CN116283148A - A kind of non-steam curing ultra-high performance concrete for bridge pier body and preparation method thereof - Google Patents

Abstract

The invention discloses a non-steam curing ultra-high performance concrete for bridge pier bodies and a preparation method thereof. The concrete comprises 566-693 parts by weight of cement, 332-426 parts by weight of auxiliary cementitious materials, 600-700 parts by weight of Fine aggregate, 700-800 parts by weight of coarse aggregate, 156-195 parts by weight of steel fiber, 25-34 parts by weight of water reducer, and 164-184 parts by weight of water. The preparation method is as follows: mix cement, auxiliary cementitious material with fine aggregate and coarse aggregate; mix water and water reducer evenly and then add the mixture; finally add steel fiber for stirring; under standard curing conditions, the bridge pier is obtained The body uses steam-free ultra-high performance concrete. The working performance and physical and mechanical performance of the ultra-high-performance concrete of the invention can meet the physical and mechanical technical requirements of bridge piers.

Description

A kind of non-steam curing ultra-high performance concrete for bridge pier body and preparation method thereof

technical field

The invention relates to concrete and a preparation method thereof, in particular to a non-steam curing ultra-high performance concrete for bridge piers and a preparation method thereof.

Background technique

As a load-bearing structure, the bridge pier body requires high mechanical properties and durability of the concrete material. Traditionally, reinforced concrete is used as the main material to prepare bridge structures such as the bridge pier body. Ultra-high performance concrete has excellent compressive and flexural properties. And has a high modulus of elasticity to resist deformation.

Among the existing patents, Du Jiegui in patent CN217517339U proposed an ultra-high-performance concrete bridge connecting plate applied to bridges, which belongs to the invention for bridge structures; Liu Muyu in CN13430919A announced a pier structure based on lightweight ultra-high-performance concrete, The invention is also directed to bridge structures. The existing applications of ultra-high performance concrete in the field of bridge engineering are mostly proposed for bridge reinforcement methods or for bridge structure improvement. And in CN115611563A, propose a kind of ultra-high performance concrete that is used for municipal bridge by Zhang Wei, propose to adopt the alkaline water agent that contains organic penetration component, inorganic penetration component and hydration catalytic component as admixture to improve ultra-high performance concrete The preparation method of high-performance concrete performance, the overall preparation cycle is long, and the whole process of preparing ultra-high-performance concrete is relatively cumbersome; in CN111302733A, Chen Luyi et al. proposed a kind of non-steamed ultra-high-performance concrete for bridge wet joints It aims to improve the shrinkage and creep of shrinkage joints, but the compressive strength of 28d material is only above 110MPa, and the flexural strength is only above 14MPa. The physical and mechanical properties are low and it is difficult to be used in bridge load-bearing structures.

Traditional ultra-high-performance concrete components need high-temperature steam curing to improve the mechanical properties and durability of ultra-high-performance concrete, but after high-temperature steam curing, ultra-high-performance concrete may produce strength shrinkage and cause cracks in the structure. High-performance concrete can avoid structural problems in subsequent service; at the same time, due to the low content of ultra-high-performance concrete on the market, the preparation cost is much higher; and most of the existing bridges are reinforced concrete structures, and the maintenance cost after corrosion is high .

Contents of the invention

Purpose of the invention: The purpose of the present invention is to provide a steam-free ultra-high performance concrete for bridge pier bodies with excellent mechanical properties and no steam curing;

The second object of the present invention is to provide a method for preparing the above-mentioned non-steam curing ultra-high performance concrete for bridge pier body.

Technical solution: The non-steam-cured ultra-high performance concrete for bridge pier body according to the present invention comprises the following components in parts by weight:

Wherein, the auxiliary gelling material includes fly ash and silica fume, or coal ash, silica fume and mineral powder or glass microspheres, wherein the weight of fly ash is 55%-70%.

Wherein, the fine aggregate is natural river sand, and the fineness modulus is 2.3-3.0.

Wherein, the coarse aggregate is basalt gravel, the particle size of the aggregate is 5-10 mm, and the mud content is ≤0.5%. The amount of coarse aggregate should be greater than or equal to the amount of fine aggregate. And the elastic modulus is high, which improves the fluidity and elastic modulus of ultra-high performance concrete.

Wherein, the water reducer is a polycarboxylate water reducer, and the weight of the added water reducer accounts for 1.8% to 3.5% of the total mass of cement and auxiliary cementitious materials, depending on the water reducing rate and solid content of the water reducer. Decide.

Wherein, the cross-sectional diameter of the steel fiber is 0.18-0.22 mm, the fiber length is 19-21 mm, and the aspect ratio is 90-110.

Among them, the shape of the steel fiber is end-hook type, the tensile strength is ≥ 2000MPa, which is different from the straight steel fiber used in ordinary times, and can effectively improve the flexural strength and fracture toughness of ultra-high performance concrete and compared with the straight steel fiber Fibers have little effect on the working properties of concrete.

Wherein, the cement is PII52.5 cement.

The above-mentioned method for preparing the steam-cured ultra-high performance concrete for the pier body of the bridge comprises the following steps:

(1) mixing cement, auxiliary cementitious material, coarse aggregate and fine aggregate;

(2) After mixing water and water reducing agent, slowly add to the above mixture, and continue to stir to form a concrete matrix;

(3) Slowly add steel fibers into the concrete matrix, after stirring, let it stand, demould, and cure to obtain steam-free ultra-high performance concrete for bridge piers.

Wherein, in step (1), (2), (3), the mode of stirring is mechanical stirring; Wherein, the rotating speed of the stirring in step (1) is 45-50r/min, and the time is 3～4min; Step ( The rotational speed of stirring in 2) is 45-50r/min, and the time is 4-6min; the rotational speed of stirring in step (3) is 45-50r/min, and the time is 5-8min.

Wherein, in step (3), according to the concrete maintenance and test standard GB/T 50081-2019 concrete physical and mechanical performance test method standard, after the concrete is formed, it is left to stand for 1 day, demolded and transferred to a standard curing room for maintenance for 28 days. The room temperature is controlled at 20±2°C, and the relative humidity is controlled above 95%.

Beneficial effects: Compared with the prior art, the present invention achieves the following remarkable effects: (1) The present invention can meet the physical and mechanical properties and work performance required by the viaduct bridge at the present stage, has higher fluidity and expansion, and can It meets the requirements for on-site construction of large-volume bridge piers or the preparation of prefabricated components. Due to its high fluidity and expansion, it has a flat surface after forming and vibrating to meet the requirements of the shape of the pier body. (2) The steam curing process is eliminated, and the concrete is cured under standard curing conditions, which saves the electric energy and heat energy of high temperature steam curing, reduces the cost of ultra-high performance concrete in the curing process, and can be cured without steam curing Reach the required strength level of the pier body. Due to its high physical and mechanical properties, it can make up for the risks of cracking and corrosion of traditional reinforced concrete bridge piers, and reduce maintenance costs. It can be applied in construction fields such as bridge piers. (3) In the present invention, glass microspheres etc. are added to the auxiliary cementitious material as filling materials to improve the compactness of the ultra-high performance concrete and effectively reduce the bulk density of the ultra-high performance concrete. (4) The ultra-high-performance concrete prepared by the present invention has a higher content of coarse aggregate and the fine aggregate is natural river sand, which can effectively reduce manufacturing costs and because the coarse aggregate content≥fine aggregate content, the coarse aggregate The lower specific surface area and higher elastic modulus improve the fluidity and elastic modulus of ultra-high performance concrete. (5) Most of the existing patents are aimed at the structural aspects of bridge panels or pier bodies, and few are aimed at the materials used for bridge pier bodies. The present invention can be used to fill the vacancy for the materials themselves.

Detailed ways

The present invention will be further described in detail below.

Example 1

All raw materials of the present invention are commercially available. The cement material selected in this embodiment is PII52.5 type cement; the fly ash in the auxiliary cementitious material is Class I fly ash; the steel fiber is an end-hook steel fiber with a length of 20mm; The silicon oxide content is higher than 95%; the mineral powder is S95 mineral powder; the water reducer is a high-efficiency polycarboxylate water reducer with a water reducing rate of 30%. The ultra-high performance concrete of the present embodiment, weigh material by following weight:

Wherein, the auxiliary gelling material contains 188 parts by weight of fly ash, 94 parts by weight of silica fume, and 94 parts by weight of mineral powder.

Concrete preparation process is as follows:

(1) Add 566 parts by weight of water, 376 parts of auxiliary cementitious material, 700 parts by weight of fine aggregate, and 700 parts by weight of coarse aggregate into a concrete mixer and stir for 4 minutes at a speed of 45 r/min to obtain a uniform dry mix material.

(2) Stir and mix 25 parts by weight of high-efficiency superplasticizer and 156 parts by weight of water evenly, and then slowly add to the dry mixture at a mixer speed of 45r/min for 4 minutes to form a concrete matrix with good fluidity.

(3) Slowly disperse the steel fibers in parts by weight into the mixer, and continue stirring for 5 minutes to ensure that the steel fibers are uniformly dispersed in the concrete matrix.

(4) After the concrete is formed, let it stand for 1 day, and transfer it to a standard curing room for curing for 28 days. The temperature in the curing room is controlled at 20±2°C, and the relative humidity is controlled above 95%.

When the curing age reaches 28 days, the 28-day compressive strength, flexural strength, fracture toughness, and elastic modulus of ultra-high performance concrete are tested according to the standard GB/T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are as follows Table 1 shows.

Example 2

The cement material selected in this embodiment is PII52.5 type cement; the fly ash in the auxiliary cementitious material is Class I fly ash; the steel fiber is an end-hook steel fiber with a length of 20mm; The silicon oxide content is higher than 95%; the water reducer is a high-efficiency polycarboxylate water reducer with a water reducing rate of 40%; the solid content is 20%. The ultra-high performance concrete of the present embodiment, weigh material by following weight:

Wherein, the auxiliary gelling material contains 250 parts by weight of fly ash and 82 parts by weight of silica fume.

Concrete preparation process is as follows:

(1) Add 693 parts by weight of cement, 332 parts of auxiliary cementitious materials, 600 parts by weight of fine aggregate, and 800 parts by weight of coarse aggregate into a concrete mixer and stir for 3 minutes at a speed of 45 r/min to obtain a uniform dry mix .

(2) Stir and mix 31 parts by weight of high-efficiency superplasticizer and 164 parts by weight of water evenly, and then slowly add to the dry mixture at a mixer speed of 45r/min and a mixing time of 6min to form a concrete matrix with good fluidity.

(3) Slowly disperse the steel fibers in parts by weight into the mixer, and continue stirring for 8 minutes to ensure that the steel fibers are uniformly dispersed in the concrete matrix.

(4) After the concrete is formed, let it stand for 1 day, and transfer it to a standard curing room for curing for 28 days. The temperature in the curing room is controlled at 20±2°C, and the relative humidity is controlled above 95%.

When the curing age reaches 28 days, the 28-day compressive strength, initial crack strength, flexural strength, fracture toughness, and elastic modulus of ultra-high performance concrete are tested according to the standard GB/T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" , and the test results are shown in Table 1.

Example 3

The cement material selected in this embodiment is PII52.5 type cement; the fly ash in the auxiliary cementitious material is Class I fly ash; the steel fiber is an end-hook steel fiber with a length of 20mm; The silicon oxide content is higher than 95%; the superplasticizer is a high-efficiency polycarboxylate superplasticizer with a solid content of 20%. The ultra-high performance concrete of the present embodiment, weigh material by following weight:

Wherein, the auxiliary gelling material contains 200 parts by weight of fly ash, 82 parts by weight of silica fume and 50 parts by weight of glass microspheres.

Concrete preparation process is as follows:

(1) Add 693 parts by weight of cement and 332 parts of auxiliary cementitious materials, 600 parts by weight of fine aggregate and 800 parts by weight of coarse aggregate into a concrete mixer and stir for 3 minutes at a speed of 45 r/min to obtain a uniform dry mix .

(2) Stir and mix 34 parts by weight of high-efficiency superplasticizer and 164 parts by weight of water evenly, and then slowly add to the dry mixture at a mixer speed of 45r/min for 6 minutes to form a concrete matrix with good fluidity.

(3) Slowly disperse the steel fibers in parts by weight into the mixer, and continue stirring for 6 minutes to ensure that the steel fibers are uniformly dispersed in the concrete matrix.

(4) After the concrete is formed, let it stand for 1 day, and transfer it to a standard curing room for curing for 28 days. The temperature in the curing room is controlled at 20±2°C, and the relative humidity is controlled above 95%.

When the curing age reaches 28 days, the 28-day compressive strength, flexural strength, fracture toughness, and elastic modulus of ultra-high performance concrete are tested according to the standard GB/T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are as follows Table 1 shows.

Example 4

The cement material selected in this embodiment is PII52.5 type cement; the fly ash in the auxiliary cementitious material is Class I fly ash; the steel fiber is an end-hook steel fiber with a length of 20mm; The silicon oxide content is higher than 95%; the superplasticizer is a high-efficiency polycarboxylate superplasticizer with a solid content of 20%. The ultra-high performance concrete of the present embodiment, weigh material by following weight:

Wherein, the auxiliary gelling material contains 200 parts by weight of fly ash, 125 parts by weight of silica fume and 51 parts by weight of glass microspheres.

Concrete preparation process is as follows:

(1) Add 598 parts by weight of cement and 426 parts of auxiliary cementitious materials and 600 parts by weight of fine aggregate and 800 parts by weight of coarse aggregate into a concrete mixer and stir for 4 minutes at a speed of 45 r/min to obtain a uniform dry mix .

(2) Stir and mix 31 parts by weight of high-efficiency superplasticizer and 164 parts by weight of water evenly, and then slowly add to the dry mixture at a mixer speed of 45r/min and a mixing time of 6min to form a concrete matrix with good fluidity.

(3) Slowly disperse the steel fibers in parts by weight into the mixer, and continue stirring for 8 minutes to ensure that the steel fibers are uniformly dispersed in the concrete matrix.

(4) After the concrete is formed, let it stand for 1 day, and transfer it to a standard curing room for curing for 28 days. The temperature in the curing room is controlled at 20±2°C, and the relative humidity is controlled above 95%.

When the curing age reaches 28 days, the 28-day compressive strength, flexural strength, fracture toughness, and elastic modulus of ultra-high performance concrete are tested according to the standard GB/T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are as follows Table 1 shows.

The specific physical and mechanical properties of table 1 embodiment 1-4

Example 1 Example 2 Example 3 Example 4 Expansion/mm 600 580 590 440 Bulk density Kg/m3 2652 2630 2632 2581 Compressive strength/MPa 140.19 166.93 165.24 152.89 Flexural strength/MPa 18.59 20.78 19.10 21.26 Fracture toughness KJ/m ² 17.41 18.50 17.93 18.97 Elastic modulus GPa 49.23 53.35 53.04 52.56

Claims (10)

1. a bridge pier body is characterized in that, comprising the following components by weight:

2. The steam-free ultra-high performance concrete for the bridge pier body according to claim 1, wherein the auxiliary cementitious material includes fly ash and silica fume, or coal ash, silica fume and mineral powder or glass microbeads. 3. The non-steamed ultra-high performance concrete for bridge pier body according to claim 2, characterized in that the mass of the fly ash accounts for 55% to 70% of the total mass of the auxiliary cementitious materials. 4. The steam-free ultra-high performance concrete for bridge pier body according to claim 1, characterized in that, the fine aggregate is natural river sand, and the fineness modulus is 2.3-3.0. 5. The steam-free ultra-high performance concrete for bridge pier body according to claim 1, characterized in that, the coarse aggregate is basalt gravel, the particle size of the aggregate is 5-10mm, and the mud content is ≤0.5% . 6. The steam-free ultra-high performance concrete for bridge pier body according to claim 1, characterized in that, the water reducer is a polycarboxylate water reducer, and the weight of the added water reducer accounts for the amount of cement and auxiliary glue. 1.8% to 3.5% of the total mass of condensate. 7. The steam-free ultra-high performance concrete for bridge pier body according to claim 1, characterized in that, the cross-sectional diameter of the steel fiber is 0.18-0.22 mm, the fiber length is 19-21 mm, and the aspect ratio is 90-110 . 8. The non-steam curing ultra-high performance concrete for bridge pier body according to claim 1, characterized in that, the shape of the steel fiber is end hook type. 9. The steam-free ultra-high performance concrete for bridge pier body according to claim 1, characterized in that, the cement is PII52.5 cement. 10. A method for preparing the bridge pier body according to claim 1, comprising the following steps: (1) mixing cement, auxiliary cementitious material, coarse aggregate and fine aggregate; (2) After mixing water and water reducing agent, slowly add to the above mixture, and continue to stir to form a concrete matrix; (3) Slowly add steel fibers into the concrete matrix, after stirring, let it stand, demould, and cure to obtain steam-free ultra-high performance concrete for bridge piers.