CN111689729A

CN111689729A - Self-compacting concrete and preparation method thereof

Info

Publication number: CN111689729A
Application number: CN202010433725.5A
Authority: CN
Inventors: 罗名笑; 罗建北
Original assignee: Shenzhen Dongdayang Building Material Co ltd
Current assignee: Shenzhen Dongdayang Building Material Co ltd
Priority date: 2020-05-20
Filing date: 2020-05-20
Publication date: 2020-09-22

Abstract

The invention relates to the technical field of concrete, in particular to self-compacting concrete and a preparation method thereof, wherein the self-compacting concrete comprises 340-365 parts of Portland cement; 190 portions of water and 210 portions of water; 835 parts of waste concrete block coarse aggregate 820 and 835 parts of cement; 850-875 parts of waste organic glass fine aggregate; 90-110 parts of fly ash; 75-80 parts of slag powder; 7.3-8.0 parts of a water reducing agent; 0.8-1.2 parts of polypropylene fiber; 2.1-3.0 parts of ester surfactant; the self-compacting concrete can be used for various members of buildings, has obviously improved fluidity, compressive strength and splitting tensile strength compared with the common self-compacting concrete, and overcomes the advantage that the compressive strength and the tensile strength of the concrete are weakened when organic glass is used for replacing fine aggregate for the concrete.

Description

Self-compacting concrete and preparation method thereof

Technical Field

The invention relates to the technical field of concrete, in particular to self-compacting concrete and a preparation method thereof.

Background

The self-compacting concrete is concrete which can flow and compact under the action of self gravity, can completely fill a template even if compact steel bars exist, and does not need additional vibration. The principle of preparing the self-compacting concrete is that through the selection and collocation of the additive, the cementing material and the coarse and fine aggregates and the elaborate design of the proportion, the fluidity of the concrete is increased, and meanwhile, the concrete has enough plastic viscosity, so that the aggregates are suspended in cement paste, the problems of segregation and bleeding do not occur, the concrete can freely flow and fully fill the space in a template, and a compact and uniform gelled structure is formed. The self-compacting concrete in the prior art generally comprises cement, fly ash, slag powder, broken stone coarse aggregate, sand fine aggregate, a water reducing agent and water, and the proportion of each component in the self-compacting concrete is obtained by calculation according to the pouring requirement.

However, natural aggregates such as natural crushed stones and sands used in self-compacting concrete are gradually exhausted due to the exploitation over the years, and the price is continuously increased, so that certain pressure is brought to the development of the building industry, and a material for replacing the natural aggregates needs to be found. On one hand, with the continuous acceleration of the urbanization process, a large number of buildings are built every year, and meanwhile, a plurality of buildings are dismantled, so that a lot of building waste materials containing bricks, concrete blocks, broken ceramic tiles and the like are generated; on the other hand, with the rapid development of plastic product industry, plastic products are inseparable from people's life and production, and a large number of plastic products are widely used, for example, organic glass which is one of plastics, and the chemical name of organic glass is polymethyl methacrylate, which is a high molecular compound polymerized from methyl methacrylate, is an important thermoplastic plastic with earlier development, is widely used in life, has small specific gravity, high light transmittance, good insulating property and low cost, and can be used for doors and windows, lamp shades, display racks and the like, but the large-scale production and use of organic glass inevitably accompanies the generation of a large number of waste organic glass, and the waste organic glass can be processed and crushed to form regenerated organic glass particles.

The method is one of the current development directions, namely, the waste concrete blocks are made into recycled coarse aggregate to replace natural broken stone, and the waste organic glass is made into recycled fine aggregate to replace sand to prepare recycled self-compacting concrete, but after the waste concrete is used for a certain period, the strength of the recycled coarse aggregate of the waste concrete is lower than that of the natural broken stone due to environmental influences such as weathering or air corrosion, and the like, so that the strength, durability and other properties of the produced recycled aggregate concrete are also lower than that of common concrete; and organic glass is incompatible with water, after the organic glass is added into concrete, the organic glass can not be well adsorbed with the liquid phase of the concrete, after the concrete is solidified, the interface bonding strength between the organic glass and the set cement is weak, when the concrete receives external impact, the external impact can not be well transmitted to the organic glass through the set cement, so that the set cement needs to bear more loads, the load borne by the organic glass is less than that of the set cement, the load borne by the organic glass and the set cement is greatly different, after a certain limit is exceeded, the organic glass and the set cement can be separated, the concrete is cracked, the compression resistance and the tensile strength of the concrete using the organic glass are weakened, and the improvement is needed.

Disclosure of the invention

Aiming at the defects in the prior art, the invention aims to provide the self-compacting concrete which has the advantages of overcoming the defect that when organic glass is used for concrete instead of fine aggregate, the compression strength and the tensile strength of the concrete are weakened.

The second purpose of the invention is to provide a preparation method of the self-compacting concrete, which is used for preparing the self-compacting concrete.

In order to achieve the first object, the invention provides the following technical scheme: the self-compacting concrete comprises the following components in parts by weight: 340 portions and 365 portions of Portland cement; 190 portions of water and 210 portions of water; 835 parts of waste concrete block coarse aggregate 820 and 835 parts of cement; 850-875 parts of waste organic glass fine aggregate; 90-110 parts of fly ash; 75-80 parts of slag powder; 7.3-8.0 parts of a water reducing agent; 0.8-1.2 parts of polypropylene fiber; 2.1-3.0 parts of ester surfactant.

By adopting the technical scheme, the compressive strength and the tensile strength of the concrete can be enhanced by adding the polypropylene fiber, so that the strength reduction caused by replacing natural aggregate with regenerated aggregate is compensated, and the polypropylene fiber has good compatibility with thick and thin cement base materials and other additives and can stably exist in the concrete due to the abnormal and stable chemical property and no absorption of other substances to carry out chemical reaction with the polypropylene fiber; meanwhile, through adding the ester surfactant, the oleophylic group of the ester surfactant is compatible with the surface of the organic glass, and the hydrophilic group is compatible with water, so that the adsorption between the organic glass and the water is enhanced, after the organic glass is added into the concrete, the adsorption between the surface of the organic glass and the liquid phase of the concrete cement can be enhanced, after the concrete is condensed, the interface bonding strength between the organic glass and the concrete set cement is enhanced, when the concrete is impacted from the outside, the load can be uniformly dispersed onto the organic glass through the set cement, and the ester surfactant can enhance the adsorption between the polypropylene fiber and the water, so that the polypropylene fiber can be more uniformly dispersed in the water, and the fluidity, the compressive strength and the tensile strength of the concrete are improved.

Further, the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

Further, the length of the polypropylene fiber is 20-24mm, and the diameter of the polypropylene fiber is 0.03-0.04 mm.

By adopting the technical scheme, when the length of the polypropylene fiber is too long, the polypropylene fiber is easy to wind, so that the polypropylene fiber is agglomerated, the strength of the agglomerated part in the concrete is reduced, and the quantity of other parts of polypropylene fiber in the concrete is reduced, so that the tensile property and the crack resistance of the concrete are reduced; when the polypropylene fiber is too short, the connection area between the polypropylene fiber and the concrete matrix is reduced, when the concrete is subjected to tensile force, the connection strength between the polypropylene fiber and the concrete matrix is not large enough, and the polypropylene fiber is easy to separate from the concrete matrix, so that the tensile strength and the crack resistance of the concrete are reduced.

Further, the ester surfactant is polyoxyethylene sorbitan fatty acid ester.

By adopting the technical scheme, the polyoxyethylene sorbitan fatty acid ester has strong hydrophilicity and is easy to dissolve in water, so the polyoxyethylene sorbitan fatty acid ester can be dissolved in water and then added into concrete and stably exists in the concrete, meanwhile, the surface activity of the polyoxyethylene sorbitan fatty acid ester is not influenced by the pH of the environment, the concrete is in an alkaline environment, and the polyoxyethylene sorbitan fatty acid ester can further play a surface activity role in the concrete and also comprises 0.5-0.7 part of hexamethyl phosphoric triamide.

By adopting the technical scheme, the stability of the polyoxyethylene sorbitan fatty acid ester under the illumination condition can be improved by adding hexamethylphosphoric triamide as a light stabilizer.

In order to achieve the second object, the invention provides the following technical scheme: the preparation method adopts a reaction kettle and comprises the following steps:

s1: weighing portland cement, water, waste concrete block coarse aggregate, waste organic glass fine aggregate, fly ash, slag powder, a polycarboxylic acid water reducing agent, polypropylene fiber, polyoxyethylene sorbitan fatty acid ester and hexamethyl phosphoric triamide according to the proportion;

s2: firstly adding portland cement, fly ash, slag powder and polypropylene fibers into a reaction kettle, starting the reaction kettle to stir at the rotating speed of 30r/min for 5-6min, then reversely stirring the reaction kettle at the rotating speed of 30r/min for 5-6min, then adding waste concrete block coarse aggregate and waste organic glass fine aggregate, and continuously stirring the reaction kettle at the rotating speed of 30r/min for 5-6 min;

s3: adding the weighed water, and continuously stirring at the rotating speed of 30r/min for 5-6 min;

s4: adding 7 parts of the weighed polycarboxylate superplasticizer into a reaction kettle, stirring the reaction kettle for 2min at the rotating speed of 30r/min every time of adding once, and then continuously adding the polycarboxylate superplasticizer until the polycarboxylate superplasticizer is added completely;

s5: mixing polyoxyethylene sorbitan fatty acid ester and hexamethylphosphoric triamide, adding a small amount of water until the polyoxyethylene sorbitan fatty acid ester and the hexamethylphosphoric triamide are dissolved, then adding the polyoxyethylene sorbitan fatty acid ester and the hexamethylphosphoric triamide aqueous solution into a reaction kettle, and continuously stirring the reaction kettle at the rotating speed of 30r/min for 8-9min to obtain the self-compacting concrete.

By adopting the technical scheme, because the density of the polypropylene fiber is lower, the portland cement, the fly ash, the slag powder and the polypropylene fiber are stirred by using the reaction kettle, then the polypropylene fiber, the portland cement, the fly ash and the slag powder are fully mixed by stirring in the reverse direction, then the waste concrete block coarse aggregate and the waste organic glass fine aggregate are added into the reaction kettle, the reaction kettle is continuously stirred to fully and uniformly stir the concrete dry material, and at the moment, the components in the concrete are uniformly mixed by adding water; and then firstly adding the polyoxyethylene sorbitan fatty acid ester and hexamethylphosphoric triamide into water together for dissolving, so that the hexamethylphosphoric triamide has a protection effect on the polyoxyethylene sorbitan fatty acid ester, then adding the polyoxyethylene sorbitan fatty acid ester and the hexamethylphosphoric triamide into a reaction kettle, and continuously stirring the reaction kettle to obtain the self-compacting concrete.

Further, in step S1, the polypropylene fibers are treated in advance as follows:

a1: placing the polypropylene fibers in a stirrer, and adding water until the water is over the polypropylene fibers;

a2: adding quartz sand grinding aid with average particle size of 0.6-0.8mm, stirring for 1-1.5h, taking out polypropylene fiber, washing the stirrer and polypropylene fiber with water, and drying to obtain coarse polypropylene fiber.

By adopting the technical scheme, the surface of the polypropylene fiber becomes rough after being ground by the quartz sand grinding aid, the friction force between the polypropylene fiber and the concrete matrix is enhanced, the polypropylene fiber interacts with the concrete matrix, the connection strength between the polypropylene fiber and the concrete matrix is enhanced, and the compression strength and the splitting tensile strength of the concrete are improved.

Furthermore, the rough polypropylene fiber is subjected to modification treatment, which comprises the following steps

B1: adding potassium permanganate into a stirrer, wherein the weight ratio of the potassium permanganate to the rough polypropylene fibers is 10%, adding the rough polypropylene fibers, adding water until the water submerges the rough polypropylene fibers, stirring and dissolving the potassium permanganate, and stirring for 2 hours by using the stirrer;

b2: and D, taking out the rough polypropylene fiber treated in the step B1, washing with water, and drying to obtain the modified polypropylene fiber.

A3: adding potassium permanganate into a stirrer, wherein the weight ratio of the potassium permanganate to the polypropylene fiber is 10%, adding the polypropylene fiber, adding water until the water submerges the polypropylene fiber, stirring and dissolving the potassium permanganate, and stirring for 2 hours by using the stirrer;

a4: taking out the polypropylene fiber, washing with water and drying.

By adopting the technical scheme, as the surface of the polyethylene fiber which is not processed is smooth and incompatible with water, after the polyethylene fiber is added into the concrete, the polyethylene fiber can not be well dispersed in a concrete matrix, and the connection strength with the concrete matrix is not high, the surface of the polyethylene fiber is oxidized by potassium permanganate, so that polar groups are introduced into the surface of the polyethylene fiber, the hydrophilicity of the surface of the polyethylene fiber is increased, and the polyethylene fiber is easier to be fully distributed in the concrete; meanwhile, the polycarboxylic acid high-efficiency water reducing agent improves the dispersibility of cement particles, fly ash particles and slag powder particles in concrete, so that the cement particles, the fly ash particles and the slag powder particles can more easily enter the fork between the polypropylene fiber surfaces, and after the concrete is condensed, the fork on the polypropylene fiber surfaces can go deep into the concrete matrix, so that the compressive strength and the splitting tensile strength of the concrete are obviously improved.

Further, in the step B1, dilute sulfuric acid is added, wherein the mass fraction of the dilute sulfuric acid is 50%, and the dosage of the dilute sulfuric acid is 5% of the weight of the polypropylene fiber.

By adopting the technical scheme, the addition of dilute sulfuric acid enhances the oxidizing capability of potassium permanganate.

In conclusion, the invention has the following beneficial effects:

1. the polypropylene fiber is added to enhance the physical properties of the concrete, thereby making up the strength reduction caused by replacing natural aggregate with recycled aggregate;

2. by adding polyoxyethylene sorbitan fatty acid ester, the oleophylic group of the polyoxyethylene sorbitan fatty acid ester is compatible with organic glass, and the hydrophilic group is compatible with water, so that the strength of the enhanced water adsorbed on the glass is enhanced, and the interface strength between the glass and the concrete matrix is enhanced after the concrete is condensed;

3. the polyethylene fibers are ground by using the quartz sand, so that the surfaces of the polyethylene fibers are rough, the friction force between the polyethylene fibers and the concrete matrix is increased, and the polyethylene fibers are not easy to separate from the concrete matrix when the concrete is subjected to tension after being condensed; the polyethylene fiber surface is oxidized by the oxidant, so that polar groups are introduced to the polyethylene fiber surface, the hydrophilicity of the polyethylene fiber is increased, and the polyethylene fiber is easier to be fully distributed in concrete.

Detailed Description

The present invention will be described in further detail with reference to examples.

Wherein the cement is lubricous P.O 42.5 Portland cement; the fly ash is secondary fly ash of Hunan Baolong science and technology development Limited company; slag powder grade S95 slag powder of Shanghai harmonica new material science and technology Limited; water is tap water in Shenzhen city; the waste organic glass fine aggregate is a product of a Dalang horizontal renewable resource recycling station in Dongguan city, and the waste concrete block coarse aggregate is a C30 grade waste concrete block of Jiangsu summer doctor environmental science and technology Limited company; the polycarboxylate superplasticizer is prepared from a polycarboxylate superplasticizer produced by Shanghai-phobia-metallurgy industry Co., Ltd; the polypropylene fiber is a product produced by Changzhou Tianyi company; the polyoxyethylene sorbitan fatty acid ester is a product produced by Nantong Orno chemical Co., Ltd; the potassium permanganate is selected from products of Guangdong Xin science and technology company; the hexamethylphosphoric triamide is selected from products of Shanghai Yizhen chemical industry Co.Ltd; the dilute sulfuric acid is 50% by mass of tin-free Aiftit chemical raw materials, Inc.

Example 1: the self-compacting concrete comprises the components and corresponding parts by weight shown in Table 1, and is prepared by the following steps:

s1: weighing portland cement, water, waste concrete block coarse aggregate, waste organic glass fine aggregate, fly ash, slag powder, polycarboxylic acid water reducing agent, polypropylene fiber and polyoxyethylene sorbitan fatty acid ester according to the proportion.

S2: firstly adding portland cement, fly ash, slag powder and polypropylene fibers into a reaction kettle, starting the reaction kettle to stir at the rotating speed of 30r/min for 6min, then reversely stirring the reaction kettle at the rotating speed of 30r/min for 5min, then adding waste concrete block coarse aggregate and waste organic glass fine aggregate, and continuously stirring the reaction kettle at the rotating speed of 30r/min for 5 min.

S3: adding the weighed water, and continuously stirring at the rotating speed of 30r/min for 6 min.

S4: and (3) adding 7 parts of the weighed polycarboxylic acid water reducing agent into a reaction kettle, stirring the reaction kettle for 2min at the rotating speed of 30r/min every time of adding, and then continuously adding the polycarboxylic acid water reducing agent until the polycarboxylic acid water reducing agent is completely added.

S5: adding a small amount of water into the polyoxyethylene sorbitan fatty acid ester for dissolving, then adding the water solution of the polyoxyethylene sorbitan fatty acid ester into the reaction kettle, and continuously stirring the reaction kettle at the rotating speed of 30r/min for 8min to obtain the self-compacting concrete.

The mud content of the waste concrete block coarse aggregate is 2.3 percent, the water content is 1.5 percent, the average grain diameter is 8mm, the water content of the waste organic glass fine aggregate is 0.4 percent, and the average grain diameter is 0.4 mm; the modified polypropylene fibers had an average length of 24mm and an average diameter of 0.03 mm.

Example 2: a self-compacting concrete, differing from example 1 in that it is obtained by the following steps:

s1: weighing portland cement, water, waste concrete block coarse aggregate, waste organic glass fine aggregate, fly ash, slag powder, a polycarboxylic acid water reducing agent, polypropylene fiber, polyoxyethylene sorbitan fatty acid ester and hexamethyl phosphoric triamide according to the proportion.

S2: firstly adding portland cement, fly ash, slag powder and polypropylene fibers into a reaction kettle, starting the reaction kettle to stir at the rotating speed of 30r/min for 6min, then reversely stirring the reaction kettle at the rotating speed of 30r/min for 5min, then adding waste concrete block coarse aggregate and waste organic glass fine aggregate, and continuously stirring the reaction kettle at the rotating speed of 30r/min for 6 min.

S3: adding the weighed water, and continuously stirring at the rotating speed of 30r/min for 5 min.

S5: mixing polyoxyethylene sorbitan fatty acid ester and hexamethylphosphoric triamide, adding a small amount of water until the polyoxyethylene sorbitan fatty acid ester and the hexamethylphosphoric triamide are dissolved, then adding the polyoxyethylene sorbitan fatty acid ester and the hexamethylphosphoric triamide aqueous solution into a reaction kettle, and continuously stirring the reaction kettle for 9min at the rotating speed of 30r/min to obtain the self-compacting concrete.

The mud content of the waste concrete block coarse aggregate is 2.3 percent, the water content is 1.5 percent, the average grain diameter is 8mm, the water content of the waste organic glass fine aggregate is 0.4 percent, and the average grain diameter is 0.4 mm; the modified polypropylene fibers had an average length of 20mm and an average diameter of 0.04 mm.

The components included and the corresponding parts by weight are shown in table 1.

Example 3: a self-compacting concrete: the difference from the example 2 is that the polypropylene fiber is pre-treated for standby, and the method comprises the following steps:

a1: 10kg of polypropylene fibers were placed in a stirrer and water was added until the water was over the polypropylene fibers.

A2: adding a quartz sand grinding aid with the particle size of 0.6mm, stirring for 1.5h, taking out the polypropylene fiber, washing the stirrer and the polypropylene fiber with water, and drying to obtain the coarse polypropylene fiber.

Example 4: a self-compacting concrete: the difference from example 3 is that the coarse polypropylene fibers were also modified by the steps of:

A2: adding a quartz sand grinding aid with the particle size of 0.8mm, stirring for 1h, taking out the polypropylene fibers, washing the stirrer and the polypropylene fibers with water, and drying to obtain the coarse polypropylene fibers.

B1: adding 1kg of potassium permanganate into a stirrer, adding 10kg of coarse polypropylene fibers, adding water until the water submerges the coarse polypropylene fibers, stirring and dissolving the potassium permanganate, and stirring for 2 hours by using the stirrer.

A3: adding 1kg of potassium permanganate into a stirrer, adding polypropylene fibers, adding water until the water submerges the polypropylene fibers, stirring and dissolving the potassium permanganate, adding 0.5kg of dilute sulfuric acid with the mass fraction of 50%, and stirring for 2 hours by using the stirrer;

a4: and taking out the polypropylene fiber, washing with water, and drying to obtain the modified polypropylene fiber for later use.

Example 5: a self-compacting concrete: the difference from the example 3 is that in the step B1, dilute sulfuric acid with a mass fraction of 50% is added, 1kg of potassium permanganate and 0.5kg of dilute sulfuric acid are added into a stirrer, 10kg of coarse polypropylene fibers are added, water is added until the water is over the coarse polypropylene fibers, the potassium permanganate is stirred and dissolved, and the stirrer is used for stirring for 2 hours.

TABLE 1 Components and their respective parts by weight in examples 1-5

TABLE 1

Comparative example

Comparative example 1: a self-compacting concrete is prepared by the following steps:

d1: 340kg of portland cement, 90kg of fly ash, 76kg of slag powder and 1.1kg of polypropylene fiber are added into a reaction kettle, the reaction kettle is started to stir for 6min at the rotating speed of 30r/min, then the reaction kettle is reversely stirred for 5min at the rotating speed of 30r/min, 835kg of natural macadam and 875kg of natural sand are added, and the reaction kettle is continuously stirred for 5min at the rotating speed of 30 r/min.

D2: adding the weighed water, and continuously stirring at the rotating speed of 30r/min for 6 min.

D3: and (3) adding 7 parts of the weighed polycarboxylic acid water reducing agent into a reaction kettle, stirring the reaction kettle for 2min at the rotating speed of 30r/min every time of adding, and then continuously adding the polycarboxylic acid water reducing agent until the polycarboxylic acid water reducing agent is completely added.

D4: and continuously stirring the reaction kettle at the rotating speed of 30r/min for 8min to obtain the self-compacting concrete.

The mud content of the natural macadam is 1.3 percent, the water content is 1.5 percent, the average grain diameter is 8mm, the water content of the natural sand is 0.4 percent, the mud content is 1 percent, and the average grain diameter is 0.4 mm; the polypropylene fibers had an average length of 24mm and an average diameter of 0.03 mm.

The components included and the corresponding parts by weight are shown in table 2.

Comparative example 2: a self-compacting concrete: the difference from comparative example 1 is that no polypropylene fiber is included, the components included and the corresponding parts by weight are shown in table 2.

TABLE 2 Components and their respective parts by weight in comparative examples 1-2

TABLE 2

Comparative example 3:

step 1: and weighing portland cement, water, waste concrete block coarse aggregate, waste organic glass fine aggregate, fly ash, slag powder and a polycarboxylic acid water reducing agent according to the proportion.

Step 2: firstly adding portland cement, fly ash and slag powder into a reaction kettle, starting the reaction kettle to stir for 6min at the rotating speed of 30r/min, then reversely stirring the reaction kettle for 5min at the rotating speed of 30r/min, then adding waste concrete block coarse aggregate and waste organic glass fine aggregate, and continuously stirring the reaction kettle for 5min at the rotating speed of 30 r/min.

And step 3: adding the weighed water, and continuously stirring at the rotating speed of 30r/min for 6 min.

And 4, step 4: and (3) adding 7 parts of the weighed polycarboxylic acid water reducing agent into a reaction kettle, stirring the reaction kettle for 2min at the rotating speed of 30r/min every time of adding, and then continuously adding the polycarboxylic acid water reducing agent until the polycarboxylic acid water reducing agent is completely added.

And 5: and continuously stirring the reaction kettle at the rotating speed of 30r/min for 8min to obtain the self-compacting concrete.

TABLE 3 Components and their respective parts by weight in comparative example 3

TABLE 3

Performance test

Test one: slump flow test.

And (2) test II: and (5) testing the strength.

Test subjects: examples 1 to 8 were selected as test samples 1 to 8, and comparative examples 1 to 2 were selected as control samples 1 to 2.

Test method

Test one: slump flow tests were carried out on concrete in the technical specification for the application of self-compacting concrete (JGJ-T283-.

And (2) test II: the compressive strength and the splitting tensile strength of the concrete are tested by adopting the standard of the test method for the mechanical property of the common concrete (GB/T50081-2016).

TABLE 4 summary of test data for examples 1-8 and comparative examples 1-2

TABLE 4

As can be seen from Table 4, it can be seen from example 1 and comparative example 2 that when polypropylene fibers and polyoxyethylene sorbitan fatty acid ester are blended into the concrete, the compressive strength and the tensile strength at cleavage are obviously improved, which indicates that the self-compacting concrete prepared in the present invention reaches or even exceeds the performance index of the common self-compacting concrete.

It can be seen from example 1 and comparative example 3 that, when polypropylene fibers and polyoxyethylene sorbitan fatty acid ester were added to concrete using recycled aggregate, both the compressive strength and the cleavage tensile strength were significantly improved as compared to recycled concrete without adding polypropylene fibers and polyoxyethylene sorbitan fatty acid ester.

From the examples 1-2, it can be seen that when hexamethylphosphoric triamide light stabilizer is added into the concrete, the compressive strength and the cleavage tensile strength of the concrete are both improved to a certain extent, which indicates that after the hexamethylphosphoric triamide light stabilizer is added, the stability of the polyoxyethylene sorbitan fatty acid ester under the illumination can be improved, so that the performance of the concrete is improved, and that when the polyoxyethylene sorbitan fatty acid ester is added into the concrete, the compressive strength and the cleavage tensile strength of the concrete can be effectively improved, because the polyoxyethylene sorbitan fatty acid ester enhances the adsorption of the recycled aggregates with the liquid phase of the concrete, and after the concrete is coagulated, the interface bonding strength of the recycled aggregates with the concrete set is improved.

From examples 2-3, it can be seen that after the polypropylene fibers are ground by the quartz sand grinding aid, the fluidity of the concrete is reduced, but the compressive strength and the tensile strength of the cleavage are both obviously improved, at this time, because the polypropylene fibers are ground by the quartz sand grinding aid, the surfaces of the polypropylene fibers are branched, the friction force between the polypropylene fibers and the concrete matrix is enhanced, the polypropylene fibers interact with the concrete matrix, the flowing of the concrete is not facilitated, the fluidity of the concrete is reduced, but the connection strength between the polypropylene fibers and the concrete matrix is enhanced, and the compressive strength and the tensile strength of the cleavage of the concrete are improved.

From examples 2 to 4, it can be seen that, after the potassium permanganate is used to oxidize the polypropylene fiber surface, the fluidity, compressive strength and tensile strength of the concrete are all significantly improved, and at this time, since the potassium permanganate oxidizes the polypropylene fiber surface, polar groups are introduced into the polypropylene fiber surface, so that the adsorption between the polypropylene fiber surface and water is enhanced, thereby enhancing the strength between the polypropylene fiber surface and the concrete interface, and the polypropylene fiber can be more easily dispersed into the concrete matrix, enhancing the dispersion degree of the polypropylene fiber, and after the concrete is coagulated, improving the connection strength between the polypropylene fiber and the concrete matrix. Meanwhile, the polycarboxylic acid high-efficiency water reducing agent improves the dispersibility of cement particles, fly ash particles and slag powder particles in concrete, so that the cement particles, the fly ash particles and the slag powder particles can more easily enter the fork between the polypropylene fiber surfaces, and after the concrete is condensed, the fork on the polypropylene fiber surfaces can go deep into the concrete matrix, so that the compressive strength and the splitting tensile strength of the concrete are obviously improved.

From examples 4-5, it can be seen that the addition of dilute sulfuric acid enhances the oxidizing property of potassium permanganate, so that more polar groups are introduced into the surface of polypropylene fiber.

It can be seen from example 1 and comparative example 1 that, when the polyoxyethylene sorbitan fatty acid ester is not added to the concrete, the natural aggregate is used in the comparative example, but the fluidity, compressive strength and tensile strength at cleavage of the concrete are all significantly reduced, because the polyoxyethylene sorbitan fatty acid ester can enhance the adsorption between the polypropylene fibers and water, and at the same time, the dispersity of the polypropylene fibers is enhanced, so that the polypropylene fibers are more uniformly dispersed in the concrete, and after the concrete is coagulated, the bonding strength between the polypropylene fibers and the concrete matrix is enhanced, thereby improving the fluidity, compressive strength and tensile strength at cleavage of the concrete.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. The self-compacting concrete is characterized by comprising the following components in parts by weight:

340 portions of Portland cement and 365 portions of

190 portions of water

Waste concrete block coarse aggregate 820 and 835 parts

875 parts of waste organic glass fine aggregate 850-sand glass

90-110 parts of fly ash

75-80 parts of slag powder

7.3-8.0 parts of water reducing agent

0.8 to 1.2 portions of polypropylene fiber

2.1-3.0 parts of ester surfactant.

2. The self-compacting concrete of claim 1, wherein the water reducer is a polycarboxylic acid high-efficiency water reducer.

3. A self-compacting concrete according to claim 1, characterized in that said polypropylene fibres have a length of 20-24mm and a diameter of 0.03-0.04 mm.

4. The self-compacting concrete of claim 1, wherein the ester surfactant is a polyoxyethylene sorbitan fatty acid ester.

5. The self-compacting concrete according to claim 1, further comprising 0.5-0.7 parts of hexamethylphosphoric triamide.

6. A method for preparing self-compacting concrete, for preparing a self-compacting concrete according to any one of claims 1 to 5, wherein the method for preparing the self-compacting concrete uses a reaction kettle, and comprises the following steps:

7. The method for preparing self-compacting concrete according to claim 6, wherein in the step of S1, the polypropylene fibers are treated in advance as follows:

8. The method for preparing self-compacting concrete according to claim 7,

9. The method for preparing self-compacting concrete according to claim 8, wherein dilute sulfuric acid is further added in the step B1, and the mass fraction of the dilute sulfuric acid is 50% and the amount of the dilute sulfuric acid is 5% of the weight of the polypropylene fiber.