Technical & Industry Knowledge Base

Improper adjustment of the trowel blade angle will have the following adverse effects on the concrete surface Poor surface flatness If the blade angle is too large, the blade will cut into the concrete surface excessively when the trowel is running, resulting in scratches of varying depths on the concrete surface, making it difficult to form a flat surface. If the blade angle is too small, the contact area between the blade and the concrete surface is too large, and the pressure is insufficient, so that the unevenness of the concrete surface cannot be effectively smoothed, making the concrete surface flatness fail to meet the requirements. Reduced finish When the blade angle is not appropriate, such as a slightly large angle, the blade cannot evenly squeeze and smooth the concrete surface during the troweling process, which will cause uneven distribution of cement slurry on the surface. In some places, the cement slurry is excessively scraped away, and in some places, too much is retained, thereby affecting the surface finish and making the surface look rough and matte. If the angle is too small, the blade will not compact the concrete surface enough, and the pores on the surface cannot be effectively filled and closed, which will also reduce the surface finish of the concrete. Marks and cracks Improper blade angle adjustment will cause the trowel to exert uneven force on the concrete surface during operation. If the angle is too large, the scraping force of the blade will be too strong, which will easily leave obvious marks on the concrete surface. In severe cases, excessive scraping may cause micro cracks on the concrete surface. Uneven force caused by inappropriate angles may also cause inconsistent shrinkage in different parts of the concrete surface, which in turn causes surface cracks and affects the durability and aesthetics of the concrete structure. Uneven strength distribution Due to improper blade angles, the compaction degree of the concrete surface is different during the troweling process, which will lead to differences in the density of different areas of the concrete surface. For example, in areas with too large angles, the concrete is over-extended and the surface is too dense, while in areas with smaller angles, the concrete density is insufficient, which makes the strength distribution of the concrete surface uneven, reducing the overall quality and performance of the concrete.

There are many differences in the construction process between concrete pavement with large slump and concrete pavement with small slump, as follows Mixing Concrete with large slump: The mixing time needs to be appropriately increased, generally 30-60 seconds longer than concrete with small slump, to ensure that the concrete is mixed evenly, so that the excess water is fully mixed with cement and other materials to avoid segregation. At the same time, the amount of water should be strictly controlled and accurately measured, because the amount of water has a greater impact on the slump. Concrete with small slump: When mixing, pay attention to controlling the mixing force and time to avoid excessive mixing that causes the concrete to be too dry and hard, and lose good workability. Generally, the mixing time is relatively short, so that all materials can be evenly mixed. Transportation Concrete with large slump: Prevent concrete from segregation and water evaporation during transportation. The mixer truck should maintain a uniform speed, avoid sudden braking and sharp turns, and reduce the shaking of the concrete in the tank. At the same time, the tank body can be covered with a sunshade to prevent direct sunlight from causing water to evaporate too quickly and affect the slump. Concrete with small slump: During transportation, care should be taken to prevent excessive loss of concrete slump. If the transportation time is long, some plastic preservation measures can be considered, such as adding an appropriate amount of retarder. However, attention should be paid to the amount of retarder added to avoid affecting the setting time and strength of the concrete. Pouring Concrete with large slump: The pouring speed should not be too fast and should be controlled within a certain range, such as the pouring volume per minute should not exceed 1-1.5 cubic meters to avoid rapid flow and accumulation of concrete in the formwork, resulting in loose vibration or segregation. At the same time, it is necessary to avoid excessive free fall height of concrete. When it exceeds 2m, auxiliary tools such as string barrels and chutes need to be used. Concrete with small slump: Due to its poor fluidity, some auxiliary measures are needed during pouring to ensure that the concrete can fill every corner of the formwork. For example, artificial auxiliary spreading can be used to evenly distribute the concrete in the formwork to avoid concrete accumulation or local vacancies. Vibration Concrete with large slump: It is advisable to use a low-frequency vibrator, and the vibration frequency is generally 2000-3000 times/minute. Avoid using a high-frequency vibrator to cause over-vibration of the concrete. The vibration time should not be too long. The vibration time at each point should be controlled within 20-30 seconds, and the concrete surface no longer sinks significantly, no bubbles appear, and cement slurry appears on the surface. Concrete with small slump: It is usually necessary to use a high-frequency vibrator, and the vibration frequency is generally 3000-5000 times/minute to improve the fluidity and density of the concrete. The vibration time should be appropriately extended, and the vibration time at each point may take 30-40 seconds to ensure that the concrete is vibrated and dense, but it is also necessary to prevent excessive slurry on the concrete surface due to over-vibration. Surface finishing and maintenance Concrete with large slump: When finishing, wait for the surface moisture to evaporate properly before proceeding, generally 1-2 hours after the concrete pouring is completed. The specific time is determined according to the site environment and the concrete coagulation. Usually 2-3 times of plastering are required to eliminate moisture and defects on the surface. Plastic film, geotextile, etc. should be used to cover the surface immediately during curing to prevent the water from evaporating too quickly and causing the surface to lose water and crack. The curing time is generally not less than 14 days. Concrete with small slump: Plastering can be done in time after the concrete surface is slightly dry, generally about 0.5-1 hour after pouring. Due to its low moisture content and fast surface drying, fewer plastering times may be required, but attention should be paid to the plastering quality to ensure that the surface is flat and smooth. It should also be covered and moisturized in time during curing. The curing time is generally not less than 7 days, but if the environment is dry or the temperature is high, the curing time should be appropriately extended.

Concrete pavement with large slump needs to pay more attention to the pouring, vibrating, finishing and maintenance during construction to ensure the construction quality, as follows 🎨 Pouring stage Control the pouring speed: Since the concrete has a large slump and good fluidity, the pouring speed should not be too fast to prevent the concrete from flowing and accumulating quickly in the formwork, resulting in loose vibration or segregation. Avoid excessive height difference: The free fall height of concrete should be controlled within 2m. If it exceeds this height, auxiliary tools such as string tubes and chutes should be used to prevent the concrete from segregating due to large drop and affecting the overall performance of the pavement. 🎨 Vibration stage Reasonable selection of vibration equipment: It is advisable to use a low-frequency vibrator, and the vibration frequency is generally 2000-3000 times/minute. Avoid using a high-frequency vibrator to cause over-vibration of the concrete, which will cause the aggregate to sink, the cement slurry to float, and the stratification and segregation. Control vibration time: The vibration time should not be too long. The surface of the concrete no longer sinks significantly, bubbles no longer appear, and cement slurry appears on the surface. Generally, the vibration time at each point is controlled within 20-30 seconds. 🎨 Surface finishing link Timely surface finishing: Since the surface of concrete with large slump has more moisture, it is necessary to wait for the surface moisture to evaporate properly before finishing. Generally, it is 1-2 hours after the concrete pouring is completed. The specific time needs to be determined according to the site environment and the concrete setting conditions. Too early surface finishing will cause surface marks or unevenness, and too late will affect the surface finishing effect. Multiple surface finishing: Usually 2-3 surface finishings are required. The first surface finishing is carried out after the concrete surface is initially dehydrated, mainly for rough leveling; the second surface finishing is carried out before the initial setting of the concrete, further slurry lifting and smoothing; the third surface finishing is carried out before the final setting of the concrete, mainly to eliminate fine surface cracks and defects, making the road surface smoother and flatter. 🎨 Maintenance stage Timely covering: After the concrete surface is finished, it should be covered with plastic film, geotextile, etc. immediately to prevent the surface from drying out and cracking due to rapid evaporation of water. The covering should be tight to ensure that the concrete surface is always moist. Extended curing time: The strength of concrete with large slump increases relatively slowly. The curing time should be appropriately extended, generally not less than 14 days. During the curing period, water should be sprinkled regularly to keep the covering moist, so that the concrete can harden under suitable humidity conditions and improve the strength and durability of the road surface.

During the construction of concrete pavement, the influence of slump on pavement strength is mainly reflected in the following aspects 🎈Changes in water-cement ratio: Slump mainly affects pavement strength by affecting the water-cement ratio of concrete. Generally speaking, the larger the slump, the more water is used in concrete. According to the theory of concrete strength, under the condition of certain cement type and dosage, the larger the water-cement ratio, the lower the strength of concrete after hardening. This is because excessive water will form more pores and channels during the hardening process of concrete, and the pores left after the evaporation of water will reduce the density of concrete, thereby reducing the strength of concrete. For example, when the slump increases by 20-30mm from the appropriate value, the water-cement ratio may increase by 0.05-0.1, and the 28-day compressive strength of the pavement may decrease by 10%-20%. 🎈Cement slurry distribution: The appropriate slump can make the cement slurry evenly distributed in the concrete, wrapped on the surface of the aggregate, play a good bonding role, make the internal structure of the concrete dense, and thus ensure the strength of the pavement. If the slump is too small, the concrete is too dry and hard, and the cement paste is difficult to evenly wrap the aggregate, which will lead to more uncemented aggregate particles in the concrete, forming a weak link and reducing the overall strength of the road surface. On the contrary, if the slump is too large, the cement paste will sink due to its own weight, resulting in uneven distribution inside the concrete, resulting in relatively less cement paste in the upper part of the concrete and lower strength, while the lower part may be segregated due to excessive cement paste, which also affects the strength of the road surface. 🎈Aggregate interface bonding: The interfacial bonding strength between aggregate and cement paste in concrete is crucial to the overall strength of concrete. When the slump is appropriate, the cement paste can fully contact and bond well with the aggregate surface. When the slump is not appropriate, such as too large, the cement paste layer around the aggregate will be too thick. During the hardening process of concrete, due to the large shrinkage of the cement paste, micro cracks are easily generated at the interface between the aggregate and the cement paste, weakening the interfacial bonding strength, thereby reducing the strength of the road surface; and if the slump is too small, the cement paste cannot wet the aggregate surface well, which will also lead to poor interfacial bonding and affect the strength of the road surface. In concrete pavement construction, the slump should be strictly controlled, and concrete with appropriate slump should be selected according to construction conditions and design requirements to ensure that the pavement strength meets the design standards.

In concrete pavement construction, the adjustment of slump needs to be carried out according to the characteristics of different construction scenarios. The following are some adjustment methods for common construction scenarios High temperature environment: Reason: The increase in temperature will accelerate the cement hydration rate and the water evaporation rate, resulting in faster loss of concrete slump and reduced fluidity. Adjustment method: Appropriately increase the slump. It is generally recommended to increase it by 2040mm compared with normal temperature construction. For example, the slump is controlled at 80100mm at normal temperature, and it can be adjusted to 100140mm at high temperature. At the same time, measures can be taken to reduce the temperature of raw materials, such as shading aggregates, spraying water to cool down, using underground cold water to mix concrete, and adding ice cubes to the mixing water to control the concrete outlet temperature ≤30℃. Low temperature environment: Reason: Low temperature will prolong the setting time of concrete and deteriorate the construction performance. If the slump is too small, the concrete may be difficult to vibrate and compact. Adjustment method: The slump should not be too large, usually controlled at 3060mm. Warm water can be used to mix concrete to increase the temperature of the concrete out of the machine, and the amount of admixture can be appropriately reduced to avoid too long setting time of the concrete. In addition, attention should be paid to the insulation and maintenance of the concrete to prevent freezing. Longdistance transportation: Reason: Long transportation time will cause the slump of concrete to be lost. If the initial slump is small, it may be difficult to meet the construction requirements when arriving at the construction site. Adjustment method: Appropriately increase the slump when setting off, such as increasing it by 2030mm compared to normal construction. For example, the normal construction slump is 80100mm, and it can be set to 100130mm during longdistance transportation. At the same time, on the basis of the continuous lowspeed rotation of the mixer tank (24 rpm), a transport retarder can be added to ensure that the slump loss rate is ≤30% within 2 hours. Pumping construction: Reason: Pumping requires concrete to have good fluidity and pumpability to pass through the pipeline smoothly and reach the pouring location. Adjustment method: The slump is usually controlled at 120180mm. It is necessary to select a suitable pumping agent and adjust its dosage according to the pumping distance, height and pipeline layout. At the same time, optimize the concrete mix ratio and control the sand ratio at around 35%45% to improve the fluidity and water retention of the concrete. Nonpumping construction: Reason: If manual paving or small mechanical paving is used, the concrete does not need to have high fluidity like pumping, but it still needs to have a certain workability to facilitate paving and vibration. Adjustment method: The slump is generally controlled at 3080mm. If the slump is increased by one level (i.e., by 20 30 mm), in addition to increasing the sand content by more than 1% to ensure stability and workability, the amount of water (5 10 kg/m3) and cement (10 kg per cubic meter) must be increased accordingly. In actual construction, the optimal slump and mix ratio should be determined through tests according to specific conditions, and inspection and adjustment should be carried out strictly in accordance with relevant standards and specifications to ensure the construction quality of the concrete pavement.

In concrete pavement construction, the reasonable control of concrete slump directly affects the construction quality and mechanical operation efficiency. The specific standards are as follows 1. Conventional slump range Ordinary concrete pavement Slump: 120~180mm (about 150mm is appropriate) Applicable scenarios: Applicable to laser leveling machine or paver construction to ensure that the fluidity of concrete meets the requirements of mechanical paving and vibration. Special requirements pavement High slump: 180~220mm (when adding water reducer) Applicable scenarios: Complex reinforcement structure or high temperature dry environment, it is necessary to improve the fluidity of concrete to avoid segregation. Low slump: 80~120mm (dry hard concrete) Applicable scenarios: Construction with slipform paver, or projects with high early strength requirements. 2. Key factors affecting slump selection Construction process Laser leveling machine: requires a higher slump (120~180mm) to facilitate mechanical vibration and leveling. Slipform paver: The slump should be strictly controlled at 80~120mm to avoid deformation of the structure due to excessive fluidity. Environmental conditions Hot and dry weather: The slump can be appropriately increased (+20~30mm) to reduce the slump loss caused by water evaporation. Low temperature or rainy season: The slump can be appropriately reduced (-10~20mm) to prevent concrete segregation. Material properties When the coarse aggregate particle size is large and the grading is poor, the slump needs to be increased to ensure workability. Adding water reducer can reduce the water-cement ratio and improve strength while maintaining the slump. 3. Construction precautions Slump test Each truck of concrete needs to be tested for slump before unloading. If the deviation exceeds ±20mm, it needs to be adjusted (such as adding admixtures or secondary mixing). Time control The mixing and pouring of concrete must be completed before the initial setting (usually ≤2 hours) to avoid slump loss due to too long time. Common Problems Slump is too large: it is easy to cause bleeding and segregation, which can be improved by adding fly ash or reducing the water-cement ratio. Slump is too small: poor fluidity, it is necessary to add water reducer or increase the water consumption appropriately (need to be verified by the laboratory). 4. Reference Standards "Technical Specifications for Construction of Highway Cement Concrete Pavement" (JTG/T 3650-2020): The recommended slump is 100~180mm, which is adjusted according to the construction machinery. "Concrete Structure Engineering Construction Quality Acceptance Code" (GB 50204-2015): The slump detection frequency is required to be no less than once every 100m³. Reasonable control of slump can ensure the construction quality, durability and appearance smoothness of concrete pavement. The specific parameters need to be determined in combination with design requirements, construction technology and environmental conditions.

In concrete pavement construction, the reasonable control of concrete slump directly affects the construction quality and mechanical operation efficiency. The specific standards are as follows 1. Conventional slump range Ordinary concrete pavement Slump: 120~180mm (about 150mm is appropriate) Applicable scenarios: Applicable to laser leveling machine or paver construction to ensure that the fluidity of concrete meets the requirements of mechanical paving and vibration. Special requirements pavement High slump: 180~220mm (when adding water reducer) Applicable scenarios: Complex reinforcement structure or high temperature dry environment, it is necessary to improve the fluidity of concrete to avoid segregation. Low slump: 80~120mm (dry hard concrete) Applicable scenarios: Construction with slipform paver, or projects with high early strength requirements. 2. Key factors affecting slump selection Construction process Laser leveling machine: requires a higher slump (120~180mm) to facilitate mechanical vibration and leveling. Slipform paver: The slump should be strictly controlled at 80~120mm to avoid deformation of the structure due to excessive fluidity. Environmental conditions Hot and dry weather: The slump can be appropriately increased (+20~30mm) to reduce the slump loss caused by water evaporation. Low temperature or rainy season: The slump can be appropriately reduced (-10~20mm) to prevent concrete segregation. Material properties When the coarse aggregate particle size is large and the grading is poor, the slump needs to be increased to ensure workability. Adding water reducer can reduce the water-cement ratio and improve strength while maintaining the slump. 3. Construction precautions Slump test Each truck of concrete needs to be tested for slump before unloading. If the deviation exceeds ±20mm, it needs to be adjusted (such as adding admixtures or secondary mixing). Time control The mixing and pouring of concrete must be completed before the initial setting (usually ≤2 hours) to avoid slump loss due to too long time. Common Problems Slump is too large: it is easy to cause bleeding and segregation, which can be improved by adding fly ash or reducing the water-cement ratio. Slump is too small: poor fluidity, it is necessary to add water reducer or increase the water consumption appropriately (need to be verified by the laboratory). 4. Reference Standards "Technical Specifications for Construction of Highway Cement Concrete Pavement" (JTG/T 3650-2020): The recommended slump is 100~180mm, which is adjusted according to the construction machinery. "Concrete Structure Engineering Construction Quality Acceptance Code" (GB 50204-2015): The slump detection frequency is required to be no less than once every 100m³. Reasonable control of slump can ensure the construction quality, durability and appearance smoothness of concrete pavement. The specific parameters need to be determined in combination with design requirements, construction technology and environmental conditions.

In the operation of concrete power trowel, the angle adjustment of the disc and blade is crucial to the finishing effect. The specific parameters are as follows 1. Power trowel disc Angle range: Usually there is no need to adjust the angle (the disc is flat design), and the slurry lifting effect is controlled by speed and pressure. Applicable stage: After the initial setting of concrete (there is a slight indentation when pressing with fingers but it is not sticky), it is used for surface slurry lifting and preliminary leveling. 2. Power trowel blade First finishing: The blade angle is 10°~15°, and the operation is low speed (300~400rpm), mainly to eliminate surface floating slurry and slight bumps. Second finishing: The angle is gradually increased to 25°~30°, and compacted at medium and high speed (400~600rpm) to enhance the surface density and gloss. Special needs: If an ultra-flat surface is required (such as industrial floor), the angle can be adjusted to 30°~45° during the last finishing, but it is necessary to ensure that the concrete strength is sufficient for support. 3. Adjustment principles Degree of concrete hardening: As the initial setting time of concrete goes by, gradually increase the blade angle to avoid roughening or sanding of the surface due to overly soft concrete. Ambient temperature: In hot and dry weather, the angle needs to be appropriately reduced to reduce the cutting force of the blade on the concrete and prevent surface cracking. Surface requirements: Conventional angles can be used for ordinary pavements, and high-precision projects (such as airport runways) need to be strictly adjusted according to design parameters. 4. Common errors and solutions Angle is too small: It is easy to leave floating slurry, resulting in insufficient surface strength, and the angle needs to be increased in time to make up for it. Angle is too large: It may scratch the hardened concrete, so the angle needs to be reduced and the finishing speed needs to be accelerated. By reasonably controlling the angle and rotation speed, the surface flatness of the concrete can be within ±2mm/3m to meet the needs of different projects.

In the construction of concrete pavement, the main significance of laying double-layer steel mesh is to improve the overall strength, durability and crack resistance of the pavement, especially for projects with high requirements for bearing capacity. The following are its specific functions and applicable scenarios: 1. Core role Enhance tensile strength Concrete has strong compressive resistance but weak tensile resistance. The double-layer steel mesh significantly improves the tensile resistance of the pavement through the synergistic effect of the upper and lower layers of steel bars, reducing the risk of cracking caused by load or temperature stress. Disperse load stress The double-layer steel mesh can evenly disperse the concentrated load to a larger area, reduce local stress concentration, and extend the service life of the pavement. Control crack expansion When concrete shrinks or bends, the steel mesh can restrain the development of cracks and prevent cracks from penetrating the entire pavement structure. Improve fatigue resistance For pavements that frequently bear dynamic loads (such as heavy vehicle rolling), double-layer steel mesh can enhance the fatigue resistance of the structure and delay aging and damage. 2. Applicable scenarios Heavy-load traffic sections Airport runways, port terminals, highways and other pavements that need to bear high loads. Complex geological conditions In areas with a high risk of uneven foundation settlement, double-layer steel mesh can reduce structural cracking caused by foundation deformation. Special environmental requirements In high temperature or severe cold areas, steel mesh can help resist temperature stress; in humid environments, double-layer arrangement can increase the thickness of the protective layer and improve corrosion resistance. 3. Construction points Arrangement of steel mesh Usually, the upper steel bar is located 5~10cm below the top of the road surface, and the lower steel bar is close to the bottom. The middle is fixed by a bracket or a horse stool to ensure the thickness of the protective layer (generally 3~5cm). Selection of steel bar specifications The diameter and spacing of the steel bar need to be determined according to the design load calculation. The common specifications are φ8~φ16mm and the spacing is 15~30cm. Connection and fixation The steel mesh is connected by binding or welding to ensure integrity; the steel bars can be increased or reinforced in local weak areas. 4. Precautions Concrete pouring quality Double-layer steel mesh may affect the fluidity of concrete. The slump needs to be strictly controlled, and vibration compaction should be ensured to avoid voids. Construction sequence Lay the bottom steel mesh first, and then lay the upper steel mesh after the concrete is poured (or pour in two times). The specific needs to be adjusted according to the design requirements. Maintenance and protection Perform maintenance in time after construction to prevent steel corrosion and concrete shrinkage and cracking. Through reasonable design and construction, the double-layer steel mesh can significantly improve the comprehensive performance of concrete pavement, especially suitable for projects with high requirements for durability and safety.

The following are the specific operating steps and precautions for concrete laser leveling machines and trowels to help construction workers complete their work efficiently A. Concrete laser leveling machine operating steps 1. Preparation before construction Equipment inspection: Confirm that the laser transmitter, leveling machine head, vibrator, travel system and other components are operating normally and that the battery/fuel is sufficient. Benchmark setting: Arrange fixed points (such as steel chisels) around the construction area, install the laser transmitter and calibrate the level to ensure that the laser covers the entire work surface. Concrete paving: Use a dump truck or a spreader to evenly spread the concrete to the designed thickness (usually 2-3cm higher than the leveling machine scraper height), and ensure that the concrete slump meets the requirements (generally 120-180mm). 2. Leveling operation Start the equipment: Turn on the laser receiver, adjust the scraper to the preset height, and start the vibration and leveling functions. Straight line operation: The operator controls the equipment to travel in a straight line at a uniform speed along the long side, and the laser system automatically adjusts the scraper height to complete the vibration and rough leveling. Cross operation: After the initial leveling, repeat the operation in the vertical direction to eliminate surface ripples. 3. Corner treatment For corners and column root areas that cannot be covered by the laser leveler, first use a scraper to manually scrape and then use a small vibrating beam to assist in compaction. 4. Shutdown and maintenance After the operation is completed, turn off the equipment and clean the residual concrete on the surface. Immediately cover with a film or spray a curing agent to prevent the concrete from losing water too quickly. B. POWER Trowel machine operation steps 1. Preparation before construction Equipment inspection: Confirm that the trowel motor, blade/disc, protective cover and other components are intact, and the fuel/battery is sufficient. Confirmation of concrete status: There is a slight indentation on the concrete surface when pressing with fingers, but it is not sticky (initial setting stage), and there is no water seepage on the surface. Environmental control: In hot and dry weather, water should be sprinkled in advance to moisten the ground to avoid dust. 2. Disc trowel machine operation (slurry lifting stage) Initial slurry lifting: Install the disc, adjust the speed to 600-800rpm, move slowly from the edge to the center, overlap 1/3 of the working width, and eliminate surface bumps. Secondary compaction: After the concrete strength increases slightly, reduce the speed to 400-600rpm, raise the slurry and compact it again to ensure a uniform surface. 3. Blade trowel operation (finishing stage) Angle adjustment: first adjust the blade angle to 10-15°, finish at low speed (300-400rpm), and gradually increase the angle to 25-30° to improve the surface density. Finishing in multiple passes: usually 2-3 times, with an interval of about 30 minutes between each pass, subject to the concrete surface strength. 4. Edge and corner treatment For areas that cannot be reached by machinery, use a handheld trowel or manual trowel to finish. 5. Shutdown and maintenance After the operation, thoroughly clean the concrete residue on the blade/disc and check the bearing lubrication. C. Operation precautions Time control The laser leveling machine must be completed before the initial setting of the concrete (about 1-2 Hours), the trowel machine needs to start after the initial setting to avoid sanding too early or difficulty in finishing too late. Concrete quality requirements Strictly control the slump and setting time of concrete to avoid affecting the leveling effect due to material problems. Equipment safe operation The operator needs to wear protective equipment such as non-slip shoes and goggles. Personnel are prohibited from entering the working area when the equipment is moving. Special weather response The operation speed should be accelerated in hot weather to avoid the concrete surface hardening too quickly; construction should be suspended on rainy days and unsolidified concrete should be covered. Common problem handling Surface sanding: Check whether the trowel machine is operated too early or the concrete water-cement ratio is too high. Local unevenness: Correct by manual filling or secondary vibration. Through standardized operation and detail control, the concrete surface flatness can be ensured to be within ±3mm/3m, meeting the high-precision requirements of industrial plants, commercial floors, etc.

The trowel and concrete laser leveler are usually used together in concrete construction to improve the flatness of the ground and construction efficiency. The following is the working process and precautions of the two: 🎈 1. Workflow Laser leveler rough leveling △ Applicable stage: Before initial setting after concrete pouring (about 1-2 hours after pouring, the specific time depends on the concrete ratio and ambient temperature). △ Operation points: The laser leveler sets the reference plane through the laser transmitter, automatically levels and vibrates the concrete, and quickly completes the rough leveling of a large area. Focus on the corners, column roots and other areas that are difficult for the laser leveler to cover, and manually assist in scraping. Trowel fine leveling △ Applicable stage: after the initial setting of concrete (when there is a slight indentation when pressing with fingers but it is not sticky). Operation steps: △ Disc trowel: First use a disc trowel to perform preliminary slurry lifting and compaction to eliminate surface bumps. △ Blade trowel: After the concrete strength is further improved, use a blade trowel for fine finishing to form a smooth surface. △ Note: The trowel needs to be divided into 2-3 Operate over and adjust the blade angle (from low to high) each time to gradually increase the surface density. 🎈 2. Key points of cooperation Time control △ The laser leveling machine needs to complete the rough leveling before the initial setting of the concrete to avoid the difficulty of vibrating the concrete after hardening. △ The trowel machine needs to start working after the initial setting of the concrete. Too early will cause sand on the surface, and too late will make it difficult to compact. Division of labor and cooperation △ The laser leveling machine is responsible for efficient leveling of large areas, and the trowel machine is responsible for local finishing and surface treatment. △ For the corners that the laser leveling machine cannot reach, it is necessary to manually use a scraper to initially level it, and then the trowel machine will handle it. Technical parameter matching △ The leveling accuracy of the laser leveling machine must meet the design requirements (such as ±3mm/3m), providing a good foundation for the trowel. △ The angle and speed of the trowel blade need to be adjusted according to the strength of the concrete to avoid over-grinding or under-grinding. 🎈 3. Precautions Concrete maintenance Cover and maintain in time after the operation is completed to prevent surface cracking. Environmental factors The operation interval should be shortened in hot and dry weather to avoid excessive water loss of concrete. Equipment maintenance The laser leveling machine needs to calibrate the laser transmitter regularly, and the trowel blade needs to clean the concrete residue in time. Through reasonable process arrangement and equipment coordination, the quality and efficiency of concrete construction can be significantly improved, which is suitable for large-scale ground projects such as industrial plants, parking lots, and airport runways.

⛳ Two methods of concrete pavement leveling ♬●●♬Traditional manual leveling method ◑◐Construction method: Use a 3-4m light ruler to scrape the concrete surface, remove excess water and slurry, fill the low-lying areas with concrete, vibrate and re-trim, remove and trim the high parts, and then smooth them appropriately. The vibrator rod will also be used to "quickly insert and slowly pull out" to fully vibrate the concrete. The moving distance of each rod is generally not more than 1.5 times its effective radius (can be controlled as 30cm), and the distance from the template is less than 0.5 times the effective radius of the vibration. Vibrate until the slurry overflows on the surface of the concrete mixture, no longer sinks significantly, and no obvious bubbles overflow; then use the vibration beam to walk back and forth 2-3 times to level and raise the slurry to make the surface flat and uniform. ◑◐Applicable scenarios: Applicable to small projects, rural roads with narrow construction sites or relatively low requirements for flatness. For example, some self-built roads in rural areas, internal roads in small factory areas, etc. ◑◐Advantages: The equipment is simple and easy to obtain, the cost is low, the operation is relatively easy, and the technical requirements for operators are relatively low. ◑◐Disadvantages: The construction efficiency is low, the labor intensity of manual operation is high, the flatness control accuracy is limited, and it is difficult to meet the requirements of large-area, high-precision road projects. ♬●●♬Concrete laser leveling machine leveling method ◑◐Construction method: The laser emitted by the transmitter is used as the reference plane, and the leveling head is controlled in real time through the laser receiver on the laser leveling machine. Just like the laser leveling machine equipped with a HONDA GX690 engine (power 18.4kW/25HP, fuel tank capacity 19L), the steel bar is tied after the formwork of the civil engineering project. Before pouring concrete, the elevation is set on the column reinforcement and led to the laser leveling control system. When the pouring personnel scrape the elevation, the elevation is controlled to be 5-10mm higher than the design elevation, and then the machine operator uses the equipment to accurately level the concrete surface. The leveling width is 3m (9.84ft), and it adopts hydraulic screw conveying paving mode. The vibration system is hydraulic vibration, with a maximum excitation force of 2000N, which can be automatically calibrated and controlled at a certain frequency. After the water seepage of the concrete pouring surface is completed, the laser leveling instrument is used for re-measurement, the water accumulation is filled, and the 3-meter scraper is used to rotate and level it, and then the single-disc trowel is used to level the slurry. ◑◐Applicable scenarios: It is widely used in large-scale industrial plants, large shopping malls, warehouses, underground garages, airport runways, docks and other large-scale concrete floor projects with high requirements for ground flatness, horizontality and strength. For example, the workshop floor of a large automobile manufacturing plant, the floor of a large logistics storage center, etc. ◑◐Advantages: It can achieve high-precision and fast leveling of concrete, and the flatness and levelness of the ground are more than 3 times higher than conventional methods, and the density and strength are increased by more than 20%; it can improve work efficiency by more than 50% and save about 35% of labor; it can lay high-strength concrete, low-slump concrete and fiber concrete; and it can also automatically control the longitudinal and transverse slopes. The equipment has an all-aluminum body and is light in weight (net weight 835kgs / 1841lbs), which is convenient for operation under various working conditions. It is also equipped with an anti-skid system, a hydraulic brake system and a trailer system, a more precise height adjustment rod, a standard soft landing system for the working head, and switch detection and valve port calibration functions to ensure stable machine performance after long-term use. It is also equipped with two types of tires (inflated narrow tires and inflated wide tires) to adapt to different working conditions. ◑◐Disadvantages: The equipment has high purchase costs, high professional and technical requirements for operators, and requires professional training; the site requirements are relatively high, and it is inconvenient to operate in narrow and complex terrain sites. ⛳ Concrete pavement leveling skills ◑◐Pre-construction preparation skills: Before construction, ensure that the roadbed is stable, the formwork is strong and installed straight and flat, and set up a support device every 1m. Accurately measure and lay out the construction site to determine the road elevation and slope. At the same time, clean the construction site to ensure that the ground is clean, dust-free, and oil-free. If there are cracks or unevenness on the ground, it needs to be repaired first. In addition, the quality control of raw materials and mechanical debugging must be done well to ensure the quality of concrete and the normal operation of equipment (such as the laser leveling machine equipped with the HONDA engine mentioned above). ◑◐Concrete spreading skills: Spread the material during pouring. When unloading with a dump truck or a mixer truck, it is strictly forbidden to concentrate the material on a few points to prevent concrete accumulation and ensure that the concrete mixture is evenly distributed. ◑◐Vibration operation skills: Use the vibrator to "insert quickly and pull out slowly" to avoid missing vibration and over-vibration. Control the moving distance of the vibrator and the distance from the formwork. For equipment using a hydraulic vibration system (such as the relevant laser leveling machine), the exciting force should be reasonably adjusted according to the characteristics of the concrete and construction requirements. ◑◐Surface treatment skills: Correct minor defects in the leveling process in time; rub the surface with a grinding disc to compact the slurry before the initial setting to eliminate water seepage channels and tiny cracks; complete the finishing and embossing processes before the final setting, and finish 3-4 times. Moisturize in time during hot and windy weather in summer to prevent the surface from evaporating too quickly and forming a hard shell. ⛳ Measures to improve leveling efficiency and quality ♬●●♬Improve efficiency ◑◐Equipment upgrade and reasonable configuration: When conditions permit, give priority to equipment such as advanced laser leveling machines with the above parameters. Its hydraulic screw conveying paving mode and larger leveling width can improve construction efficiency. At the same time, according to the scale of the project and the conditions of the construction site, reasonably match other auxiliary equipment, such as concrete mixers, pump trucks, etc., to ensure smooth connection between concrete supply and construction. ◑◐Construction process optimization: Scientifically plan the construction sequence and operation area, adopt a segmented flow operation method, and reduce the waiting time between each process. For example, reasonably arrange the connection between concrete pouring, vibration, and leveling with a laser leveler (operated according to its performance parameters) to avoid idle work. ◑◐Personnel training and management: Strengthen the skills training of operators to enable them to master the operation of construction equipment (especially laser levelers) and construction processes, and improve their operating proficiency and accuracy. At the same time, optimize the division of labor, clarify the responsibilities of each position, and improve the efficiency of teamwork. ♬●●♬Improve quality ◑◐Strictly control the quality of raw materials: Select raw materials such as cement, aggregates, and admixtures of qualified quality, control the mix ratio, and ensure that the strength and workability of concrete meet the design requirements. For example, cement should be selected from brands with stable strength and reliable quality, and the particle size and mud content of aggregates should meet the standards. ◑◐Strengthen process quality inspection: During the construction process, use measuring instruments such as levels and theodolites to monitor road elevation, flatness, slope and other indicators in real time, and make timely adjustments when deviations are found. At the same time, do a good job in testing the slump of concrete and the compaction density. For laser leveling machine construction, it is necessary to regularly check whether the laser system and hydraulic system of the equipment (such as checking the accuracy of its height adjustment rod, the performance of the hydraulic brake system, etc.) are normal. ◑◐Protect the finished product: After the concrete pavement construction is completed, timely take maintenance measures such as covering and sprinkling water, and the maintenance time is not less than 14 days. Set up warning signs to restrict the passage of vehicles and pedestrians before the concrete strength reaches the design requirements to prevent damage to the road surface.