Replies

1. 
   StephenR | Apr 27, 2000 08:03pm | #2

   *
   scooter, use the wire mesh. it controls and prevents the bigger cracks from occurring. fibers add strength and prevent the smaller cracks. wire mesh still better for your application. use both to make the job real tight. i use the heavier ga. wire mesh when doing mudwork for extra strength.

2. 
   Guest_ | Apr 27, 2000 08:16pm | #3

   *
   Scooter,

   What Gabe said is true. Properly installed mesh will outperform fibers. Mesh is rarely properly installed however. Most concrete guys just throw down the mesh and pour concrete over it. For it to achieve maximum potential it must be near the center of the slab. Hooking and pulling the mesh up into the concrete works if they've got someone on the crew assigned to do just that and they leave him alone. He can't be the crew gopher and pull mesh at the same time.

   Second, fibers are not a replacement for structural reinforcement. Even the fiber manufacturers say this. It's for crack control.

   Third, your finish will be hairy and rough looking until the fibers protruding from the surface break off. I've seen guys use rubbing stones or drag a cinder block around on the surface after the concrete cures to eliminate this. Hard troweled finishes are not going to be the same with fibers as without.

   Long story short, it's more important to get a good concrete mix design for your slab than what you put into it for reinforcing. If you're in a freeze/thaw climate you'll want 5 - 7% air entrainment, high range water reducer, chert free aggregate (no pop out spalls)and make sure the finishers leave the water buckets and baptizing brushes back at the shop. Concrete is expensive to place and more expensive to get rid of. Get the job done right and enjoy a long service life.

   Eric

1. 
   Guest_ | Apr 28, 2000 03:52am | #4

   *We used fiber plus 6 x 6 10 ga. mesh plus # 4 rebar on 24" centers with 4000 # mix 5" thick , on a 42 x 56 slab sawed in 6 equal sq.s in August , as of 4-27 ,, "" ZERO "" cracks

1. 
   Guest_ | Apr 28, 2000 07:01am | #5

   *Good advice above - the key word in your post to me is 'driveway' which has to take much higher loads in general than a walkway and therefore what might seem overkill for a walkway isn't overkill when you will have vehicular traffic, possibly heavy. In that case you might want to increase the depth of compacted subbase fill (crushed stone) - 6"-9" isn't necessarily excessive and consider upping the thickness of concrete to 5" or 6" (you didn't say). Also important is overlapping and tieing the mesh - we just demo'ed an old concrete slab with a crack right up a non-overlapped mesh joint. We don't generally do concrete driveways in this area of the country (NJ) - doesn't hold up to our winters.

3. 
   Guest_ | Apr 28, 2000 07:02am | #6

   *
   A sub is going to install a concrete walkway and driveway, and instead of using 4" wire as reinforcing, is going to have the concrete supplier add fiberglass strand reinforcing. He claims it is just as good.

   While I have heard of this before, my thought is no way, I want the tried and true 4" wire as reinforcing. I am not a concrete guy, so any opinions here will be respected.

1. 
   Guest_ | Apr 27, 2000 06:39pm | #1

   *You may not be a concrete expert but you are the stakeholder in this exercise, so if you want mesh you should get mesh.Properly installed mesh will outperform fibre impregnated concrete.Gabe