CN118184269A - Alkali-resistant glass fiber ultra-high performance concrete and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of preparation of ultra-high performance concrete, discloses alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof, and belongs to the technical field of building materials. The alkali-resistant glass fiber ultra-high performance concrete comprises the following raw materials in parts by weight: 80-100 parts of Portland cement, 100-120 parts of aggregate, 90-100 parts of admixture, 200-220 parts of purified water, 10-15 parts of water reducer and 30-50 parts of glass fiber. According to the invention, the alkali-resistant glass fiber is introduced by optimizing raw material ingredients, so that the defects of poor durability, weak fatigue resistance, easiness in corrosion, easiness in entanglement and non-uniform dispersion of the steel fiber ultra-high performance concrete and the basalt fiber ultra-high performance concrete in the prior art are overcome. The compressive property, the splitting resistance, the fracture resistance, the durability and the toughness of the concrete material are improved, and the shrinkage and the cracking of the concrete are reduced.

Description

Alkali-resistant glass fiber ultra-high performance concrete and preparation method thereof

Technical Field

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

Background technique

At present, ordinary ultra-high performance concrete is a low water-cement ratio concrete made by mixing and other processes with high-quality raw materials, adding appropriate amounts of mineral admixtures and high-efficiency water reducers. This concrete has the characteristics of high strength, good fluidity and excellent durability.

In the prior art, the common externally added fibers of ordinary ultra-high performance concrete are mainly steel fibers and basalt fibers. Although they can improve the flexural properties of ultra-high performance concrete specimens, due to the weakly alkaline environment in the concrete, steel fibers and basalt fibers are often corroded, which is not conducive to the durability and corrosion resistance of ultra-high performance concrete.

Therefore, it is necessary to propose an alkali-resistant glass fiber ultra-high performance concrete with simple mix ratio, strong corrosion resistance, excellent durability, good flexural resistance, compressive resistance and splitting resistance and a preparation method thereof.

Summary of the invention

The object of the present invention is to provide an alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof, so as to solve the problems raised in the background technology.

To achieve the above object, the present invention provides the following technical solutions:

In a first aspect, the present invention provides an alkali-resistant glass fiber ultra-high performance concrete, which is composed of the following components, by weight: 80-100 parts of Portland cement, 100-120 parts of aggregate, 200-300 parts of admixture, 200-220 parts of pure water, 10-15 parts of water reducer, and 30-50 parts of glass fiber.

Preferably, the water-to-cement ratio of the alkali-resistant glass fiber ultra-high performance concrete is 0.17-0.20.

Preferably, the silicate cement is PO42.5 composite silicate cement.

Preferably, the aggregate comprises: coarse sand, fine sand, and silt sand.

Preferably, the admixture is fly ash, slag powder, or silica fume.

Preferably, the water reducer is a polycarboxylic acid high performance water reducer.

Preferably, the PO42.5 composite silicate cement mainly consists of clinker, kiln dust and hydraulic cementitious materials in a ratio of 4:1:2. It has a fast hardening speed and a compressive strength of not less than 42.5 MPa after standard curing for 28 days.

Preferably, the ratio of coarse sand, fine sand and silt sand is 7:7:6.

Preferably, the coarse sand fineness modulus is 3.1-3.7, and the average particle size is 0.5 mm; the fine sand fineness modulus is 2.3-3.0, and the average particle size is 0.42 mm; the silt fineness modulus is 1.6-2.2, and the average particle size is 0.3 mm.

Preferably, the ratio of fly ash, slag powder and silica ash is 1:1:3.

Preferably, the alkali-resistant glass fibers include bundled alkali-resistant glass fibers of 6 mm, 12 mm, and 24 mm in length, discrete alkali-resistant glass fibers of 6 mm in length, and alkali-resistant glass fiber twisted yarns.

The bundled alkali-resistant glass fiber is a high-performance alkali-resistant glass chopped fiber, the surface of which is covered with a wetting agent with a content of ≥16.5% _ZrO2 , a moisture content of ≤0.5%, and a tensile strength of 1000-1700MPa, so that the glass fiber is not easily corroded in an alkaline environment, thereby improving the durability of the concrete structure.

The discrete alkali-resistant glass fiber is a highly dispersed alkali-resistant chopped fiber with a moisture content of ≤0.5% and a tensile strength of 1700MPa. It is very easy to mix with the mixture to form a uniform three-dimensional reinforced network structure in the matrix to control and prevent cracking of the ready-mixed concrete.

In a second aspect, the present invention provides a method for preparing alkali-resistant glass fiber ultra-high performance concrete, comprising the following steps:

Step 1: Add the weighed silicate cement, coarse sand, fine sand, silt sand and admixtures into the drum concrete mixer in sequence and stir for 2 minutes to mix evenly.

Step 2: Add the weighed water reducer into the weighed water, stir evenly, then add to the dry-mixed concrete, continue stirring for 6 minutes, add the weighed alkali-resistant glass fiber while stirring, continue stirring for 2 minutes to obtain an alkali-resistant glass fiber ultra-high performance concrete mixture.

The beneficial technical effects of the present invention are as follows:

1. The present invention optimizes the raw material formula and enables the added alkali-resistant glass fiber to be quickly and evenly dispersed in the concrete matrix, so as to improve the shortcomings of the prior art, such as poor durability, weak fatigue resistance, easy fiber corrosion, easy entanglement, and uneven dispersion of steel fiber ultra-high performance concrete and basalt fiber ultra-high performance concrete.

2. The present invention can improve the compressive strength, splitting resistance, flexural strength, durability and toughness of concrete materials and reduce shrinkage cracking of concrete.

3. By adding polycarboxylic acid high-performance water-reducing agent, the working performance and durability of concrete can be improved, and the quality of ultra-high performance concrete can be improved.

4. By adding slag powder, part of the cement can be replaced, the amount of cement used in ultra-high performance concrete can be reduced, and environmental pollution and resource consumption can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a statistical diagram of the compressive strength of an alkali-resistant glass fiber ultra-high performance concrete according to the present invention.

FIG. 2 is a statistical diagram of the splitting tensile strength of an alkali-resistant glass fiber ultra-high performance concrete according to the present invention.

FIG. 3 is a statistical diagram of the flexural strength of an alkali-resistant glass fiber ultra-high performance concrete according to the present invention.

FIG. 4 is a local microstructure diagram (100 um) of an alkali-resistant glass fiber ultra-high performance concrete sample of the present invention.

FIG. 5 is a local 200um microstructure diagram (200um) of an alkali-resistant glass fiber ultra-high performance concrete sample of the present invention.

FIG6 is a flow chart of a method for preparing alkali-resistant glass fiber ultra-high performance concrete according to the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with Figures 1 to 6 of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, but not all of the embodiments.

Example 1

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof. The preparation raw materials, measured by weight, include: 80-100 parts of silicate cement, 100 parts of aggregate, 90 parts of admixture, 200-220 parts of pure water, 10-15 parts of water reducing agent, and 30 parts of 6mm-long, clustered glass fibers.

As shown in FIG5 , the preparation method of the ultra-high performance concrete of alkali-resistant glass fiber is as follows: weighed silicate cement, coarse sand, fine sand, silt sand, and admixture are added into a drum concrete mixer one by one, and stirred for 2 minutes to mix evenly; weighed water is added, and stirring is continued for 6 minutes, and then a water reducer is added and stirred for 2 minutes, and while stirring, weighed alkali-resistant glass fiber is added, and stirring is continued for 2 minutes to obtain an alkali-resistant glass fiber ultra-high performance concrete mixture with a water-cement ratio of 0.17.

The reason why the alkali-resistant glass fiber is added last in the preparation process of the present invention is that the surface of the alkali-resistant glass fiber is covered with a wetting agent, and the wetting agent coating on the surface of the alkali-resistant glass fiber will be damaged during the long-term stirring process of the concrete. Therefore, in order to make the alkali-resistant glass fiber give full play to its corrosion-resistant effect, the alkali-resistant glass fiber is added last in the preparation of the plain ultra-high performance concrete.

Example 2

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof. The preparation raw materials, measured by weight, include: 80-100 parts of silicate cement, 100 parts of aggregate, 90 parts of admixture, 200-220 parts of pure water, 10-15 parts of water reducing agent, and 30 parts of 12mm long, clustered glass fibers.

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof are shown in Example 1.

Example 3

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof. The preparation raw materials, measured by weight, include: 80-100 parts of silicate cement, 100 parts of aggregate, 90 parts of admixture, 200-220 parts of pure water, 10-15 parts of water reducing agent, and 30 parts of 24mm long, clustered glass fibers.

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof are shown in Example 1.

Example 4

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof. The preparation raw materials, measured by weight, include: 80-100 parts of silicate cement, 100 parts of aggregate, 90 parts of admixture, 200-220 parts of pure water, 10-15 parts of water reducing agent, and 40 parts of 12mm long, clustered glass fibers.

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof are shown in Example 1.

Example 5

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof. The preparation raw materials, measured by weight, include: 80-100 parts of silicate cement, 100 parts of aggregate, 90 parts of admixture, 200-220 parts of pure water, 10-15 parts of water reducing agent, and 50 parts of 12mm long, clustered glass fibers.

Example 6

Ultra-high performance concrete and a preparation method thereof, wherein the preparation raw materials include, by weight: 80-100 parts of silicate cement, 100 parts of aggregate, 90 parts of admixture, 200-220 parts of pure water, and 10-15 parts of water reducing agent.

An alkali-resistant glass fiber ultra-high performance concrete and a preparation method thereof are shown in Example 1.

The only difference between Comparative Example 1 and Example 1 is that 0.5 parts of discrete alkali-resistant glass fibers are added to the original ratio.

The only difference between Comparative Example 2 and Example 2 is that 0.5 parts of discrete alkali-resistant glass fibers are added to the original ratio.

The only difference between Comparative Example 3 and Example 3 is that 0.5 parts of discrete alkali-resistant glass fibers are added to the original ratio.

The products of Examples 1-5 and Comparative Examples 1-3 were used as the fiber admixture specifications for alkali-resistant glass fiber ultra-high performance concrete to prepare alkali-resistant glass fiber ultra-high performance concrete. The specific preparation method is as follows:

Weighed ordinary Portland cement, coarse sand, fine sand, silt sand and admixtures were added to a drum concrete mixer, stirred for 2 minutes to mix evenly, weighed water was added, continued stirring for 6 minutes, and then water reducer was added and stirred for 2 minutes. While stirring, weighed alkali-resistant glass fiber was added and continued stirring for 2 minutes to obtain an alkali-resistant glass fiber ultra-high performance concrete mixture with a water-binder ratio of 0.17. After standing indoors for 24 hours, the mixture was demoulded and cured in a constant temperature and humidity standard curing box for 3 days, 7 days, and 28 days.

The strength test of alkali-resistant glass fiber ultra-high performance concrete was carried out in accordance with T/CBMF 37-2018 "Basic Properties and Test Methods of Ultra-High Performance Concrete". The specimens of 100mm×100mm×100mm and 100mm×100mm×400mm were placed in a drying oven at 60℃ and dried to constant weight before the strength test was carried out.

(1) Test the compressive strength of the prepared alkali-resistant glass fiber ultra-high performance concrete:

σ-compressive strength of the sample, unit: MPa;

F- failure load of the specimen, unit N;

A-compressed area of the specimen, in mm ² .

(2) Test the splitting tensile strength of the prepared alkali-resistant glass fiber ultra-high performance concrete:

f _ts - splitting tensile strength of the specimen, in MPa;

F- failure load of the specimen, unit N;

A-compressed area of the specimen, in mm ² .

(3) Test the flexural strength of the prepared alkali-resistant glass fiber ultra-high performance concrete:

f _f - flexural strength of the specimen, in MPa;

F- failure load of the specimen, unit N;

l-span between supports, in mm;

b-specimen cross-sectional width, in mm;

h- specimen cross-section height, in mm.

The strength test results are shown in Table 1.

It can be seen from the data in Table 1 and Figures 2 and 3 that, relative to the ultra-high performance concrete prepared with alkali-resistant glass fibers obtained in Examples 1-6 and Comparative Examples 1-3, the fiber concrete mixed with 30 components of 12 mm long bundled fibers and 0.5 components of 6 mm long discrete fibers has significantly improved flexural strength and splitting tensile strength. This is because the addition of fibers inhibits the generation of concrete cracks. It can be seen from the test data of Example 6 in Table 1 and Figure 1 that the compressive strength of the concrete is slightly weakened after the addition of fibers. This is because the addition of alkali-resistant glass fibers reduces the density of the ultra-high performance concrete, resulting in a decrease in the compressive strength of the concrete material.

Table 1 Strength test

Figure 4 (100um) and Figure 5 (200um) are the experimental microstructures of the alkali-resistant glass fiber ultra-high performance concrete in which 30 parts of 12mm clustered alkali-resistant glass fibers are mixed with 0.5 parts of discrete alkali-resistant glass fibers in comparative example 2 of the present invention. As shown in Figure 4 (100um) and Figure 5 (200um), the alkali-resistant glass fibers are randomly distributed in the matrix, further improving the grip and adhesion of the cement matrix to the alkali-resistant glass fibers. Some fibers span across the cracks, and the alkali-resistant glass fibers that bridge the matrix concrete on both sides of the cracks are subjected to the pulling action, thereby improving the bending bearing capacity and deformation capacity of the alkali-resistant glass fiber ultra-high performance concrete.

The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims (8)

1. An alkali-resistant glass fiber ultra-high performance concrete, characterized in that it is composed of the following components by mass: 80-100 parts of Portland cement, 100-120 parts of aggregate, 200-300 parts of admixture, 200-220 parts of pure water, 10-15 parts of water reducing agent, and 30-50 parts of glass fiber; The silicate cement is PO42.5 composite silicate cement; The aggregates include: coarse sand, fine sand, and silt sand; The admixtures are fly ash, slag powder and silica ash; The water reducing agent is a polycarboxylic acid high performance water reducing agent. 2. The alkali-resistant glass fiber ultra-high performance concrete according to claim 1 is characterized in that the ratio of the PO42.5 composite silicate cement clinker, kiln dust and hydraulic cementitious material is 4:1:2. 3. The alkali-resistant glass fiber ultra-high performance concrete according to claim 1, characterized in that the ratio of coarse sand, fine sand and silt sand is 7:7:6. 4. The alkali-resistant glass fiber ultra-high performance concrete according to claim 1 is characterized in that the coarse sand fineness modulus is 3.1-3.7, and the average particle size is 0.5 mm; the fine sand fineness modulus is 2.3-3.0, and the average particle size is 0.42 mm; the silt sand fineness modulus is 1.6-2.2, and the average particle size is 0.3 mm. 5. The alkali-resistant glass fiber ultra-high performance concrete according to claim 1, characterized in that the ratio of fly ash, slag powder and silica fume is 1:1:3. 6. The alkali-resistant glass fiber ultra-high performance concrete according to claim 1 is characterized in that the alkali-resistant glass fibers include clustered 6 mm, 12 mm, and 24 mm long alkali-resistant glass fibers, discrete 6 mm long alkali-resistant glass fibers, and alkali-resistant glass fiber twisted yarns. 7. A method for preparing an alkali-resistant glass fiber ultra-high performance concrete according to any one of claims 1 to 6, characterized in that it comprises the following steps: Step 1: Add the weighed silicate cement, coarse sand, fine sand, silt sand and admixtures into the drum concrete mixer in sequence and stir for 2 minutes to mix evenly; Step 2: Add the weighed water reducer into the weighed water, stir evenly, then add to the dry-mixed concrete, continue stirring for 6 minutes, add the weighed alkali-resistant glass fiber while stirring, continue stirring for 2 minutes to obtain an alkali-resistant glass fiber ultra-high performance concrete mixture. 8. The method for preparing an alkali-resistant glass fiber ultra-high performance concrete according to claim 7, characterized in that the prepared alkali-resistant glass fiber ultra-high performance concrete mixture is vibrated at 70 Hz and cured for 28 days under standard curing conditions to obtain a finished alkali-resistant glass fiber ultra-high performance concrete.