CEMENT-BASED COMPOSITION FOR EXTRUSION MOLDING, USED PAPER-RECYCLED PULP SHEET, AND PRODUCTION OF USED PAPER- RECYCLED PULP SHEET

摘要

PROBLEM TO BE SOLVED: To obtain a cement extrusion molding composition that gives cement extrusion moldings of high strength by using a reclaimed pulp sheet that is prepared by dry-loosening pulp sheet of used paper having a specific tensile strength and has a certain value of freeness as a reinforcing pulp fiber used in cement extrusion molding composition. SOLUTION: As a reinforcing pulp fiber to be used for cement molding composition, is cited the pulp sheet from used paper having a freeness of >=400 mL that is prepared by dry-loosening the pulp sheet of used paper. This composition includes silica aggregate additionally, the content of the used paper pulp sheet is 1-10 pts.wt. per 100 pts.wt. of the total amount of the cement and silica aggregate. The used paper-reclaimed pulp includes >=15 wt.% of cellulose fibers of 150μm length and <=1 wt.% of cellulose fibers of >=1,200μm. The reclaimed paper pulp sheet is prepared by adding a paper-strengthening agent and a freeness-increasing agent, then subjecting the pulp mixture to the vacuum dehydration followed by the thermal compression treatment.