Internally curing cement based materials
A method of curing cementitious material comprising added a carboxylated bleached wood pulp fiber to the material during mixing. The fiber has a carboxyl content of from 10 to 70 meq/100 g cellulose fiber. The fibers are 0.1 to 5% by weight of the dry weight of the cementitious material. The structure produced by the method. The autogenous shrinkage of the cementitious material is reduced.
1. A method of curing cement to reduce autogenous shrinkage comprising:
providing a mixture comprising cementitious material, water and carboxylated bleached wood pulp fiber;
allowing the mixture to cure;
the cementitious material comprises cement;
the carboxylated fibers have a carboxyl content of 10 to 70 meq/100 g of cellulose fiber;
the carboxylated fibers are 0.1 to 5% by weight of the dry weight of the cementitious material;
the carboxylated fibers are made by the oxidation process and stabilized to convert aldehyde groups to carboxyl groups; and,
the water to cement material ratio is a high performance concrete ratio.
2. The method of claim 1 , wherein the fibers have a carboxyl content of 20 to 60 meq/100 g of cellulose fiber.
3. The method of claim 1 , wherein the fibers have a carboxyl content of 30 to 50 meq/100 g of cellulose fiber.
4. The method of claim 1 , wherein the fibers are 025 to 0.75% by weight of the dry weight of the cementitious material.
5. The method of claim 1 , wherein the cementitious material further comprises aggregate material.
6. The method of claim 5 , wherein the fibers have a carboxyl content of 20 to 60 meq/100 g of cellulose fiber.
7. The cementitious structure of claim 5 wherein the fibers have, a carboxyl content of 30 to 50 meq/100 g of cellulose fiber.
8. The cementitious structure of claim 5 , wherein the fibers have a carboxyl content of 35 to 45 meq/100 g of cellulose fiber.
9. The method of claim 5 , wherein the fibers are 0.25 to 0.75 by weight of the dry weight of the cementitious material.
10. A method of reducing the autogenous shrinkage of cement or concrete comprising:
providing a mixture comprising cementitious material, water and carboxylated bleached wood pulp fiber;
allowing the mixture to cure;
the carboxylated fibers have a carboxyl content of 10 to 70 meq/100 g of cellulose fiber;
the carboxylated fibers are 0.1 to 5% by weight of the dry weight of the cementitious material;
the carboxylated fibers are made by the oxidation process and stabilized to convert aldehyde groups to carboxyl groups; and
the water to cement material ratio is a high performance concrete ratio.