CN1858019A - Self compacting high strength mortar - Google Patents

Abstract

The present invention belongs to the field of building material technology, and is especially one kind of self compacting high strength mortar. The self compacting high strength mortar consists of portland cement, stone powder, silica fume, expansion agent and water reducing agent of polycarboxylate in certain weight proportion. The self compacting high strength mortar with new type of water reducing agent has very low flowability loss, 28 day compressive strength as high as 70-90 MPa and construction convenience and low cost.

Description

A self-compacting high-strength mortar

technical field

The invention belongs to the technical field of building materials, and in particular relates to a self-compacting high-strength mortar, which can be used as a grouting material.

Background technique

In recent years, the application of reinforced concrete structures with dense bars has been increasing. Due to the small spacing between steel bars, it is not convenient to vibrate such concrete structures when pouring, and it is necessary to use concrete with self-compacting functions. Therefore, self-compacting concrete in the world Applications are growing rapidly. In the reserved holes for shear studs of continuous bridges with reinforced concrete structures, the steel bars and shear nails are interlaced, and the spacing between the steel bars is smaller, and the minimum spacing between the steel bars may be less than 15 mm. According to the requirements of reinforced concrete that the maximum aggregate particle size is less than 3/4 of the minimum steel bar spacing (in the case of vibrating), the maximum aggregate particle size should be less than 11mm. In the case of such a small spacing between steel bars that cannot be vibrated, it is more appropriate to directly use self-compacting mortar without coarse aggregate.

Self-compacting mortar can also be called grouting material, which has been widely used in the secondary grouting of industrial equipment installation. However, these grouting materials often use special cement and special fine aggregate, and the price is relatively expensive; on the other hand, these grouting materials often lose fluidity quickly and require mixing and use, and are not suitable for mixing and conveying in large batches.

Contents of the invention

The object of the present invention is to provide a self-compacting high-strength mortar that has the function of compensating shrinkage or micro-expansion and is cheap, and can be used for pouring reserved holes of steel-concrete bridges.

The self-compacting high-strength mortar proposed by the present invention is composed of cement, stone powder, silica fume, expansion agent and water reducer, and the weight percentage of each component is:

Components % by weight

Cement 20%～30%

Stone powder 8%～12%

Silica fume 1.2%～2.1%

UEA expansion agent 2%～4.5%

Yellow sand with a diameter of 0~2.5mm 32%~48%

Water reducing agent 0.50%～0.84%

Water 6.8%～13.6%,

The total amount thereof satisfies 100%.

In the present invention, the cement is one of Portland cement or ordinary Portland.

In the present invention, the stone powder is Shuangfei powder, or heavy calcium carbonate, or calcite powder, with a fineness of 300 mesh.

In the present invention, the water reducer is a polycarboxylate water reducer.

Preparation method of the present invention can be divided into following 2 kinds:

(1) Temporary preparation method: Weigh the raw materials accurately according to the proportion, mix the water reducer and water for later use, add yellow sand, cement, stone powder, silica fume and UEA expansion agent into the mixer, dry stir for 1-3 minutes, and then mix the mixed Add the water with superplasticizer into the mixer and stir for 2-4 minutes to get the desired product. The temporary preparation method is suitable for the situation of large-scale use, which can be prepared on site or transported to the construction site after being prepared in the factory (the transportation distance is less than 1 hour).

(2) Prefabricated dry-mixed mortar method: Weigh the raw materials accurately according to the proportion, dry the yellow sand, then add the yellow sand, cement, stone powder, silica fume and UEA expansion agent into the mixer, and stir for 10-20 minutes to make Dry blends are packaged quantitatively according to certain specifications, and the packaging must be moisture-proof. At the site of use, mix the dry mix, water, and water reducer in proportion to the mixer, and mix evenly with an electric mixer to obtain the desired product.

Compared with the grouting materials in the market, the present invention is cheap, easy to use, and convenient for mixing and transporting in large batches; if necessary, it can also be made into a double-package premixed material, which can be used after being mixed on site.

The present invention has been tested by relevant departments, (see Appendix B Measuring Method of Fluidity of Cement Net Paste in JGJ56-84 "Quality Standards and Test Methods of Concrete Water Reducer"), its fluidity is greater than 20cm, and there is basically no loss of fluidity within 2 hours , 28d self-compacting mortar with compressive strength as high as 70-90MPa.

The present invention has following advantage:

1. Since the self-compacting mortar of the present invention has high fluidity, it can be poured directly without vibrating, and the loss of fluidity over time is small (the fluidity within 2 hours remains basically unchanged), and the mortar strength is as high as 70~ 90MPa, especially suitable for reinforced concrete structures with dense reinforcement.

2. Since the present invention adopts Portland cement, ordinary Portland cement and ordinary yellow sand, the cost of mortar is greatly reduced.

3. Since the raw materials of the present invention are all mass-produced commercially available finished products, the raw materials are easy to obtain and are suitable for wide application.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the examples. All samples were formed without plugging or vibrating, just scraping the surface.

Example 1: Self-compacting high-strength mortar prepared with ordinary Portland cement. See Table 1 for raw materials and specifications, and Table 2 for material ratios and properties.

Table 1 Material Specification or grade source cement PO42.5 ordinary silicate cement Shanghai Seal Cement Group Silica fume EM920U Elkem International Trading Shanghai Co., Ltd. stone powder Double Fly Powder, Frozen Brand Changxing Lijiaxiang Fenghua Micro Powder Factory expansion agent UEA Shanghai Newman New Building Material Factory yellow sand Pass 2.5mm sieve Ordinary yellow sand Superplasticizer PC new concrete high-efficiency water reducer; pH neutral; solid content 40%; viscosity (coated - 4 cups) 40s Shanghai Aoshen Architectural Chemical Technology Co., Ltd.

Table 2 Self-compacting high-strength mortar prepared with ordinary Portland cement and its comparative examples project Matching ratio 1 comparative example Material consumption % by weight cement 22.3 25 stone powder 12 0 Silica fume 1.2 0 UEA expansion agent 3 0 yellow sand 48 75 Superplasticizer 0.5 0 water 13 12.5 performance Fluidity (2 hours)/cm 22(21) Table jumping fluidity 16 Compressive strength/MPa 71 54 Flexural strength/ 12 9 28d Size change rate/% 0.01 0.01

Example 2: Self-compacting high-strength mortar prepared with Portland cement. The specifications and manufacturers of the materials used are shown in Table 3. The ratio and performance of the materials are shown in Table 4.

table 3 Material Specification or grade source cement P II 52.5R Jiaxin Jingyang Cement Silica fume EM920U Elkem International Trading Shanghai Co., Ltd. stone powder double fly powder Shanghai stone powder factory expansion agent UEA Shanghai Newman New Building Material Factory yellow sand Pass 2.5mm sieve Ordinary yellow sand Superplasticizer GLENIUM SP-8CN Shanghai Master Building Materials Co., Ltd.

Table 4 Self-compacting high-strength mortar prepared with Portland cement and its comparative examples project Matching 2 comparative example Material consumption % by weight cement 30 25 stone powder 12 0 Silica fume 2 0 UEA expansion agent 3 0 yellow sand 40.59 75 Superplasticizer 0.81 0 water 11.6 12.5 performance Fluidity (2 hours)/cm 21(21) Table jumping fluidity 16 Compressive strength/MPa 85 58 Flexural strength/ 13 10 28d Size change rate/% 0.02 0.01

Example 3: Using ordinary Portland cement, a self-compacting high-strength mortar was prepared according to the prefabricated dry-mixed mortar method. See Table 5 for raw material specifications, and Table 6 for dry powder ratios.

table 5 Material Specification or grade source cement PO 42.5 Shanghai Cement Plant Silica fume EM920U Elkem International Trading Shanghai Co., Ltd. stone powder double fly powder Shanghai stone powder factory expansion agent UEA Shanghai Hualian Admixture Factory yellow sand Pass 2.5mm sieve Ordinary yellow sand, dry Superplasticizer GLENIUM SP-8CN Shanghai Master Building Materials Co., Ltd.

Table 6 Dry powder ratio of self-compacting high-strength mortar prepared with Portland cement Material Amount by weight% Remark cement 30 All dry ingredients are pre-mixed into a dry powder stone powder 12 Silica fume 2.1 UEA expansion agent 4.5 yellow sand 38.9 water 10.4 Superplasticizer 0.84

Add dry powder, water, and water reducing agent into the mixer, mix evenly with an electric mixer, and then pour the sample. The properties of the mortar are shown in Table 7.

Table 7 performance item value Fluidity (2 hours)/cm 23(22) Compressive strength/MPa 92 Flexural strength/ 13.5 28d Size change rate/% 0.02

Claims (4)

1. A self-compacting high-strength mortar, characterized in that it is composed of cement, stone powder, silica fume, expansion agent, and water reducing agent, and the weight percentage of each component is: Components % by weight Cement 20%～30% Stone powder 8%～12% Silica fume 1.2%～2.1% UEA expansion agent 2%～4.5% Yellow sand with a diameter of 0~2.5mm 32%~48% Water reducing agent 0.50%～0.84% Water 6.8%～13.6%, The total amount thereof satisfies 100%. 2. The self-compacting high-strength mortar according to claim 1, characterized in that the cement is one of Portland cement or ordinary Portland. 3. The self-compacting high-strength mortar according to claim 1, characterized in that the stone powder is Shuangfei powder with a fineness of 300 mesh. 4. The self-compacting high-strength mortar according to claim 1, characterized in that the water reducer is polycarboxylate water reducer.