CN109650827B

CN109650827B - High-temperature-resistant low-burning-loss concrete dry-spraying material

Info

Publication number: CN109650827B
Application number: CN201910000236.8A
Authority: CN
Inventors: 不公告发明人
Original assignee: 63653 Troops of PLA
Current assignee: 63653 Troops of PLA
Priority date: 2019-01-01
Filing date: 2019-01-01
Publication date: 2021-07-30
Anticipated expiration: 2039-01-01
Also published as: CN109650827A

Abstract

The invention discloses a high-temperature-resistant low-burning-loss concrete dry spraying material, which relates to the field of building materials, and is characterized in that high-bauxite chamotte is used as an aggregate, aluminate cement is used as a cementing material, fine powder of the high-bauxite chamotte is used as heat-resistant powder, silica powder is used as an admixture, silicate cement is used as a coagulation accelerating component, and sodium tripolyphosphate and sodium hexametaphosphate in a certain proportion are used as a composite water reducing agent and a coagulation time regulator; the weight percentage of each component is as follows: 50-70% of bauxite chamotte aggregate, 20-35% of bauxite chamotte fine powder, 7.5-15% of aluminate cement, 5-10% of silica micropowder, 2-5% of portland cement, 0.05-0.2% of sodium tripolyphosphate and 0-0.2% of sodium hexametaphosphate. The invention can adopt a semi-dry method spraying construction process for construction, can realize that the concrete setting accelerating time is adjusted within the range of 2-15 min according to requirements, the concrete strength grade can reach C20, and has the characteristics that the compressive strength loss is less than 50% at 1000 ℃, and the burning loss is less than 5% (mass percentage).

Description

High-temperature-resistant low-burning-loss concrete dry-spraying material

Technical Field

The invention belongs to the field of building materials, and relates to a high-temperature-resistant low-burning-loss concrete dry spraying material.

Background

The sprayed concrete is a concrete which is formed by conveying a concrete spraying material which is matched according to a certain proportion by a spraying machine by utilizing compressed air or other power through a pipeline and spraying the concrete spraying material on a sprayed rock surface, a structure and a building at a high speed for solidification and hardening. The sprayed concrete has the advantages of simple and easy construction, flexibility and the like, and is widely applied to the lining and supporting construction of the rock wall. The sprayed concrete mainly has two construction modes of dry spraying and wet spraying. Wherein, the dry spraying is to press and send dry mixture (coagulation promoting component is mixed in) by a concrete sprayer, and then the mixture is sprayed out after being mixed with water at a nozzle; the wet spraying is carried out by pumping the concrete mixture mixed with water to a nozzle, adding accelerating agent, and spraying under the assistance of compressed air.

In underground enclosed spaces where high temperatures such as explosions and the like are accompanied by the release of hazardous substances, shotcrete is also required for the lining and support of rock walls or buildings. However, the common sprayed concrete has poor fire resistance, and can be cracked at a high temperature of 1000 ℃ to lose the supporting capability. This is because ordinary shotcrete using silicate cement such as portland cement and ordinary portland cement as a cementitious material generates a certain amount of calcium hydroxide in addition to hydration products such as dicalcium silicate and tricalcium silicate when the cement is hydrated, and cracks in the concrete are generated by rapid decomposition and "secondary digestion" of the calcium hydroxide at high temperatures. In addition, the common sprayed concrete has higher burning loss at high temperature. On one hand, the aggregate river sand adopted by the common sprayed concrete contains a large amount of calcium carbonate, and the calcium carbonate can be decomposed at a high temperature lower than 1000 ℃ to generate carbon dioxide gas. On the other hand, a large amount of crystal water is introduced during cement hydration, and the crystal water is removed from hydration products and evaporated at high temperature, so that the burning loss of concrete is further increased. Therefore, in order to reduce the influence of high temperature on the concrete structure and cause structural failure, the shotcrete itself must have certain fire resistance. In addition, in order to reduce the air pressure in the closed space at high temperature to reduce the leakage of harmful substances, it is necessary to control the total amount of small molecules such as water, carbon dioxide, and sulfur oxides generated by pyrolysis of the concrete components.

Disclosure of Invention

The invention aims to provide a high-temperature-resistant low-burning-loss concrete dry spraying material formula, wherein the setting time of sprayed concrete prepared by using the formula can be adjusted within 3-15 minutes, the strength grade can reach C20, and the concrete dry spraying material formula has the characteristics that the compressive strength loss is less than 50% and the burning loss is less than 5% (mass percentage) at 1000 ℃.

In order to achieve the purpose, the invention adopts the following technical scheme: a high-temperature-resistant low-burning-loss concrete dry spraying material takes high-bauxite chamotte as aggregate, aluminate cement as a cementing material, high-bauxite chamotte powder as heat-resistant powder, silica micropowder as an admixture, silicate cement as a coagulation accelerating component, and sodium tripolyphosphate and sodium hexametaphosphate in a certain proportion as a composite water reducing agent and a setting time regulator; the weight percentage of each component is as follows: 50-70% of bauxite chamotte aggregate, 20-35% of bauxite chamotte fine powder, 7.5-15% of aluminate cement, 5-10% of silicon micropowder, 0.05-0.2% of sodium tripolyphosphate and 0-0.2% of sodium hexametaphosphate.

Further: the manufacturing method comprises the following steps:

s1: putting 5-0 mm high-alumina aggregate, 200-mesh high-alumina powder, CA50-A900 aluminate cement, silica micropowder, 42.5 common silicate cement, sodium tripolyphosphate and sodium hexametaphosphate into a stirrer according to the mass parts of the components in the formulas 1-3 in the table 1, and continuously stirring for 3 minutes to prepare a concrete dry-mixed material;

s2: quickly adding a certain amount of water into the dry concrete mixture to prepare fresh concrete, and measuring the initial setting time of the fresh concrete;

s3: placing fresh concrete into a triple die with the thickness of 4cm multiplied by 16cm, vibrating and compacting, and curing for 3 days at the temperature of 20 ℃ to obtain a hardened concrete product;

s4: the compressive strength and the flexural strength of the hardened concrete, the mass loss after heat treatment at 1000 ℃ for 60 minutes, and the compressive strength after high-temperature treatment at 1000 ℃ were measured.

Further: the bauxite chamotte aggregate is bauxite primary, secondary, tertiary or quaternary material, the maximum particle size is 3-5 mm, and the mud content (powder with the particle size less than 0.088 mu m) and the water absorption rate are less than 5%; coarse sand or extra-coarse sand, the fineness modulus is 3.5-4, the particle size is continuously distributed, and the density is more than 2.45g/cm^3.。

Further: the aluminate cement is CA50-A900 aluminate cement with high strength grade, the 3-day compressive strength of the standard mortar prepared from the aluminate cement is more than 55MPa, and the initial setting time is 1-3 hours.

Further: the bauxite chamotte powder has a particle size specification of 200 meshes, the median diameter D50 is 40-50 mu m in a laser particle size analysis test, D10 is larger than 2.5 mu m, and D90 is smaller than 130 mu m.

Further: the silicon micro powder adopts SiO with the average grain diameter of 0.1-0.5 mu m₂The content is more than 90 percent.

Further: the portland cement is high-alkalinity portland cement such as portland cement clinker, ordinary portland cement or composite portland cement, and the high alkalinity of the portland cement can promote the hydration of aluminate cement and shorten the setting time of concrete.

Further: the sodium tripolyphosphate and the sodium hexametaphosphate are chemically pure, are powdery and can be dissolved quickly, and the small-amplitude adjustment of the setting time of the concrete is realized through the change of the proportion of the sodium tripolyphosphate to the sodium hexametaphosphate.

Compared with the prior art, the invention is characterized in that:

(1) the refractory aluminate cement with high strength grade is used as a cementing material, the high-alumina bauxite clinker with low high-temperature burning loss is used as aggregate and heat-resistant powder, and the strength grade of the sprayed concrete can still reach C20 under the condition of reducing the using amount of cement in the concrete through the filling effect of silica micropowder, high-temperature ceramic reaction and the water reducing effect of sodium tripolyphosphate and sodium hexametaphosphate, so that the high-temperature resistance of the concrete is improved, and the high-temperature strength loss of the concrete is reduced;

(2) the setting accelerating effect of the high-alkalinity portland cement on the aluminate cement is utilized, and the setting time adjusting effect of the sodium tripolyphosphate and the sodium hexametaphosphate is exerted, so that the quick setting and the quick hardening of the concrete are realized without damaging the later strength development of the concrete;

(3) compared with the common sprayed concrete, the high-temperature-resistant low-burning-loss sprayed concrete prepared by the invention has good fire resistance and low high-temperature burning loss.

Detailed Description

The invention will be further illustrated by the following examples, which are intended to be purely exemplary of the invention and are not to be construed as being limited thereto, the listed materials being in accordance with the requirements set forth for the materials indicated above.

A high-temperature-resistant low-burning-loss concrete dry spraying material takes high-bauxite chamotte as aggregate, aluminate cement as a cementing material, high-bauxite chamotte powder as heat-resistant powder, silica micropowder as an admixture, silicate cement as a coagulation accelerating component, and sodium tripolyphosphate and sodium hexametaphosphate in a certain proportion as a composite water reducing agent and a setting time regulator; the weight percentage of each component is as follows: 50-70% of bauxite chamotte aggregate, 20-35% of bauxite chamotte fine powder, 7.5-15% of aluminate cement, 5-10% of silicon micropowder, 0.05-0.2% of sodium tripolyphosphate and 0-0.2% of sodium hexametaphosphate.

The bauxite chamotte aggregate with the specification of 0-5 mm and the bauxite chamotte powder with the size of 200 meshes are products of Taigor refractory material Co., Ltd, Zhengzhou, Henan; the selected aluminate cement is Zhengzhou cyanine CA50-A900 aluminate cement; the silicon micropowder is a zirconium composite silica fume product with the average particle size of 0.45 mu m produced by constant new material science and technology limited in Anhui mussel; the selected Portland cement is 42.5 ordinary Portland cement of a Xinjiang Tianshan cement factory; sodium tripolyphosphate and sodium hexametaphosphate are purchased from Hubei Xingcheng chemical group GmbH, are chemically pure, are in powder form, and can be dissolved quickly.

Example 1:

s1: putting 5-0 mm high-alumina aggregate, 200-mesh high-alumina powder, CA50-A900 aluminate cement, silica micropowder, 42.5 common silicate cement, sodium tripolyphosphate and sodium hexametaphosphate into a stirrer according to the mass parts of the components in the formula 1 in the table 1, and continuously stirring for 3 minutes to prepare a concrete dry-mixed material;

s2: adding 242kg of water into the dry concrete mixture quickly to obtain fresh concrete, and measuring the initial setting time of the fresh concrete to be 15 minutes;

s4: the compressive strength of the hardened concrete was measured to be 30MPa, the flexural strength was measured to be 5.0MPa, the mass loss after heat treatment at 1000 ℃ for 60 minutes was 4.5%, and the compressive strength after heat treatment at 1000 ℃ was measured to be 25 MPa.

Example 2:

s1: putting 5-0 mm high-alumina aggregate, 200-mesh high-alumina powder, CA50-A900 aluminate cement, silica micropowder, 42.5 ordinary portland cement and sodium hexametaphosphate into a stirrer according to the mass parts of the components in the formula 2 in the table 1, and continuously stirring for 3 minutes to prepare a concrete dry-mixed material;

s2: 245kg of water is quickly added into the dry concrete mixture to prepare fresh concrete, and the initial setting time of the fresh concrete is measured to be 10 minutes;

s4: the compressive strength of the hardened concrete was measured to be 35MPa, the flexural strength at room temperature was measured to be 5.5MPa, the mass loss after heat treatment at 1000 ℃ for 60 minutes was measured to be 4.9%, and the compressive strength after heat treatment at 1000 ℃ was measured to be 22 MPa.

Example 3:

s1: putting 5-0 mm high-alumina aggregate, 200-mesh high-alumina bauxite clinker, CA50-A900 aluminate cement, silica micropowder and sodium tripolyphosphate into a stirrer according to the mass parts of the components in the formula 3 in the table 1, and continuously stirring for 3 minutes to prepare a concrete dry-mixed material;

s2: quickly adding 243kg of water into the dry concrete mixture to prepare fresh concrete, and measuring the initial setting time of the fresh concrete to be 2-5 minutes;

s4: the compressive strength of the hardened concrete was measured to be 28MPa, the flexural strength at room temperature was measured to be 4.8MPa, the mass loss after heat treatment at 1000 ℃ for 60 minutes was measured to be 4.4%, and the compressive strength after heat treatment at 1000 ℃ was measured to be 24 MPa.

TABLE 1 formula (kg/m) of dry-spraying material for high-temp. -resistant low-burning loss concrete³）

The comparison of the examples 1-3 shows that: according to the invention, the refractory aluminate cement with high strength grade is used as a cementing material, the high-alumina bauxite clinker with low high-temperature burning loss is used as an aggregate and a heat-resistant powder material, and the strength grade of the sprayed concrete can still reach C20 under the condition of reducing the use amount of cement in the concrete through the filling effect of the silica powder, the high-temperature ceramic reaction and the water reducing effect of sodium tripolyphosphate and sodium hexametaphosphate, so that the high-temperature resistance of the concrete is improved, and the high-temperature strength loss of the concrete is reduced; the setting accelerating effect of the high-alkalinity portland cement on the aluminate cement is utilized, and the setting time adjusting effect of the sodium tripolyphosphate and the sodium hexametaphosphate is exerted, so that the quick setting and the quick hardening of the concrete are realized without damaging the later strength development of the concrete; meanwhile, compared with the common sprayed concrete, the high-temperature-resistant low-burning-loss sprayed concrete prepared by the invention has good fire resistance and low high-temperature burning loss.

In the description of the present invention, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a reference structure" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The high-temperature-resistant low-burning-loss concrete dry spraying material is characterized in that: the method comprises the following steps of (1) taking bauxite chamotte as an aggregate, CA50-A900 aluminate cement as a cementing material, bauxite chamotte powder as a heat-resistant powder material, silica micropowder as an admixture, 42.5 ordinary portland cement as a set accelerating component, and sodium tripolyphosphate and sodium hexametaphosphate in a certain proportion as a composite water reducing agent and a setting time regulator; the dosage ratio of each component is as follows: 5-0 mm bauxite chamotte aggregate 1258.4 kg/m³501.6kg/m of bauxite chamotte powder³275 kg/m of CA50-A900 aluminate cement³42.5 ordinary Portland cement 55 kg/m³Sodium tripolyphosphate 1.5 kg/m³Sodium hexametaphosphate 1.5 kg/m³165 kg/m of silica micropowder³(ii) a The aluminate cement is CA50-A900 aluminate cement with high strength grade, the 3-day compressive strength of the standard mortar prepared from the aluminate cement is more than 55MPa, and the initial setting time is 1-3 hours; the bauxite chamotte powder has a granularity specification of 200 meshes, the median diameter D50 is 40-50 mu m in a laser granularity analysis test, D10 is larger than 2.5 mu m, and D90 is smaller than 130 mu m; the silicon micro powder adopts SiO with the average grain diameter of 0.1-0.5 mu m₂The content is more than 90 percent; the sodium tripolyphosphate and the sodium hexametaphosphate are chemically pure, are powdery and can be dissolved quickly, and the small-amplitude adjustment of the setting time of the concrete is realized through the change of the proportion of the sodium tripolyphosphate to the sodium hexametaphosphate.

2. The high-temperature-resistant low-burning-loss concrete dry spraying material as claimed in claim 1, which is characterized in that: the manufacturing method comprises the following steps:

s1: putting 5-0 mm bauxite chamotte aggregate, 200-mesh bauxite chamotte powder, CA50-A900 aluminate cement, silica micropowder, 42.5 common silicate cement, sodium tripolyphosphate and sodium hexametaphosphate into a stirrer according to the using amounts of the components, and continuously stirring for 3 minutes to obtain a concrete dry-mixed material;