How to ensure stable construction quality when using laser leveling machine to level large-area floor concrete?

1. Construction preparation stage

 

– Site cleaning and base treatment:

– Before construction, the site should be thoroughly cleaned to remove debris, garbage and loose parts of the original ground. For example, for the renovation project of old factory buildings, all oil stains and broken concrete blocks on the ground need to be cleaned up. For the base, if there is any unevenness, it needs to be repaired and compacted. If the base is a soil foundation, it should be layered and rolled according to the design requirements to make its compaction degree reach more than 90%, providing a solid foundation for concrete pouring.
– At the same time, the drainage slope should be set. According to the purpose of the site and the design requirements, the general drainage slope is not less than 0.3% – 0.5%. Through precise measurement and layout, determine the drainage direction and slope control points to ensure smooth drainage and avoid water accumulation affecting the quality of the floor.

 

– Material preparation and inspection:

– Select qualified concrete raw materials, including cement, sand and gravel, admixtures, etc. Cement should be selected with strength grades that meet the design requirements, such as ordinary Portland cement P.O42.5 or P.O52.5, and the stability and setting time of cement should be checked. The particle size and mud content of sand and gravel should meet the specifications. For example, the maximum particle size of coarse aggregate should not be greater than 31.5mm, and the mud content should not exceed 1%; the mud content of fine aggregate should not exceed 3%.
– Strictly design and test the concrete mix ratio. According to the use function of the floor (such as heavy-duty industrial floor, ordinary warehouse floor, etc.), strength requirements and construction environment, the best mix ratio is determined through laboratory trial mixing. During the construction process, concrete mixing should be carried out strictly according to the mix ratio, and the performance indicators such as slump of concrete should be tested regularly. The slump is generally controlled between 120-180mm to ensure good working performance of concrete.

 

– Equipment commissioning and calibration:

– Before construction, fully commission the concrete laser leveling machine. Check the operating status of the engine or motor to ensure the normal operation of the power system. For example, the engine should start quickly, run smoothly, and have no abnormal noise and shaking. For the laser system, it is necessary to perform precise calibration and adjust the height and angle of the laser transmitter so that the laser plane it emits is consistent with the design elevation of the floor.
– Calibrate the scraper, vibrator and other working parts of the leveler. The flatness error of the scraper should be controlled within ±1mm, and the frequency and amplitude of the vibrator should be adjusted according to factors such as the slump and thickness of the concrete. Generally, the vibration frequency is between 3000-5000 times/minute, and the amplitude is between 3-5mm to ensure that the concrete can be fully vibrated and leveled.

 

2. Construction process stage

 

– Concrete pouring and spreading:

– Use appropriate concrete pouring methods, such as pumping or self-unloading. During the pouring process, the pouring speed and height should be controlled to avoid segregation of concrete. For example, when pumping concrete, the discharge port height should not exceed 1.5m, and the concrete should be evenly distributed on the site.
– Use the spreading function of the laser leveler or cooperate with other spreading equipment to spread the concrete evenly on the site. The thickness of the material should be slightly higher than the design elevation, generally 10-20mm higher, to leave a margin for the leveling work. During the material laying process, care should be taken to avoid the accumulation of concrete in one place, resulting in excessive local thickness.

 

– Laser leveling operation:

– When operating the laser leveling machine, the equipment should be kept moving at a uniform speed, and the speed is generally controlled between 1-2m/min. The operator should adjust the scraper height and vibration frequency of the leveling machine in time according to the laser signal and the automatic leveling function of the equipment. For example, when the laser receiver detects that the ground is higher than the design elevation, the leveling machine automatically adjusts the scraper to descend and scrapes off excess concrete; when it is lower than the design elevation, the scraper rises, and the vibrator strengthens the vibration to fill the low-lying area with concrete.
– During the leveling process, attention should be paid to the connection of adjacent construction areas. The leveling work of adjacent areas should be completed before the initial setting of the concrete, and the flatness and density of the connection should be guaranteed. Generally, the overlapping construction method is adopted, and the overlapping width is between 10-20cm to ensure the flatness and integrity of the entire floor.

 

– Quality inspection and control:

– Professional quality inspection personnel are equipped to check the flatness, density and elevation of the floor in real time during the construction process. Use tools such as level, 2m ruler and feeler gauge for inspection. For example, for each construction area (such as 100-200 square meters), use 2m ruler and feeler gauge to check the flatness, and the flatness error should be controlled within ±3mm; use level to check the elevation, and the elevation error should be controlled within ±5mm.
– For parts that do not meet the quality requirements, timely adjustments and repairs should be made. If it is found that the local flatness exceeds the tolerance, it can be repaired by using a small leveling tool or manual smoothing method; for areas with insufficient density, use a flat vibrator to vibrate again or an inserted vibrator to supplement the vibration.

 

3. Construction completion stage

 

– Finishing and maintenance:

– After the concrete is leveled, the finishing treatment is carried out according to the use requirements of the floor. If it is an industrial floor that requires wear resistance, mechanical smoothing and manual fine smoothing can be carried out after the initial setting of the concrete. Mechanical troweling generally uses a driving trowel, and the number of troweling passes is not less than 3 times, so that the floor surface reaches a certain gloss and hardness.
– After finishing, timely maintenance should be carried out. You can use methods such as covering with plastic film, straw mats or spraying curing agents. The curing time is determined according to factors such as the type of concrete and the ambient temperature, and is generally not less than 7-14 days. During the curing period, the concrete surface should be kept moist to avoid cracks in the concrete due to water loss.

 

– Finished product protection and quality acceptance:

– During the curing period, the floor should be protected as a finished product, and warning signs should be set up to prevent people and vehicles from walking or working on the floor that does not meet the strength requirements. For example, for heavy-duty industrial floors, heavy vehicles are strictly prohibited from passing when the concrete strength does not reach more than 70% of the design strength.
– After the curing period, quality acceptance is carried out in accordance with design requirements and relevant standards. The acceptance content includes indicators such as the flatness, strength, and thickness of the floor. For example, the thickness and strength of the floor can be tested by core sampling, and the strength should reach the designed strength level; a laser flatness meter is used to test the flatness of the entire floor to ensure that the flatness of large-area floors meets quality requirements.