CN103449786B - Cement-based composite material for steel box girder bridge deck, as well as preparation and pavement thereof - Google Patents

Abstract

The invention relates to a cement-based composite material for steel box girder bridge deck pavement, a preparation method and a pavement method thereof. The purpose is to provide a light-weight, high-toughness cement-based composite material suitable for the pavement of large-span steel box girder bridges. The proportion of each component is calculated by weight: cement 849-881, quartz sand 339 ～425, ceramic sand 215～273, fly ash 100～226, silica fume 30～56, water 275～295, water reducing agent 10～13, steel fiber 40～80, organic fiber 6.5～13, epoxy resin 20 ~30. Through material optimization, the durability of the pavement layer of the bridge deck is improved, the overall self-weight is reduced, and the construction cost is saved at the same time, which is suitable for the pavement of the steel box girder bridge with a large span.

Description

A cement-based composite material for steel box girder bridge deck and its preparation and pavement

technical field

The invention belongs to the field of material science and engineering, and in particular relates to a cement-based composite material for a steel box girder bridge deck, a preparation method and a paving method thereof.

Background technique

Steel box girder bridges are widely used in the construction of bridges and municipal projects at home and abroad because of their significant advantages such as light weight, steel saving, and easy prefabrication and installation. The steel box girder bridge deck pavement scheme of welding shear members + steel mesh + concrete + waterproof bonding layer + surface layer SMA after laying the anti-rust layer with steel plates is only suitable for bridges of about 200m, which greatly limits the large bridges in my country construction innovation.

The traditional solution for large-span steel box girder decks has the following problems: 1) Under the dual effects of repeated traffic loads and high and low temperature loads, cement concrete is prone to fatigue cracking, which leads to water intrusion and aggravates the corrosion of steel bars, reducing the The service life of the bridge; 2) Due to the large self-weight of ordinary concrete, poor mechanical properties and durability, etc., the elevation of the bridge span is largely limited; 3) Since the concrete of the main girder is completed before the pavement, There is a large difference in working age between the concrete and the post-cast pavement concrete, which causes a difference in shear stress between the first-cast concrete and the post-cast concrete due to different shrinkage values, which causes additional stress to the structure and raises higher requirements for the toughness of the concrete. requirements. It can be seen from this that the current design of bridge pavement materials does not fully meet the span development requirements of the actual bridge construction business, and it is urgent to optimize the bridge pavement materials.

At present, proposing a new pavement structure and developing lightweight aggregates and optimized admixtures on the basis of ordinary cement-based materials are the main technical means to solve this problem. However, the use of ordinary lightweight aggregate concrete has problems of insufficient strength and durability, and fatigue cracking is common. At the same time, during the construction vibration of light aggregate concrete, light aggregate, fine aggregate, unhydrated cement particles and cement The density of the slurry is different, and mineral admixtures such as light aggregate and fly ash are prone to float up, resulting in delamination of the pavement material, affecting its wear resistance and service life.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, to provide a light-weight, high-toughness cement-based composite material suitable for pavement of large-span steel box girder bridges and its preparation method. Through material optimization, the bridge is improved. It improves the durability of the surface pavement and reduces the overall self-weight, while saving the engineering cost, and is suitable for the pavement of large-span steel box girder bridges.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A cement-based composite material for a steel box girder bridge deck, the proportion of each component is calculated as follows in parts by weight:

Cement 849~881,

Quartz sand 339~425,

Pottery sand 215-273,

Fly ash 100~226,

Silica fume 30~56,

Water 275～295,

Water reducing agent 10~13,

Steel fiber 40~80,

Organic fiber 6.5~13,

Epoxy resin mixture 20-30,

The epoxy resin mixture is a mixture of epoxy resin and curing agent added during the preparation of cement-based composite materials; the organic fiber is polyvinyl alcohol fiber (PVA).

According to the above-mentioned scheme, described cement selects P.O52.5 portland cement for use.

According to the above scheme, the fineness modulus of the ceramic sand is 3.1-3.7, the bulk density is 800-900kg/m ³ , and the water absorption is 10-15%; the fineness modulus of the quartz sand is 1.0-1.5.

According to the above scheme, the epoxy resin is bisphenol A epoxy resin or non-ionic water-based epoxy resin, and the epoxy equivalent is 195 ± 5; the curing agent is a polyamine curing agent, and the active hydrogen equivalent is 400 ± 5 .

According to the above scheme, the fly ash is Class II fly ash or Class I fly ash; the silica fume has an average particle size of 0.1-0.3 μm and a specific surface area of 20-28 m ² /g.

According to the above scheme, the water reducer is a naphthalene water reducer or a polycarboxylate water reducer.

According to the above solution, the steel fiber is a multi-anchor carbon cold-drawn steel wire cutting type with a length of 25-35mm.

According to the above scheme, the polyvinyl alcohol fiber has a length of 11-13 mm and a density of 1.3 g/cm ³ .

According to the above scheme, the preparation method of the cement-based composite material comprises the following steps:

1) Mix the epoxy resin and its curing agent evenly to obtain the epoxy resin component for later use; soak the pottery sand in water to fully absorb water and saturate it, take it out and dry it until the saturated surface is dry;

2) After feeding cement, quartz sand, pottery sand, fly ash and silica fume, add water and water reducer, stir and mix evenly, then add the epoxy resin component that has been mixed evenly, stir and mix evenly, and finally add Polyvinyl alcohol fibers, stir until the fibers can be evenly distributed.

According to the above scheme, the paving method of the cement-based composite material may further comprise the steps:

1) Spray a layer of interface adhesive on the steel box girder bridge slab in advance.

2) Transport the prepared lightweight high-toughness cement-based composite material to the construction site by concrete tank truck, pour it directly into the road groove where the side formwork is installed, and make repairs manually.

3) Immediately after the paving is completed, vibrate with a vibrating rod, control the thickness of the material to 6-8cm, scrape it, smooth it mechanically, and finally cover it with a plastic film.

The beneficial effects of the present invention are:

1) In ordinary cement-based materials, cement, mineral admixtures, and quartz sand with an average particle size of no more than 0.15mm are used as the matrix, and the organic random distribution of short fibers designed by mesomechanics and composite steel fibers are used to strengthen and toughen The components can produce a "bridging" effect, play the role of energy consumption, buffer and connect the various fragments, greatly improve the compressive and flexural strength, improve the material toughness and limit the crack expansion, and control the crack width. Cracks can be formed in a stable state during the tension process. When the tensile strain capacity exceeds 1%, the crack width will be stable at about 60 μm. With the increase of the tensile strain capacity, the crack width does not change, and the number of micro cracks continues. Increase.

2) Since the fine aggregate is partially replaced by light clay sand and mineral admixtures are added at the same time, under the premise of ensuring the compressive strength and working performance of the cement-based material, it also has a porous structure that can reduce the weight of the bridge and reduce vibration and noise.

3) The addition of organic polymers greatly improves the interface properties of the material. The hydration product C-S-H gel and needle-like Afm crystals interweave with the polymer network to form a double network structure that crosses each other, making the entire mortar system become It is denser and has significantly improved flexural strength and durability.

4) The material has the characteristics of high toughness, high bearing capacity, high durability, excellent working performance and strong sustainability. It also has good energy dissipation and shock absorption characteristics, which is convenient for construction and saves costs. Its 28d compressive strength>80MPa; 28d flexural strength>10MPa; bulk density<2050kg/m ³ ; fatigue life>2 million times; fracture toughness index η30>25; 28d shrinkage rate<8×10-4. In addition, the invention not only has an excellent effect in improving the service performance of the concrete pavement, but also can reduce the construction cost and has good economic benefits, so it is especially suitable for paving the steel box girder bridge deck.

Detailed ways

Below in conjunction with embodiment further clarifies content of the present invention, but not as the limitation to protection scope of the present invention.

Example 1

Ingredients (by weight): P·O52.5 Portland cement 881, quartz sand (fineness modulus 1.0) 425, pottery sand (fineness modulus 3.7, bulk density 900kg/m ³ , water absorption 15%) 273, Class I fly ash 100, silica fume (particle size 0.3μm, specific surface area 28m ² /g) 30, water 275, naphthalene-based water reducing agent 10, steel fiber (length 35mm) 80, Polyvinyl alcohol fiber (13mm, density 1.3g/cm ³ ) 13, mixture of bisphenol A epoxy resin (epoxy equivalent 195±5) and polyamine curing agent (active hydrogen equivalent 400±5) 20. The specific surface area test standard of silica fume adopts GB/T19587-2004.

Weigh each raw material in proportion, first soak the clay sand for 10 hours to make it fully saturated with water; mix the epoxy resin and its curing agent in proportion, stir and mix evenly; take out the soaked clay sand and add it in the saturated surface dry state In the stirring pot, (the water absorption rate of the ceramic sand used should be measured in advance, and deducted from the external water); then add the quartz sand and powder into the stirring pot, dry mix for 2 minutes, then slowly add steel fiber, dry mix for 2 minutes, Then add water and high-efficiency water reducer during the stirring process, stir for 3 minutes, then add the uniformly mixed epoxy resin component and stir for 3 minutes, and finally add organic fibers slowly during the stirring process to ensure that the fibers can be evenly distributed, and stir for 5 minutes; stirring time The termination of the fiber slurry is based on the fact that the fiber slurry does not form agglomerates or agglomerates, so as to ensure that the fibers are fully dispersed, that is, to obtain a lightweight and high-toughness cement-based composite material.

(2) Pavement of lightweight and high-toughness cement-based composite materials

1) Before construction, put all the required equipment on standby and spray a layer of interface adhesive on the bridge beam plate in advance.

2) Use a concrete tank truck to transport the prepared lightweight high-toughness cement-based composite material to the construction site, pour it directly into the road groove where the side form is installed, and manually make up evenly. If segregation is found, use a shovel to turn it over.

3) Immediately after the paving is completed, use a vibrating rod to vibrate. After vibrating, the thickness is controlled to 6cm, then perform operations such as scraping and mechanical polishing, and finally cover the plastic film to inhibit the evaporation of water on the surface, so as to reduce or even eliminate Plastic cracking, improving appearance quality, and improving durability.

The performance test of the cement-based composite material prepared in this example was measured according to the "Test Regulations for Highway Engineering Cement and Cement Concrete" (JTG E30-2005): 28d compressive strength 91MPa; 28d flexural strength 14MPa; bulk density measured 2030kg/m ³ ; fatigue life of 2.13 million times; fracture toughness index η30=31, 28d shrinkage rate of 7.2×10 ^-4 .

Example 2

Ingredients (by weight): P·O52.5 Portland cement 849, quartz sand (fineness modulus 1.5) 339, pottery sand (fineness modulus 3.1, bulk density 800kg/m ³ , water absorption 10%) 215, Class II fly ash 226, silica fume (particle size: 0.1μm, specific surface area: 20m ² /g) 56, water 295, polycarboxylate superplasticizer 13, steel fiber (length: 25mm) 40. Polyvinyl alcohol fiber (11mm, density 1.3g/cm ³ ) 13. Mixture of non-ionic water-based epoxy resin (epoxy equivalent 195±5) and polyamine curing agent (active hydrogen equivalent 400±5) 30.

Preparation method is with embodiment 1.

Pavement of lightweight and high toughness cement-based composite materials:

1) Before construction, put all the required equipment on standby and spray a layer of interface adhesive on the bridge beam plate in advance.

2) Use a concrete tank truck to transport the prepared lightweight high-toughness cement-based composite material to the construction site, pour it directly into the road groove where the side form is installed, and manually make up evenly. If segregation is found, use a shovel to turn it over.

3) Immediately after the paving is completed, use a vibrating rod to vibrate. After vibrating, the thickness is controlled to 8cm, then perform operations such as scraping and mechanical polishing, and finally cover the plastic film to inhibit the evaporation of water on the surface, so as to reduce or even eliminate Plastic cracking, improving appearance quality, and improving durability.

The performance test of the main materials prepared in this embodiment was measured according to the "Test Regulations for Highway Engineering Cement and Cement Concrete" (JTGE30-2005): 28d compressive strength 83MPa; 28d flexural strength 11MPa; measured bulk density 1950kg/m ³ ; fatigue The service life is 2.09 million times; the fracture toughness index η30=27, and the 28d shrinkage rate is 5.8×10 ^-4 .

Example 3

Ingredients (by weight): P·O52.5 Portland cement 860, quartz sand (fineness modulus 1.5) 380, pottery sand (fineness modulus 3.5, bulk density 850kg/m ³ , water absorption 12%) 245, Class II fly ash 150, silica fume (particle size: 0.2μm, specific surface area: 25m ² /g) 40, water 280, polycarboxylate superplasticizer 10, steel fiber (length: 30mm) 50. Polyvinyl alcohol fiber (12mm, density 1.3g/cm ³ ) 13. Mixture of bisphenol A epoxy resin (epoxy equivalent 195±5) and polyamine curing agent (active hydrogen equivalent 400±5) 25.

The preparation method is the same as in Example 1.

Paving method is the same as embodiment 2.

The performance test of the main materials prepared in this embodiment is measured according to the "Test Regulations for Highway Engineering Cement and Cement Concrete" (JTGE30-2005): 28d compressive strength 85MPa; 28d flexural strength 12MPa; measured bulk density 2000kg/m ³ ; fatigue The service life is 2.21 million times; the fracture toughness index η30=29; the 28d shrinkage rate is 6.4×10 ^-4 .

Claims (7)

1. a steel box girder bridge face cement-base composite material, is characterized in that the proportioning of each component is counted by weight:

Cement 849 ~ 881,

Quartz sand 339 ~ 425,

Pottery sand 215 ~ 273,

Flyash 100 ~ 226,

Silicon ash 30 ~ 56,

Water 275 ~ 295,

Water reducer 10 ~ 13,

Steel fiber 40 ~ 80,

Organic fibre 6.5 ~ 13,

Epoxy resin composition 20 ~ 30,

Wherein, described epoxy resin composition is the mixture of the epoxy resin that adds when preparing of cement-base composite material and solidifying agent thereof, epoxy resin selects bisphenol A epoxide resin or non-ion aqueous epoxy resin, epoxy equivalent (weight) 195 ± 5, solidifying agent is polynary amine curing agent, active hydrogen equivalent weight 400 ± 5; Described organic fibre is polyvinyl alcohol fiber; The fineness modulus of described pottery sand is 3.1 ~ 3.7, tap density 800-900kg/m ³, water-intake rate 10-15%; The fineness modulus 1.0 ~ 1.5 of described quartz sand;

Described steel box girder bridge face cement-base composite material is adopted and is prepared with the following method:

1) epoxy resin and solidifying agent thereof are mixed, obtain epoxy resin ingredient for subsequent use; Pottery sand is soaked in water, makes it fully absorb water saturated, take out and dry in the air to saturated dry surface;

2) after cement, quartz sand, pottery sand, flyash, silicon ash are fed intake, add water and water reducer, be uniformly mixed, add the epoxy resin ingredient mixed again, be uniformly mixed, finally add polyvinyl alcohol fiber, being stirred to fiber can equally distributed state.

2. cement-base composite material as claimed in claim 1, is characterized in that cement selection PO 52.5 silicate cement in component.

3. cement-base composite material as claimed in claim 1, is characterized in that described flyash is II level flyash or I level flyash; Described silicon ash median size is at 0.1 ~ 0.3 μm, and specific surface area is: 20 ~ 28m ²/ g.

4. cement-base composite material as claimed in claim 1, is characterized in that described water reducer is naphthalene water reducer or polycarboxylate water-reducer.

5. cement-base composite material as claimed in claim 1, it is characterized in that described steel fiber is the carbon element cold-drawn wire cut-out type of multi-anchor fixed point, length is 25 ~ 35mm.

6. cement-base composite material as claimed in claim 1, is characterized in that described polyvinyl alcohol fiber length 11 ~ 13mm, density 1.3g/cm ³.

7. the method for paving of the cement-base composite material described in any one of claim 1 to 6, is characterized in that comprising the following steps:

1) in advance one deck interface adhesive is sprayed to steel box girder bridge beam slab;

2) utilize concrete tank that the lightweight high tenacity cement-base composite material prepared is transported to working-yard, directly pour into and install in the road groove of side form, manually make up a deficiency;

3) vibrate with shock club immediately after having paved, it is 6 ~ 8cm that material thickness controls, and strikes off, mechanical troweling, last covered with plastic film.