joints in the surfacebed?

[BauTomTom]

Hallo

are there some experiences in the setting out of the joints in the surface bed? you need to provide some construction joints and also some saw cut joints in the concrete floor on the ground (surface bed)

how should this areas be specified? squares like 4m x 4m?

can they be also rectangular? 1m x 4m?

i thing this shapes are rather not to recommend because the different length would show different shrinkage behaviors.

BauTomTom

 

[Ron]

The sections should be as square as practicable. If they must be rectangular, the ratio of length-to-width should not exceed 1.2:1.

There are essentially 4 types of joints. Construction joints, which divide areas of completed construction for the day, isolation joints to separate column blockouts (and other cast-in-place features that are not part of the floor) from the surrounding floor, expansion joints (rarely, rarely needed in floor construction) and control joints (most commonly, saw-cut).

The control joints should be cut the SAME day as placement, as soon as the saw can cut into the concrete without causing edge raveling of the cut.

The control joint depth should be at least 1/5 of the slab thickness, preferably 1/4 of the thickness.

The spacing of control joints should be between 24 and 36 times the thickness of the slab. For instance, if your slab is 150mm thick, the joint spacing should be no greater than 5m, preferably less. Your estimate of about 4m x 4m is good for most slabs.

 

[Ron]

BTT...here is a link to an FAQ with a little more info on this...

Cracking FAQ

 

[BauTomTom]

-- to Ron --

perfect, thanks really a lot for your infos. This was now a crash course into the joints

I think I got it now, the rules and the types

Thanks

BauTomTom