What issues should be paid attention to during the construction of concrete pavement with large slump?

🎨 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.

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