Full-life-cycle crack control method for large industrial terrace

Abstract

The invention relates to a large-scale industrial terrace full-life-cycle crack control method, which realizes full-life-cycle control of terrace cracks through the steps of foundation cooperative compensation, concrete multi-scale crack arresting system construction, intelligent stress release bin separation process, total-factor dynamic monitoring and active repair and the like. According to the method, the foundation is treated through layered compaction and a composite reinforced structure, mineral fibers and an expanding agent are doped to optimize the concrete performance, intelligent separated-bin pouring is conducted through the BIM technology, real-time monitoring and automatic repairing are conducted by deploying a sensor network, cracks are effectively controlled, the durability of the terrace is improved, and the maintenance cost is reduced; and the method has remarkable economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building construction, in particular to a large industrial floor full life cycle crack control method. BACKGROUND

[0002] The current large factory floor construction generally adopts artificial joint cutting process, and the crack control rate is only 58.3%. There are two technical defects: first, the joint cutting precision completely depends on the experience of workers, and the actual construction has a joint cutting depth deficiency rate as high as 30%, which directly leads to an edge collapse angle rate of more than 25%, significantly reducing the structural integrity of the floor; second, the timing of joint cutting lacks scientific basis, and early joint cutting is easy to cause damage to the concrete edge, and late joint cutting leads to irregular crack expansion due to internal stress concentration. For example, after a traditional joint cutting process is adopted in a certain automobile manufacturing plant project, a large area of cracks appears on the floor after only one year of use, and the maintenance cost is as high as 85 yuan / square meter.

[0003] The traditional method adopts mechanical joint cutting after 24-48 hours, and the joint depth is only 1 / 4-1 / 5 of the plate thickness (40-60 mm). Since the joint cutting time lags behind the initial setting shrinkage of the concrete, early plastic cracks have already been generated; at the same time, the shallow joint cutting cannot fully release the subsequent dry shrinkage stress, leading to more than 60% of the cracks passing through the joint position and forming irregular cracks. Field statistics show that the joint cutting precision has large human differences, and the collapse angle rate is 25%, and the stress concentration at the edge even induces new cracks.

[0004] In the prior art, polypropylene fibers are widely used to enhance the crack resistance of concrete. Polypropylene (PP) fibers are difficult to disperse in the cement slurry due to their hydrophobic surface, and the agglomeration rate reaches 14.7% after 3-5 minutes of stirring. The local obstruction of the fiber group to the engagement of the aggregate makes the effective cross-sectional tensile strength of the area decrease by about 30%. In addition, the elastic modulus of PP fibers (3-5 GPa) is much lower than that of the hardened cement matrix (25-30 GPa), which has limited contribution to the inhibition of dry shrinkage cracks after 28 days.

[0005] For soft ground, the traditional construction adopts a single cushion treatment process. Large factories are often built on backfill soil or coastal soft clay. The traditional method only makes a 300 mm thick sand gravel cushion with a compaction degree of 90%. The soft ground consolidates and settles by 10-20 mm within 12 months, while the concrete slab has great stiffness, and the differential settlement generates additional bending moment at the bottom of the slab, which is prone to longitudinal through cracks. The actual measurement shows that when the differential settlement exceeds 1.5 / 1000 (15 mm / 10 m), the tensile strain at the top of the slab can break through 150 µε, causing 2-3 mm wide cracks. The traditional process does not consider the anisotropy of the stress distribution of the foundation, and the compaction degree of the cushion has large dispersion (85%-92%), which aggravates the occurrence of uneven settlement. At the same time, there is no effective settlement compensation structure to dynamically adjust the stress distribution of the foundation.

[0006] Under the action of high-frequency dynamic load such as forklift, the traditional floor design does not consider the cumulative effect of fatigue damage. The measurement shows that when the 10t forklift is fully loaded and starts and brakes, the peak impact of a single tire on the ground can reach 60kN, and the frequency is 150 times / day. The fatigue limit of traditional C30 concrete is only about 55% of the static strength, and after 100,000 times of repeated loading, micro-cracks are accumulated, and the crack width expands from 0.1mm to 1mm, and the floor surface peels off.

[0007] At present, most factories only do one-time acceptance when they are delivered, and there is a lack of online crack monitoring. Once cracks appear, they have usually expanded to 2-3mm, and can only be repaired by large-area epoxy grouting or overall renovation, with a repair cost of ≥85yuan / m 2 , and huge production loss. The existing technology relies on manual inspection, and the crack discovery lag time is more than 30 days, resulting in a 3-5 times increase in repair cost. A pharmaceutical factory project did not timely handle the initial 0.2mm cracks, and after 3 months, the cracks expanded to 1.5mm, requiring regional replacement construction, with a direct economic loss of 2 million yuan. The traditional monitoring method has three major shortcomings: low monitoring frequency (once a week), poor data accuracy (error >0.5mm), and lack of early warning mechanism, which cannot realize dynamic tracking and accurate repair of crack development. SUMMARY

[0008] The present application aims to overcome the defects of the prior art and provide a large industrial floor full life cycle crack control method, which solves the crack problem of large factory floor caused by concrete shrinkage deformation, uneven settlement of foundation and dynamic load impact; especially without additional increase in structural layer thickness and steel consumption, how to use material, structure and process integration means to improve the crack control rate of large factory floor from the existing 58% to more than 90%, and to stabilize the crack width within 0.3mm within 2 years of use, while reducing the repair cost by more than 30%.

[0009] In order to solve the above technical problems, the present application is implemented as follows: A large industrial floor full life cycle crack control method, characterized in that it comprises: Foundation cooperative compensation stage: based on the difference in foundation bearing capacity, layered compaction and composite reinforcement structure are used for cooperative treatment, wherein the composite reinforcement structure is composed of at least two layers of geogrid with tensile strength ≥30kN / m and stress diffusion cushion layer, forming a dynamic settlement compensation area; Construction of concrete multi-scale crack resistance system: three-dimensionally distributed mineral fibers, expansion compensation components and nano-scale pore optimization agents are mixed into the reference concrete, and a composite matrix with tensile strength improved by ≥20% and shrinkage rate reduced by ≥35% is formed through forced dispersion process; Intelligent stress release and sub-warehouse process: according to the stress characteristics of the floor, the non-equal-area pouring unit is divided by using the building information model (BIM), the skip-pouring method with an interval of ≥48 hours is adopted, and the stress gradient control is realized by cooperating with the joint cutting opportunity mathematical model; Full-element dynamic monitoring and active repair: a multi-parameter sensor network is pre-buried, real-time collection of crack expansion and settlement displacement data is realized through an Internet of Things platform, and when the monitoring value exceeds the preset threshold value, a micro-pressure grouting repair system is automatically triggered to implement precise intervention.

[0010] The large industrial floor full-life-cycle crack control method, characterized in that: the foundation cooperative compensation stage further comprises: Measuring the bearing capacity and settlement difference of the foundation; Designing and constructing at least two layers of geogrids with a tensile strength of ≥30 kN / m; Setting a stress diffusion cushion layer between the geogrids, and the thickness of the cushion layer is determined according to the predicted value of the uneven settlement of the foundation; Forming a dynamic settlement compensation area to adapt to the deformation of the foundation under load.

[0011] The large industrial floor full-life-cycle crack control method, characterized in that: the concrete multi-scale crack resistance system construction further comprises: Selecting basalt fibers with a length of 12 mm, a diameter of 18 μm, and a tensile strength of ≥3800 MPa; Selecting UEA expanding agent with a magnesium oxide content of 8.5% and an expansion rate of 0.025% (7d); Selecting nano-SiO2 with a particle size of 40 nm and a specific surface area of 180 m 2 / g; Ensuring three-dimensional random distribution of the fibers in the concrete by forced dispersion process to form a uniform composite matrix.

[0012] The large industrial floor full-life-cycle crack control method, characterized in that: the intelligent stress release and sub-warehouse process further comprises: Using the building information model (BIM) technology, according to the stress characteristics and design requirements of the floor, the non-equal-area pouring unit is divided; Adopting the skip-pouring method with an interval of ≥48 hours to reduce the internal stress of the concrete; Cooperating with the joint cutting opportunity mathematical model to determine the optimal joint cutting opportunity to realize stress gradient control.

[0013] The large industrial floor full-life-cycle crack control method, characterized in that: the full-element dynamic monitoring and active repair further comprises: Pre-burying a multi-parameter sensor network, including a crack width sensor, a displacement sensor, and a pressure sensor; The crack expansion and settlement displacement data of the floor are collected in real time through the Internet of Things platform. When the monitoring value exceeds the preset threshold value, the micro-pressure grouting repair system is automatically triggered to implement precise intervention.

[0014] The micro-pressure grouting repair system comprises an automatically controlled grouting pump and a precisely positioned grouting head, and the grouting material is epoxy resin or cement-based repair mortar with a viscosity of less than or equal to 200 cP.

[0015] The preset threshold value comprises a crack width threshold value of not greater than 0.3 mm and a settlement displacement threshold value of daily expansion of not greater than 0.02 mm, and the threshold value can be adjusted according to the use environment and design requirements of the floor.

[0016] The geogrid is laid in a cross-laying mode, and the thickness of the stress dispersion cushion layer is not less than 50 mm.

[0017] The forced dispersion process comprises dry mixing of fibers for 30 seconds and then adding liquid materials for mixing for 120 seconds in the mixing process.

[0018] The beneficial effects of the present application are as follows: Through the above technical solution, the present application provides a large-scale industrial floor full-life-cycle crack control method. Through the treatment in the foundation cooperative compensation stage, the method effectively enhances the bearing capacity of the foundation, and through the design of the composite reinforcement structure, the deformation of the foundation under the action of the load is adapted, thereby significantly improving the overall stability of the floor. The construction of the concrete multi-scale crack resistance system, by mixing mineral fibers, expansion compensation components and nano-scale pore optimization agents, not only improves the tensile strength of the concrete, but also significantly reduces the shrinkage rate, effectively reducing the generation of cracks. The application of the intelligent stress release partition process, using BIM technology to divide and skip-pour the pouring unit, and cooperating with the accurate control of the joint cutting time, realizes the effective release of the internal stress of the concrete, further improving the crack resistance of the floor. The deployment of the full-element dynamic monitoring and active repair system realizes the real-time monitoring of the floor cracks through the pre-embedded sensor network and the Internet of Things platform. When the monitored cracks exceed the preset threshold value, the system can automatically trigger the micro-pressure grouting repair, ensuring the timely repair of the cracks and prolonging the service life of the floor.

[0019] The method significantly reduces the maintenance and repair costs in the later stage by improving the durability of the floor and reducing the generation of cracks. The automated monitoring and repair system reduces the need for manual inspection and intervention, further reducing costs. Since the method effectively extends the service life of the floor and reduces maintenance costs, it has significant economic benefits. At the same time, it also indirectly improves the efficiency and economic benefits of industrial floors by reducing production interruptions and equipment damage caused by floor cracks. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be described in further detail below with reference to the drawings and embodiments: Figure 1 is a foundation treatment profile.

[0021] Figure 2 is an intelligent warehouse layout plan. DETAILED DESCRIPTION

[0022] The technical solutions of the embodiments of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all embodiments. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application. As shown in Figure 1 , 2 : A large-scale industrial floor life cycle crack control method, which comprises: Foundation collaborative compensation stage: based on the difference in foundation bearing capacity, hierarchical compaction and composite reinforcement structure are used for collaborative treatment, wherein the composite reinforcement structure is composed of at least two layers of geogrid with tensile strength ≥ 30 kN / m and stress diffusion cushion layer, forming a dynamic settlement compensation area; The foundation collaborative compensation stage further comprises: Measuring the bearing capacity and settlement difference of the foundation; Design and construction of at least two layers of geogrid with tensile strength ≥ 30 kN / m; Setting stress diffusion cushion layer between the geogrids, the thickness of the cushion layer is determined according to the predicted value of uneven settlement of the foundation; further, the laying mode of the geogrid is cross-laying, and the thickness of the stress diffusion cushion layer is not less than 50 mm.

[0023] Forming a dynamic settlement compensation area to adapt to the deformation of the foundation under load.

[0024] Concrete multi-scale crack resistance system construction: mixing three-dimensional randomly distributed mineral fibers, expansion compensation components and nano-scale pore optimization agents in the reference concrete, forming a composite matrix with tensile strength improvement ≥ 20% and shrinkage reduction ≥ 35% through forced dispersion process; The concrete multi-scale crack resistance system construction further comprises: Basalt fibers with a length of 12 mm, a diameter of 18 μm, and a tensile strength of ≥3800 MPa are selected; A UEA expanding agent with a magnesium oxide content of 8.5% and an expansion rate of 0.025% (7d) is selected; Nano-SiO2 with a particle size of 40 nm and a specific surface area of 180 m 2 / g is selected; The forced dispersion process is used to ensure that the fibers are randomly distributed in three dimensions in the concrete to form a uniform composite matrix. The forced dispersion process comprises dry mixing the fibers for 30 seconds and then adding liquid materials for mixing for 120 seconds during the mixing process.

[0025] The intelligent stress release sub-bay process: according to the stress characteristics of the floor, the non-equal-area pouring unit is divided by using the building information model BIM, the skip-bay pouring method with an interval of ≥48 hours is adopted, and the stress gradient control is realized by cooperating with the joint cutting opportunity mathematical model; The intelligent stress release sub-bay process further comprises: The non-equal-area pouring unit is divided by using the building information model BIM technology according to the stress characteristics and design requirements of the floor; The skip-bay pouring method with an interval of ≥48 hours is adopted to reduce the internal stress of the concrete; The optimal joint cutting opportunity is determined by cooperating with the joint cutting opportunity mathematical model to realize stress gradient control.

[0026] Full-element dynamic monitoring and active repair: a multi-parameter sensor network is embedded, crack expansion and settlement displacement data are collected in real time through an Internet of Things platform, and when the monitoring value exceeds the preset threshold value, a micro-pressure grouting repair system is automatically triggered to implement precise intervention.

[0027] The full-element dynamic monitoring and active repair further comprises: The multi-parameter sensor network comprises a crack width sensor, a displacement sensor, and a pressure sensor; Crack expansion and settlement displacement data of the floor are collected in real time through an Internet of Things platform; When the monitoring value exceeds the preset threshold value, a micro-pressure grouting repair system is automatically triggered to implement precise intervention.

[0028] Further, the micro-pressure grouting repair system comprises an automatically controlled grouting pump and a precisely positioned grouting head, and the grouting material is epoxy resin or cement-based repair mortar with a viscosity of ≤200 cP.

[0029] Further, the preset threshold value comprises a crack width threshold value of not greater than 0.3 mm and a settlement displacement threshold value of daily expansion of not greater than 0.02 mm, and the threshold value can be adjusted according to the use environment and design requirements of the floor.

[0030] Dynamic monitoring system: Assembly Model / parameter Installation method Crack sensor FSS-2000, range 0-5mm, accuracy 0.01mm Embedded during floor pouring, spacing 6m*6m grid Data collector DTU-600, supporting NB-IoT communication 1 per 200 square meters Cloud platform Aliyun IoT platform, alarm threshold: crack width≥0.3mm or daily expansion≥0.02mm Push to management end APP in real time Beneficial effects (quantitative comparison) Index Traditional method The application Lifting range 28-day shrinkage rate 0.045% 0.026% ↓42.2% Load crack rate (10 million times of forklift cycle) 82% 24.5% ↓70.1% Crack control rate (2 years) 58.3% 95.6% ↑37.3% Repair cost ￥85 / ㎡ ￥51 / ㎡ ↓40% Through a series of measures of the present application, the floor 28-day shrinkage is greatly reduced, the probability of floor cracks is greatly reduced, the corresponding repair cost is greatly reduced, good economic benefits are generated, and the time cost and economic cost of later maintenance are obviously reduced.

[0031] Specific operation steps: Stage 1: foundation treatment Compacted foundation: heavy roller (YZ18 type) compaction 6 times, compaction degree ≥95%; Coating interface layer: epoxy resin mixed solution rolling, spread quartz sand within 30min; Interface layer formula: Epoxy resin E44: curing agent T31 = 3:1 (weight ratio) Quartz sand: particle size 0.5-1mm, dosage 30% of resin weight Coating amount: 1.5 kg / m 2 (Dry film thickness 0.8mm) Laying geogrid: weak area first lays lower geogrid → spreads 30mm medium sand → lays upper geogrid → covers 20mm medium sand again; Through the above foundation treatment method, the bearing capacity of soft foundation can be effectively enhanced and the uneven settlement of foundation can be reduced, so that the slab cracking caused by uneven settlement can be greatly reduced and the load crack rate can be reduced.

[0032] Stage 2: concrete pouring According to BIM, the area is supported (single bin area: hard base area ≤36㎡, soft area ≤16㎡); different single bin areas are adopted for hard base area and soft area, which can maximize the reduction of slab cracks caused by uneven settlement of foundation.

[0033] Concrete mixing: forced mixer (JS750), first dry mixing fiber for 30s → adding liquid material for 120s; By adding anti-cracking fiber to the concrete and fully mixing, the fiber is distributed in three dimensions in the concrete to resist cracking, limit crack expansion, and effectively reduce the 28-day shrinkage.

[0034] Skip-pouring: adjacent bins are spaced apart by ≥48 hours, and the insertion interval of the vibrating rod is ≤400mm; skip-pouring makes the internal stress of each bin of concrete fully released, reducing the stress cracks of the concrete.

[0035] Stage 3: joint cutting and maintenance Joint timing: cut joints when the floor slab reaches more than 25% of the design strength. Generally, the principle of not damaging the concrete is followed, and the second day after summer can be cut. According to the pouring temperature of the day, such as 35℃, it can be cut off within 10h-12h. It is accurate to not break the edge and not appear cracks, and try to be as early as possible, at the same time, it is necessary to pay attention to, it must be cut after the formwork is removed. The joint should be as regular as possible and beautiful.

[0036] Joint parameters: depth = floor thickness x 1 / 3 (example: 240mm thick floor cut 80mm), width 3mm; Cover curing: curing uses water and geotextile cover curing, and geotextile cover also plays the role of product protection.

[0037] Jointing: It is a strategy of "treatment", mainly through the pre-set weak point (joint) to passively accommodate and control the inevitable shrinkage and temperature deformation of concrete, guide the potential destructive random cracks into regular controllable joints, so as to improve the integrity and service life of the floor. Effectively reduce the risk of floor cracking.

[0038] Curing: It is a strategy of "prevention" and "nourishment", which actively and positively promotes the full internal reaction of concrete by providing a good hydration environment (humidity, temperature, time), ensures that it obtains the internal quality of design requirements such as strength, durability, etc., and prevents early defects and cracks caused by rapid water loss and temperature difference. It focuses on protecting internal performance.

[0039] Both complement each other and are indispensable. Through jointing and curing, the 28-day shrinkage rate is reduced and the crack control rate is improved.

[0040] Stage 4: Monitoring and maintenance Sensor activation: power on after curing, sampling frequency 1 / hour; Data criteria: crack width ≥0.3mm or single-day expansion ≥0.02mm triggers alarm; Repair measures: injection of epoxy resin slurry (viscosity ≤200cP), pressure grouting machine (0.5MPa) construction.

[0041] Through real-time monitoring of crack development by sensors, the early warning area is analyzed and repaired in time to prevent further development of cracks and reduce losses to a minimum, making repair easier, thereby greatly improving crack control rate and reducing repair costs.

[0042] The above are only examples provided by the present application and are not intended to limit the present application. Although the present application is described in detail with reference to the examples, those skilled in the art can modify the technical solutions described in the foregoing examples or make equivalent replacements to some of the technical features, but any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for controlling cracks throughout the entire life cycle of large industrial flooring, characterized in that... It includes: Foundation Co-compensation Stage: Based on the difference in foundation bearing capacity, a combination of layered compaction and composite reinforcement structure is adopted for treatment. The composite reinforcement structure consists of at least two layers of geogrid with tensile strength ≥30kN / m and stress diffusion cushion layer, forming a dynamic settlement compensation zone. Construction of a multi-scale crack-resistant concrete system: Three-dimensional randomly distributed mineral fibers, expansion compensation components and nano-scale pore optimizers are incorporated into the reference concrete, and a composite matrix with tensile strength increased by ≥20% and shrinkage reduced by ≥35% is formed through a forced dispersion process; Intelligent stress relief compartmentalized process: Based on the stress characteristics of the floor, the building information model (BIM) is used to divide non-uniform area casting units, and a skip-casting method with an interval of ≥48 hours is adopted. Combined with the mathematical model of the cutting timing, stress gradient control is achieved. Full-element dynamic monitoring and proactive repair: A multi-parameter sensor network is pre-embedded to collect crack expansion and settlement displacement data in real time through an IoT platform. When the monitored value exceeds the preset threshold, the micro-pressure grouting repair system is automatically triggered to implement precise intervention.

2. The method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 1, characterized in that: The foundation-coordinated compensation stage further includes: Measure the bearing capacity and settlement differences of the foundation; Design and construct at least two layers of geogrid with a tensile strength ≥ 30 kN / m; A stress diffusion cushion layer is set between the geogrids, and the thickness of the cushion layer is determined according to the predicted value of uneven settlement of the foundation. A dynamic settlement compensation zone is formed to accommodate the deformation of the foundation under load.

3. The method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 1, characterized in that: The construction of the multi-scale crack-resistant concrete system further includes: Select basalt fibers with a length of 12mm, a diameter of 18μm, and a tensile strength ≥3800MPa; UEA expansion agent with a magnesium oxide content of 8.5% and an expansion rate of 0.025% (7d) was selected; Select a particle size of 40 nm and a specific surface area of ​​180 m². 2 / g of nano-SiO2; By employing a forced dispersion process, the fibers are ensured to be distributed randomly in three dimensions within the concrete, forming a uniform composite matrix.

4. The method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 1, characterized in that: The intelligent stress relief compartmentalization process further includes: Using Building Information Modeling (BIM) technology, the concrete pouring units with non-uniform areas are divided according to the stress characteristics and design requirements of the floor. A skip-pour method with an interval of ≥48 hours is adopted to reduce internal stress in the concrete; By combining the mathematical model of cutting timing, the optimal cutting timing is determined in order to achieve stress gradient control.

5. The method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 1, characterized in that: The comprehensive dynamic monitoring and proactive repair further includes: A multi-parameter sensor network is pre-embedded, including crack width sensors, displacement sensors, and pressure sensors; Real-time data on crack expansion and settlement displacement of the floor are collected through an IoT platform. When the monitored value exceeds the preset threshold, the micro-pressure grouting repair system is automatically triggered to implement precise intervention.

6. The method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 1, characterized in that: The micro-pressure grouting repair system includes an automatically controlled grouting pump and a precisely positioned grouting head. The grouting material is epoxy resin or cement-based repair mortar with a viscosity ≤200 cP.

7. The method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 1, characterized in that: The preset thresholds include: a crack width threshold of no more than 0.3 mm and a settlement displacement threshold of no more than 0.02 mm per day. These thresholds can be adjusted according to the floor's usage environment and design requirements.

8. The method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 2, characterized in that: The geogrid is laid in a cross-laying manner, and the thickness of the stress diffusion layer is not less than 50mm.

9. A method for controlling cracks throughout the entire life cycle of large industrial flooring according to claim 3, characterized in that: The forced dispersion process includes first dry-mixing the fibers for 30 seconds during the stirring process, and then adding liquid materials and mixing for 120 seconds.

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