CN109851269B

CN109851269B - Composite admixture for improving durability of common concrete through improved gradation

Info

Publication number: CN109851269B
Application number: CN201910066725.3A
Authority: CN
Inventors: 张炜; 梁晓彤; 胡一智; 阮家铭; 黄宁宁; 李龙; 卢军宇; 林震
Original assignee: Guangdong Fute New Materials Technology Co ltd; Guangdong Xinye Concrete Co ltd
Current assignee: Guangdong Fute New Materials Technology Co ltd; Guangdong Xinye Concrete Co ltd
Priority date: 2019-01-24
Filing date: 2019-01-24
Publication date: 2021-07-16
Anticipated expiration: 2039-01-24
Also published as: CN109851269A

Abstract

The invention discloses a composite admixture for improving the durability of common concrete by improving gradation, which is prepared from the following raw materials in parts by weight: 150-250 parts of fly ash, 350 parts of limestone powder, 50-250 parts of slag powder, 50-250 parts of ceramic powder, 50-250 parts of volcanic ash and 0-50 parts of gypsum. According to the invention, through improving the gradation of the fly ash, the limestone powder, the slag powder, the ceramic powder and the volcanic ash, the proper fluidity can be provided for the concrete, the porosity is reduced, the compactness of a system can be increased, the consumption of water can be reduced, and the durability of the concrete is further improved; the complex and excitation of multiple admixtures can produce physical and chemical super-additive effect, the comprehensive effect is better than the sum of the mineral admixtures used alone, the mineral admixtures compounded in proper proportion improve the pore structure of the concrete, improve the compactness of the concrete and improve the durability of the concrete.

Description

Composite admixture for improving durability of common concrete through improved gradation

Technical Field

The invention relates to the field of building materials, in particular to a composite admixture for improving the durability of common concrete by improving gradation.

Background

The composite admixture is a powder material which is prepared by independently grinding two or more than two mineral materials to specified fineness and then mixing the two or more than two mineral materials according to a certain proportion or grinding the two or more than two mineral materials to specified fineness after mixing the two or more than two mineral materials according to a certain proportion. The gelled materials interact in the mixing process to generate effects of induction activation, surface microcrystallization, interface coupling and the like, so that the added composite mineral admixture can effectively improve the workability of concrete and the compactness, strength and durability of the hardened concrete. However, as the current research on mineral admixtures per se is not thorough and comprehensive enough, the preparation and application of the mineral admixtures are lack of systematic theoretical guidance, so that the mineral admixtures still have many problems in practical application.

CN105293964B discloses a composite admixture for improving the durability of common concrete, which comprises 40-50 parts of waste residue, 20-25 parts of tailings, 0.5-0.8 part of desulfurized gypsum, 0.1-0.5 part of polyester fiber, 0.5-1 part of polypropylene fiber, 1-2 parts of silicon powder, 2-4 parts of powder and 1-5 parts of activating agent; the waste residue consists of fly ash and metallurgical waste residue, wherein the mass parts of the fly ash and the metallurgical waste residue are as follows: 2: 0.5-1; and/or the tailings are a mixture of high-alumina silicate tailings, magnesium iron silicate tailings and siliceous rock tailings. CN105948643B discloses a stone powder concrete composite admixture and a preparation method thereof, 20-70% of stone powder, 10-40% of smelting waste residue, 0-25% of burnt clay, 0-25% of pozzolanic material, 10-40% of cement clinker, 0-10% of dolomite and 0-15% of gypsum. The smelting waste slag is one or more of phosphorus slag, nickel slag, manganese slag, steel slag, iron slag, lead-zinc slag and copper slag. CN108751759A discloses a composite admixture for improving the durability of common concrete and a preparation method thereof, comprising 30-50 parts of fly ash micro-beads, 1.8-2.6 parts of high-strength steel-like fiber, 13-15 parts of silicon powder, 2-3 parts of sulphoaluminate clinker, 0.5-1.7 parts of desulfurized gypsum, 5-10 parts of nano-silica, 16-20 parts of scraps, 2.5-8.5 parts of glass powder, 20-30 parts of acrylic emulsion, 5-8 parts of sodium dialkylbenzenesulfonate, 3-6 parts of polyvinyl alcohol, 3-9 parts of magnesium chloride, 0.5-0.9 part of carboxymethyl cellulose, 1.6-3 parts of etched glass fiber and 5-10 parts of phenolic resin. The anti-permeability performance, the durability and the mechanical strength resistance of the concrete can be obviously improved, and the cracking phenomenon of the concrete is greatly reduced. According to the technical scheme, the compound admixture is compounded in a diversified manner through the synergistic cooperation effect of multiple substances, the respective advantages of the compound admixture are exerted, the hydration heat is reduced, the water consumption is reduced, the working performance of the concrete is improved, the later strength increasing rate of the admixture is exerted, the durability of the concrete is improved, and the stone powder is fully utilized in the admixture. However, they do not consider that the admixture itself can further enhance the durability of concrete by improving gradation and composite excitation, and more fully exert the effects of various admixtures.

In view of the foregoing, the prior art still lacks a composite admixture that further provides durability to concrete by improving admixture gradation and composite excitation.

Disclosure of Invention

The invention aims to provide a composite admixture capable of greatly improving the durability of concrete by improving the gradation and the composite excitation of the components of the composite admixture aiming at the defects in the prior art. The specific technical scheme is as follows.

The composite admixture for improving the durability of common concrete by improving gradation is prepared from the following raw materials in parts by weight:

the feed is prepared from the following raw materials in parts by weight:

150 portions of fly ash and 250 portions, 350 portions of limestone powder and 200 portions, 50 to 250 portions of slag powder, 50 to 250 portions of ceramic powder, 50 to 250 portions of volcanic ash and 0 to 50 portions of gypsum,

wherein, the gradation of the fly ash is that 0-10um accounts for 20-40 wt%, 10-20um accounts for 20-35 wt%, 20-30um accounts for 10-25 wt%, 30-45um accounts for 5-10 wt%, 45-60um accounts for 0-5 wt%; the limestone powder has a grading of 0-20um to 30-65 wt%, 20-30um to 20-40 wt%, and 30-45um to 5-10 wt%; the grading of the slag powder is that 20-40 wt% of 0-15um, 30-50 wt% of 15-30um and 15-30 wt% of 30-45 um; the grading of the ceramic powder is 0-20um accounting for 30-45 wt%, 20-30um accounting for 30-50 wt%, 30-45um accounting for 10-20 wt%, the grading of the volcanic ash is 0-20um accounting for 5-25 wt%, 20-30um accounting for 20-30 wt%, 30-45um accounting for 20-30 wt%, and 45-120um accounting for 5-25 wt%.

The composite admixture can be classified into common type, early strength type and easy flowing type, wherein the common type can be classified into I, II and III type, and the usable admixture can generally contain a composite admixture formed by mixing a certain amount of grinding aid or gypsum with fly ash, slag powder, silica fume, volcanic ash or volcanic slag, limestone powder, phosphorous slag powder, steel slag powder and the like. In particular, the invention belongs to the common II-level composite admixture. The fly ash is fine ash collected from flue gas generated after coal combustion, is main solid waste discharged from a coal-fired power plant, contains a large amount of spherical glass beads, quartz, mullite and a small amount of mineral crystalline phase, and mainly contains silicon dioxide and aluminum oxide as active ingredients. The limestone powder basically belongs to inert substances, and the natural volcanic ash has large water demand and high activity, so that the limestone powder can be better matched with the volcanic ash by adding a certain amount of limestone powder, and the fluidity of the whole system can be improved under the condition of reducing the mixing amount of the limestone, thereby improving the activity of the system. The slag is a powder material which is obtained by quenching, granulating and grinding a melt which is obtained by smelting pig iron in a blast furnace and takes aluminosilicate as a main component to a certain fineness and has latent hydraulicity. The ceramic powder has small specific gravity and porous interior, and can achieve the special effects of corrosion resistance, frost resistance and earthquake resistance. The volcanic ash mainly comprises silicon dioxide, aluminum oxide and ferric oxide, is similar to the components of the fly ash, but has multi-edge volcanic ash particles, and the fly ash is a waste discharged by a coal-fired power plant and is approximately spherical, so that the fluidity of the volcanic ash is much smaller than that of the fly ash, the fly ash has a water reducing effect, the volcanic ash has a water increasing effect, and the two are matched with each other under a certain proportion to achieve a better effect. When the invention compounds a plurality of admixtures, the super-additive effect can be produced, the comprehensive effect is better than the sum of the mineral admixtures which are used independently, and the mineral admixtures compounded according to a proper proportion can make up for the deficiencies in the concrete, thereby improving the pore structure of the concrete, improving the compactness of the concrete and improving the durability of the concrete.

The invention also designs the gradation of the fly ash, the limestone powder, the slag powder, the ceramic powder and the volcanic ash, the proper gradation directly influences the ratio real coefficient of the admixture and can provide the concrete with proper fluidity, and because the raw materials have continuity in the production process of the concrete, the conditions are complex and changeable, if the gradation matching is accurately carried out every time like scientific experiments, the conditions are unrealistic, therefore, the gradation of the composite admixture in a proper proportion range needs to be determined, as long as the produced admixture meets the range, the proper fluidity can be obtained, the void ratio is reduced, the compactness of the system can be increased, the water consumption can be reduced, and the durability of the concrete is further improved.

Preferably, the silicon ash also comprises 0 to 50 weight portions.

The siliceous dust is a superfine siliceous powder material which is produced by that a large amount of Si02 and Si gas with strong volatility are produced in an ore-smelting electric furnace when ferrosilicon and industrial silicon (metallic silicon) are smelted in an iron alloy factory, and the gas is rapidly oxidized, condensed and precipitated with air after being discharged. The silica fume has very fine particles, average particle size of 0.1-0.3 micron and specific surface area 80-100 times that of cement. The silica fume is used as mineral admixture and is added into concrete, so that the strength, compactness, impermeability, wear resistance, chemical corrosion resistance and the like of the concrete can be improved, and the concrete has the functions of good water retention, prevention of segregation and bleeding, reduction of pumping resistance of concrete and the like, and has a good effect of improving the performance of the concrete. Particularly, the reasonable mixing amount of the silica fume is 5%.

Preferably, the feed additive is prepared from the following raw materials in parts by weight: 200 portions of 180-class fly ash, 300 portions of 240-class limestone powder, 200 portions of 100-class slag powder, 200 portions of 100-class ceramic powder, 200 portions of 100-class volcanic ash, 5-30 portions of gypsum and 5-20 portions of silica fume.

The raw material proportioning range is better, and the durability of the concrete is better.

Preferably, the water-based paint also comprises 1-10 parts of an additive, wherein the additive comprises an activating agent, a water reducing agent and a high molecular polymer reinforcing agent.

Preferably, the activating agent is prepared from sodium hydroxide, sodium metasilicate, calcium sulfate and acrylic acid according to the weight ratio of (2-6): (1-7): (3-5): (0.1-0.5).

Preferably, the water reducing agent is an FT-I type polycarboxylic acid high-performance water reducing agent, and is prepared by graft copolymerization of the following raw materials in parts by weight: 2-4 parts of unsaturated carboxylic acid, 3.5-5 parts of unsaturated ester, 0.3-0.7 part of cross-linking agent, 0.5-1.5 parts of polyether macromonomer, 0.5-1.5 parts of cationic unsaturated monomer and 0.07-0.15 part of chain transfer agent; the reducing agent accounts for 0.25 to 0.45 percent of the total mass of the reactants, and the oxidizing agent accounts for 0.45 to 0.6 percent of the total mass of the reactants; adjusting the concentration of the polymer to be 20-60% by water, and carrying out room-temperature free radical polymerization to obtain the slow-release cationic anti-mud polycarboxylic high-performance water reducer.

The water reducer is prepared by the method, and is disclosed in Chinese patent CN105542091A, and the water reducer is a slow-release cationic mud-resistant polycarboxylic acid high-performance water reducer and a preparation method thereof. The water reducing agent can play a good slow release role on the premise of ensuring high water reducing rate.

Preferably, the polymer is one or more of hydroxyethyl methyl cellulose, polycarbonate fiber and hydroxypropyl methyl cellulose.

The polymer can be used as a stable component to reduce sedimentation and prevent bleeding.

When the concrete is prepared, sand and stones with proper proportion need to be added.

Preferably, the application comprises the steps of preparing concrete, preparing mortar, manufacturing a wall material, producing an aerated concrete product and producing a pavement brick.

The invention has the following beneficial effects:

(1) according to the invention, through improving the gradation of the fly ash, the limestone powder, the slag powder, the ceramic powder and the volcanic ash, the proper fluidity can be provided for the concrete, the porosity is reduced, the compactness of a system can be increased, the consumption of water can be reduced, and the durability of the concrete is further improved;

(2) the multiple admixtures of the invention are improved in gradation and composite excitation, can generate physical and chemical super-additive effects, the comprehensive effect of the admixture is superior to the sum of the single use of mineral admixtures, and the mineral admixtures compounded in proper proportion improve the pore structure of the concrete, improve the compactness of the concrete and improve the durability of the concrete;

(3) the composite admixture has the advantages of low cost, wide application and good market prospect.

Detailed Description

The following further illustrates embodiments of the invention:

herein, the source and performance index of the cement selected from PII42.5R cement, fly ash, limestone powder, slag powder, ceramic powder and volcanic ash are shown as follows.

The cement adopts Huarun PII42.5R cement, and the performance indexes are as follows

The fly ash is level II fly ash of Nanning power plant, and the performance index is as follows

The stone powder is composed of limestone powder, and its performance index is as follows

The slag powder is a group Tai mineral powder with the following performance indexes

The ceramic powder is a south China sea genuine source, and the performance indexes are as follows

Synthesis example synthesis of FT-I type polycarboxylic acid high performance water reducing agent

Preparing materials in a first step: 0.75kg of L-ascorbic acid and 156kg of water are fully stirred to prepare a solution A; 12.25kg of maleic anhydride, 29kg of hydroxyethyl acrylate, 12.5kg of polyethylene glycol maleic diester, 10.10kg of dimethyl diallyl ammonium chloride, 0.66kg of mercaptopropionic acid and 156kg of water are fully stirred to prepare a solution B.

The second step of polymerization: adding 75kg of isobutylene alcohol polyoxyethylene ether, 75kg of isoamylol polyoxyethylene ether and 200kg of water into a glass reactor with a thermometer and an electric stirrer, stirring until the materials are completely dissolved, adding 1.07kg of 30 percent hydrogen peroxide, stirring uniformly, and beginning to dropwise add A, B materials at the initial temperature of 20-30 ℃; dropwise adding the material A for 2h, dropwise adding the material B for 1.5h, preserving heat for 1.5h after dropwise adding is finished, and finally adjusting the pH value of the solution to 6-7 by using a potassium hydroxide aqueous solution to prepare the slow-release cationic anti-mud polycarboxylic acid high-performance water reducing agent with the solid content of 30%.

Preparation examples preparation of composite admixtures

Preparation of example 1

(1) Preparing concrete raw materials of the following raw materials for later use:

(2) grading: sieving the fly ash according to 0-10um, 10-20um, 20-30um, 30-45um and 45-60um, and collecting the sieved fly ash for later use; ball-milling limestone powder, then screening according to 0-20um, 20-30um and 30-45um, and collecting after screening for later use; ball-milling the slag powder, then screening according to 0-15um, 15-30um and 30-45um, and collecting for later use after screening; ball-milling the ceramic powder, then screening according to 0-20um, 20-30um and 30-45um, and collecting after screening for later use; ball-milling the volcanic ash, then screening according to 0-20um, 20-30um, 30-45um and 45-120um, and collecting after screening for later use;

(3) preparing an admixture: mechanically mixing 1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume, wherein the gradation of the fly ash is that 0-10um accounts for 30%, 10-20um accounts for 35%, 20-30um accounts for 25%, 30-45um accounts for 5% and 45-60um accounts for 5%; the limestone powder has a grading of 0-20um 65%, 20-30um 30% and 30-45um 5%; the grading of the slag powder is 0-15um 40%, 15-30um 30% and 30-45um 30%; the ceramic powder is 0-20um 45%, 20-30um 35%, 30-45um 20%, the volcanic ash is 0-20um 25%, 20-30um 30%, 30-45um 30%, 45-120um 20%, and the composite admixture A1 is obtained by mixing and homogenizing.

Preparation of example 2

This example describes only the differences from example 1 in the gradation of the admixture of this preparative example.

(3) Preparing an admixture: the method comprises the following steps of mechanically mixing 1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume, wherein the gradation of the fly ash is that 0-10um accounts for 40%, 10-20um accounts for 25%, 20-30um accounts for 20%, 30-45um accounts for 10% and 45-60um accounts for 5%; the limestone powder has a grading of 0-20um to 60%, 20-30um to 30%, and 30-45um to 10%; the grading of the slag powder is that 0-15um accounts for 35%, 15-30um accounts for 45%, and 30-45um accounts for 20%; the ceramic powder is composed of 40% of 0-20um, 40% of 20-30um and 20% of 30-45um, and the volcanic ash is composed of 20% of 0-20um, 28% of 20-30um, 27% of 30-45um and 25% of 45-120um, and the composite admixture A2 can be obtained by mixing and homogenizing.

Example 3

(3) Preparing an admixture: mechanically mixing 1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume, wherein the gradation of the fly ash is that 0-10um accounts for 25%, 10-20um accounts for 35%, 20-30um accounts for 25%, 30-45um accounts for 10% and 45-60um accounts for 5%; the limestone powder has a grading of 0-20um 65%, 20-30um 28% and 30-45um 7%; the grading of the slag powder is 0-15um accounting for 30%, 15-30um accounting for 50% and 30-45um accounting for 20%; the ceramic powder is composed of 40% of 0-20um, 40% of 20-30um and 20% of 30-45um, and the volcanic ash is composed of 20% of 0-20um, 30% of 20-30um, 25% of 30-45um and 25% of 45-120um, and the composite admixture A3 can be obtained by mixing and homogenizing.

Example 4

(3) Preparing an admixture: the method comprises the following steps of mechanically mixing 1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume, wherein the gradation of the fly ash is that 0-10um accounts for 38%, 10-20um accounts for 32%, 20-30um accounts for 18%, 30-45um accounts for 10% and 45-60um accounts for 3%; the limestone powder has a grading of 58% of 0-20um, 32% of 20-30um and 10% of 30-45 um; the grading of the slag powder is 0-15um 40%, 15-30um 30% and 30-45um 30%; the ceramic powder is 0-20um 40%, 20-30um 45%, 30-45um 15%, the volcanic ash is 0-20um 20%, 20-30um 30%, 30-45um 30%, 45-120um 20%, and the composite admixture A4 is obtained by mixing and homogenizing.

Example 5

(3) Preparing an admixture: mechanically mixing 1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume, wherein the gradation of the fly ash is 25 percent of 0-10um, 30 percent of 10-20um, 30 percent of 20-30um, 10 percent of 30-45um and 5 percent of 45-60 um; the limestone powder has a grading of 57% of 0-20um, 33% of 20-30um and 10% of 30-45 um; the grading of the slag powder is 0-15um accounting for 30%, 15-30um accounting for 50% and 30-45um accounting for 20%; the ceramic powder is graded with 0-20um accounting for 38%, 20-30um accounting for 42% and 30-45um accounting for 20%, and the volcanic ash is graded with 0-20um accounting for 25%, 20-30um accounting for 25%, 30-45um accounting for 25% and 45-120um accounting for 25%, and the composite admixture A5 can be obtained by mixing and homogenizing.

Comparative examples

Comparative example 1

In this example, only the differences from example 1 are described, and the blends of the preparation examples have different gradations, specifically:

(3) preparing an admixture: the method comprises the following steps of mechanically mixing 1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume, wherein the gradation of the fly ash is that 0-10um accounts for 10%, 10-20um accounts for 10%, 20-30um accounts for 10%, 30-45um accounts for 30% and 45-60um accounts for 40%; the limestone powder has a grading of 0-30um to 10%, 30-60um to 10%, 60-90um to 20%, and 90-150um to 60%; the grading of the slag powder is 0-15um accounting for 10%, 15-30um accounting for 10%, 30-45um accounting for 10%, and 45-60um accounting for 70%; the ceramic powder is 0-20um 10%, 20-45um 20%, 45-80um 70%, the volcanic ash is 0-20um 10%, 20-45um 10%, 45-80um 10%, 80-120um 70%, and the composite admixture B1 is obtained by mixing and homogenizing.

Comparative example 2

(3) Preparing an admixture: the method comprises the following steps of mechanically mixing 1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume, wherein the gradation of the fly ash is that 0-10um accounts for 60%, 10-20um accounts for 20%, 20-30um accounts for 10%, 30-45um accounts for 5% and 45-60um accounts for 5%; the limestone powder has a grading of 0-30um to 60%, 30-60um to 20%, 60-90um to 10%, and 90-150um to 10%; the grading of the slag powder is 0-15um accounting for 60%, 15-30um accounting for 20%, 30-45um accounting for 10%, and 45-60um accounting for 10%; the ceramic powder has the grading of 0-20um accounting for 60%, 20-45um accounting for 30% and 45-80um accounting for 10%, and the grading of volcanic ash has the grading of 0-20um accounting for 60%, 20-45um accounting for 20%, 45-80um accounting for 10% and 80-120um accounting for 10%.

Comparative example 3

The admixture of the preparation example is not provided with gradation

1500g of fly ash, 2000g of limestone powder, 500g of slag powder, 500g of ceramic powder, 500g of volcanic ash and 50g of silica fume;

(2) ball milling and mixing: sequentially feeding the raw materials of limestone powder, slag powder, ceramic powder, volcanic ash and silica fume into a ball mill for ball milling for 2 hours, wherein the fly ash does not need to be ball milled, and then mixing all the raw materials for homogenization to obtain the composite admixture B3.

Test examples

Determination of Admixture Properties

The prepared composite admixtures of examples 1-5 and comparative example were subjected to a basic parameter test, the fineness was measured according to GB/T1345 standard, and the mortar fluidity was measured according to the test of national standard "Cement mortar fluidity measuring method" (GB/T2419). The mortar strength is tested according to the national standard cement mortar strength test method (GB/T17671-1999), and the 3d,7d,28d,60d and 90d flexural strength and compressive strength of the test sample are respectively measured in the test. The water content is tested according to appendix A of national Standard fly ash for Cement and concrete (GB/T1596-2017).

Testing of concrete Properties

(1) The prepared composite admixtures of examples A1-A5 and comparative examples B1-B3 were charged into a blender, followed by addition of 7.5kg of cement, 35kg of gravel, 27kg of sand and 5.8kg of water and blending for 3min, and the concrete mixture was put into a pre-prepared test mold in two layers with a small shovel, the charged thicknesses of each layer being approximately equal;

(2) the formed concrete was taken out, subjected to a pumping pressure test, and the compressive strength was measured after the concrete was formed 28 days later.

The pumping pressure and the compressive strength of the concrete are tested according to the general concrete mechanical property test method (GB/T50081).

TABLE 4.2.1.1-1 Performance specifications

Examples 1-5 show that the fineness of the raw materials in the fineness measurement is less than 25, the fluidity ratio is greater than 100, the 7d activity index is greater than 70, the 28d activity index is greater than 75, the compressive strength of the mortar is increased by 0.95, the water content is less than 1.0, the performance of the raw materials is excellent, and the concrete performance test shows that the workability of the concrete is obviously improved, the pumping pressure is reduced, and the compressive strength of the mortar is improved by 28 days. Comparative example 1 had a larger proportion of large particles, comparative example 2 had a larger proportion of small particles, and comparative example 3 had no gradation and showed a larger decrease than examples 1 to 5.

Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A composite admixture for improving the durability of ordinary concrete by improving gradation, which is characterized in that: the feed is prepared from the following raw materials in parts by weight:

200 parts of 180-parts of fly ash, 300 parts of 240-parts of limestone powder, 200 parts of 100-parts of slag powder, 200 parts of 100-parts of ceramic powder, 200 parts of 100-parts of volcanic ash, 5-30 parts of gypsum, 5-20 parts of silica fume and 1-10 parts of an additive, wherein the additive comprises an activating agent, a water reducing agent and a polymer reinforcing agent, and the activating agent is prepared from sodium hydroxide, sodium metasilicate, calcium sulfate and acrylic acid according to the weight ratio (2-6): (1-7): (3-5): (0.1-0.5);

wherein, the gradation of the fly ash is 0-10um to 30-40 wt%, 10-20um to 20-35 wt%, 20-30um to 10-25 wt%, 30-45um to 5-10 wt%, 45-60um to 0-5 wt%; the limestone powder has a grading ratio of 0-20um 57-65 wt%, 20-30um 28-33 wt%, and 30-45um 5-10 wt%; the grading of the slag powder is that 20-40 wt% of 0-15um, 30-50 wt% of 15-30um and 15-30 wt% of 30-45 um; the grading of the ceramic powder is 0-20um accounting for 30-45 wt%, 20-30um accounting for 35-50 wt%, 30-45um accounting for 10-20 wt%, the grading of the volcanic ash is 0-20um accounting for 20-25 wt%, 20-30um accounting for 20-30 wt%, 30-45um accounting for 20-30 wt%, and 45-120um accounting for 20-25 wt%.

2. The composite admixture of claim 1, wherein: the water reducing agent is an FT-I type polycarboxylic acid high-performance water reducing agent and is prepared by graft copolymerization of the following raw materials in parts by weight: 2-4 parts of unsaturated carboxylic acid, 3.5-5 parts of unsaturated ester, 0.3-0.7 part of cross-linking agent, 0.5-1.5 parts of polyether macromonomer, 0.5-1.5 parts of cationic unsaturated monomer and 0.07-0.15 part of chain transfer agent; the reducing agent accounts for 0.25 to 0.45 percent of the total mass of the reactants, and the oxidizing agent accounts for 0.45 to 0.6 percent of the total mass of the reactants; adjusting the concentration of the polymer to be 20-60% by water, and carrying out room-temperature free radical polymerization to obtain the slow-release cationic anti-mud polycarboxylic high-performance water reducer.

3. The composite admixture of claim 1, wherein: the polymer reinforcing agent is one or more of hydroxyethyl methyl cellulose, polycarbonate fiber and hydroxypropyl methyl cellulose.

4. Use of the composite admixture of any one of claims 1 to 3, wherein said use comprises the preparation of concrete, the preparation of mortar, the manufacture of wall materials, the production of aerated concrete products, the production of road bricks.