阅读说明：本技术 超大面积混凝土地面及其裂缝控制方法 (Super-large-area concrete ground and crack control method thereof ) 是由 李菁 余登飞 于 2021-08-06 设计创作，主要内容包括：超大面积混凝土地面及其裂缝控制方法涉及建筑领域。超大面积混凝土地面,自上而下依次为混凝土面层、应力吸收层、混凝土垫层、碎石层；所述混凝土面层的原料中含有钢纤维和聚丙烯纤维。本发明将钢纤维和聚丙烯纤维掺入轻骨料混凝土中,大大提高了混凝土的立方体抗压强度和劈裂抗拉强度,从而有利于控制或减少裂缝的出现。(A super-large area concrete ground and a crack control method thereof relate to the field of buildings. The concrete ground with the super-large area sequentially comprises a concrete surface layer, a stress absorption layer, a concrete cushion layer and a crushed stone layer from top to bottom; the concrete surface layer comprises steel fibers and polypropylene fibers. According to the invention, the steel fibers and the polypropylene fibers are doped into the lightweight aggregate concrete, so that the cubic compressive strength and the splitting tensile strength of the concrete are greatly improved, and the occurrence of cracks is favorably controlled or reduced.)

1. The concrete ground with the ultra-large area is characterized in that a concrete surface layer, a stress absorption layer, a concrete cushion layer and a crushed stone layer are sequentially arranged from top to bottom;

the concrete surface layer comprises steel fibers and polypropylene fibers.

2. The concrete floor having an oversized area as recited in claim 1, wherein said stress absorbing layer is made of a material containing asphalt and sand.

3. The concrete floor with ultra large area according to claim 1, wherein a protective layer is further arranged above the concrete surface layer, and the protective layer sequentially comprises from top to bottom: a top coating formed by coating the solvent-free epoxy finish paint, a stirring layer formed by coating the solvent-free epoxy paint and carborundum aggregate after mixing, a coating layer formed by coating the solvent-free epoxy primer and a wear-resistant ground layer formed by coating the metal aggregate.

4. The concrete floor of claim 1, wherein the concrete floor is filled with foam boards at the interface with the wall and the wall stud, and the foam boards are located on the stress absorbing layer.

5. The ultra large area concrete floor of claim 1, wherein reinforcing steel is provided within said gravel layer or below said gravel layer.

6. The crack control method for the ultra-large area concrete ground according to claim 1, wherein the preparation method of the raw materials of the concrete surface layer comprises the following steps:

(1) preparation:

stacking all raw materials respectively, wherein the raw materials comprise cement, fine aggregate, coarse aggregate, fly ash, a water reducing agent, water, steel fiber and polypropylene fiber;

(2) and (3) dry mixing:

mixing and dry-mixing cement, fine aggregate, coarse aggregate, fly ash, steel fiber and polypropylene fiber to obtain premix, wherein the volume ratio of the steel fiber isThe volume fraction of the polypropylene fiber is

(3) Adding water and mixing:

adding or reducing water agent and water into the premix, and stirring and mixing to obtain the concrete surface layer raw material.

7. The crack control method for the ultra-large area concrete ground according to claim 6, further comprising a stress absorption layer formed by paving a mixture of asphalt and sand between the concrete ground layer and the cushion layer, wherein the asphalt content percentage in the stress absorption layer is 70-75%.

8. The crack control method for concrete floor with extra large area as claimed in claim 6, wherein the place where the wall, the wall pillar and the concrete floor with extra large area are connected is filled with a foam board, the foam board separates the concrete surface layer from the wall and the wall pillar.

9. The crack control method for ultra-large area concrete ground according to claim 6, wherein the concrete cushion layer is prepared by a layer-by-layer casting method, and a new layer of concrete is cast after the previously cast concrete is soaked or the previously cast concrete surface is coated with high-grade mortar.

10. The crack control method for the ultra-large area concrete ground according to claim 6, wherein the primary pouring length of the ground layer is calculated without setting the expansion joint:

the calculation formula is as follows: l-27.093 b_t-27.029〃+15.665，

In the formula: l is the maximum one-time pouring length without cracking of the concrete floor layer, and the unit is m;

b_tthe design value of the tensile strength in the concrete ground surface layer is expressed in MPa;

"is the coefficient of friction between the structural layers.

Technical Field

The invention relates to the field of buildings, in particular to a concrete floor crack control method and a prepared concrete floor.

Background

The specified thickness in GB/T51025-2016 of super large area concrete ground seamless construction technical Specification of China is not more than 700mm, the short edge is not less than 40m, or the area is not less than 1600m²The concrete ground which needs to take special technical measures to prevent the temperature change and the contraction of the concrete from generating harmful cracks is the concrete ground with an ultra-large area.

Due to the consideration of the appearance and the use function of the structure, the extra-large area concrete structure needs no seam or few seams. If the extra-large area concrete structure is not provided with a seam, cracks can easily appear, the appearance and the durability of the structure can be influenced by the appearance of the cracks, and the life and property safety of people can be influenced more seriously. The main reason for cracking of the concrete with the oversized area is that the internal and external temperature and moisture of a structure or a member change, so that the volume of the concrete shrinks or expands, when the shrinkage and expansion of the concrete are restrained, the internal part of the concrete generates tensile stress, and when the internal tensile stress of the concrete exceeds the tensile strength of the concrete, the concrete cracks.

Disclosure of Invention

The invention aims to provide a concrete floor with an ultra-large area, which can not generate cracks for a long time when no cracks are arranged.

The invention also aims to provide a crack control method of the concrete ground with the ultra-large area, so as to reduce or relieve the generation of cracks of the concrete ground with the ultra-large area.

The technical problem solved by the invention can be realized by adopting the following technical scheme:

the concrete ground with the ultra-large area is characterized in that a concrete surface layer, a stress absorption layer, a concrete cushion layer and a crushed stone layer are sequentially arranged from top to bottom;

the concrete surface layer comprises steel fibers and polypropylene fibers.

Firstly, the steel fiber and the polypropylene fiber are doped into the lightweight aggregate concrete, so that the cubic compressive strength and the splitting tensile strength of the concrete are greatly improved, and the occurrence of cracks is favorably controlled or reduced. In addition, the doped fibers are selected, and the selected steel fibers and the selected polypropylene fibers do not influence the mix proportion of the concrete, are simple to operate and do not influence the construction period. Finally, the invention optimizes the layer structure of the concrete ground, adds the stress absorbing layer between the concrete surface layer and the concrete cushion layer, reduces the interlayer binding force between two adjacent layers of concrete through the stress absorbing layer, and can further control or reduce the occurrence of cracks.

Preferably, the raw material of the stress absorbing layer contains asphalt and sand. The restraint stress that the concrete surface course received has greatly reduced, but can not cause the bearing capacity's of concrete surface course reduction.

Preferably, the top of concrete surface course still is provided with the inoxidizing coating, and the inoxidizing coating is from last to being down in proper order: a top coating formed by coating the solvent-free epoxy finish paint, a stirring layer formed by coating the solvent-free epoxy paint and carborundum aggregate after mixing, a coating layer formed by coating the solvent-free epoxy primer and a wear-resistant ground layer formed by coating the metal aggregate. According to the concrete floor, the protective layer is arranged above the surface layer, so that the surface layer is prevented from being damaged by external factors, and the service life of the concrete floor is prolonged.

Preferably, the ultra-large area concrete ground is filled with a foam board at the junction with the wall body and the wall column, and the foam board is positioned on the stress absorption layer. Thereby the hard connection of wall body or wall post is cut off to the concrete surface course, makes the concrete surface course self-contraction, and then further control or reduce the appearance of crack.

Preferably, reinforcing steel bars are arranged in the gravel layer or below the gravel layer. Thereby supporting the concrete ground with an oversized area.

The crack control method of the concrete ground with the ultra-large area is characterized in that the preparation method of the raw materials of the concrete surface layer comprises the following steps:

(1) preparation:

stacking all raw materials respectively, wherein the raw materials comprise cement, fine aggregate, coarse aggregate, fly ash, a water reducing agent, water, steel fiber and polypropylene fiber;

(2) and (3) dry mixing:

mixing and dry-mixing cement, fine aggregate, coarse aggregate, fly ash, steel fiber and polypropylene fiber to obtain premix, wherein the volume ratio of the steel fiber isThe volume fraction of the polypropylene fiber is

(3) Adding water and mixing:

adding or reducing water agent and water into the premix, and stirring and mixing to obtain the concrete surface layer raw material.

Preferably, the concrete pavement further comprises a stress absorption layer formed by adding a mixture of asphalt and sand between the concrete ground layer and the cushion layer, wherein the asphalt in the stress absorption layer accounts for 70-75% by mass

Preferably, the place of the juncture of the wall body, the wall column and the oversized area concrete ground is filled with a foam board, and the foam board separates the concrete surface layer from the wall body and the wall column.

Preferably, the concrete cushion layer is prepared by adopting a layer-by-layer pouring method, and a new layer of concrete is poured after the concrete which is poured firstly is soaked or the high-grade mortar is coated on the surface of the concrete which is poured firstly.

Preferably, the primary pouring length of the ground layer is calculated under the condition that no expansion joint is arranged:

the calculation formula is as follows: l-27.093 b_t-27.029 "plus 15.665, wherein: l is the maximum one-time pouring length without cracking of the concrete floor layer, and the unit is m; b_tThe design value of the tensile strength in the concrete ground surface layer is expressed in MPa; "is the coefficient of friction between the structural layers.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below.

The crack control method of the concrete ground with the ultra-large area comprises a preparation method of raw materials of a concrete surface layer, and comprises the following steps:

(1) preparation:

stacking all raw materials respectively, wherein the raw materials comprise cement, fine aggregate, coarse aggregate, fly ash, a water reducing agent, water, steel fiber and polypropylene fiber;

(2) and (3) dry mixing:

mixing and dry-mixing cement, fine aggregate, coarse aggregate, fly ash, steel fiber and polypropylene fiber to obtain premix, wherein the volume ratio of the steel fiber isThe volume fraction of the polypropylene fiber is According to the invention, the steel fiber with the volume ratio of 0.12-0.18% and the polypropylene fiber with the volume ratio of 0.10-0.14% are added into the concrete, and after the steel fiber and the polypropylene fiber are doped into the lightweight aggregate concrete, the cubic compression strength and the splitting tensile strength of the concrete are greatly improved; the length-diameter ratio of the polypropylene fibers is 167-281, so that the ultimate tensile bearing capacity of the concrete is improved; the steel fiber and the polypropylene fiber do not influence the design of the mix proportion of the concrete, so the operation is simple, the construction period is not influenced, and the application prospect in the control of cracks of the concrete floor surface layer with the ultra-large area is good. Meanwhile, the light concrete can effectively reduce the friction cohesion between the concrete surface layer and the cushion layer.

(3) Adding water and mixing:

adding or reducing water agent and water into the premix, and stirring and mixing to obtain the concrete surface layer raw material. The water consumption of concrete can be effectively reduced by adopting the doping of the water reducing agent, the cement consumption can be reduced by the doping of the water reducing agent under the same strength requirement, so that the hydration heat of cement is reduced, and meanwhile, the fluidity and the workability of concrete can be enhanced by the doping of the water reducing agent; the steel fiber and the polypropylene fiber are firstly mixed in a dry mode and then mixed with water, so that the dispersibility and uniformity of the steel fiber and the polypropylene fiber in concrete are guaranteed; the coarse aggregate concrete has large pores, and when the cement is hydrated and dehydrated, the water in the pores of the aggregate can be transferred into the cement mortar with smaller pore diameter, so that the self-shrinkage of the cement is greatly reduced.

The concrete surface layer prepared by the invention is made of lightweight aggregate concrete, the lightweight aggregate concrete is concrete adopting lightweight aggregate, and the apparent density is not more than 1950kg/m³. The lightweight aggregate concrete has the characteristics of light weight, high strength, heat preservation, fire resistance and the like, and has good deformability, lower elastic modulus, and contraction and creep in general conditionsAnd is also larger.

Construction preparation of concrete surface layer raw materials: the base layer is inspected according to relevant specifications, and the surface of the base layer is soaked by sprinkling water before the surface layer is poured.

Transportation of concrete surface layer raw materials: the transportation time is controlled within 30min, and the transportation is carried by a tank truck with a mixing function. By shortening the transportation time, the slump of the steel-polypropylene fiber concrete is reduced by about a half after 30 min.

In the step (2), the steel fiber is corrugated steel fiber, and the main properties of the corrugated steel fiber are as follows: diameter of 30mm, length of 0.6mm, length-diameter ratio of 50 and tensile strength of 506 MPa. The invention can effectively inhibit the shrinkage cracking of the lightweight aggregate concrete by doping the steel fibers in the concrete, and improves the tensile strength and the toughness of the concrete. The main properties of polypropylene fibers: the density was 0.91g/cm³34.2mm in diameter, 19mm in length, 599MPa in breaking strength, 27.6% in elongation at break and 4665MPa in elastic modulus. According to the invention, the polypropylene fibers are added into the concrete, so that the number of the polypropylene fibers in the concrete per unit area is large, the compactness of the concrete can be improved, the frost resistance, the impermeability and the corrosion resistance to various harmful media of the concrete are enhanced, and the service life of a fiber concrete building is prolonged.

The method for reducing the binding strength between concrete layers comprises the following steps:

and adding asphalt-sand mixed material between the concrete ground layer and the cushion layer to serve as a stress absorption layer. The invention adopts the asphalt-sand mixed material as the stress absorbing layer, thereby greatly reducing the constraint stress of the concrete surface layer without reducing the bearing capacity of the concrete surface layer. The mass content percentage of the asphalt in the stress absorbing layer is 70-75%, and the friction coefficient of the asphalt-sand stress absorbing layer is 0.15-0.2. In the asphalt-sand stress absorbing layer, when the weight percentage of asphalt is 75%, the friction coefficient is only 0.15, so that the constraint effect of the cushion layer on the concrete surface layer is greatly reduced, the constraint stress of the concrete surface layer is also greatly reduced, and the one-time pouring length is increased. The asphalt in the stress absorbing layer adopts AH-70 road petroleum asphalt. The invention adopts asphalt as a high-viscoelasticity material, has strong deformation recovery capability, and particularly has an effect on the homing of the concrete after shrinkage or expansion deformation. The sand in the stress absorption layer is standard sand. The invention adopts the standard sand as the other main component of the asphalt-sand stress absorbing layer material, has the characteristics of convenient material acquisition, high strength, good durability and no influence on the material performance by the external environment, and particularly has the advantages of low manufacturing cost, convenient construction and no influence on the construction period. By adopting the method, the measures of arranging the post-pouring belt and the construction joints adopted in the traditional construction method are omitted, and few or no joints are arranged in the design and construction of the concrete floor with the ultra-large area.

The method for reducing the edge constraint strength of the concrete floor layer comprises the following steps:

firstly, placing a foam board on a peripheral wall body to separate the peripheral wall body from a cast-in-place concrete floor layer, and enabling the cast-in-place concrete floor layer to be capable of freely shrinking; secondly, the constraint between the concrete floor and the column is the same as that of the wall body, and the periphery of the column is completely separated by the foam board; and after the concrete ground surface layer is poured, cutting off the foam board higher than the concrete ground surface layer, and trowelling the foam board between the concrete ground surface layer and the peripheral wall body or the column by using cement mortar. The invention adopts the foam plate for partition, reduces the restriction on the concrete floor and prevents the generation of cracks.

The method for reducing the constraint strength between the cast-in-place concrete and the cast-in-place concrete comprises the following steps:

the method comprises the following steps of soaking the concrete poured firstly or coating high-grade mortar on the surface of the concrete poured firstly, and then carrying out the subsequent concrete pouring process. The invention adopts the mode that the concrete poured in advance is soaked or the high-grade mortar is coated on the surface of the concrete poured in advance, thereby preventing the water on the contact surface from being sucked away by the concrete poured in advance, influencing the contraction of the concrete to generate cracks and improving the cohesive force of the concrete poured in advance.

The method for configuring the anti-crack reinforcing steel bar comprises the following steps:

the method comprises the following steps that reinforcing steel bars with the diameter of 8-10 mm are selected for the arrangement of the concrete ground structure with the ultra-large area, the distance between longitudinal bars is 10-30 cm, and the distance between transverse bars is 20-60 cm; the reinforcing bar is established 5 ~ 6cm departments under the board surface, has reduced the interval of reinforcing bar. The invention reduces the space between the steel bars, thereby increasing the number of the steel bars in unit area, further increasing the contact surface between the steel bars and the concrete, reducing the temperature shrinkage stress on the concrete and preventing the concrete from generating cracks. The side wall of the reinforcing steel bar in the tenth embodiment is provided with the reticular veins, so that the bonding force with concrete is increased while the area is further increased.

The method adopts a jumping-cabin method for construction, which fully utilizes the 'resisting and releasing' characteristic principle that the performance of concrete is not stable in a period of 5 to 10 days and internal stress is easy to release before the concrete is completely solidified, divides a large-area concrete plane mechanism into a plurality of areas, and constructs according to the principles of 'block planning, block partition construction, layered pouring and integral forming', and the mode of the method is the same as that of Chinese checkers, namely, one section is poured at intervals. The interval time of two adjacent sections is not less than 7 days, so that the violent temperature difference and drying action of the initial concrete construction part are avoided, and a post-cast strip is not required to be left. Calculating the primary pouring length of the ground layer under the condition of not arranging an expansion joint: the calculation formula is as follows: l-27.093 b_t-7.029 "plus 15.665, wherein: l is the maximum one-time pouring length without cracking of the concrete floor layer, and the unit is m; b_tThe design value of the tensile strength in the concrete ground surface layer is expressed in MPa; "is the coefficient of friction between the structural layers. The invention fits the one-time maximum pouring length L without cracking of the concrete floor layer and the design value b of the tensile strength in the concrete floor layer through a fitting relation_tAnd the friction coefficient between the structural layers, the probability of crack generation is further reduced and the time of crack generation is delayed by checking the calculation of large-scale finite element analysis software ABAQUS and accurately controlling the one-time pouring length.

The concrete ground prepared by the crack control method of the concrete ground with the ultra-large area has the following structure from top to bottom: the surface layer is a C25 fine stone concrete layer with the thickness of 100 mm; the stress absorbing layer is A thick asphalt-sand mix; the cushion layer is a C25 concrete cushion layer with the thickness of 200 mm; the base layer is a 300mm thick graded crushed stone layer, wherein the surface layer is added with 0.12-0.18% of steel fiber and 0.10-0.14% of polypropylene fiber in volume ratio, and the length-diameter ratio of the polypropylene fiber is 167-281, and the mixture is mixed and dry-mixed. According to the invention, the steel fiber with the volume ratio of 0.12-0.18% and the polypropylene fiber with the volume ratio of 0.10-0.14% are added into the concrete, and after the steel fiber and the polypropylene fiber are doped into the lightweight aggregate concrete, the cubic compression strength and the splitting tensile strength of the concrete are greatly improved; the length-diameter ratio of the polypropylene fibers is 167-281, so that the ultimate tensile bearing capacity of the concrete is improved; the steel fiber and the polypropylene fiber do not influence the design of the mix proportion of the concrete, so the operation is simple, the construction period is not influenced, and the application prospect in the control of cracks of the concrete floor surface layer with the ultra-large area is good.

The surface course top on concrete ground still is provided with the inoxidizing coating, and the structure of inoxidizing coating is from last to being down in proper order: a solvent-free epoxy topcoat of 1mm thickness; a mixed stirring layer of solvent-free epoxy intermediate coating material with the thickness of 1mm and carborundum aggregate; a solvent-free epoxy primer layer; the metal aggregate wear-resistant ground layer. The protective layer is arranged above the surface layer, so that the surface layer is prevented from being damaged by external factors, and the service life of the concrete ground is prolonged.

In specific implementation, the steel-polypropylene fiber reinforced concrete crack resistance mechanism is as follows: because the polypropylene fiber has higher tensile strength, the polypropylene fiber can absorb the energy generated by the concrete shrinkage when being added into the concrete. The method can effectively prevent the development of concrete microcracks, prevent new cracks from being generated, enhance the continuity inside the structure and well solve the problem of brittleness of the concrete. The polypropylene fiber has small density, and after the polypropylene fiber is added into concrete, the crack resistance and the plastic shrinkage resistance of the concrete are greatly improved. This is mainly because polypropylene fibers have a low elastic modulus and good flexibility, and when they are distributed in concrete, they can form a three-dimensional disorientation supporting net, which can act like a sunning net.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.