Contraction joint-mesh and dowel placement

[kedpe]

I have a contraction joint detail with 18" dowel bar (in basket) centered about a T/4 deep sawed joint. The welded wire fabric is shown ending 12" from each side of the joint. This produces a 3" gap with no reinforcing, since the dowel bar is only 9" on either side of the joint. Should the WWF overlap the dowel bar by 3" or will this work?

 

[apsix]

If it was my detail I would stop the WWF approx 4" from the joint. There must be an increased risk of cracking away from the joint without any overlap, but there is probably no ill effect usually.

 

[csd72]

I agree with apsix.

The further away from the joint your WWF stopes the more likely there will be cracking outside the joint.

One end of the dowel bars should be graesed, so they shouldnt be relied on to prevent cracking

csd

 

[civilperson]

Two different joints are described in the postings: The greased dowel vs the rebar. The WWF can be continous across the sawn joint with the rebar acting as connection and shear transfer, (weakened plane joint). The smooth bar in greased whistles is a shear transfer only and the the WWF should be stopped short of the joint location.

 

[apsix]

civilperson
As per the thread heading, all of the first 3 postings were in relation to dowelled joints.
As you say there is an alternative way to achieve a similar result.
I would typically use a dowelled joint where it doubles as a construction joint, ie. a break in the pour.