slag powder or ultrafine quartz powder; The volume proportion of the steel fiber in the raw material is 1.5-2.5%; The particle size of the ultrafine fly ash, ultrafine limestone powder, ultrafine slag powder or ultrafine quartz powder is less than 10 μm.

2. The ultra-high performance concrete according to claim 1, characterized in that: The cement is silicate cement or ordinary silicate cement.

3. The ultra-high performance concrete according to claim 1, characterized in that: The strength grade of the cement is ≥52.

5.

4. The ultra-high performance concrete according to claim 1, characterized in that: The silica fume is grade 90 silica fume.

5. The ultra-high performance concrete according to claim 1, characterized in that: The ultrafine fly ash is FⅠ grade fly ash.

6. The ultra-high performance concrete according to claim 1, characterized in that: The ultra-fine slag powder is granulated blast furnace slag powder of grade S95 or above.

7. The ultra-high performance concrete according to claim 1, characterized in that: The expansion agent is a magnesium oxide expansion agent.

8. The ultra-high performance concrete according to claim 1, characterized in that: The water reducing agent has a water reducing rate of ≥30%.

9. The method for preparing ultra-high performance concrete according to any one of claims 1 to 8, characterized in that: The following steps are involved: The raw materials are mixed according to a proportion to obtain the ultra-high performance concrete.

10. The preparation method according to claim 9, characterized in that: The following steps are involved: (1) mixing the cement, silica fume, ultrafine fly ash, micron-sized filler, expansion agent and quartz sand to obtain a dry mix; (2) adding the polycarboxylic acid high-performance water reducing agent and water to the dry mix, stirring to obtain a colloidal mixture; (3) adding the steel fiber to the colloidal mixture and stirring to obtain a UHPC mixture; (4) After the UHPC mixture is cast and formed, it is allowed to stand and cured to obtain the ultra-high performance concrete.

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