1. The quick-hardening early-strength concrete convenient for construction is characterized by being prepared from the following raw materials in parts by weight:

17.0-19.0 parts of cement, 31.93-49.25 parts of gravel, 25-29 parts of sand, 1.3-2.0 parts of fly ash, 1.3-2.0 parts of silica fume, 5.0-6.7 parts of quick-hardening early strength agent, 0.05-0.07 part of boric acid, 0.6-1.3 parts of additive and 6.5-8.0 parts of water;

the main components of the quick-hardening early strength agent comprise amorphous calcium aluminate and calcium sulfate;

the admixture comprises polycarboxylic acid water reducing mother liquor, polycarboxylic acid slump retaining mother liquor, a retarder, cellulose ether, an air entraining agent, a defoaming agent and water.

2. The quick-hardening early-strength concrete convenient for construction according to claim 1, characterized in that: the main components of the rapid hardening early strength agent are amorphous calcium aluminate and calcium sulfate, and the weight ratio of the amorphous calcium aluminate to the calcium sulfate is (7.5-8.5): (1.5-2.5).

3. The quick-hardening early-strength concrete convenient for construction according to claim 1, characterized in that: the rapid hardening early strength agent also comprises triethanolamine, and the weight ratio of the sum of the amorphous calcium aluminate and the calcium sulfate to the triethanolamine is 1: (0.15-0.2).

4. The quick-hardening early-strength concrete convenient for construction according to any one of claims 1 to 3, characterized in that: the additive is prepared from the following raw materials in parts by weight:

160 portions of polycarboxylic acid water reducing mother liquor, 140 portions of polycarboxylic acid slump retaining mother liquor, 300 portions of retarder, 0.2-0.5 portion of cellulose ether, 0.5-1.5 portions of air entraining agent, 5-10 portions of sodium nitrite, 0.2-0.4 portion of defoaming agent and 740 portions of water 730.

5. The quick-hardening early-strength concrete convenient for construction according to claim 4, characterized in that: in the additive, the sum of the solid contents of the polycarboxylic acid water reducing mother liquor and the polycarboxylic acid slump retaining mother liquor is 9.0-10.5%.

6. The quick-hardening early-strength concrete convenient for construction according to claim 5, characterized in that: the weight ratio of the polycarboxylic acid water-reducing mother liquor to the polycarboxylic acid slump-retaining mother liquor is (12-16): (10-14);

the main component of the polycarboxylic acid water-reducing mother liquor is selected from one or more of a polycarboxylic acid high-efficiency water reducing agent, a polyether polycarboxylic acid water reducing agent and a hyperbranched modified polycarboxylic acid water reducing agent;

the main component of the polycarboxylic acid slump retaining mother liquor is polycarboxylic acid slump retaining agent.

7. The quick-hardening early-strength concrete convenient for construction according to claim 4, characterized in that: the retarder is at least one selected from white sugar, sodium gluconate, citric acid and sodium citrate.

8. The quick-hardening early-strength concrete convenient for construction according to claim 7, characterized in that: the retarder is white sugar, sodium gluconate, citric acid and sodium citrate; according to the weight ratio, the ratio of the sum of the weights of the white sugar and the sodium gluconate to the sum of the weights of the citric acid and the sodium citrate is (0.8-2): 5.

9. a method for preparing a quick-hardening early-strength concrete convenient for construction according to any one of claims 1 to 8, characterized in that: the method comprises the following steps:

according to the formula proportion, the cement, the broken stone, the sand, the fly ash, the silica fume, the quick-hardening early strength agent, the boric acid and the additive are uniformly mixed, and then the water is added and the mixture is uniformly mixed, so that the quick-hardening early strength concrete is prepared.

10. The method for preparing a quick-hardening early-strength concrete convenient for construction according to claim 9, wherein the preparation of the admixture comprises the steps of:

uniformly mixing cellulose ether, a retarder and sodium nitrite according to the formula of an additive to obtain a mixture; adding the mixture into 45-50% of water under stirring, and uniformly stirring; and then sequentially adding the polycarboxylic acid water-reducing mother liquor, the polycarboxylic acid slump-retaining mother liquor, the air entraining agent, the defoaming agent and the rest 50-55% of water, and uniformly stirring to obtain the additive.

Background

The concrete pavement has the advantages of high strength, good stability, strong durability, long service life and the like, so the concrete pavement is widely applied to expressways, national roads, local roads and the like. However, with the rapid development of national economic construction and highway traffic industry, road surface damage is becoming more and more serious due to rapid increase of traffic volume and old roads. Once the road surface is damaged, in order to reduce the influence on the traffic, the road surface needs to be quickly repaired and the traffic needs to be recovered, but the repair work is not easy.

In the maintenance and repair engineering of a concrete pavement which is locally damaged, the existing method mainly comprises the prefabrication and assembly technology and the repair by adopting special materials, wherein the special materials are special cement and/or special additives. In the repair of special materials, special cement is most commonly used for repair, and the special cement mainly used for repairing cement concrete pavements at present comprises rapid hardening portland cement, high alumina cement, rapid hardening sulphoaluminate cement and magnesium phosphate cement. Although the special cement can meet the design strength requirement of a road surface and recover the traffic, the inventor finds that the special cement has some defects more or less: the rapid hardening portland cement has large drying shrinkage and poor bonding of new and old concrete; hydration products of the high-alumina cement are unstable at high temperature and are easy to generate crystal form transformation; the research on the magnesium phosphate cement is not deep, and the production and the application are both limited; the setting time of the sulphoaluminate cement is not easy to regulate and control, and the workability after actual production and transportation can not be ensured.

Therefore, in order to minimize the influence when the road surface is repaired, the road repairing work must be completed in the shortest time, and meanwhile, the construction quality must meet the traffic requirement.

Disclosure of Invention

The application provides a fast-hardening early-strength concrete convenient for construction and a preparation method thereof.

In a first aspect, the application provides a quick-hardening early-strength concrete convenient for construction, which adopts the following technical scheme: the quick-hardening early-strength concrete convenient for construction is prepared from the following raw materials in parts by weight:

17.0-19.0 parts of cement, 31.93-49.25 parts of gravel, 25-29 parts of sand, 1.3-2.0 parts of fly ash, 1.3-2.0 parts of silica fume, 5.0-6.7 parts of quick-hardening early strength agent, 0.05-0.07 part of boric acid, 0.6-1.3 parts of additive and 6.5-8.0 parts of water;

the main components of the quick-hardening early strength agent comprise amorphous calcium aluminate and calcium sulfate;

the admixture comprises polycarboxylic acid water reducing mother liquor, polycarboxylic acid slump retaining mother liquor, a retarder, cellulose ether, an air entraining agent, a defoaming agent and water.

Amorphous calcium aluminate, calcium sulfate and water are matched with each other, can react rapidly to generate ettringite, and then are matched with cement, so that the initial setting of concrete can be completed within 10 min; however, the existing concrete is not generally ready for use, but is transported to a construction site by a mixer truck after being mixed in a mixing plant, so that boric acid and an additive prepared from polycarboxylic acid water reducing mother liquor, polycarboxylic acid slump retaining mother liquor, a retarder, cellulose ether, an air entraining agent, an antifoaming agent and water are added into the formula, and the initial setting time of the concrete can be controlled to be about 1h on the premise of not damaging the early strength of the concrete. In the application, each component is mutually matched, so that the concrete with good early strength performance and capable of meeting the construction performance of concrete for 1h can be prepared, and the compressive strength of the concrete can reach more than 30MPa in 4 h. By using the concrete, pavement repair can be completed in the shortest time, and the construction quality meets the traffic requirement.

Preferably, the main components of the quick-hardening early strength agent are amorphous calcium aluminate and calcium sulfate, and the weight ratio of the amorphous calcium aluminate to the calcium sulfate is (7.5-8.5): (1.5-2.5).

By adopting the technical scheme, the amorphous calcium aluminate and the calcium sulfate are matched with each other, so that the concrete can be quickly hardened in a short time, the hardened strength is high, and the 4-hour compressive strength can reach more than 30 MPa.

In another embodiment, the rapid hardening early strength agent further comprises triethanolamine, and the weight ratio of the sum of the amorphous calcium aluminate and calcium sulfate to the triethanolamine is 1: (0.15-0.2).

By adopting the technical scheme, the triethanolamine, the amorphous calcium aluminate and the calcium sulfate are compounded, so that the concrete with rapid hardening and high early strength can be obtained, and meanwhile, the workability of the concrete can be improved.

Preferably, the additive is prepared from the following raw materials in parts by weight in total amount of the additive:

160 portions of polycarboxylic acid water reducing mother liquor, 140 portions of polycarboxylic acid slump retaining mother liquor, 300 portions of retarder, 0.2-0.5 portion of cellulose ether, 0.5-1.5 portions of air entraining agent, 5-10 portions of sodium nitrite, 0.2-0.4 portion of defoaming agent and 740 portions of water 730.

By adopting the technical scheme, the admixture compounded by the components is applied to the concrete, the workability of the concrete can be improved, the initial setting time of the concrete is prolonged, and the early strength and the later strength of the concrete can be enhanced.

In the admixture, sodium nitrite mainly functions as a rust inhibitor and also has a certain effect of an early strength agent. Use the admixture of this application, reducible concrete is to the corruption of reinforcing bar.

Preferably, in the admixture, the sum of the solid contents of the polycarboxylic acid water reducing mother liquor and the polycarboxylic acid slump retaining mother liquor is 9.0-10.5%. More preferably, the weight ratio of the polycarboxylic acid water-reducing mother liquor to the polycarboxylic acid slump-retaining mother liquor is (12-16): (10-14).

Preferably, the solid content of the polycarboxylic acid water-reducing mother liquor is 40%, and the main component of the polycarboxylic acid water-reducing mother liquor is selected from one or more of a polycarboxylic acid high-efficiency water reducing agent, a polyether polycarboxylic acid water reducing agent and a hyperbranched modified polycarboxylic acid water reducing agent; more preferably, the main components of the polycarboxylic acid water-reducing mother liquor are a polycarboxylic acid high-efficiency water reducing agent and a polyether polycarboxylic acid water reducing agent. More preferably, the polycarboxylic acid high-efficiency water reducing agent and the polyether polycarboxylic acid water reducing agent are mixed according to the mass ratio of (1-1.5): 1 is compounded in proportion.

Preferably, the solid content of the polycarboxylic acid slump-retaining mother liquor is 50%, and the main component of the polycarboxylic acid slump-retaining mother liquor is a polycarboxylic acid slump-retaining agent.

The main components of the polycarboxylic acid high-efficiency water reducing agent and the polyether polycarboxylic acid water reducing agent are prepared into the polycarboxylic acid water reducing mother liquor with the solid content of 40 percent, and the water reducing rate is high. The main component is polycarboxylic acid slump retaining agent which is prepared into polycarboxylic acid slump retaining mother liquor with the solid content of 50 percent, and the slump of concrete can be reduced. The compatibility of the two components is good, the compatibility with other components of the concrete is also good, and the components are matched with each other, so that the concrete which has good cohesiveness, no segregation and no bleeding and is convenient for pumping construction can be prepared. In addition, the polycarboxylic acid water reducing mother liquor and the polycarboxylic acid slump retaining mother liquor are matched with the fly ash and the silica fume, so that the strength of the concrete can be enhanced: the early strength can be improved by 35 to 50 percent, and the strength can be improved by 10 to 15 percent in 28 days. And the early slump loss of the concrete is very small and almost negligible.

In the application, the sum of the solid contents of the polycarboxylic acid water reducing mother liquor and the polycarboxylic acid slump retaining mother liquor is equal to the solid content of the polycarboxylic acid slump retaining mother liquor multiplied by the weight ratio of the polycarboxylic acid water reducing mother liquor to the admixture multiplied by the solid content of the polycarboxylic acid slump retaining mother liquor multiplied by the weight ratio of the polycarboxylic acid slump retaining mother liquor to the admixture.

Preferably, the retarder is selected from at least one of white sugar, sodium gluconate, citric acid and sodium citrate; further preferably, the retarder is white sugar, sodium gluconate, citric acid and sodium citrate; according to the weight ratio, the ratio of the sum of the weights of the white sugar and the sodium gluconate to the sum of the weights of the citric acid and the sodium citrate is (0.8-2): 5.

the retarder compounded by white sugar, sodium gluconate, citric acid and sodium citrate is matched with boric acid, so that the initial setting time of the concrete can be controlled within 50-70min, and meanwhile, the plasticity of the concrete is not damaged and the contraction influence is not caused.

Preferably, the air entraining agent is an alkylphenol ethylene oxide polycondensate air entraining agent.

The defoaming agent is at least one of polyether modified silicon defoaming agent and organic silicon defoaming agent.

The cellulose ether is hydroxypropyl methyl cellulose ether.

The cement is PO42.5R ordinary portland cement; the fly ash is grade II fly ash; the crushed stone is continuous graded crushed stone with the grain diameter of 5-25 mm; the sand is continuous graded medium sand.

In a second aspect, the present application provides a method for preparing a quick-hardening early-strength concrete convenient for construction, which adopts the following technical scheme:

the preparation method of the quick-hardening early-strength concrete convenient for construction comprises the following steps:

according to the formula proportion, the cement, the broken stone, the sand, the fly ash, the silica fume, the quick-hardening early strength agent, the boric acid and the additive are uniformly mixed, and then the water is added and the mixture is uniformly mixed, so that the quick-hardening early strength concrete is prepared.

Preferably, the preparation of the admixture comprises the following steps:

uniformly mixing cellulose ether, a retarder and sodium nitrite according to the formula of an additive to obtain a mixture; adding the mixture into 45-50% of water under stirring, and uniformly stirring; and then sequentially adding the polycarboxylic acid water-reducing mother liquor, the polycarboxylic acid slump-retaining mother liquor, the air entraining agent, the defoaming agent and the residual 50-55% of water.

Firstly, cellulose ether, a retarder and sodium nitrite are uniformly mixed, and are more easily dispersed and dissolved compared with the method of independently adding the cellulose ether into water, and then, the mixture of the cellulose ether, the retarder and the sodium nitrite is added into 40-50% of water under stirring, so that the rapid dispersion of the cellulose ether, the retarder and the sodium nitrite is facilitated; and finally, sequentially adding the polycarboxylic acid water-reducing mother liquor, the polycarboxylic acid slump-retaining mother liquor, the air entraining agent, the defoaming agent and the residual 50-55% of water to prepare the homogeneous and stable admixture. The admixture prepared by the method can improve the basic performance of concrete.

In summary, the present application has the following beneficial effects:

in this application, each component is mutually supported, and the constructability is good in 1h for the concrete that makes, and meanwhile, compressive strength can reach more than 30MPa at 4h, uses the concrete of this application, can accomplish the road surface and repair and construction quality and reach the requirement of expert car in the shortest time.

Detailed Description

The present application will be described in further detail with reference to examples. Specifically, the following are described: the following examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer; the starting materials used in the following examples are all those conventionally commercially available except where specifically noted.

Table 1 raw material source table

Raw materials	Source and/or model
		High-efficiency polycarboxylic acid water-reducing mother liquor	SICHUAN YONGJIAN BUILDING MATERIAL Co.,Ltd.
Polyether polycarboxylic acid water-reducing mother liquor	Saint George chemical Co Ltd of Hebei
		Hyperbranched modified polycarboxylic acid water reducer	Shandongteng new building materials Co Ltd
Polycarboxylic acid slump retaining agent	Beijing Zhongan Yuanda Science and Technology Development Co.,Ltd.
		Air entraining agent for alkyl phenol ethylene oxide polycondensate	XINYI JINGSHANG BUILDING MATERIAL Co.,Ltd.
Polyether modified silicon defoaming agent	GB-120 of chemical Co., Ltd, Shandong, China
		Organic silicon defoaming agent	GB-122 of chemical Limited of Jinan nation

The cement is PO42.5R ordinary Portland cement;

the fly ash is grade II fly ash;

the crushed stone is continuous graded crushed stone with the grain diameter of 5-25 mm;

the sand is continuous graded medium sand.

Preparation example

Preparation example 1

The preparation of the admixture is as follows:

uniformly mixing 0.005kg of hydroxypropyl methyl cellulose ether, 4kg of sodium gluconate and 0.1kg of sodium nitrite in a mixing system to obtain a mixture; then adding 7.3kg of water into the stirring system, adding the mixture into the stirring system under stirring, and uniformly stirring; then, 3.2kg of polycarboxylic acid water-reducing mother liquor, 2.5kg of polycarboxylic acid slump-retaining mother liquor, 0.01kg of alkylphenol oxirane polycondensate air entraining agent, 0.005kg of polyether modified silicon defoaming agent and 7.3kg of water are sequentially added and stirred uniformly to obtain the additive 1.

The main component of the polycarboxylic acid water reducing mother liquor is a hyperbranched modified polycarboxylic acid water reducing agent, the solid content of the hyperbranched modified polycarboxylic acid water reducing agent is 40%, and the main component of the polycarboxylic acid slump retaining mother liquor is a polycarboxylic acid slump retaining agent, and the solid content of the polycarboxylic acid slump retaining mother liquor is 50%; in the additive, the sum of the solid contents of the polycarboxylic acid water-reducing mother liquor and the polycarboxylic acid slump-retaining mother liquor is 9.95%.

Preparation examples 2 to 4

Preparation examples 2 to 4 differed from preparation example 1 only in that: the polycarboxylic acid water-reducing mother liquor has different main components and dosage, specifically: in preparation example 2, the polycarboxylic acid water-reducing mother liquor is prepared from a polycarboxylic acid high-efficiency water-reducing agent and a polyether polycarboxylic acid water-reducing agent in a weight ratio of 1: 1.

In preparation example 3, the polycarboxylic acid water-reducing mother liquor is prepared from a polycarboxylic acid high-efficiency water-reducing agent and a polyether polycarboxylic acid water-reducing agent in a weight ratio of 1.5: 1.

In preparation example 4, the polycarboxylic acid water-reducing mother liquor is prepared from a polycarboxylic acid high-efficiency water-reducing agent and a polyether polycarboxylic acid water-reducing agent in a weight ratio of 2: 1.

Preparation examples 5 to 6

Preparation examples 5 to 6 differed from preparation example 3 only in that: the consumption of the polycarboxylic acid water-reducing mother liquor and the polycarboxylic acid slump-retaining mother liquor is different, and specifically comprises the following steps:

in preparation example 5, 3.5kg of polycarboxylic acid water-reducing mother liquor and 2.2kg of polycarboxylic acid slump-retaining mother liquor are used; at this time, in the additive, the sum of the solid contents of the polycarboxylic acid water-reducing mother liquor and the polycarboxylic acid slump-retaining mother liquor is 9.83%.

In preparation example 6, 1.4kg of polycarboxylic acid water-reducing mother liquor and 4.3kg of polycarboxylic acid slump-retaining mother liquor are used; at this time, in the additive, the sum of the solid contents of the polycarboxylic acid water-reducing mother liquor and the polycarboxylic acid slump-retaining mother liquor is 10.66%.

Preparation examples 7 to 8

Preparation examples 7 to 8 differed from preparation example 5 only in that: the retarder components and amounts were varied and are shown in table 2 below.

TABLE 2

Examples

Example 1

The preparation method of the quick-hardening early-strength concrete convenient for construction comprises the following steps:

concrete was prepared by uniformly mixing 18kg of cement, 37.16kg of crushed stone, 27kg of sand, 1.4kg of fly ash, 1.4kg of silica fume, 6.4kg of rapid hardening early strength agent (3.2kg of amorphous calcium aluminate and 3.2kg of calcium sulfate), 0.06kg of boric acid and 1.08kg of admixture 1 (prepared from preparation example 1), followed by adding 7.5kg of water and uniformly mixing.

Example 2

The preparation method of the quick-hardening early-strength concrete convenient for construction comprises the following steps:

concrete was prepared by uniformly mixing 17kg of cement, 40.444kg of crushed stone, 26kg of sand, 1.3kg of fly ash, 1.3kg of silica fume, 5.8kg of rapid hardening early strength agent (2.9kg of amorphous calcium aluminate and 2.9kg of calcium sulfate), 0.056kg of boric acid and 1.2kg of the admixture 1 (prepared in preparation example 1), and then adding 6.9kg of water to uniformly mix them.

Example 3

The preparation method of the quick-hardening early-strength concrete convenient for construction comprises the following steps:

concrete was prepared by uniformly mixing 16kg of cement, 42.447kg of crushed stone, 26kg of sand, 1.2kg of fly ash, 1.2kg of silica fume, 5.5kg of quick-hardening early strength agent (2.75kg of amorphous calcium aluminate and 2.75kg of calcium sulfate), 0.053kg of boric acid and 1.1kg of the admixture 1 (prepared in preparation example 1), and then adding 6.5kg of water to uniformly mix them.

Examples 4 to 8

Examples 4-8 differ from example 1 only in that: the components and/or the dosage of the quick-hardening early strength agent are different, and the specific formulation of the quick-hardening early strength agent in the examples 4 to 8 is shown in the following table 3.

TABLE 3 concrete compounding ratio of the quick hardening early strength agent in examples 4-8

Examples 9 to 15

Examples 9-15 differ from example 4 only in that: the additives prepared in different preparation examples were selected, and the specific selection of the additives in examples 9 to 15 is shown in Table 4 below.

TABLE 4 selection of admixtures for examples 9-15

Examples	Additive agent
		Example 9	Admixture 2 obtained in preparation example 2
Example 10	Admixture 3 obtained in preparation example 3
		Example 11	Admixture 4 obtained in preparation example 4
Example 12	Admixture 5 obtained in preparation example 5
		Example 13	Admixture 6 obtained in preparation example 6
Example 14	Admixture 7 obtained in preparation example 7
		Example 15	Admixture 8 obtained in preparation example 8

Comparative example

Comparative example 1

Comparative example 1 differs from example 1 only in that: in comparative example 1, white sugar was used instead of boric acid.

Comparative example 2

Comparative example 2 differs from example 1 only in that: in comparative example 2, boric acid was not added.

Comparative example 3

Comparative example 3 differs from example 1 only in that: in comparative example 3, the boric acid was 0.14 kg.

Comparative example 4

Comparative example 4 differs from example 14 only in that: in comparative example 4, the rapid hardening early strength agent was amorphous calcium aluminate.

Comparative example 5

Comparative example 5 differs from example 14 only in that: in comparative example 5, no retarder was used in the admixture.

Performance test

The initial slump and the expansion of the concrete prepared in examples 1-15 and comparative examples 1-5 are detected according to the standard GB/T50080-2016 common concrete mixture performance detection method standard, after the initial slump and the initial expansion of the concrete are detected, the concrete sample is kept still for 1 hour, the slump and the expansion of the concrete for 1 hour are detected, and the detection results are shown in the following table 5.

The compressive strength and the flexural strength of the concrete samples prepared in examples 1-15 and comparative examples 1-5 are detected according to the standard GB/T50081-2002 Standard test methods for mechanical Properties of ordinary concrete, the compressive strength and the flexural strength of the concrete samples in 4 hours and the compressive strength and the flexural strength of the concrete samples in 28 days are respectively detected, and the detection results are shown in Table 5 below.

The specification of a test piece for detecting the compressive strength is 100 multiplied by 100 mm; the test piece specification for testing the breaking strength is 100 multiplied by 400 mm.

TABLE 5 test data sheet

Combining example 1 and comparative examples 1-3 and table 5, it can be seen that the concrete has set for 1h with white sugar instead of boric acid; when no boric acid is added, the concrete cannot have fluidity for 1 hour only by virtue of the retarding components in the admixture; when the mixing amount of the boric acid is high, the retarding effect is enhanced, the good fluidity of the concrete for 1 hour can be ensured, and the flexural strength and the compressive strength of the concrete for 4 hours can be greatly reduced; that is to say, the boric acid and the additive are matched with each other, so that the workability of the concrete can be greatly improved, and the setting time of the concrete is prolonged, namely, the hydration of a cementing material can be slowed down by the mutual matching of the boric acid and the additive, the workability of the concrete for 1 hour is greatly improved, the setting time of the concrete is prolonged, and the construction performance of the concrete for 1 hour is ensured.

Combining example 14 and comparative example 4, and table 5, it can be seen that the early strength agent for rapid hardening is only amorphous calcium aluminate, the loss of concrete is small, and the 4h flexural strength and compressive strength are small.

By combining example 14 and comparative example 5, and by combining table 5, it can be seen that when no retarder is used in the admixture, the loss of workability for 1h of concrete is large, and it can be seen that the retarder in the admixture can act together with boric acid to ensure the workability for 1h of concrete.

The present embodiment is only for explaining the present application, and it is not limited to the present application, 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 application.