During the construction process, how to ensure that the operators of the laser leveling machine can strictly abide by the operating procedures?

    Using a power trowel to handle large-span and high-standard floor projects is a systematic project, and it is by no means as simple as "starting up and smoothing". It involves the meticulous management of the entire process from the initial preparation, concrete batching, laser leveling to power troweling and finishing. The following are the key technical points of these large-scale and high-standard projects, which are elaborated at three levels: "Basic guarantee", "core control", and "advanced advancement". These key points are the prerequisites for success or failure. If they cannot be achieved, there is no need to talk about anything else. Density and flatness: The foundation must be uniformly compacted to prevent uneven settlement in the later stage. The flatness of the cushion layer (usually gravel or plain concrete) is of vital importance. Its elevation error should be strictly controlled (such as within ±10mm), otherwise a large amount of concrete will be wasted and the final flatness will be affected. Waterproofing and moisture-proofing: In areas with high groundwater levels, reliable waterproof and moisture-proof layers must be applied to prevent water vapor from rising and affecting the quality and service life of concrete.   Low water-binder ratio: This is the lifeline of high-strength and wear-resistant floors. The water-cement ratio is usually required to be controlled below 0.45, and the lower the better. A low water-cement ratio can reduce bleeding, enhance strength and wear resistance, and minimize shrinkage cracks. Aggregate selection: Choose coarse and fine aggregates with good gradation and high hardness. The maximum aggregate particle size should not be too large (usually ≤25mm) to ensure the uniformity of the surface slurry. Admixtures and additives Mineral powder/fly ash: Reasonable use can improve workability, reduce hydration heat, and decrease temperature difference cracks. Water reducing agent: Highly efficient water reducing agents must be used to significantly reduce water consumption while ensuring fluidity. Fiber: In large-span floor slabs, it is strongly recommended to add polypropylene synthetic fibers, which can effectively suppress plastic shrinkage cracks in concrete.   Reasonable pouring sequence and direction: Develop a detailed pouring plan to ensure continuous supply of concrete and avoid cold joints. For large-scale construction, it is necessary to pour in separate compartments and arrange the construction joints reasonably. This is the core operational step to achieve high flatness and high finish. High-precision laser leveling Equipment selection: A laser leveler with a laser emitter + laser receiver + automatic control hydraulic system must be used. This is the only way to achieve ultra-high flatness. Reference setting: The position of the laser emitter must be stable to ensure that there is no signal obstruction throughout the entire operation area. The elevation control points need to be rechecked multiple times. The "one-time molding" concept: The laser screed integrates scraping, vibration and leveling into one, leveling the concrete at the designed elevation in one go to form a dense and uniform base layer. This is the foundation for the subsequent work of the polishing machine. The "golden time window" for operating a power trowel machine The operation of the power trowel must closely follow the initial setting process of the concrete and be carried out in stages: Phase One: Preliminary slurry extraction (before initial setting) Timing: After the concrete pouring and laser leveling, when a person stands on it and sinks by about 3-5mm. Equipment: Use a disc smear. Operation: Run at low speed, press down the protruding aggregates on the surface, bring up the slurry, eliminate the slight tooth marks left by the screed, and make the surface tend to be uniform. The aim is not to smooth it out, but to compact and lift the slurry. Phase Two: Compaction and Polishing (initial setting to final setting) Timing: When a person stands and sinks about 1-2mm, there is no standing water on the surface, and a slight indentation appears when pressed with a finger. This is the most crucial moment. Equipment: Replace with a blade (power trowel). Operation Angle control: At the beginning, the Angle between the power trowel blade and the ground should be small (almost parallel) to perform low-speed and large-area finishing. Multiple cross-operation: Cross the light at least 2 to 3 times along both the longitudinal and transverse directions. Each time, increase the blade Angle appropriately compared to the previous time and raise the rotational speed. Objective: Eliminate the marks left by the disc, fully compact the surface slurry, and achieve a dense and bright effect. Phase Three: Final Calendering (before final setting) Timing: When standing on it, there is almost no sinking. Only by pressing hard with fingers can marks be left. Operation: The blade is at the maximum Angle to the ground and runs at high speed. This polishing is done to achieve an extremely high degree of smoothness and eliminate all spatula marks. Note: All operations must be completed before the concrete loses its plasticity. It is strictly prohibited to sprinkle water or cement for finishing.   For airports, high-standard factories, etc., the following key points also need to be considered: Seam treatment technology Precise joint cutting: Cutting should be carried out immediately when the concrete reaches a certain strength (usually 6 to 12 hours after pouring, when it can be cut with a toothless saw without chipping). The depth of the cut seam should be 1/3 to 1/4 of the plate thickness, aiming to induce shrinkage cracks to occur at the predetermined position. Grouting material: Use high-quality and durable grouting glue to protect the seam edge from being damaged by hard objects such as forklifts. A complete maintenance system Timeliness: Start curing immediately after the final finishing is completed and the concrete surface is about to dry. Method selection Spray curing agent: Most suitable for large-scale construction, it can form a film to prevent water evaporation. It is necessary to ensure that the spraying is uniform and full coverage. Covering and water retention maintenance: If geotextiles, films, etc. are used for covering and continuous watering for moisture retention, the effect is the best but the cost is relatively high. Curing period: At least 7 days. For high-grade concrete with crack resistance requirements, it is recommended to cure for 14 days. Construction of special functional layers (if necessary) Wear-resistant aggregates (quartz sand, metal, alloy) : The timing of spreading: It should be carried out after laser leveling and before initial setting when the base concrete reaches a state "sufficient to bear the weight of people and spreader". Spread in several portions: Spread at least twice (60%/40% of the total amount) to ensure even distribution. Integrated finishing: After spreading, the wear-resistant aggregate is completely pressed into the surface layer of the concrete through the disc and blade operation of the power trowel machine and integrates with it. Sealant curing agent Construction should be carried out after the curing period has expired and the floor is completely dry. Through effective penetration and chemical reactions with the components in concrete, it can significantly enhance surface hardness, wear resistance and impermeability, making it a powerful tool for creating ultra-long-life floors. Stage Key points Objectives and Descriptions Preparatory work The foundation cushion layer is flat and dense Provide a stable foundation for the floor Low water-cement ratio concrete + fiber Ensure the material's own strength and crack resistance Core construction High-precision laser leveling The foundation for achieving ultra-high flatness (FF/FL value) Master the "Three Stages" of polishing The initial setting involves extracting the slurry, finishing before the final setting, and finally calendering to achieve a smooth finish Post-processing Cut the seams accurately and promptly Guide and control shrinkage cracks Maintain with sufficient time and materials Ensure the development of concrete strength and prevent cracking Function improvement Wear-resistant aggregates are evenly spread and integrated Enhance the surface wear resistance and impact resistance Penetrating sealant curing agent Significantly enhance hardness, density and chemical resistance The key to success lies in integrating all the above points into a seamless and controlled process. Any oversight in any link may lead to all previous efforts being wasted. Therefore, a high-quality construction team, advanced equipment and strict on-site management are all indispensable.   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.    

    Concrete engineering construction involves multiple links such as material transportation, mixing, pouring and curing. The working environment is complex (such as high-altitude, edge and heavy machinery operation), which is prone to cause safety accidents such as collapse, fall from height and mechanical injury. For common safety issues, response measures should be formulated throughout the entire process of "prevention – control – emergency response". Specifically, they can be classified by risk types as follows:   The spacing of the vertical rods of the formwork support is too large, there is no base plate at the bottom of the vertical rods/the foundation is unstable. Improper sequence of concrete pouring (such as not pouring in layers, resulting in local load exceeding the limit); The formwork was removed too early (the concrete strength did not meet the design requirements). The foundation pit/slope support was inadequate, causing deformation due to the load of concrete pouring. Preliminary design and verification The formwork support and scaffolding must be designed by professionals in accordance with the specifications, calculating the load-bearing capacity of the vertical rods, the spacing of the horizontal rods, and the setting of the sweeping rods to ensure the anti-overturning and anti-deformation capabilities. The foundation pit/slope support plan should be specially designed in combination with geological conditions (such as soft soil and quicksand layers). When necessary, support forms such as sheet piles and soil nail walls should be adopted. Over-excavation is strictly prohibited. Construction process control Before setting up the support, the foundation should be leveled and compacted. Wooden pads or steel sections should be placed at the bottom of the vertical poles to prevent uneven settlement. Concrete pouring should follow the principle of "layering, symmetry and gradual progress". The thickness of each layer should not exceed 30cm (for pumped concrete). It is prohibited to stack materials on one side or pour them in a concentrated manner, which may cause the support to be biased. Before the formwork is removed, the concrete strength must be tested (by the rebound method or the same condition test block test). It can only be removed when it reaches 75% (for beams and slabs) or 100% (for cantilever components) of the designed strength, and the removal sequence follows the principle of "remove the later supports first, and then remove the later supports". For high formwork (height ≥8m) and deep foundation pits (depth ≥5m), "deformation monitoring" should be implemented. Daily data on the settlement of supports and slope displacement should be recorded. Work should be immediately halted for rectification if the warning values are exceeded (such as settlement ≥10mm).   The pouring platform and scaffolding have no guardrails or toe boards, or the height of the guardrails is insufficient (less than 1.2 meters). The worker is not wearing a safety belt, or the safety belt is not fastened to a secure support point. No closed protection or warning signs have been set up at the edge openings (such as elevator shafts and stairwells). Standardization of protective facilities For high-altitude pouring platforms (such as floor slab and beam pouring), 1.2-meter-high guardrails must be set up, with 18-cm-high toe boards at the bottom, and close-mesh safety nets (flame-retardant type) hung on the outside of the guardrails. Elevator shafts and reserved openings shall be sealed with "tools" (such as steel mesh + cover plates), and it is strictly prohibited to temporarily block them with debris. The scaffold working layer is fully covered with scaffold boards, with no gaps between the boards. The probe boards (extending more than 15cm beyond the crossbars) must be fixed or removed. Personnel operation specifications Workers engaged in high-altitude operations must wear "double-hook safety belts" and use them "high up and low down" (the safety belt's hanging point should be higher than the work position). It is strictly prohibited to walk on the edges of unprotected beams and slabs. Before starting work, check the integrity of protective facilities. If loose railings or damaged safety nets are found, stop work immediately for repair. High-altitude concrete pouring operations are prohibited in severe weather conditions such as heavy rain and winds above level 6.   The concrete mixer and vibrator have no protective cover or the protective cover is damaged. The equipment operators work without a license and operate in violation of regulations (such as cleaning the residue in the mixer by hand). There are irrelevant personnel staying within the working radius of pump trucks or tank trucks, causing collisions or crushing. Intrinsic safety of equipment The transmission parts of the mixing plant and vibration equipment (such as gears and belts) must be equipped with "fixed protective covers", and the strength of the protective covers must meet the requirements of impact resistance. The material rods and outriggers of the concrete pump truck are equipped with "limit alarm devices", and steel plates are placed under the outriggers (to prevent subsidence). Before operation, make sure the outriggers are stable. Before using the equipment, conduct a "pre-shift inspection", with a focus on checking the braking, steering and leakage protection devices. Do not start the equipment if they are not up to standard. Personnel and on-site control Equipment operators must pass training and assessment and hold a "Special Operations Operator Certificate" to work. It is strictly prohibited to operate without a certificate or after drinking alcohol. When cleaning or maintaining the mixer, it must be "powered off and locked" (with a warning sign), and there must be a dedicated person to supervise. Live operation is strictly prohibited. The operation areas of pump trucks and tank trucks are set up with "warning zones" (isolated by warning tapes or guardrails), and irrelevant personnel are prohibited from entering. Drivers should observe the surrounding environment before operation.   The cables of mobile equipment such as vibration rods and water pumps are damaged and the insulation layer is aged. The temporary power supply did not adopt the "three-phase five-wire system", and the grounding and zero connection protection was missing. Waterproof electrical appliances were not used in damp environments (such as pouring basements or working during the rainy season). Standardization of temporary electricity usage Temporary power supply at the construction site must be laid by professional electricians, strictly adhering to the principle of "one machine, one switch, one leakage protector, one box" (each device is equipped with an independent switch and a leakage protection device). The operating current of the leakage protection device should be ≤30mA, and the operating time should be ≤0.1s. The cables of mobile devices shall adopt "wear-resistant and waterproof rubber-sheathed cables". It is strictly prohibited to drag or crush the cables. The cable joints shall be sealed with waterproof tape. Distribution boxes and switch boxes should be installed in dry and rain-proof locations. The grounding resistance of the box body should be no more than 4Ω. The box door should be locked and a "Electrical Safety Sign" should be affixed. Working environment and operation protection When working in a damp environment, operators should wear "insulating shoes" and "insulating gloves", and insulating sleeves should be added to the handles of the vibration rods. Lighting fixtures should use "36V safe voltage" (such as in basements and deep well pouring), and the use of 220V ordinary bulbs is strictly prohibited. Regularly test the insulation resistance of temporary power lines. Replace the cables immediately when the insulation value is lower than 0.5MΩ.   The tools and materials piled up on the concrete hopper and scaffolding were not fixed and fell, injuring the people below. Workers working at heights randomly throw tools and waste materials (such as bolts and broken formwork). There is no horizontal protective layer for cross-operation (such as pouring above and cleaning below). Material management The amount of concrete and tools stacked on the aerial work platform shall not exceed the load-bearing limit of the platform, and they shall be firmly fixed (such as binding the hopper with iron wire). It is prohibited to stack irrelevant sundries on scaffolding and formwork. After work, waste materials should be cleared in time to avoid accumulation. When transporting materials vertically (such as using a tower crane to transport concrete hoppers), the hoppers must be covered, overloading is strictly prohibited, and a "warning zone" should be set up below. Cross-operation protection When performing cross-operation up and down, a "horizontal safety protection layer" (such as fully laid scaffolding boards or safety flat nets) should be set in the middle, and the spacing between the protection layers should not exceed 10 meters. Workers working at heights are strictly prohibited from throwing any objects downward. Tools should be placed in tool bags to prevent them from falling. The personnel working below must wear "safety helmets", with complete brims and chin straps, and the chin straps must be fastened tightly.   The construction site is equipped with a "first aid kit" (including tourniquets, bandages, fracture fixation splints, etc.), and 1-2 part-time first aid workers are trained. Special emergency response plans should be formulated for accidents such as collapses and electric shocks. An emergency drill should be organized once every quarter to ensure that personnel master escape and first aid skills. An "emergency passage" is set up on site, with a width of no less than 1.2 meters and no debris blocking it. Emergency lighting (automatically activates after power failure) covers key areas. When a collapse occurs, immediately stop the operation, organize personnel to evacuate to a safe area, and strictly prohibit blind rescue (to prevent secondary collapse). At the same time, contact professional rescue teams (such as the fire department). When an electric shock occurs, first "cut off the power supply" or use an insulating tool to remove the injured person from the power source, and then perform cardiopulmonary resuscitation (send to the hospital if necessary). When mechanical injury occurs, immediately stop the operation of the equipment, stop bleeding and bandage the wound. For those with fractures, avoid moving them at will and send them to the hospital promptly.   The safety management of concrete engineering should adhere to the principle of "prevention first and combination of prevention and control". Through the triple guarantee of "technical measures (such as support verification, protective design) + management measures (such as personnel training, on-site inspection) + emergency measures (such as plan drills, first aid preparations)", risk control should be integrated throughout the entire construction process, and at the same time, the safety awareness of all personnel should be strengthened. Eliminate the "three violations" behaviors of "illegal command, illegal operation and violation of labor discipline", and reduce the occurrence of safety accidents from the root.   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.      

When the concrete laser leveling machine fails, it needs to be repaired. Generally speaking, maintenance is a good way to help the leveling machine to restore health, but some leveling machines still have a lot of small problems after maintenance. What is this ? In fact, because some maintenance personnel in the maintenance of concrete laser leveling machine, the error caused by the error, the following error in the maintenance of concrete laser leveling machine when do not make it again.