What Is a Steel Trowel?

Cement calendering is a special engineering project. It is a phenomenon formed after the concrete floor is flattened for 6-8 hours, evenly spread on the construction surface with plain ash and rolled out with a trowel. It is necessary to pay attention to the main points such as the wetness of the base layer, the method of spreading, and the setting of the mortar.

Cement calendering

1. Material mix ratio

(1) Cement mortar: The mix ratio of surface cement mortar should not be less than 1: 2, and its consistency should not be greater than 3.5cm. The cement mortar must be mixed well and the color is consistent.

(2) Cement stone chipping slurry: If the surface layer uses cement stone chipping slurry, the mixing ratio is 1: 2, and the water-cement ratio is 0.3 to 0.4, and special maintenance work is required.

Cement calendering curing conditions

After the cement mortar surface layer is applied, it should be cured under normal temperature and humid conditions.

(1) Conservation should be timely. If the watering is too early, peeling is easy, and if it is too late, cracks or sanding may occur. Generally, it should be cured after 24 h in summer, and it should be cured after 48 h in spring and autumn, and the curing time should be no less than 7 days. It is best to spread the sawdust and water it for conservation. When watering, apply a watering can to keep the sawdust moist.

(2) If slag portland cement is used, the curing time should be extended to 14 days.

Cement calendering

(3) During the curing period, the strength of the cement mortar surface layer is less than 5. Before OMPa, do not walk or perform other operations on it to avoid damaging the ground.

At present, Beijing, Xi'an, Shenyang and other places use curing spirits to maintain cement floors. Cement floor curing spirit is an inorganic polymer water-based coating, which can be applied with brushes, rollers, and sprayers or spray air sprays. It is mainly used for new cement mortar and bean stone concrete floors. Due to its penetration and solidification, premature dehydration of the cement floor forms a denser, harder surface layer on its surface, thus maintaining and hardening it; it can also improve surface hardness when used on old cement floors that have been sanded. Compared with the traditional curing methods (watering, grass curtain or silver powder), it can save 60Kg / m2 of curing water, improve the work efficiency by 3 to 4 times, increase the rebound strength by 20 to 40%, and increase the wear resistance by 50% , And it is conducive to fire prevention and hygiene at the construction site.

Since 1986, Liaoning, Hebei and other places have developed it for the maintenance of cast-in-situ concrete walls, and have achieved good results.

Precautions for cement calendering

When spraying, pay special attention to the following points:

The curing spirit is a viscous liquid with a specific density of 1.30 or more. When using it, dilute it with clean tap water to a specific density of 1.16.

The curing spirit is strongly alkaline, and care should be taken not to touch the skin and clothing during operation.

eyepiece.

If there are decorative materials or finishes such as metal, glass, paint, brick, etc. indoors and outdoors, they must be strictly protected.

Brush tools should be cleaned immediately after use.

When other decorative materials have to be made, it should be done after spraying the curing spirit 7d.

The conservation spirit should be stored in plastic buckets. If it is frozen in winter below -5 , it should be thawed with water bath before use and stirred

Mix well before applying.

It should be sealed during storage. If there is a small amount of sediment, it can still be applied after filtration.