Application Cases of Fully Automated Power Trowel in Large-Area Floor Construction

  Slump: Slump reflects the fluidity of concrete. If the slump is too large, the concrete is too thin and soft, and it is easy to seep water and slurry when troweling, making it difficult to form a solid surface, and cracks are easy to appear on the surface after troweling; if the slump is too small, the concrete is too dry and hard, and it is difficult for the trowel blade to effectively trowel it, which will cause uneven surface and increase the workload of the trowel. Setting time: The setting time of concrete is crucial for troweling. If troweling is performed before the initial setting of concrete, the concrete is still in a plastic state and can be easily smoothed by the trowel, but troweling too early may damage the internal structure of the concrete and affect its strength; if troweling is performed after the final setting, the concrete has hardened, and it is difficult for the trowel to operate it effectively, leaving trowel marks on the surface, and it is impossible to achieve the ideal flatness and finish.   Speed: The speed of the trowel directly affects the troweling effect. If the speed is too low, the blade will not be able to vibrate and smooth the concrete surface enough, and the cement slurry on the concrete surface cannot be evenly distributed, resulting in poor surface finish; if the speed is too high, the concrete surface will be subjected to excessive centrifugal force, which may cause cement slurry splashing, and will also increase the wear and energy consumption of the machine. Power: The power determines the working capacity of the trowel. If the power is insufficient, when encountering large concrete resistance during the troweling process, the trowel may be underpowered, resulting in unsmooth rotation of the blade, affecting the troweling effect; if the power is too high, it may cause energy waste, and it is easy to cause excessive vibration and damage to the concrete surface if the operation is improper.   Operation technique: The operator's operation technique has a great impact on the troweling effect. Skilled operators can reasonably control the travel speed, direction and troweling time of the trowel according to the state of the concrete and the performance of the trowel, so that the concrete surface can achieve a flat and smooth effect; while unskilled operators may encounter problems such as uneven travel speed, overlapping or missing troweling areas, resulting in poor troweling quality. Judgment ability: Experienced operators can accurately judge the setting time and state of concrete and choose the right time to perform the troweling operation. They can also adjust the parameters and operation methods of the troweling machine in time according to the problems that occur during the troweling process, such as bubbles and trowel marks on the surface; while inexperienced operators may not be able to accurately judge these situations, thus affecting the troweling effect.   Temperature: The ambient temperature has a significant impact on the setting time and troweling effect of concrete. In a high temperature environment, the moisture of concrete evaporates quickly, the setting time is shortened, the troweling operation time window becomes smaller, and surface shrinkage cracks are prone to occur; in a low temperature environment, the setting time of concrete is prolonged, and the troweling quality may be affected by the freezing of the internal moisture of the concrete during troweling, and it will also increase the difficulty of starting the troweling machine and energy consumption. Humidity: If the ambient humidity is too high, the moisture on the concrete surface is not easy to evaporate, which will delay the setting time of the concrete, resulting in water seepage on the surface after troweling; if the humidity is too low, the moisture on the concrete surface evaporates too quickly, and problems such as surface dryness and peeling are prone to occur, affecting the troweling effect. Wind speed: Higher wind speed will accelerate the evaporation of moisture on the concrete surface, causing uneven drying of the concrete surface, increasing the difficulty of polishing, and may also cause cracks on the polished surface.  

If the concrete laser leveling machine works in the summer, it will need to face hot temperatures for a long time. However, if the leveling machine is always under high temperature, it will actually cause many adverse reactions. For example, the tires will be more likely to be damaged or The water in the water tank will evaporate at an accelerated rate, so in order to protect the concrete laser leveler, when you need to operate the leveler at high temperatures, you should take appropriate precautions in advance. How to take precautions when the concrete laser leveling machine works under high temperature conditions ●First, because the summer is hot and the temperature is continuous, so if the concrete laser leveling needs to work for a long time, it means that the vehicle tires are always exposed to high temperatures. At this time, you should pay attention to the tires caused by high temperatures. Rubber softening problem. Moreover, if you encounter sharp objects during the work, a tire blowout may occur. Therefore, this requires car owners to check the air pressure level in the tires in advance before the concrete laser leveling machine is working. If the tire temperature is found to be relatively high during the work, appropriate cooling measures need to be taken. There are two misunderstandings to avoid here. The two cooling measures of directly pouring cold water and deflating the air are very undesirable because they will cause damage to the tires and even cause a puncture later. ●Second, if the concrete laser leveling machine works under high temperature conditions for a long time, the water in the water tank will evaporate more quickly, so the owner should pay more attention to how much cooling water is left and what temperature the water temperature meter shows. , if you find that the water volume is not enough, you should stop the car immediately, but you cannot add water immediately at this time, but you should add water after the temperature has cooled down a little. When adding water, be careful to avoid burns. ●Third, ther e are two particularly dangerous time periods that require more vigilance, mainly at noon and dusk. After a morning of working with the concrete laser leveling, especially in summer when the temperature is high, people can easily become sleepy during the noon period, which can lead to fatigue driving and lack of concentration, so accidents often occur. It is also easier to get tired at dusk because of the hard work of the day. In this case, the car owner can drink something refreshing, or stop and rest, and then continue the work of the concrete laser leveling machine when his mental state is better.

    The detection methods and acceptance standards for the flatness and smoothness of the floor after the construction by the concrete laser leveling machine are a very professional and important issue. Although laser levelings can achieve extremely high quality standards, the final acceptance relies on objective data. The following are the detailed testing methods and acceptance criteria: Flatness is the greatest advantage of the laser leveling machine, and its acceptance criteria are much higher than those of traditional processes. Straightedge and feeler gauge method (traditional, commonly used) Tools: 2-meter or 3-meter national standard straightedge (or electronic straightedge), feeler gauge. Method: Place the straightedge steadily on the ground and use a feeler gauge to measure the maximum gap between the bottom of the straightedge and the ground. At least 10 points should be measured in the same area (such as a slab or a room), and the measurement points should be randomly distributed and cover key parts such as the edges of walls and the bases of columns. Advantages: Simple tools, convenient operation and intuitive. Disadvantage: It reflects local "wavy" undulations and cannot accurately measure the overall flatness of a large area. Level or total station measurement method (elevation method) Tools: High-precision level, tower ruler or total station. Method: Set up measurement points on the ground in a certain grid (for example, 1m×1m or 2m×2m), measure the elevation value of each point with a level, and then calculate the height difference between any two points or the standard deviation of the entire area. Advantages: The data is precise and can generate an elevation map of the entire ground, making it the most scientific. Disadvantages: It takes a long time and requires high technical skills from the operators. F-Number System (Internationally recognized and the most scientific method) This is the method stipulated in the ASTM E1155 standard of the United States. It is currently the mainstream and highest standard for evaluating the flatness of the floor internationally, and is particularly suitable for high-standard floors constructed by laser levelings. Tools: Specialized floor profile meters (such as DipStick, DynaPulse, etc.) or continuous inertial profile measurement vehicles. Evaluation index F_F value (flatness value) : It measures the undulation of the large wavelength (>600mm) of the floor, reflecting the degree of "tilt" or "wave" of the floor. The larger the F_F value, the flatter the overall floor. F_L value (levelness value) : It measures the undulation of the small wavelength (<600mm) of the floor surface, reflecting the degree of "roughness" or "micro-vibration" of the floor surface. The larger the F_L value is, the smoother the local area of the floor will be. Method: Measurement and calculation are carried out by professionals and equipment in accordance with standard procedures. Domestic traditional standard (ruler method Ordinary industrial floor: Within a 2-meter straightedge range, the flatness deviation is ≤ 4mm. High-standard industrial floor /VNA ultra-flat floor: Within a 2-meter straightedge range, the flatness deviation is ≤ 2mm. For VNA flooring, it is usually required to be ≤ 1.5mm / 2m. International F-Number Standard (Recommended for high-standard projects) Ordinary industrial floor: F_F 20 / F_L 15 High-standard warehouse/logistics center: F_F 35 / F_L 25 VNA narrow channel library/super flat floor: F < sub > F < / sub > 50 / F < sub > L < / sub > 40 or higher (F < sub > F < / sub > 60 / F < sub > L < / sub > 50) Commercial floor (such as supermarkets) : F_F 25 / F_L 20 Note: The specific F value should be clearly stipulated in the project contract or design documents. Smoothness is a comprehensive concept, encompassing appearance, wear resistance, dust resistance, etc., and it is more dependent on visual inspection and functional acceptance. Visual inspection method Method: Observe the floor surface from different angles under well-lit conditions. Inspection contents Color uniformity: Whether the surface color is consistent, and whether there are obvious color differences, water marks, excessive or insufficient cement slurry. Defects: Whether there are honeycombs, pitted surfaces, holes, peeling, sanding, or exposed stones. Cracks: Check for visible plastic shrinkage cracks and dry shrinkage cracks to the naked eye. Focus on inspecting corners and areas with stress concentration. Bubbles: The quantity and size of surface bubbles. Generally, it is required that there should not be too many bubbles with a diameter greater than 2mm. Mark and gloss: Whether the surface is smooth and if there are any obvious machine marks or manual marks. Hard object scratching method Tools: Keys, coins and other hard objects. Method: Use a hard object to scratch the surface with a certain force. Judgment: If only light white scratches are left, it indicates that the surface hardness is good. If there is obvious sand grain shedding or deep grooves, it indicates that the surface strength is insufficient and sanding may occur. Rebound instrument method Tool: Concrete rebound tester. Method: Indirectly calculate the strength of the floor surface through the rebound value. This method has certain errors and needs to be corrected in accordance with the standards. Judgment: The rebound value should meet the design strength requirements. Abrasion resistance test (Laboratory) For places with high wear resistance requirements, cores can be taken on-site and sent to the laboratory for "abrasion tests" (such as ASTM C779). Visual quality Color: The surface color is uniform and consistent, without obvious color differences or contamination. Defects: The surface is dense and smooth, free from quality defects such as honeycombing, pitting, cracks, sanding, peeling, and hollowing. Seam: The cutting seam should be straight, with uniform width and depth, and no missing edges or corners. Surface hardness and anti-dusting property Scratching with a hard object should not produce sanding or loose substances. In daily use, the movement of vehicles and the movement of people should not cause dust to rise on the ground. In addition to flatness and smoothness, the following indicators also need to be paid attention to Elevation and slope Tools: Level, total station. Standard: The allowable deviation between the measured elevation and the designed elevation is usually ±10mm. In areas with drainage requirements, the slope should comply with the design requirements and there should be no water accumulation. Levelness (not flatness) Tools: Laser leveler, level. Standard: It refers to the degree of inclination of the entire floor relative to the absolute horizontal plane. For equipment foundations with strict level requirements, the allowable error is very small (such as ±3mm/10m). Inspection items Main detection tools Reference for High-standard acceptance Flatness 2-meter straightedge, feeler gauge ≤ 2mm / 2m (Recommended ≤ 1.5mm / 2m) F-Number measurement system F_F 50 / F_L 40 (Applicable to VNA floor) Smoothness Visual inspection, hard object scratches The color is uniform, without cracks, sanding or holes, and there is no sanding when scratched Elevation Level, total station ±10mm Slope Level, total station It meets the design requirements and there is no water accumulation Important Notice Prior agreement: All acceptance criteria (especially the methods and standards for flatness) must be clearly stipulated in the contract before construction to avoid disputes later on. Comprehensive inspection: During the acceptance process, a combination of a thorough census and key spot checks should be conducted; it is not advisable to merely focus on a few points. Environmental conditions: The inspection should be carried out after the concrete has reached a certain strength and the surface should be cleaned thoroughly. For high-standard floors constructed by laser leveling machines, it is strongly recommended to introduce the F-Number system for acceptance, as it can most scientifically and comprehensively evaluate the quality and performance of the floor, especially suitable for projects with extreme requirements for the ground such as automated warehouses and logistics centers.   Note: The parameters provided in this document are for reference only and are not mandatory. Due to differences in technical characteristics between different brands and models of laser levelers, please consult the manufacturer for a suitable solution before actual operation. This reference document assumes no responsibility for any issues arising from failure to follow the manufacturer's instructions.