1. The high-crack-resistance premixed concrete prepared from the calcareous stone powder is characterized by comprising a cementing material, sand, stone, an additive and water, wherein the cementing material consists of cement, the calcareous stone powder and a mineral admixture.

2. The high crack resistance premixed concrete prepared by the calcareous stone powder according to claim 1, wherein the using amount of the cementing material is more than or equal to 330kg/m³。

3. The high crack resistance premixed concrete prepared by using the calcareous stone powder as claimed in claim 1, wherein the cement accounts for 70-80% of the cementitious material, the calcareous stone powder accounts for 10-15% of the cementitious material, and the mineral admixture accounts for 5-15% of the cementitious material.

4. The high crack resistance ready-mixed concrete prepared from calcareous stone powder according to claim 1, wherein the mineral admixture comprises at least one of fly ash, mineral powder, silica fume and microbeads.

5. The high crack resistance ready-mixed concrete prepared from calcareous stone powder according to claim 1, wherein the calcareous stone powder comprises at least one of limestone powder, marble stone powder and dolomite rock powder.

6. The high crack resistance ready-mixed concrete prepared from calcareous stone powder according to claim 1, wherein the sand comprises at least one of river sand and machine-made sand, the stone is 5-25 mm continuous graded broken stone, the sand content of the concrete is 40-50%, and the water-to-gel ratio is 0.35-0.50.

7. The high anti-cracking premixed concrete prepared by using calcareous stone powder as claimed in claim 1, wherein the additive is a polycarboxylic acid type high-performance water reducing agent, and comprises at least one of a water-reducing polycarboxylic acid type high-performance water reducing agent and a slump-retaining polycarboxylic acid type high-performance water reducing agent.

8. The high crack resistance premixed concrete prepared by using the calcareous stone powder as claimed in claim 1, wherein the calcareous stone powder is limestone powder, and the mineral admixture is a mixture of mineral powder and silica fume; or the calcareous stone powder is marble stone powder, and the mineral admixture is a mixture of microbeads and silica fume; or the calcareous stone powder is dolomite stone powder, and the mineral admixture is mineral powder.

9. The preparation method for preparing the high crack resistance ready-mixed concrete by using the calcareous stone powder according to any one of claims 1 to 8, which is characterized by comprising the following steps:

1) preparing clear paste, mortar or common concrete for different lithologic calcareous stone powders, and determining the workability, compressive strength, shrinkage cracking performance and adaptability of an additive;

2) according to the types of the calcareous stone powder, different types of mineral admixtures and different types of admixtures are matched to carry out concrete tests, and the selection and matching of different lithologic calcareous stone powders, the mineral admixtures and the admixtures are determined;

3) weighing the raw materials according to the test result of the step 2), and uniformly mixing to prepare the high crack resistance premixed concrete.

Background

Concrete is the most basic building material and plays a significant role in infrastructure construction. The most used material in the concrete material is coarse and fine aggregate, along with the rapid development of the building industry, natural sand resources are increasingly in short supply and are unevenly distributed, river sand is inevitably replaced by machine-made sand, however, the problem of stone powder consumption in the sand making process and the problem of overhigh stone powder content in the machine-made sand become research hotspots in the concrete industry, the particle size of the stone powder is generally smaller than 0.075mm and is generally used as an inert filler in concrete, however, the stone powder is relatively extensive in the using process, different types of calcareous stone powder have different influences on the concrete, and particularly, the workability, compressive strength and shrinkage rate of the concrete are greatly influenced. At present, the application research of the stone powder in the concrete mostly focuses on the influence of the stone powder on the mechanical property and the durability of the concrete, the research on the influence of the variety, the particle size distribution and the dosage of the stone powder on the performance of the concrete is not systematic and comprehensive, and especially, the research on the aspects of selecting proper mineral admixtures and additives and carrying out reasonable concrete mixing proportion design is less aiming at the characteristics of different kinds of calcareous stone powder. Therefore, on the basis of determining the influence rule of different types of calcareous stone powder in concrete, the method for comprehensively utilizing the stone powder has important significance for the application of machine-made sand concrete.

The fly ash, the mineral powder and the silica fume are common mineral admixtures, the calcareous stone powder can participate in the formation of a concrete structure, and the compatibility of functional chemical materials is obviously influenced, so that the rheological property, the mechanical property and the long-term service performance of the concrete are changed. The invention patent CN102674782A discloses a method for preparing concrete by using basalt micropowder-slag micropowder-limestone powder as admixture, the raw materials are composed of gelled material, excitant, aggregate, admixture and water; the cementing material is formed by compounding cement, basalt micropowder, slag micropowder and limestone powder, CN103626438A discloses an anti-crack high-strength limestone resource full-utilization concrete, the concrete consists of water, cement, limestone powder, machine-made sand, broken stone, fiber, a shrinkage reducing agent and a water reducing agent, CN108191337A discloses a concrete prepared by using artificial sand and limestone powder, and the concrete comprises the following raw materials in parts by weight: 340-480 parts of a cementing material, 690-820 parts of an admixture, 990-1100 parts of a coarse aggregate, 190-210 parts of water and 1-3 parts of a water reducing agent; the cementing material consists of cement and fly ash; the admixture is composed of artificial sand and stone powder, and CN110981335A discloses a preparation method and a use method of a novel concrete anti-cracking cementing material, wherein the cementing material comprises the following raw materials in percentage by mass: 2-10% of limestone powder, 20-40% of fly ash, 20-40% of slag powder, 1-3% of a water reducing agent and the balance of cement. However, none of the above patent documents classifies the stone powder according to its lithological properties and types, and in order to prevent cracking of the concrete, it is necessary to add shrinkage reducing agent or expanding agent during the mixing of the concrete, thereby increasing the construction cost.

Based on the influence law of different kinds of calcareous stone powder on the performance of concrete, the method selects different kinds of mineral admixtures and different kinds of polycarboxylic acid high-performance water reducing agents in a mode of making up for deficiencies, reasonably designs the mix proportion of the concrete, and carries out full index test and crack risk assessment to obtain the method for preparing the high-crack-resistance premixed concrete by using the calcareous stone powder.

Disclosure of Invention

Aiming at the problems of the existing stone powder in the preparation of concrete, the invention discloses a method for preparing high-crack-resistance premixed concrete by using calcareous stone powder. By researching the influence rule of different kinds of calcareous stone powder on the workability, compressive strength and shrinkage of concrete, different kinds of mineral admixtures and different kinds of water reducing agents are reasonably matched, and on the basis of not adding a shrinkage reducing agent or an expanding agent, the high-crack-resistance premixed concrete is prepared, and the refinement and resource utilization of the calcareous stone powder are realized.

The invention relates to high-crack-resistance premixed concrete prepared from calcareous stone powder, which specifically comprises a cementing material, sand, stone, an additive and water.

Specifically, the cementing material consists of cement, stone powder and mineral admixture.

Specifically, the dosage of the cementing material is more than or equal to 330kg/m³。

Specifically, the cement accounts for 70-80% of the cementing material, the stone powder accounts for 10-15% of the cementing material, and the mineral admixture accounts for 5-15% of the cementing material.

Specifically, the mineral admixture comprises at least one of fly ash, mineral powder, silica fume and microbeads.

Specifically, the calcareous stone powder comprises at least one of limestone powder, marble stone powder and dolomite rock powder. Specifically, the sand comprises river sand and machine-made sand, the stone is 5-25 mm continuous graded broken stone, the concrete sand rate is 40-50%, and the water-to-glue ratio is 0.35-0.50.

Specifically, the admixture is a polycarboxylic acid high-performance water reducing agent, and comprises at least one of a water-reducing polycarboxylic acid high-performance water reducing agent and a slump-retaining polycarboxylic acid high-performance water reducing agent, and the water reducing agent is a product sold by the applicant or other products sold on the market.

Specifically, the calcareous stone powder is limestone powder, and the mineral admixture is a mixture of mineral powder and silica fume; research shows that limestone powder has little influence on the workability of concrete, but can reduce the mechanical property of the concrete and improve the shrinkage rate of the concrete. The limestone powder is compounded with the mineral powder and the silica fume to make up the disadvantages of the limestone powder in mechanical property and shrinkage performance, on the basis, the concrete mixing proportion design can meet the requirements, the high crack resistance premixed concrete prepared from the limestone powder has no special requirements on the water reducing agent, and the composition of the water reducing agent can be compounded and adjusted according to the requirements on the fluidity and slump retention of the concrete.

The calcareous stone powder is marble stone powder, and the mineral admixture is a mixture of microbeads and silica fume; researches show that the marble stone powder has large influence on the initial fluidity of concrete, the slump loss of the concrete is fast, and the shrinkage rate is large, so that a water-reducing polycarboxylic acid high-performance water reducing agent and a slump-retaining polycarboxylic acid high-performance water reducing agent are used in a compounding way; the microbeads are adopted as mineral admixture, so that the adverse effect of marble stone powder on the initial fluidity of concrete can be partially offset, and the reduction of the mixing amount of the water reducer is facilitated; the adoption of the silica fume as the admixture can effectively reduce the shrinkage of the concrete prepared from the marble stone powder.

The limestone powder is dolomite limestone powder, and the mineral admixture is mineral powder; researches show that the dolomite powder has small influence on the initial fluidity of the concrete, but easily causes the accelerated slump loss of the concrete, has a micro-expansion effect and can compensate the concrete shrinkage. Therefore, the dolomite fines for preparing the high-crack-resistance ready-mixed concrete preferably adopt the mineral powder as a mineral admixture, and adopt the water-reducing polycarboxylic acid high-performance water reducing agent and the slump-retaining polycarboxylic acid high-performance water reducing agent for compounding use, thereby reducing the slump loss of the concrete, improving the compressive strength and simultaneously reducing the shrinkage.

The invention also relates to a method for preparing the high-crack-resistance premixed concrete by using the calcareous stone powder, which specifically comprises the following steps:

1) preparing clear paste, mortar or common concrete for different lithologic calcareous stone powders, and determining the workability, compressive strength, shrinkage cracking performance and adaptability of an additive;

2) according to the types of the calcareous stone powder, different types of mineral admixtures and different types of admixtures are matched to carry out concrete tests, and the selection and matching of different lithologic calcareous stone powders, the mineral admixtures and the admixtures are determined;

3) weighing the raw materials according to the test result of the step 2), and uniformly mixing to prepare the high crack resistance premixed concrete.

According to the invention, different kinds of mineral admixtures and additives are blended by analyzing the characteristics of different kinds of calcareous stone powder, wherein the mineral admixtures and the calcareous stone powder are matched for mainly improving the problem of shrinkage cracking of concrete, and the additives are selected for mainly realizing the adjustment of the initial fluidity and the fluidity maintenance of the concrete, so that the preparation of the high-crack-resistance premixed concrete by the calcareous stone powder is realized under the condition of not additionally adding a shrinkage reducing agent or an expanding agent, the manufacturing cost of the concrete is reduced, the refinement and resource utilization of the calcareous stone powder are realized, and the problems of the work deterioration and the shrinkage cracking of the concrete caused by the blending of the calcareous stone powder are also avoided.

Detailed Description

PO42.5 ordinary portland cement, secondary fly ash, S95 mineral powder, silica fume and microbeads are used as cementing materials, different lithologic stone powder is added, proper additives, river sand, 5-10mm and 10-25mm continuous graded large stone and small stone are selected as raw materials to be mixed with concrete, the performance and the hardening performance of freshly mixed concrete are tested, and the mass unit of each raw material in the mixing proportion is kg/m³。

The experimental process sets up benchmark concrete JZ, and the mix proportion is: 304 cement, 76 fly ash, 888 sand, 288.6 small stone, 673.4 large stone, 160 water and 5.32kg of additive, wherein the additive is a water-reducing polycarboxylic acid high-performance water reducing agent.

Example 1

The high-crack-resistance premixed concrete S1 comprises the following components in percentage by weight: cement 304, silica fume 19, mineral powder 19, limestone powder 38, sand 888, small stones 288.6, large stones 673.4, water 160 and an additive 5.32kg, wherein the additive is a water-reducing polycarboxylic acid high-performance water reducing agent.

Example 2

The high-crack-resistance premixed concrete D1 comprises the following components in parts by weight: cement 304, silica fume 19, micro-beads 19, marble stone powder 38, sand 888, small stone 288.6, large stone 673.4, water 160 and an additive 5.32kg, wherein the additive is a compound water reducing agent of a water reducing polycarboxylic acid high-performance water reducing agent and a slump retaining polycarboxylic acid high-performance water reducing agent.

Example 3

The high-crack-resistance premixed concrete B1 comprises the following components in parts by weight: 304 cement, 38 mineral powder, 38 dolomite stone powder, 888 sand, 288.6 small stone, 673.4 large stone, 160 water and 5.32kg of additive, wherein the additive is a compound water reducing agent of a water reducing polycarboxylic acid high-performance water reducing agent and a slump retaining polycarboxylic acid high-performance water reducing agent.

Comparative example 1

The premixed concrete S2 comprises the following components in percentage by weight: cement 304, silica fume 19, fly ash 19, limestone powder 38, sand 888, small stones 288.6, large stones 673.4, water 160 and an additive 5.32kg, wherein the additive is a water-reducing polycarboxylic acid high-performance water reducing agent.

Comparative example 2

The premixed concrete D2 comprises the following components in percentage by weight: cement 304, mineral powder 19, fly ash 19, marble stone powder 38, sand 888, small stone 288.6, large stone 673.4, water 160 and an additive 5.32kg, wherein the additive is a compound water reducing agent of a water reducing polycarboxylic acid high-performance water reducing agent and a slump retaining polycarboxylic acid high-performance water reducing agent.

Comparative example 3

The premixed concrete B2 comprises the following components in percentage by weight: cement 304, silica fume 38, dolomite stone powder 38, sand 888, small stone 288.6, large stone 673.4, water 160 and an additive 5.32kg, wherein the additive is a compound water reducing agent of a water reducing polycarboxylic acid high-performance water reducing agent and a slump retaining polycarboxylic acid high-performance water reducing agent.

The performance parameters of the reference concrete, the example concrete and the comparative concrete are shown in table 1.

TABLE 1 test results of concrete Performance parameters

	JZ	S1	D1	B1	S2	D2	B2
								Initial slump/mm	210	205	215	210	190	185	190
Workability	Good wine	Good wine	Good wine	Good wine	Good wine	In	Good wine
								Isolated bleeding	Is free of	Is free of	Is free of	Is free of	Micro-meter	Is free of	Micro-meter
1d adiabatic temperature rise value	26.1	18.9	19.2	19.5	23.7	22.8	24.1
								3d adiabatic temperature rise value	38.2	37.2	38.4	37.5	37.6	37.7	37.9
7d adiabatic temperature rise value	40.0	39.2	40.5	40.4	39.7	40.1	40.9
								Slump loss of 1 h/mm	/	10	5	10	20	15	20
Slump 2h loss/mm	/	20	15	15	40	40	45
								28d compressive strength/MPa	42.1	42.5	43.2	42.2	41.5	41.1	41.2
Tensile strength at cleavage/MPa	3.05	4.05	4.23	4.33	3.15	3.34	3.26
								Static compression modulus of elasticity/GPa	31.4	33.2	35.4	33.8	31.3	32.5	31.8
Shrinkage test (. mu.. di-elect cons.) 3d	79	68	67	68	266	315	287
								Shrinkage test (. mu.. di-elect cons.) 28d	136	119	120	124	384	396	391
300 times frost resistance	/	F300	F300	F300	/	/	/
								Resistance to chloride ion penetration (RCM method) 10-12m2/s	/	8.2	8.8	8.0	/	/	/