CN115304311A

CN115304311A - Ultrahigh-performance concrete and preparation method thereof

Info

Publication number: CN115304311A
Application number: CN202210825474.4A
Authority: CN
Inventors: 张平
Original assignee: Fujian Sankai Building Materials Co ltd
Current assignee: Fujian Sankai Building Materials Co ltd
Priority date: 2022-07-14
Filing date: 2022-07-14
Publication date: 2022-11-08

Abstract

The invention relates to the field of building materials, in particular to an ultra-high performance concrete and a preparation method thereof, wherein the ultra-high performance concrete comprises the following raw material components: the ultra-high performance concrete adopts solid waste materials such as fly ash, silica fume, limestone powder, slag powder and the like to replace cementing materials such as cement, adopts cheap common sand to replace high-quality quartz sand, adopts short-cut steel fiber to replace expensive coppered steel fiber, adopts the cheap raw materials to replace original high-quality expensive raw materials, can greatly reduce the material cost of the ultra-high performance concrete, and simultaneously ensures that the physical mechanical property and the durability of the ultra-high performance concrete are not obviously reduced.

Description

Ultra-high performance concrete and preparation method thereof

Technical Field

The invention relates to the field of building materials, in particular to an ultra-high performance concrete and a preparation method thereof.

Background

Ultra-high performance concrete (UHPC) is a new generation cement-based composite material with excellent mechanical properties and good durability, and is widely applied to the fields of high-rise buildings, large-span bridges, ocean engineering, hydraulic engineering, nuclear power engineering, special structures and the like. Compared with common concrete and high-performance concrete, UHPC has excellent performance. Aspect of mechanical propertiesThe UHPC is far superior to common concrete and high-strength concrete, the compressive strength is higher than 100MPa, the breaking strength is higher than 12MPa, and the fracture energy can reach 30000 J.m ² . The traditional concrete belongs to a brittle material, has better compression resistance, but has very poor fracture and shear resistance, while the UHPC is doped with a fiber material, so that the fracture and shear resistance and toughness are greatly improved, and compared with the traditional concrete, the UHPC has one order of magnitude higher fracture strength and two orders of magnitude higher fracture energy. In the aspect of durability, because the water-to-gel ratio of the UHPC is very low, the compact packing of raw material particles is particularly compact, the porosity is only below 9 percent, even the porosity of the UHPC is close to 2 percent, and the pore diameter of a pore structure in the UHPC structure is about 10 nm. Therefore, the UHPC has extremely low permeability, strong environmental medium erosion resistance and abrasion resistance, and the durability is far superior to that of the traditional concrete.

UHPC breaks through many of the limitations of cement-based materials in performance and application. Whether the composition of structural material components, the performance of cement-based materials, the composition of fiber reinforced materials or the combination of other structural materials opens up a lot of development spaces, and the application of UHPC in various engineering is started at present, so that the development and application of UHPC are high-grade soon once the performance and advantages of UHPC are recognized.

Currently, the promotion and application obstruction of UHPC is still large, wherein the raw materials of the UHPC generally adopt high-quality quartz sand and quartz powder as aggregates, copper-plated micro steel fibers as reinforcing fiber materials, high-activity silica fume, fly ash and mineral powder as active admixtures, and a water reducing agent with high water reducing rate as an additive, so that the raw material cost of the UHPC is high; compared with the traditional concrete, the UHPC curing system is complicated and complicated, and generally comprises the curing processes of standing still, initial curing, final curing, natural curing and the like. Therefore, it is an urgent need to provide a concrete which has the high quality of ultra-high performance concrete, is low in cost, and is easy to produce.

Disclosure of Invention

The invention aims to overcome the technical defects in the prior art, provide the ultra-high performance concrete and solve the problem of high production cost of UHPC at present.

In order to achieve the above object, the present invention provides an ultra-high performance concrete, which comprises the following raw material components: common sand, cement, silica fume, limestone powder, fly ash, slag powder, a water reducing agent, steel fiber and water,

preferably, the ultra-high performance concrete comprises the following components in parts by weight: 300 to 500 portions of cement, 50 to 150 portions of silica fume, 400 to 600 portions of limestone powder, 50 to 150 portions of fly ash, 200 to 400 portions of slag powder and 20 to 30 portions of water reducing agent;

preferably, the steel fiber content is 2-3% of the volume content of the ultrahigh-performance concrete;

preferably, the mass ratio of water to the gelling material is 0.16-0.18: 1;

preferably, the mass ratio of the common sand to the cementing material is 0.8-1.2: 1.

preferably, the weight parts of each component are as follows: 400 parts of cement, 100 parts of silica fume, 100 parts of limestone powder, 100 parts of fly ash, 300 parts of slag powder and 25 parts of water reducing agent;

preferably, the steel fiber content is 2% of the volume content of the ultrahigh-performance concrete;

preferably, the mass ratio of water to cementitious material is 0.17:1;

preferably, the mass ratio of the common sand to the cementing material is 1:1.

preferably, the cement has an average particle diameter of 10.0 to 20.0 μm and a specific surface area of 1900 to 2100m2/kg.

Preferably, the silica fume has an average particle diameter of 1.0 to 2.0 μm and a specific surface area of 10000 to 12000m2/kg.

Preferably, the particle size of the limestone powder is 3-5 μm, the content of CaCO3 is more than or equal to 95 percent, and the water content is less than or equal to 2 percent.

Preferably, the average grain diameter of the fly ash is 5.0-10.0 μm, and the specific surface area is 2400-2600 m2/kg.

Preferably, the average grain diameter of the slag powder is 8.0-12.0 μm, and the specific surface area is 1000-1200 m2/kg.

Preferably, the water reducing agent is a polycarboxylic acid water reducing agent, the solid content is 40wt.%, and the water reducing rate is more than or equal to 25%; the steel fiber is short-cut steel fiber with the length of 4-6 mm, the diameter of 200-220 μm, the elastic modulus of not less than 150GPa and the ultimate tensile strength of not less than 2000MPa.

The invention also provides a preparation method of the ultra-high performance concrete, which comprises the steps of stirring cement, silica fume, fly ash, slag powder, limestone powder and common sand in a stirrer at a low speed for 2-3 min, then adding 70-80% by mass of a mixed solution of a polycarboxylic acid water reducing agent and water, stirring at a low speed for 1-2 min, then adding the rest by mass of the polycarboxylic acid water reducing agent and short-cut steel fibers, keeping stirring at the low speed for 2-3 min, finally stirring at a high speed for 3-4 min, placing in a mould, and maintaining to a specified age to obtain the ultra-high performance concrete.

The ultra-high performance concrete provided by the invention has the following advantages:

1. according to the invention, solid waste materials such as fly ash, silica fume, limestone powder and slag powder are adopted to replace cementing materials such as cement, cheap common sand is adopted to replace high-quality quartz sand, short-cut steel fibers are adopted to replace expensive copper-plated steel fibers, and the cheap raw materials are adopted to replace original high-quality expensive raw materials, so that the material cost of the ultra-high performance concrete can be greatly reduced, and meanwhile, the physical mechanical property and the durability of the ultra-high performance concrete are not obviously reduced.

2. According to the invention, limestone powder is used as the fine aggregate, so that the particle grading of the ultra-high performance concrete matrix is improved, the matrix is more compact, the flow property of fresh concrete is improved, and the physical mechanical property and the working performance of the concrete are increased.

3. Active SiO in silica fume, fly ash and slag powder in gelling system ₂ 、Al ₂ O ₃ Ca (OH) generated by hydration with cement ₂ And performing secondary hydration reaction (volcanic ash reaction) to generate C-S-H gel, repairing microcracks, filling pores of cement stones and interface transition regions between the cement stones and the aggregate, and improving physical and mechanical properties.

4. According to the invention, the curing mode of the ultra-high performance concrete can adopt natural curing, so that an additional high-temperature, steam and steam curing method is avoided, a pouring forming method of common concrete can be adopted, the complexity of the preparation process of the ultra-high performance concrete is greatly reduced, the preparation cost is also greatly reduced, and the expansion of the application field of the ultra-high performance concrete is facilitated.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.

The invention provides an ultra-high performance concrete, which comprises the following raw material components: common sand, cement, silica fume, limestone powder, fly ash, slag powder, a water reducing agent, steel fiber and water,

further, the ultra-high performance concrete comprises the following components in parts by weight: 300 to 500 portions of cement, 50 to 150 portions of silica fume, 400 to 600 portions of limestone powder, 50 to 150 portions of fly ash, 200 to 400 portions of slag powder and 20 to 30 portions of water reducing agent;

further, the steel fiber content is 2-3% of the volume content of the ultrahigh-performance concrete;

further, the mass ratio of water to the cementing material is 0.16-0.18: 1;

further, the mass ratio of the common sand to the cementing material is 0.8-1.2: 1.

further, the weight parts of the components are as follows: 400 parts of cement, 100 parts of silica fume, 100 parts of limestone powder, 100 parts of fly ash, 300 parts of slag powder and 25 parts of water reducing agent;

further, the steel fiber content is 2% of the volume content of the ultrahigh-performance concrete;

further, the mass ratio of water to the gelling material is 0.17:1;

further, the mass ratio of the common sand to the cementing material is 1:1.

further, the cement has an average particle diameter of 10.0 to 20.0 μm and a specific surface area of 1900 to 2100m2/kg.

Furthermore, the average particle size of the silica fume is 1.0-2.0 μm, and the specific surface area is 10000-12000 m2/kg.

Furthermore, the particle size of the limestone powder is 3-5 μm, the content of CaCO3 is more than or equal to 95 percent, and the water content is less than or equal to 2 percent.

Furthermore, the average grain diameter of the fly ash is 5.0-10.0 μm, and the specific surface area is 2400-2600 m2/kg.

Furthermore, the average grain diameter of the slag powder is 8.0-12.0 μm, and the specific surface area is 1000-1200 m2/kg.

Further, the water reducing agent is a polycarboxylic acid water reducing agent, the solid content is 40wt.%, and the water reducing rate is more than or equal to 25%; the steel fiber is short-cut steel fiber with the length of 4-6 mm, the diameter of 200-220 μm, the elastic modulus of not less than 150GPa and the ultimate tensile strength of not less than 2000MPa.

The present invention will be described in detail below by way of examples.

Example 1

This example illustrates the ultra high performance concrete of the present invention.

Weighing the following components in parts by weight: 400 parts of cement, 100 parts of silica fume, 100 parts of limestone powder, 100 parts of fly ash, 300 parts of slag powder and 25 parts of water reducing agent, wherein the content of steel fiber is 2 percent of the volume content of the ultra-high performance concrete; the mass ratio of water to the cementing material is 0.17:1; the mass ratio of the common sand to the cementing material is 1:1, stirring cement, silica fume, fly ash, slag powder, limestone powder and common sand in a stirrer at a low speed for 2min, then adding 70% by mass of mixed liquid of a polycarboxylic acid water reducing agent and water, stirring at a low speed for 1min, then adding the rest of polycarboxylic acid water reducing agent and short-cut steel fibers, stirring at a low speed for 3min, finally stirring at a high speed for 4min, placing in a mould, and maintaining to a specified age to obtain the ultrahigh-performance concrete.

Example 2

Weighing the following components in parts by weight: 300 parts of cement, 50 parts of silica fume, 400 parts of limestone powder, 50 parts of fly ash, 200 parts of slag powder and 20 parts of water reducing agent; the steel fiber content is 2% of the volume content of the ultrahigh-performance concrete; the mass ratio of water to the cementing material is 0.16:1; the mass ratio of the common sand to the cementing material is 0.8:1, stirring cement, silica fume, fly ash, slag powder, limestone powder and common sand in a stirrer at a low speed for 2min, then adding a mixed solution of 70% by mass of a polycarboxylic acid water reducing agent and water, stirring at a low speed for 2min, then adding the remaining mass of the polycarboxylic acid water reducing agent and short-cut steel fibers, keeping stirring at the low speed for 2min, finally stirring at a high speed for 3min, placing in a mould, and maintaining to a specified age to obtain the ultrahigh-performance concrete.

Example 3

Weighing the following components in parts by weight: 500 parts of cement, 150 parts of silica fume, 600 parts of limestone powder, 150 parts of fly ash, 400 parts of slag powder and 30 parts of water reducing agent; the steel fiber content is 3% of the volume content of the ultra-high performance concrete; the mass ratio of water to the cementing material is 0.18:1; the mass ratio of the common sand to the cementing material is 1.2:1, stirring cement, silica fume, fly ash, slag powder, limestone powder and common sand in a stirrer at a low speed for 3min, then adding a mixed solution of 70% by mass of a polycarboxylic acid water reducing agent and water, stirring at a low speed for 2min, then adding the rest by mass of the polycarboxylic acid water reducing agent and short-cut steel fibers, keeping stirring at a low speed for 3min, finally stirring at a high speed for 4mins, placing in a mould, and curing to a specified age to obtain the ultra-high performance concrete.

Comparative example 1

Compared with the embodiment 1, the quartz sand is used for replacing the common sand, and the other conditions are consistent.

Comparative example 2

Compared with example 1, the comparative example has the same conditions without limestone powder.

Comparative example 3

Compared with example 1, the comparative example has the same conditions without adding silica fume.

Comparative example 4

Compared with example 1, the comparative example has the same conditions without adding fly ash.

Comparative example 5

Compared with example 1, the comparative example has the same conditions without adding slag powder.

The ultra-high performance concrete prepared in examples 1 to 3 and comparative examples 1 to 5 were subjected to a performance test.

And (3) carrying out slump tests and expansion tests on the freshly mixed ultrahigh-performance concrete according to GB/T50080-2016 standard of common concrete mixture performance test methods.

The newly-mixed ultra-high performance concrete is molded, the test piece is maintained by adopting a standard maintenance system (20 +/-2 ℃ and the relative humidity of 95 percent), and the physical and mechanical properties of the concrete are tested when the concrete is maintained to a specified age. The compression strength test adopts a cubic test piece of 100mm multiplied by 100mm, and the loading rate is 1.2 MPa/s-1.4 MPa/s; the breaking strength adopts a prism test piece with the thickness of 100mm multiplied by 400mm, and the loading rate is 0.08 MPa/s-0.1 MPa/s.

The results are shown in the following table:

from the above-mentioned performances, the slump constant and the expansion degree of the ultra-high performance concrete of examples 1-3 and comparative examples 1-5 can meet the requirements of working performance, the compressive strength of the ultra-high performance concrete of each test group after being cured for 28 days under the standard condition is more than 110MPa in examples 1-3 and comparative examples 1-5, and the flexural strength of the ultra-high performance concrete of example 1-3 is more than 30MPa in 28d.

From the results of comparative examples 1 to 3 and comparative example 1, the performance of the ultra-high performance concrete obtained using the common sand and the quartz sand was not greatly different;

comparative examples 2-5 show that the addition of silica fume, limestone powder, fly ash and slag powder can greatly improve the performance of the ultra-high performance concrete, and the ultra-high performance concrete prepared by selecting the formula has the best performance.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. The ultra-high performance concrete is characterized by comprising the following raw material components: common sand, cement, silica fume, limestone powder, fly ash, slag powder, a water reducing agent, steel fiber and water.

2. The ultra-high performance concrete as claimed in claim 1, wherein the components in parts by weight are: 300 to 500 portions of cement, 50 to 150 portions of silica fume, 400 to 600 portions of limestone powder, 50 to 150 portions of fly ash, 200 to 400 portions of slag powder and 20 to 30 portions of water reducing agent;

the steel fiber content is 2-3% of the volume content of the ultrahigh-performance concrete;

the mass ratio of the water to the cementing material is 0.16-0.18: 1;

the mass ratio of the common sand to the cementing material is 0.8-1.2: 1.

3. the ultra-high performance concrete as claimed in claim 2, wherein the components are in parts by weight: 400 parts of cement, 100 parts of silica fume, 100 parts of limestone powder, 100 parts of fly ash, 300 parts of slag powder and 25 parts of water reducing agent;

the steel fiber content is 2% of the volume content of the ultrahigh-performance concrete;

the mass ratio of the water to the cementing material is 0.17:1;

the mass ratio of the common sand to the cementing material is 1:1.

4. the ultra-high performance concrete according to claim 1, wherein the cement has an average particle size of 10.0 to 20.0 μm and a specific surface area of 1900 to 2100m2/kg.

5. The ultra-high performance concrete according to claim 1, wherein the silica fume has an average particle size of 1.0 to 2.0 μm and a specific surface area of 10000 to 12000m2/kg.

6. The ultra-high performance concrete as claimed in claim 1, wherein the limestone powder has a particle size of 3-5 μm, a CaCO3 content of 95% or more, and a water content of 2% or less.

7. The ultra-high performance concrete as claimed in claim 1, wherein the fly ash has an average particle size of 5.0 to 10.0 μm and a specific surface area of 2400 to 2600m2/kg.

8. The ultra-high performance concrete as claimed in claim 1, wherein the slag powder has an average particle size of 8.0 to 12.0 μm and a specific surface area of 1000 to 1200m2/kg.

9. The ultra-high performance concrete of claim 1, wherein the water reducing agent is a polycarboxylic acid water reducing agent, the solid content is 40wt.%, and the water reducing rate is not less than 25%; the steel fiber is chopped steel fiber, the length is 4 mm-6 mm, the diameter is 200-220 mu m, the elastic modulus is not lower than 150GPa, and the ultimate tensile strength is not lower than 2000MPa.

10. The method for preparing the ultra-high performance concrete according to any one of claims 1 to 9, wherein the cement, the silica fume, the fly ash, the slag powder, the limestone powder and the common sand are stirred in a stirrer at a low speed for 2 to 3min, then a mixed solution of 70 to 80 mass percent of a polycarboxylic acid water reducing agent and water is added to be stirred at a low speed for 1 to 2min, then the polycarboxylic acid water reducing agent and the chopped steel fibers with the rest mass are added to be stirred at a low speed for 2 to 3min, finally the mixture is stirred at a high speed for 3 to 4min and is placed in a mould to be maintained for a specified age, and the ultra-high performance concrete is obtained.