Cause of errors in flat concrete surface

While concreting is going on the job site, construction errors may happen because of failure to certain methods, improper practice as well as casual attitude.

All of these errors do not contribute to failure or impairment of concrete, but they may provide harmful effect on the structure in due course.

These errors are not present throughout new construction, but also occur throughout repair or recondition works.

Given below, mostly found inappropriate finishing methods which can significantly affect the strength of flat concrete surface:

a. Adding water to the surface: It is found that the water is included to the surface and it is verified with the existence of a large paint brush, together with the other finishing tools. The brush is soaked in water and water is heaved onto the surface that is already completed.

b. Timing of finishing: Final finishing operations should be carried on as soon as the concrete has accommodated its initial set and bleeding does not occur. The waiting period is based on the amounts of water, cement, and admixtures in the mixture but mainly the temperature of the concrete surface. On a incompletely shaded slab, the portion in the sun will normally be prepared to finish prior to the part in the shade.

c. Inclusion of cement to the surface: It is frequently performed to dehydrate bleed water so that finishing can be started and it produces a thin cement-rich coating to craze or flake off easily.

e. Use of tamper: A tamper or ?jitterbug? is utilized on several jobs needlessly. This tool drives the coarse aggregate far from the surface and the finishing becomes smooth. This method, however, forms a cement-rich mortar surface layer having the ability for scale or craze. A jitterbug should be un-allowed with a well designed mixture. If it is required to complete a rough mixture, a jitterbug could be useful by applying it sensibly.

e. Jointing: If the joints are placed and located improperly, it may lead to cracking in flatwork frequently.