阅读说明：本技术 一种基于混凝土收缩理论的楼地面抗裂做法 (Floor anti-cracking method based on concrete shrinkage theory ) 是由 徐大为 张志敏 于 2021-10-21 设计创作，主要内容包括：本发明涉及一种基于混凝土收缩理论的楼地面抗裂做法,属于混凝土结构施工技术领域,用于解决混凝土收缩裂缝的问题。该方法,首先,由下至上依次完成现浇混凝土楼板、一道素水泥浆、细石混凝土找坡打平层组成的基底层施工,其次,划分混凝土浇筑区域和后浇带,在混凝土浇筑区域铺设钢筋网,钢筋网远离墙体和基底层的两个侧面布置方钢,连接螺杆配套设置单线螺母,单线螺母设置于方钢远离钢筋的一侧；然后,浇筑混凝土形成细石混凝土面层；接着,根据混凝土收缩公式计算单位混凝土收缩量,并计算混凝土在沿收缩方向上的收缩量,依据计算的横向扭转件的位移值推动扭转装置进行收缩补偿操作；最后,拆除回收方钢和扭转装置,浇筑后浇带并养护。(The invention relates to a building floor anti-cracking method based on a concrete shrinkage theory, belongs to the technical field of concrete structure construction, and is used for solving the problem of concrete shrinkage cracks. The method comprises the following steps of firstly, completing construction of a base layer consisting of a cast-in-place concrete floor slab, a plain cement mortar and a fine aggregate concrete slope-finding leveling layer from bottom to top in sequence, secondly, dividing a concrete pouring area and a post-pouring belt, laying a reinforcing mesh in the concrete pouring area, arranging square steel on two sides of the reinforcing mesh, which are far away from a wall body and the base layer, arranging a single-wire nut matched with a connecting screw rod, and arranging the single-wire nut on one side, which is far away from the reinforcing steel, of the square steel; then, pouring concrete to form a fine aggregate concrete surface layer; secondly, calculating the unit concrete shrinkage according to a concrete shrinkage formula, calculating the shrinkage of the concrete in the shrinkage direction, and pushing a torsion device to perform shrinkage compensation operation according to the calculated displacement value of the transverse torsion piece; and finally, dismantling the recovered square steel and the torsion device, pouring a post-cast strip and maintaining.)

1. A building floor anti-cracking method based on a concrete shrinkage theory is characterized by comprising the following steps:

s1, sequentially completing construction of a base layer consisting of a cast-in-place concrete floor slab, a plain cement slurry and a fine aggregate concrete slope finding and leveling layer from bottom to top, reserving a construction operation space as a post-cast strip, laying a reinforcing mesh on the base layer, arranging square steel on two sides of the reinforcing mesh, which are far away from a wall body and the base layer, through connecting screws, arranging single-wire nuts in a matched manner on the connecting screws, and arranging the single-wire nuts on one sides of the square steel, which are far away from the reinforcing steel;

s2, after the reinforcing mesh in the S1 is laid, pouring concrete to form a fine aggregate concrete surface layer;

and S3, after the concrete of the fine aggregate concrete surface layer is finally set in the step S2, twisting the single-line nut, and performing shrinkage compensation operation.

2. The anti-crack practice of claim 1, wherein the shrinkage compensation operation in step S3 comprises:

step S31, calculating the unit concrete shrinkage according to a concrete shrinkage formula, wherein the concrete shrinkage formula is as follows:

wherein, in the step (A),the concrete shrinkage at any time in unit length is as follows: mm/mm; t is time, unit: day; b is that the empirical coefficient is generally 0.01, and 0.03 is taken when the curing is poor; epsilon_y ⁰The ultimate shrinkage under the standard state is 3.24 multiplied by 10^-4The unit: mm/mm; m1 and M2 … Mn are ethyleneCarrying out actual engineering correction value according to a corresponding value taking table in an engineering structure crack control book; the first formula is the shrinkage of the concrete in the shrinkage direction, and the first formula is as follows:wherein D is the length of the concrete along the contraction direction, and the unit is as follows: the thickness of the film is mm,the concrete shrinkage at any time is shown as the following unit: mm;

step S32, providing a torsion device, wherein the torsion device comprises a transverse torsion piece and a vertical torsion piece which are fixedly connected, the vertical torsion piece is an L-shaped component, and the transverse torsion piece is fixedly arranged at the upper end of the vertical torsion piece; the lower end of the vertical torsion piece is matched with the single-thread nut in the step S1, and the single-thread nut is twisted by pushing the transverse torsion piece;

step S33, calculating the pushing length of the transverse torsion piece according to a second formula, so as to realize concrete compression compensation, wherein the second formula is as follows:wherein: x is the displacement value of the transverse torsion member, unit: mm; l is the length of the vertical twist, in units: mm; delta is the concrete shrinkage increment per day, namely the difference of the concrete shrinkage on two adjacent days; p is the single-thread nut pitch, unit: mm.

3. The anti-crack practice of claim 2, further comprising a step S4, after the concrete curing is finished, dismantling and recovering the square steel and the torsion device, and completing the post-cast strip construction and curing of the construction operation space in the step S1, thereby completing the construction of the heat-insulating fine stone concrete floor.

4. The method for crack resistance according to claim 1, wherein the construction operation space in step S1 is a rectangular area enclosed by 20 cm length in both the transverse direction and the longitudinal direction of the surface of the substrate layer.

5. The anti-cracking method according to claim 1, wherein one end of the connecting screw is welded to the steel bar, and the other end of the connecting screw passes through a preformed hole in the square steel and is locked and fixed after being rotated to a predetermined position by the single-thread nut.

6. The method of claim 5, wherein the reinforcing mesh is laid in one direction and then the reinforcing bars in the other direction are laid.

7. The anti-crack practice of claim 5 wherein the single-thread nut is an M8 single-thread A-grade fine-thread nut.

Technical Field

The invention relates to the technical field of concrete structure construction, in particular to a floor anti-cracking method based on a concrete shrinkage theory.

Background

The fine stone concrete floor is one of the main forms of floor engineering of civil buildings such as houses in China at present, and has the advantages of low cost, good technical performance, long service life and convenient construction and maintenance. The traditional fine-stone concrete ground is prepared as follows:

if a certain building ground adopts a reinforced concrete floor slab or a prefabricated slab, firstly, a base layer is processed, then, the elevation and the surface layer horizontal line are flicked, a leveling mark is made, cement paste is coated once (building glue is doped in the cement paste), then, 25-thick cement-based inorganic heat-insulating mortar type III is coated, finally, a 40-thick C25 fine stone concrete surface layer is arranged, and maintenance is carried out after vibrating, compacting, leveling and calendaring.

However, the conventional fine stone concrete floors are highly susceptible to cracks during daily use, and are classified into cracks caused by load, cracks caused by deformation, and cracks caused by mixing according to the cause of crack generation, wherein the cracks caused by the deformation change of the concrete account for 80%. It can be said that most cracks in concrete are caused by the deformation of the concrete itself.

Therefore, it is necessary to develop a floor crack resistance method based on the concrete shrinkage theory to solve the above technical problems.

Disclosure of Invention

The invention aims to provide a floor anti-cracking method based on a concrete shrinkage theory, which calculates the shrinkage value of concrete at any time by combining a relevant theoretical calculation formula with actual engineering conditions, applies certain deformation compensation to the concrete during the concrete curing period by utilizing a twisting device, fully meets the shrinkage conditions and reduces the possibility of concrete cracking from the source.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a building floor anti-cracking method based on a concrete shrinkage theory comprises the following steps:

step S1, sequentially completing construction of a base layer consisting of a cast-in-place concrete floor slab, plain cement paste and a fine aggregate concrete slope finding and leveling layer from bottom to top, reserving a construction operation space as a post-pouring zone, laying a reinforcing mesh on the base layer, arranging square steel on two sides of the reinforcing mesh, which are far away from a wall body and the base layer, through connecting screws, wherein the connecting screws are matched with single-wire nuts, and the single-wire nuts are arranged on one sides of the square steel, which are far away from the reinforcing steel;

s2, after the reinforcing mesh in the S1 is laid, pouring concrete to form a fine aggregate concrete surface layer;

and S3, after the concrete of the fine aggregate concrete surface layer is finally set in the step S2, twisting the single-line nut, and performing shrinkage compensation operation.

Further, the shrinkage compensation operation in step S3 includes:

step S31, calculating the unit concrete shrinkage according to a concrete shrinkage formula, wherein the concrete shrinkage formula is as follows:

wherein, in the step (A),the concrete shrinkage at any time in unit length is as follows: mm/mm; t is time, unit: day; b is that the empirical coefficient is generally 0.01, and 0.03 is taken when the curing is poor; epsilon_y ⁰The ultimate shrinkage under the standard state is 3.24 multiplied by 10^-4The unit: mm/mm; m1 and M2 … Mn are actual engineering correction values according to corresponding value taking tables in an engineering structure crack control book; the first formula is the shrinkage of the concrete in the shrinkage direction, and the first formula is as follows:wherein D is the length of the concrete along the contraction direction, and the unit is as follows: the thickness of the film is mm,the concrete shrinkage at any time is shown as the following unit: mm;

step S32, providing a torsion device, wherein the torsion device comprises a transverse torsion piece and a vertical torsion piece which are fixedly connected, the vertical torsion piece is an L-shaped component, and the transverse torsion piece is fixedly arranged at the upper end of the vertical torsion piece; the lower end of the vertical torsion piece is matched with the single-thread nut in the step S1, and the single-thread nut is twisted by pushing the transverse torsion piece;

step S33, calculating the pushing length of the transverse torsion piece according to a second formula, so as to realize concrete compression compensation, wherein the second formula is as follows:wherein: x is the displacement value of the transverse torsion member, unit: mm; l is the length of the vertical twist, in units: mm; delta is the concrete shrinkage increment per day, namely the difference of the concrete shrinkage on two adjacent days; p is the single-thread nut pitch, unit: mm;

and S4, after the concrete curing is finished, dismantling and recycling the square steel and the torsion device, and finishing the post-cast strip construction and curing of the construction operation space in the step S1, thereby finishing the construction of the heat-preservation fine stone concrete floor.

Further, in the step S1, the construction operation space is a rectangular area enclosed by the base layer surface in both the transverse direction and the longitudinal direction by 20 cm length.

Furthermore, one end of the connecting screw rod is connected with the steel bar in a welded mode, the other end of the connecting screw rod penetrates through the reserved hole in the square steel, and the single-wire nut is adopted to rotate to a preset position and then is locked and fixed.

Furthermore, in order to prevent treading interference caused during the arrangement of the reinforcing steel bars, when the reinforcing steel bar meshes are arranged, firstly, the reinforcing steel bars in the other direction are arranged after being arranged along one direction.

Further, considering that the size specification of the coupling screw and the nut should be properly adopted according to the size of the reinforcing steel bar, it is preferable to use a class a or B fine-toothed nut since fine adjustment operation is required, and here, the single-thread nut is M8 single-thread class a fine-toothed nut according to the diameter of the reinforcing steel bar.

Compared with the prior art, the invention has the beneficial technical effects that:

(1) the building ground anti-cracking method based on the concrete shrinkage theory can effectively prevent the expansion of micro cracks and the formation of macro cracks in the concrete, improve the anti-cracking performance of the fine aggregate concrete, remarkably improve the construction quality of the fine aggregate concrete and further prolong the service life.

(2) The building ground anti-cracking method based on the concrete shrinkage theory provided by the invention starts from the crack theory, calculates the concrete shrinkage in detail, provides accurate data for controlling the concrete shrinkage, amplifies the data through a torsion device to form a visible operable numerical value, and has guiding significance for similar concrete crack control engineering.

(3) According to the building floor crack resistance method based on the concrete shrinkage theory, the square steel and the torsion device can be prefabricated according to the building floor reinforcing bar condition and the adopted nut specification, and the device can be recycled and reused after construction is finished, so that pollution and waste are avoided, the method is green and environment-friendly, and the construction cost is saved.

(4) The floor crack resistance method based on the concrete shrinkage theory provided by the invention can be constructed together with other crack resistance measures, so that the crack resistance of concrete is further improved.

Drawings

FIG. 1 is a schematic structural view of an insulated fine-grained concrete floor according to an embodiment of the present invention;

fig. 2 is a layout view of reinforcing mesh in the thermal insulation fine stone concrete floor according to an embodiment of the present invention;

FIG. 3 is a front view of a torsion apparatus for an insulated fine concrete floor according to an embodiment of the present invention;

FIG. 4 is an enlarged view of portion A of FIG. 3;

fig. 5 is a side view of a twisting apparatus for insulating fine stone concrete floors in accordance with an embodiment of the present invention.

In the figure:

1-cast-in-place reinforced concrete floor slab; 2-plain cement slurry; 3-fine stone concrete is used for slope finding and leveling; 4-fine stone concrete surface course; 7-reinforcing steel bars; 8-square steel; 9-connecting a screw rod; 10-single-thread nuts; 11-transverse torsion; 12-vertical torsion.

Detailed Description

The concrete shrinkage theory-based floor crack resistance method proposed by the present invention is further described in detail with reference to the accompanying drawings and specific examples. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. For convenience of description, the directions of "up" and "down" described below are the same as the directions of "up" and "down" in the drawings, but this is not a limitation of the technical solution of the present invention.

From the crack generation theory, cracks of concrete are generated from deformation, and the deformation is affected by various external and internal conditions, such as temperature, humidity, surface air flow velocity, and the like. Concrete shrinkage is the largest deformation of concrete throughout its setting and subsequent use, and within the design use load, the amount of concrete shrinkage is the most significant factor in whether it develops cracks. Therefore, the shrinkage value of the concrete at any time can be calculated by combining a related theoretical calculation formula with the actual engineering condition, and a certain deformation compensation is applied to the concrete during the concrete curing period by utilizing the torsion device, so that the shrinkage condition is fully met, and the possibility of concrete cracking is reduced from the source.

The concrete shrinkage theory-based floor crack resistance practice of the present invention will be described in detail with reference to fig. 1 to 5.

Example one

The embodiment provides a building ground anti-cracking method based on a concrete shrinkage theory for heat-preservation fine-stone concrete building surface construction, which comprises the following specific implementation steps of:

step one, cleaning a base layer: cleaning and washing the sundries such as soil, floating pulp blocks and the like on the surface of the base layer, watering and wetting the base layer 1 day before laying the surface layer, and sweeping away the surface accumulated water.

Step two, bouncing elevation and surface layer horizontal line: according to the existing +500mm horizontal height mark of the wall surface, measuring the horizontal line of the ground surface layer, bouncing on the surrounding wall surface, and making the horizontal line consistent with the elevations of the corridor, the stair platform and the step outside the room.

Step three, controlling a concrete pouring area: sequentially constructing a cast-in-place reinforced concrete floor slab 1, a plain cement slurry 2 and a fine aggregate concrete slope finding leveling layer 3 from bottom to top to form a base layer; then, concrete pouring areas are divided, a construction operation space is reserved to serve as a post-pouring belt, the placing positions of the square steels 8 are measured, and all the areas are marked through elastic lines. The construction operation space is a rectangular area formed by enclosing 20 cm lengths in the transverse direction and the longitudinal direction of the surface of the substrate layer.

Step four, placing the square steel 8 and paving the steel bars 7: one end of the steel bar 7 is welded with a connecting screw 9 in advance, the other end of the steel bar is fixed with the wall, one end welded with the connecting screw 9 penetrates through the square steel 8, and the single-line nut 10 is screwed to a corresponding position. Particularly, in order to prevent the treading interference caused when the reinforcing steel bars 7 are arranged, when the reinforcing steel bar meshes are arranged, the reinforcing steel bars in the other direction are arranged after being arranged along one direction.

Step five, pouring concrete: after the reinforcing steel bars 7 in the transverse and longitudinal directions are paved, concrete is poured, rough leveling is carried out, then 1:1 cement sand is uniformly scattered on the upper surface of the fine aggregate concrete surface layer 4, and after the cement surface absorbs water, a wooden trowel is used for secondary leveling. And finally, when the surface layer begins to be condensed 2-3 hours after pouring and a footprint can be formed on the ground but does not sink, carrying out final wiping and pressing by using an iron trowel, and brushing by using a broom.

Step six, calculating: according to the data such as the concrete section length, the pouring conditions and the like, the daily concrete shrinkage increment is calculated through a corresponding formula, and the displacement value which is required to be given by the transverse torsion piece 11 every day is calculated through the formula according to the size relation of the single-line nut 10 and the torsion device. In particular, considering that the dimensions of the connecting screw 9 and the single-thread nut 10 are properly adopted according to the size of the steel bar 7, it is preferable to use a class a or B fine-thread nut because of the fine adjustment operation, where M8 is selected for the single-thread nut 10 according to the diameter of the steel bar 7.

Step seven, maintenance and shrinkage control: and after the final setting of the upper surface of the fine aggregate concrete surface layer 4 is finished, controlling the concrete shrinkage by adopting a torsion device, and performing daily displacement operation on the transverse torsion piece 11 according to calculated data in a maintenance period so as to achieve the purpose of controlling the concrete shrinkage.

Step eight, dismantling the device and pouring a post-pouring belt: and after the maintenance is finished, the recycled concrete shrinkage control device is removed, the post-cast strip is poured with high-grade micro-expansion concrete, and the whole construction is finished by corresponding leveling and maintenance measures to finish the construction of the heat-preservation fine stone concrete floor.

The sixth step specifically comprises:

calculating the concrete shrinkage per unit according to the concrete shrinkage formulaThe concrete shrinkage formula is as follows:wherein, in the step (A),the concrete shrinkage at any time in unit length is as follows: mm/mm, t is time, unit: day; b is that the empirical coefficient is generally 0.01, and 0.03 is taken when the curing is poor; epsilon_y ⁰The limit shrinkage under the standard state is 3.24 multiplied by 10^-4(ii) a M1 and M2 … Mn are corresponding value taking tables in an engineering structure crack control book, values are taken according to engineering actual conditions, the values are taken as examples, the transverse direction and the longitudinal direction are respectively 3M and 6M, the values are referred to the Mn value taking table (table I), and the shrinkage of the transverse 3M section along the axial direction is calculated by the formula (table II). The first formula is the shrinkage of the concrete in the shrinkage direction, and the first formula is as follows:wherein D is the length of the concrete along the contraction direction, and the unit is as follows: the thickness of the film is mm,the concrete shrinkage at any time is shown as the following unit: mm.

table-Mn value-taking table

TABLE II 3m concrete shrinkage at any time (mm)

As can be seen from the above table, the daily axial shrinkage of a concrete having a 3 m-long section is about 0.015mm, i.e. the daily control of the concrete shrinkage is 0.015mm, according to which the steel bar should be controlled to move 0.015mm in the concrete direction daily.

The seventh step comprises:

firstly, providing a torsion device, wherein the torsion device comprises a transverse torsion piece 11 and a vertical torsion piece 12 which are fixedly connected, the vertical torsion piece 12 is an L-shaped component, and the transverse torsion piece 11 is fixedly arranged at the upper end of the vertical torsion piece 12; the lower end of the vertical torsion member 12 is fitted with the single-threaded nut 10, and the single-threaded nut is twisted by pushing the transverse torsion member 11.

For a single-thread nut, the thread pitch is equal to the lead and is 1.25mm, i.e. the axial displacement is 1.25mm during one revolution. It is thus calculated that the daily single-thread nut 10 should be screwed through an arc of 4.32.

Next, referring to fig. 4, since the degree is too small to be controlled, the embodiment uses the torsion device to convert the radian into the horizontal displacement, and according to the trigonometric function formula, if the length of the vertical torsion member is 93mm, it is only necessary to translate the horizontal torsion member by about 7mm to rotate the nut by 4.32 °. Therefore, radian is converted into length, and micro deformation is converted into visible deformation.

According to the calculation result, the daily shrinkage of 3m concrete along the axial direction is about 0.015mm, and the square steel is pushed to displace by screwing the nut to compensate the concrete compression. The screwing degree of the nut is about 4.32 degrees every day, the vertical torsion piece and the transverse torsion piece 11 amplify the micro deformation into operable visible displacement, and the transverse torsion piece 11 is only required to be pushed by corresponding length to achieve the corresponding degree rotation effect. In the above calculation process, a formula two can be derived according to the relation and the trigonometric function:

calculating the pushing length of the transverse torsion piece according to a second formula so as to realize concrete compression compensation, wherein the second formula is as follows:wherein: x is the displacement value of the transverse torsion member, unit: mm; l is the length of the vertical twist, in units: mm; delta is the concrete shrinkage increment per day, namely the difference of the concrete shrinkage on two adjacent days; p is the single-thread nut pitch, unit: mm.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.