CN102775100B - Convenient and fast construction type active powder concrete mixed superfine cement - Google Patents

Abstract

The utility model relates to a convenient construction active powder concrete mixed with superfine cement, which belongs to the technical field of concrete. Its raw material components include ultrafine cement, sand, water, and water reducing agent. The mixing ratio of ultrafine cement, sand, water, and water reducing agent by weight is 1: (0.7～1.5): (0.14～0.2): (0.01～0.05); ultra-fine cement is made from ordinary cement or cement clinker, which is ground to a specified fineness, and its specific surface area is greater than 500m ² /kg. The invention can increase the growth rate of the strength of the active powder concrete, and make the active powder concrete get rid of the dependence on silica fume.

Description

Construction Convenience Active Powder Concrete Mixed with Superfine Cement

technical field

The invention relates to an active powder concrete, in particular to a convenient construction active powder concrete mixed with ultrafine cement, which belongs to the technical field of concrete.

technical background

In 1993, Richard et al. from Bouygues, France developed an ultra-high-performance cement-based composite material - Reactive Powder Concrete (Reactive Powder Concrete) based on ultra-fine-grained dense cement (DSP) and macro-defective cement (MDF). Powder Concrete, referred to as RPC), now Europe is usually called Ultra High Performance Concrete (Ultra High Performance Concrete, referred to as UHPC). The material is composed of active powder, cement, fine aggregate, high-strength fiber and other components, optimized through gradation design, and prepared through specific processes such as high temperature curing. It is a high-tech composite material.

The basic preparation principles of reactive powder concrete include: no coarse aggregate, adding ultra-fine active powder to minimize defect size; adding steel fiber to increase toughness; using high-efficiency water reducing agent to reduce water-binder ratio and porosity ; High temperature curing, promote the hydration reaction of gelling materials.

Compared with ordinary concrete and high-strength concrete, reactive powder concrete has excellent physical and mechanical properties: it has high compressive strength, excellent flexural strength, and exhibits considerable tensile properties, and its extremely high strength is conducive to reducing The self-weight and cross-sectional size of the structure make full use of the mechanical properties of the constituent materials and reduce the amount of materials; the addition of fine steel fibers can significantly improve the flexural strength, tensile properties and energy absorption capacity of reactive powder concrete, and delay cracks and cracks At the same time, its compressive strength has been further improved; due to the small internal porosity and low material defects of reactive powder concrete, it has excellent durability such as chloride ion penetration resistance, carbonation resistance, corrosion resistance, seepage resistance, frost resistance and wear resistance. ; In addition, the impact test shows that reactive powder concrete also has excellent impact resistance.

However, there are also some problems in reactive powder concrete: the preparation of reactive powder concrete requires a large amount of silica fume, but my country's silica fume resources are scarce, and the production of silica fume is limited, which makes it difficult to meet the needs of concrete engineering; silica fume participates in secondary water Therefore, the strength of reactive powder concrete increases slowly, which is particularly prominent in the case of normal temperature curing; too many admixtures used in reactive powder concrete will make the preparation process too cumbersome, and some admixtures themselves There is a problem of large fluctuations in composition, which is not conducive to the large-scale application of reactive powder concrete.

Contents of the invention

The object of the present invention is to provide a convenient construction active powder concrete mixed with ultrafine cement, and to prepare active powder concrete and solve related problems by using ultrafine cement. The invention can improve the growth rate of the strength of the active powder concrete, and make the active powder concrete get rid of the dependence on silicon powder, simplify the production, and easily control the stability of the material.

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

A construction-friendly active powder concrete mixed with ultrafine cement, characterized in that: the raw material components include ultrafine cement, sand, water, and water reducing agent, wherein the ultrafine cement, sand, water, and water reducing agent are calculated by weight The mix ratio is 1: (0.7~1.5): (0.14~0.2): (0.01~0.05);

As a kind of grouting material, ultra ^- fine cement ^is made from ordinary cement or cement clinker and ground to a specified fineness. High; the specific surface area of various common cements currently available is less than 500m ² /kg.

The sand mentioned is natural sand, artificial sand or quartz sand, and the particle size of the sand is not greater than 5mm, calculated according to the amount of dry sand; if the sand used is wet sand, the weight of water in the wet sand should be included in the amount of water middle;

The weight of the water reducer does not include the weight of water in the water reducer. If the water reducer contains water, the water in the water reducer should be converted into the amount of water used in the calculation.

Said water complies with the provisions of JGJ 63-89 "Standard for Concrete Mixing Water".

The convenient construction active powder concrete mixed with ultrafine cement of the present invention can further improve its performance by adding fibers during use. The fibers include various fibers suitable for active powder concrete, such as steel fibers, and the fiber content The maximum shall not exceed 6% of the volume of active powder concrete.

The beneficial effects of the present invention are as follows:

This new type of reactive powder concrete uses ultra-fine cement as the ultra-fine active powder component. Compared with the active powder concrete mixed with silica fume, the strength of the active powder concrete can be increased due to the direct hydration reaction between the ultra-fine cement and water. speed.

Ultrafine cement is easy to produce, so it can make active powder concrete get rid of the dependence on silica fume, which is beneficial to the preparation of active powder concrete.

In the process of using ultra-fine cement to prepare active powder concrete, there is no need to mix other admixtures, so as to achieve the purpose of simplifying production and make it easier to control the stability of materials.

Detailed ways

The present invention will be further described below in conjunction with embodiment:

Example:

The typical material mix ratio that the present invention adopts, and the fluidity and strength of corresponding active powder concrete are shown in the following table:

The ultra-fine cement is ultra-fine Portland cement with a strength grade of 52.5, a density of 3.07g/cm ³ , and a specific surface area of 568m ² /kg;

The sand is natural quartz sand with a particle size ranging from 40 mesh to 70 mesh;

The water mentioned complies with the provisions of JGJ63-89 of "Concrete Mixing Water Standard";

The main component of the described water reducer is polycarboxylate water reducer;

The steel fiber has a length of 8 mm, a diameter of 0.12 mm, and a tensile strength of not less than 2850 MPa.

Its production process is as follows:

Pour the weighed ultra-fine cement and sand into the mixing pot and stir slowly for 1 minute, then stir slowly for 2 minutes and pour the mixed water and water reducer into the stirring pot within the first 30 seconds, and stir quickly After 3 minutes, stir slowly for 1 minute and stop. If there is fiber added, sprinkle the fiber evenly into the mixing pot during the last 1 minute of slow stirring, and then stir quickly for 2 minutes and stop. The mixer used meets the requirements of "Planetary Cement Mortar Mixer" JC/T681-2005.

At this point a fluidity test can be performed. The fluidity test method is carried out according to the "Measurement Method for Fluidity of Cement Mortar Sand" GB/T2419-2005, but a glass plate is used instead of a jumping table for the test.

Pour the stirred mixture into the standard test mold of 40mm×40mm×160mm according to the requirements of GB/T17671-1999 of "Cement Mortar Strength Test Method (ISO Method)" Curing in a curing box with a relative humidity of not less than 90% at 1°C for 1 to 2 days. After demoulding, move the test block into a concrete accelerated curing box for curing for 2 days. The temperature of the curing box is controlled at 90±1°C. The frequency of the vibrating table is 2860 times/min, and the amplitude is 0.3-0.6mm. The concrete accelerated curing box meets the requirements of "Concrete Accelerated Curing Box" JG/T3027-1995.

The reactive powder concrete test block after curing is subjected to the compressive strength test according to the requirements of "Cement mortar strength test method (ISO method)" GB/T17671-1999.

Existing studies have shown that the compressive strength of reactive powder concrete using silica fume cured at 20°C for 28 days is 20%-30% lower than that cured with steam at 90°C. However, using the mix proportions in the above table to conduct a comparative test, it is found that without using silicon powder, the compressive strength of the material cured at 20°C for 28 days is only about 10% lower than that of steam curing at 90°C, which proves that if silicon powder is not used, the material at room temperature The growth rate of the strength of the reactive powder concrete can be significantly improved.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (3)

1. mix the construction portable type RPC of superfine cement, it is characterized in that, its material component is superfine cement, sand, water, water reducer, fiber, and the proportioning that wherein superfine cement, sand, water, water reducer are calculated by weight is 1:(0.7～1.5): (0.14～0.2): (0.01～0.05); Fibers content maximum is no more than 6% of RPC volume;

Superfine cement is that to take Portland cement or cement clinker be raw material, and grinding makes to regulation fineness, and its specific surface area is at 500～1000m ²/ kg.

2. according to construction portable type RPC of mixing superfine cement claimed in claim 1, it is characterized in that, described sand is natural sand, artificial sand or quartz sand, and the particle diameter of sand is not more than 5mm, by the consumption of dry sand, calculates; If the sand adopting is damp sand, the weight of water in damp sand should be counted in the consumption of water.

3. according to construction portable type RPC of mixing superfine cement claimed in claim 1, it is characterized in that, described water reducer weight does not comprise the weight of water in water reducer, if water reducer contains water, during calculating, water is wherein converted in the consumption of water.