CN115321908B

CN115321908B - High-performance concrete based on high-quality machine-made sand and preparation method thereof

Info

Publication number: CN115321908B
Application number: CN202210954357.8A
Authority: CN
Inventors: 邱润泽; 邱文会; 代志涛; 巩繁龙; 史鹏宇; 张欣冉; 王向丽
Original assignee: Henan Jinnuo Concrete Co ltd
Current assignee: Henan Jinnuo Concrete Co ltd
Priority date: 2022-08-10
Filing date: 2022-08-10
Publication date: 2023-05-16
Anticipated expiration: 2042-08-10
Also published as: CN115321908A

Abstract

The invention discloses high-performance concrete based on high-quality machine-made sand and a preparation method thereof, wherein the main raw materials of the high-performance concrete comprise: cement, mineral powder, fly ash, large stone, small stone, machine-made sand, facing sand, admixture, stone powder and water. The invention discovers that the cohesive force, the flexibility and the cohesive force of the mortar can be increased after the machine-made sand is modified, the mortar can be used in concrete to improve the fluidity of the concrete, has good compatibility with various concrete additives, and can further improve the processing performance of the concrete.

Description

High-performance concrete based on high-quality machine-made sand and preparation method thereof

Technical Field

The invention relates to the technical field of building materials, in particular to high-performance concrete based on high-quality machine-made sand and a preparation method thereof.

Background

In the field of concrete preparation, the stability of the raw materials has always had an important influence in the production process. The sand ratio is an important index for determining the performance of concrete, and the use of sand requires accurate control in the concrete. Meanwhile, as one of the main raw materials, the cost of sand has a key influence on the cost of concrete. In addition, in order to protect ecological balance, natural sand is limited to be picked and dug, and business concrete enterprises mainly comprising natural sand are passive in a step-by-step direction. Therefore, commercial concrete enterprises with complete sand production lines will dominate in future production processes. In recent years, the demand of the building market is huge, the rapid development of the sand market is promoted, and machine-made sand gradually occupies the market and becomes one of the best sources of building materials. At present, a plurality of concrete and mortar enterprises start to replace natural sand with machine-made sand in production, and good economic benefit is obtained.

However, the machine-made sand has the characteristics of rough particle surface, sharp polygon, large fineness modulus, poor grading, large dust content and the like, so that the mixed concrete has the problems of large water consumption, poor fluidity, serious bleeding segregation and the like compared with the concrete mixed by natural sand. Not only the quality of the mix but also the properties of the hardened concrete.

Chinese patent CN 111943605A discloses a machine-made sand concrete using synergistic agent and its preparation method, the components and formula of the concrete are as follows: 395-435 parts of cement; 0-30 parts of fly ash; 0-30 parts of mineral powder; 900.15-920.55 parts of machine-made sand; 864.85-884.45 parts of crushed stone; 9.1-9.9 parts of additive; 2.73-2.97 parts of synergist; 153-170 parts of water, wherein the synergistic agent comprises an enhancer, a dispersant, nano calcium carbonate, a foaming agent, a foam stabilizer and water. The method can reduce the consumption of the equivalent machine-made sand concrete cement, ensure the strength of the machine-made sand concrete to be unchanged or even higher, improve the durability of the machine-made sand concrete, reduce the cost of the machine-made sand concrete and reduce the risk of concrete cracking.

Chinese patent CN 113800810A discloses a reinforcing regulator for machine-made sand concrete, wherein the reinforcing regulator for machine-made sand concrete comprises, by weight, 200-300 parts of an active excitant for treating solid waste, 10-30 parts of an alcohol amine compound, 5-20 parts of a dispersing agent, 4-10 parts of a penetrating agent, 3-8 parts of a thickening agent, 30-50 parts of potassium silicate, 2-30 parts of an additive, and 500-600 parts of water; the activity excitant is a copolymer substance composed of inorganic high molecular aluminosilicate minerals containing silicon and oxygen and bonded by silane through coupling polyelectrolyte dispersing agent. The reinforcing regulator for the machine-made sand concrete provided by the invention can excite the activity of the fly ash, promote the breakage of Si-O bonds and Al-O bonds of the fly ash, accelerate the hydration speed of the fly ash, excite and destroy silicon-oxygen network crystals such as mineral powder, disintegrate glass bodies, participate in the hydration reaction of a base material and promote the further hydrolysis of slag and sodium silicate. In the prior art, the problems of poor fluidity and bleeding segregation are mostly adopted by adopting a method of adding the additive, but the invention expands around the machine-made sand, develops high-quality machine-made sand and then uses the machine-made sand for preparing concrete, and overcomes a plurality of problems brought by the traditional machine-made sand.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides high-performance concrete based on high-quality machine-made sand and a preparation method thereof. The specific technical scheme is as follows:

high-performance concrete based on high-quality machine-made sand comprises the following components: cement, mineral powder, fly ash, large stone, small stone, machine-made sand, facing sand, admixture, stone powder and water.

Preferably, the high-performance concrete based on the high-quality machine-made sand comprises the following components in parts by weight: 210 to 350 parts of cement, 50 to 80 parts of mineral powder, 80 to 100 parts of fly ash, 694 to 752 parts of marble, 300 to 340 parts of small stone, 605 to 707 parts of machine-made sand, 0 to 200 parts of facing sand, 7.8 to 11 parts of additive, 0 to 30 parts of stone powder and 150 to 300 parts of water.

Most preferably, the high-performance concrete based on the high-quality machine-made sand comprises the following components in parts by weight: 210 to 350 parts of cement, 50 to 80 parts of mineral powder, 80 to 100 parts of fly ash, 694 to 752 parts of marble, 300 to 340 parts of small stone, 605 to 707 parts of machine-made sand, 7.8 to 11 parts of additive and 150 to 300 parts of water.

Furthermore, the cement is ordinary Portland cement P.O 42.5.42.5, and the strength of the 28-day sand is more than or equal to 48MPa.

Further, the specific surface area of the mineral powder is more than or equal to 400, the compressive strength ratio is more than or equal to 7d and is more than or equal to 75%, the 28d is more than or equal to 95%, the fluidity ratio is less than or equal to 95%, and the water content is less than or equal to 1.0%.

Further, the fly ash belongs to class II ash, the water content is less than or equal to 1.0%, the loss on ignition is less than or equal to 8.0%, the fineness is less than or equal to 27%, and the water demand ratio is less than or equal to 105%.

Further, the additive is a lipid polycarboxylic acid.

Further, the water content of the machine-made sand is less than or equal to 5.0%, the fineness modulus is more than or equal to 0.9, the stone content (more than 4.75 mm) is less than or equal to 10%, and the mud powder content is as follows: less than or equal to 5 percent, the mud content less than or equal to 1.0 percent, and the mud block content less than or equal to 1.0 percent.

The invention abandons the traditional proportioning design scheme of the assumed quality method in the common concrete proportioning design rule in proportioning design, and the guiding idea of proportioning design is converted from strength design to various performance designs and from feasibility design to optimization design. The reasonable material mixing proportion design determines the dosage of various components on the premise of meeting the requirements including strength, durability, uniformity, workability, permeability, economy and the like given by related specifications, and the most economical and applicable concrete is obtained.

Compared with natural sand, the machine-made sand has the advantages of more surface edges and corners, rough surface and certain stone powder content, and the slump of the machine-made sand concrete is generally smaller, so that the bleeding performance and the cohesiveness of the concrete can be improved to a certain extent through the increase of the stone powder content, and the concrete is easier to form and pour. These functions of stone dust are particularly evident in the formulation of some low grade concretes. The stone powder can play a role of crystal nucleus in cement hydration, induce crystallization of hydration products of cement, accelerate cement hydration and participate in hydration reaction of the cement to generate hydrated calcium carbonate aluminate, and prevent ettringite from being converted into mono-sulfur hydrated calcium sulfoaluminate. The main reason for the machine-made sand reinforced concrete is that the existence of the stone powder can obviously improve the pore characteristics of the concrete, so that the cement paste-aggregate interface structure is improved, and the crystal phase of the concrete is changed to different degrees. However, in the high-strength and high-performance concrete, the working performance of the concrete is poor due to the fact that the consumption of the cementing material is large, and the excessive stone powder content or the poor grading of the machine-made sand.

And the concrete of machine-made sand is required to have particularly good workability and pumping performance when being applied to high-rise and super high-rise buildings. Compared with natural sand, the machine-made sand has the characteristics of poor grading, larger fineness modulus, rough surface, sharp particles, edges and corners and the like. The bonding between the aggregate and the cement is increased, so that the resistance of the concrete mixture is increased, the working performance of the machine-made sand concrete is poor, and the fluidity is poor. Therefore, it is very important to find a technical measure for solving the problem of poor workability of high-strength high-performance machine-made sand concrete.

Preferably, the machine-made sand is modified machine-made sand, and is prepared by the following method, wherein the parts by weight are as follows: adding 15-20 parts of 2-fluoro-4-methoxy cinnamic acid into 100-120 parts of warm water at 60-70 ℃, stirring for 30-50 min at 200-350 rpm, adding 20-30 parts of nanoclay into the mixture, performing ultrasonic treatment for 2-3 h at 200-300W and 30-40 kHz until the nanoclay is completely dispersed, mixing 3-5 parts of Tween 80 with 50-70 parts of water, adding the mixture into the nanoclay dispersion, stirring the obtained mixture at the speed of 300-450 rpm for 40-48 h at 20-30 ℃, centrifuging the mixture at 8000-10000 rpm for 20-30 min, taking the solid, washing the solid with water for 2-3 times, drying the solid at 55-60 ℃ for 20-24 h, and finally grinding the obtained nanoclay and sieving the ground nanoclay with a 300-400 mesh sieve to obtain modified clay particles; 50-60 parts of machine-made sand is added into 100-200 parts of normal hexane, 15-20 parts of modified clay particles are added into the normal hexane, ultrasonic treatment is carried out for 30-40 min at 200-300W and 30-40 kHz, centrifugal treatment is carried out for 10-15 min at 1000-2000 rpm, and solid is taken and dried at 60-70 ℃ for 5-8 h, thus obtaining the modified machine-made sand.

The invention also discloses a preparation method of the high-performance concrete based on the high-quality machine-made sand, which comprises the following steps: firstly, mixing the machine-made sand with the fly ash in the formula amount for 25-35 s to prepare a ready-mixed material, then adding the cement, the mineral powder, the large stone, the small stone, the face sand and the stone powder into the ready-mixed material according to the formula, uniformly mixing and stirring for 50-60 s, and finally adding the additive and water in the formula amount, and stirring for 100-120 s to prepare mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 10-15 h, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 75-80%, the curing temperature is 20-22 ℃, and the curing is 25-28 days, so that the high-performance concrete based on the high-quality machine-made sand can be obtained.

The invention has the following description and functions of partial raw materials in the formula:

machine-made sand: technical requirements of machine-made sand are increased in building sand (GB/T-2001) for the first time, and the method has important significance for pushing and standardizing the application of the machine-made sand. However, due to the insufficient research on the machine-made sand at the moment, the formulation of the content of the machine-made sand in the standard is greatly based on the strict formulation of the related standards of the countries such as ISO, europe and the like, which results in the fact that the limit value of the stone powder content of the building sand standard is too strict. Therefore, the new specification of the building sand (GB/T14684-2011) modifies the stone powder content limit, the machine-made sand powder content limit with MB value smaller than 1.40 is widened from below 7% to 10.0%, and the stone powder content requirements corresponding to the class I sand, the class II sand and the class III sand are respectively 1.0%, 3.0% and 5.0% for the machine-made sand with MB value larger than or equal to 1.40, but the stone powder content limit is still stricter in general.

The fly ash and mineral powder are mixed into the concrete, so that industrial solid waste can be effectively consumed, and the environment is protected. If at 1m ³ The concrete is calculated by using 200kg of mineral admixture, and the consumption of the mineral admixture of the commercial concrete in China is more than 4.6 hundred million t at present. Along with the further improvement of the infrastructure in China, the consumption of the fly ash and the mineral powder is further increased. Meanwhile, the fly ash and mineral powder are doped into the concrete, so that the cost can be saved, the strength can be improved, the erosion resistance can be improved, the effect of the water reducer can be stimulated, and the like.

The type of the polycarboxylate water reducer has a certain influence on the performance of the concrete. The polycarboxylic acid water reducer commonly used in the market at present comprises polyacrylic acid, methylpropanoic acid, maleic acid polymer and the like, and after being matched with other additives, the polycarboxylic acid water reducer with different functions is formed and mainly comprises early strength type, slump retaining type, slow release type, functional type, viscosity reducing type, mud resisting type and the like. In addition, the mixing amount of the polycarboxylate water reducer has great influence on the performance of the concrete, the too high mixing amount can cause the retarding phenomenon of the concrete and reduce the strength of the concrete, and the too low mixing amount can cause the working performance of the concrete to not meet the construction requirement. Therefore, the reasonable determination of the mixing amount of the polycarboxylate water reducer has important significance for controlling various properties of the concrete.

Compared with the prior art, the nano clay modified machine-made sand prepared by the method can increase the cohesive force, flexibility and cohesiveness of mortar, can improve the fluidity of concrete when used in the concrete, and has good compatibility with various concrete additives. In particular, the modified nano clay can change the appearance of the machine-made sand surface, can enable the mortar to be dispersed among various pores, around the pore wall and around the cement particles, has a sealing effect on the high pore structure of the mortar, and has a stretching mechanism which can apply a pulling force to the anchoring part of the modified nano clay and the mortar. By these internal forces, the mortar is kept as a whole, and the cohesive strength of the mortar is improved, thereby further improving the workability of the concrete.

Detailed Description

The sources of the main raw materials in the examples:

machine-made sand: the water content is less than or equal to 5.0 percent, the fineness modulus is more than or equal to 0.9, the stone content (more than 4.75 mm) is less than or equal to 10 percent, and the mud powder content is as follows: less than or equal to 5 percent, the mud content less than or equal to 1.0 percent, and the mud block content less than or equal to 1.0 percent.

Small stone: particle size: 5-10 mm, the content of needle-shaped particles is less than or equal to 15%, the content of mud powder is less than or equal to 3.0%, the content of mud blocks is less than or equal to 0.5%, the water content is less than or equal to 0.5%, and the super-grain diameter (more than 10 mm) is less than or equal to 10%.

A marble: particle size: 10-20 mm, the content of needle-shaped particles is less than or equal to 15 percent, the content of mud powder is less than or equal to 3.0 percent, the content of mud blocks is less than or equal to 0.5 percent, the water content is less than or equal to 0.5 percent, and the super-grain diameter (less than 10 mm) is less than or equal to 10 percent.

And (3) cement: ordinary silicate cement has the strength of 3d more than or equal to 25MPa,28d more than or equal to 48MPa, the flexural strength of 3d more than or equal to 3.5MPa,28d more than or equal to 6.5MPa, the water consumption of standard consistence is equal to or less than or equal to +/-5, the specific surface area is less than or equal to 350m < 2 >/kg, the initial setting time is more than or equal to 45min, and the final setting time is less than or equal to 600min.

Fly ash: the loss on ignition is less than or equal to 8.0 percent, the fineness is less than or equal to 27 percent, the water demand ratio is less than or equal to 105 percent, the water content is less than or equal to 1.0 percent, and the shape under a microscope is as follows: ball-shaped.

Mineral powder: the specific surface area is more than or equal to 400, the compressive strength ratio is more than or equal to 7d and more than or equal to 75%, the 28d is more than or equal to 95%, the fluidity ratio is less than or equal to 95%, and the water content is less than or equal to 1.0%.

Lipid polycarboxylic acids: model PCE-11 with water content less than or equal to 3.0.

And (3) facing sand: the water content is less than or equal to 7.0%, the fineness modulus is 0.7-0.9, the mud powder content is less than or equal to 10%, the mud content is less than or equal to 7.0%, and the mud block content is less than or equal to 1.0%.

Stone powder: mohs hardness: 4.5, density: 2.82g/cm ³ 。

Nanoclay, 1250 mesh, cat No. 085467, surface viscosity 8 mpa.s, purchased from stone house ancient cooking vessel epitaxial mineral products trade company, inc.

Example 1

The preparation method of the high-performance concrete based on the high-quality machine-made sand comprises the following steps:

firstly, mixing 707kg of modified machine-made sand with 90kg of fly ash, and carrying out dry stirring for 30s to obtain a ready-mixed material, then adding 350kg of cement, 80kg of mineral powder, 752kg of marble and 300kg of small stone into the ready-mixed material, uniformly mixing and stirring for 60s, finally adding 11kg of lipid polycarboxylic acid and 200kg of water, and stirring for 120s to obtain a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

The modified machine-made sand is prepared by the following method: adding 18kg of 2-fluoro-4-methoxycinnamic acid into 100kg of warm water at 70 ℃, stirring at 300rpm for 50min, adding 25kg of nanoclay into the mixture, performing ultrasonic treatment at 300W and 40kHz for 3h until the nanoclay is completely dispersed, mixing 3kg of Tween 80 with 60kg of water, adding the mixture into the nanoclay dispersion, stirring the mixture at 20 ℃ for 48h at a speed of 450rpm, centrifuging at 10000rpm for 30min, taking a solid, washing the solid with water for 3 times, drying the solid at 60 ℃ for 24h, and finally grinding the obtained nanoclay and sieving the ground nanoclay with a 400-mesh sieve to obtain modified clay particles; adding 50kg of machine-made sand into 200kg of normal hexane, adding 20kg of modified clay particles into the machine-made sand, carrying out ultrasonic treatment at 200W and 30kHz for 40min, centrifuging at 2000rpm for 15min, taking solid, and drying at 70 ℃ for 8h to obtain the modified machine-made sand.

Example 2

The modified machine-made sand is prepared by the following method: adding 25kg of nanoclay into 100kg of warm water at 70 ℃, carrying out ultrasonic treatment at 300W and 40kHz for 3 hours until the nanoclay is completely dispersed, mixing 3kg of Tween 80 with 60kg of water, adding the mixture into the nanoclay dispersion, stirring the mixture at 20 ℃ for 48 hours at the speed of 450rpm, centrifuging the mixture at 10000rpm for 30 minutes, taking the solid, washing the solid with water for 3 times, drying the solid at 60 ℃ for 24 hours, and finally grinding the obtained nanoclay and sieving the ground nanoclay with a 400-mesh sieve to obtain modified clay particles; adding 50kg of machine-made sand into 200kg of normal hexane, adding 20kg of modified clay particles into the machine-made sand, carrying out ultrasonic treatment at 200W and 30kHz for 40min, centrifuging at 2000rpm for 15min, taking solid, and drying at 70 ℃ for 8h to obtain the modified machine-made sand.

Example 3

firstly, adding 635kg of machine-made sand into 100kg of fly ash, and carrying out dry stirring for 30s to obtain a ready-mixed material, then adding 210kg of cement, 50kg of mineral powder, 694kg of large stone, 340kg of small stone, 200kg of facing sand and 30kg of stone powder into the ready-mixed material, uniformly mixing and stirring for 60s, finally adding 8.5kg of lipid polycarboxylic acid and 200kg of water, and stirring for 120s to obtain a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

Example 4

firstly, adding 605kg of machine-made sand into 95kg of fly ash, and carrying out dry stirring for 30s to obtain a ready-mixed material, then adding 230kg of cement, 55kg of mineral powder, 704kg of large stone, 325kg of small stone, 200kg of facing sand and 30kg of stone powder into the ready-mixed material, uniformly mixing and stirring for 60s, finally adding 9kg of lipid polycarboxylic acid and 200kg of water, and stirring for 120s to obtain a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

Example 5

firstly, 624kg of machine-made sand is mixed with 80kg of fly ash and is dry-mixed for 30s to prepare a ready-mixed material, then 270kg of cement, 60kg of mineral powder, 708kg of large stone, 334kg of small stone, 130kg of facing sand and 20kg of stone powder are added into the ready-mixed material to be uniformly mixed and stirred for 60s, and finally, 9.5kg of lipid polycarboxylic acid and 200kg of water are added to be stirred for 120s to prepare a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

Example 6

mixing 654kg of machine-made sand with 90kg of fly ash, dry-mixing for 30s to obtain a ready-mixed material, adding 320kg of cement, 60kg of mineral powder, 716kg of large stone, 308kg of small stone and 110kg of face sand into the ready-mixed material, uniformly mixing and stirring for 60s, finally adding 10.2kg of lipid polycarboxylic acid and 200kg of water, and stirring for 120s to obtain a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

Example 7

firstly, 645kg of machine-made sand is mixed with 100kg of fly ash and is dry-mixed for 30s to prepare a ready-mixed material, then 210kg of cement, 50kg of mineral powder, 694kg of large stone, 340kg of small stone, 175kg of face sand and 30kg of stone powder are added into the ready-mixed material to be uniformly mixed and stirred for 60s, and finally 7.8kg of lipid polycarboxylic acid and 200kg of water are added to be stirred for 120s to prepare a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

Example 8

mixing 656kg of machine-made sand with 90kg of fly ash, dry-mixing for 30s to obtain a ready-mixed material, adding 240kg of cement, 50kg of mineral powder, 715kg of large stone, 310kg of small stone, 160kg of facing sand and 30kg of stone powder into the ready-mixed material, uniformly mixing and stirring for 60s, adding 8kg of lipid polycarboxylic acid and 200kg of water, and stirring for 120s to obtain a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

Comparative example 1

firstly, mixing 707kg of machine-made sand with 90kg of fly ash, and carrying out dry stirring for 30s to obtain a ready-mixed material, then adding 350kg of cement, 80kg of mineral powder, 752kg of marble and 300kg of small stone into the ready-mixed material, uniformly mixing and stirring for 60s, finally adding 11kg of lipid polycarboxylic acid and 200kg of water, and stirring for 120s to obtain a mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 15 hours, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 80%, the curing temperature is 20 ℃, and curing is carried out for 28 days to obtain the high-performance concrete based on the high-quality machine-made sand.

Test example 1

The high-performance concretes prepared in examples 1 to 8 and comparative example 1 were subjected to strength test, compressive strength test, three times per group test, average value, test result as shown in Table 1, according to GB/T50081-2019 Standard of test method for physical mechanical Properties of concrete.

Table 1: results of the intensity test

The mineral admixture is favorable for reducing the consumption of cement and improving the mixing performance of concrete, is matched with machine-made sand, is favorable for improving the workability and working performance of the machine-made sand concrete, and reduces the quality defect of the concrete caused by the machine-made sand. As can be seen from table 1, the compressive strength of example 1 is maximum, and comparative examples 1, 2 and 1 show that in example 1, 2-fluoro-4-methoxycinnamic acid can bond loose clay particles together to form a layer of bonding layer on the clay surface, and has a certain strength, and the bonding layer can change the morphology of the machine-made sand surface after being mixed with the machine-made sand, so that the cohesive strength of mortar is improved, and thus the compressive strength of concrete is further improved.

Test example 2

The high-performance concrete prepared in the examples and comparative example 1 was subjected to carbonization test according to the requirements of GB/T50082-2009 test method for Long-term Performance and durability of ordinary concrete. The test sample sizes were 100mm cubic concrete samples, 3 concrete samples were tested for each set of samples, using a CCB-70B type carbonization box. Before carbonization, placing the concrete test piece into a 60 ℃ oven for continuous drying for 48 hours, placing the dried test piece into a carbonization box, wherein the distance between the test pieces is not less than 50mm, and sealing the carbonization box after placing the test piece into the carbonization box. Carbon dioxide is introduced to keep the concentration of the carbon dioxide in the box at 20+/-3%, the relative humidity is controlled at 70+/-5%, and the temperature is controlled within 20+/-2%. Taking out the powder on the section of the cut part of the test piece after carbonization for 28 days, brushing off the powder on the section of the cut part of the test piece, then spraying the powder on the cleavage surface of the concrete by using phenolphthalein alcohol solution with the concentration of 1%, wherein the uncoloured part of the cleavage surface shows that carbonization is carried out, and the uncoloured part shows that carbonization is not carried out, after 30 seconds, measuring the carbonization depth of each point by using a vernier caliper according to the condition that every 10mm of the original mark is taken as a measuring point, and calculating the following formula to the accuracy of 0.01 mm:

wherein: d, the average carbonization depth of the carbonized test piece is accurate to 0.1mm;

di-carbonization depth (mm) of each measurement point;

n is the total number of measuring points;

the test results are shown in Table 2.

Table 2 results of concrete carbonization test

Carbonization is one cause of seriously affecting the durability of concrete. It is important to enhance the carbonization resistance of concrete to improve durability, and it is understood from table 2 that example 1 has a minimum carbonization depth because the nanoclay-modified machine-made sand prepared in example 1 can increase cohesion, flexibility and cohesion of mortar and has excellent compatibility with various concrete additives. The modified clay can make mortar disperse between various pores, around the pore wall and around the cement particles, and has a stretching mechanism for applying tension to the anchoring part of the modified clay and the mortar. By these internal forces, the concrete is kept as a whole, and the durability of the concrete can be improved.

Claims

1. The high-performance concrete based on the high-quality machine-made sand is characterized by comprising the following components in parts by weight: 210 to 350 parts of cement, 50 to 80 parts of mineral powder, 80 to 100 parts of fly ash, 694 to 752 parts of marble, 300 to 340 parts of small stone, 605 to 707 parts of machine-made sand, 0 to 200 parts of facing sand, 7.8 to 11 parts of additive, 0 to 30 parts of stone powder and 150 to 300 parts of water; the machine-made sand is modified machine-made sand, and is prepared by the following method, wherein the parts by weight are as follows: adding 15-20 parts of 2-fluoro-4-methoxy cinnamic acid into 100-120 parts of warm water at 60-70 ℃, stirring for 30-50 min at 200-350 rpm, adding 20-30 parts of nano clay into the mixture until the nano clay is completely dispersed, mixing 3-5 parts of Tween 80 with 50-70 parts of water, adding the mixture into nano clay dispersion, stirring the obtained mixture at 20-30 ℃ at 300-450 rpm for 40-48 h, centrifuging the mixture at 8000-10000 rpm for 20-30 min, washing the solid for 2-3 times, drying the solid, and finally grinding and sieving the obtained nano clay to obtain modified clay particles; adding 50-60 parts of machine-made sand into 100-200 parts of normal hexane, adding 15-20 parts of modified clay particles into the machine-made sand, carrying out ultrasonic treatment, centrifuging, taking solid, and drying at 60-70 ℃ for 5-8 hours to obtain the modified machine-made sand.

2. High-performance concrete based on high-quality machine-made sand according to claim 1, characterized in that: the ultrasonic parameters are 200-300W and 30-40 kHz.

3. High-performance concrete based on high-quality machine-made sand according to claim 1, characterized in that: the grinding grain size is 300-400 meshes.

4. High-performance concrete based on high-quality machine-made sand according to claim 1, characterized in that: the additive is a lipid polycarboxylic acid.

5. High-performance concrete based on high-quality machine-made sand according to claim 1, characterized in that: the water content of the machine-made sand is less than or equal to 5.0%, the fineness modulus is less than or equal to 0.9, the mud powder content is less than or equal to 5%, the mud content is less than or equal to 1.0%, and the mud block content is less than or equal to 1.0%.

6. High-performance concrete based on high-quality machine-made sand according to claim 1, characterized in that: the cement is ordinary Portland cement P.O 42.5.42.5, and the strength of the sand is more than or equal to 48MPa after 28 days.

7. The method for preparing high-performance concrete based on high-quality machine-made sand according to any one of claims 1 to 6, characterized by comprising the following preparation steps:

firstly, mixing the machine-made sand with the fly ash in the formula amount for 25-35 s to prepare a ready-mixed material, then adding the cement, the mineral powder, the large stone, the small stone, the face sand and the stone powder into the ready-mixed material according to the formula, uniformly mixing and stirring for 50-60 s, and finally adding the additive and water in the formula amount, and stirring for 100-120 s to prepare mixed slurry; then injecting the blank into a mould, scraping the surface, solidifying for 10-15 h, and removing the mould to obtain a blank; and curing the blank, wherein the curing humidity is 75-80%, the curing temperature is 20-22 ℃, and the curing is 25-28 days, so that the high-performance concrete based on the high-quality machine-made sand can be obtained.