What may cause that a lot of sand bounces off from the mould? I have changed the Air pressure, airflow, W/C ratio. Can that be cauesed that I have not used acrylic polymer?

Views: 167

Reply to This

Replies to This Discussion

If the air flow is to high, the sand will separate from mix. 

I don't have a great understanding of CFM's but most spray guns suggest 7 cfm at 25 to 40 psi

Brian,

Can you tell us your mix design?  

Blow-back is common and there are ways to deal with it.  Not having Acrylic in your mix can increase the blow-back as your mix is not as sticky and won't consolidate as well.  Knowing your mix may help....

Another thing that can create blow back is the sand size.  Finer sand causes more blow back.

I use 0,2-0,5mm sand .
I have the opportunity to buy sand 0.4-0.8mm. Can this be better?

My face-coat test mix:
55%cement Cem I
45% sand (0,2-0,5mm)
W/C 0.27
SP 0,6% (to cement ) very strong SP

Reply to Discussion

RSS

Sponsor's Training

Concrete Countertop Mix Recipes

Featured Product

    Featured Product of the Month

Fishstone's Super-SIX-Admix™ is a proprietary blend of SIX different admixtures designed to achieve pinhole free, dense and strong concrete that will free flow in precast molds.  Super SIX makes it easy to produce Ultra high performance concrete (UHPC), also known as Engineered Concrete Composition (ECC) and Reactive Powder Concrete (RPC).  Super-SIX™  is a non-hazardous material utilizing the newest and most advanced technologies.

© 2017   Created by Tom Fischer.   Powered by

Badges  |  Report an Issue  |  Terms of Service