Title:
Deleterious Effects of Wood Forms on Concrete
surfaces
Author(s):
T. J. Reading
Publication:
Concrete International
Volume:
7
Issue:
11
Appears on pages(s):
57-62
Keywords:
concretes; deleterious substances; discoloration;
dusting (concrete); form removal; formwork (construction);
lumber; mortars (material); parting agents; plywood; sawdust;
setting (hardening); surface defects; wood.
DOI:
Date:
11/1/1985
Abstract:
Difficulties in stripping concrete forms cleanly or in stripping soft concrete surfaces, or both, may be caused by certain substances in the wood which retard or inhibit the setting of portland cement. These studies indicate that extractives carried by the sap in the pores of the wood are mostly to blame. Problems exist with all of the wood types most commonly used for nonoverlaid form lumber: Douglas fir, Ponderosa pine, and Southern pine. The less commonly used Western larch proved to be the most deleterious in these studies, however. The color of concrete surfaces may also be affected by substances in the wood. *