Polypropylene fiber for cement reinforcement, molded cement made with the fiber, method of constructing concrete structure, and method of spray concreting

Abstract

Polyolefin resin fibers for cement reinforcement which have hydrophilicity imparted thereto and show excellent adhesion to cement matrices. The fibers are ones which have been formed from a polypropylene resin by spinning and have undergone a surface modification treatment selected from oxidation treatment and fluorination treatment so that the fiber surface has an index of wetting of 38 dyn/cm or higher. The polypropylene resin fibers for cement reinforcement, when used in the application or placing of various mortars or concretes, give cement moldings improved in flexural toughness, such as flexural strength and impact strength.

1 - 7 . (canceled)  
   
   
       8 . Polypropylene fiber for cement reinforcement, comprising: 
 fibers spun out of polypropylene resin, said fibers having undergone a surface modification treatment selected between oxidation treatment and fluorination treatment so that a fiber surface has an index of wetting of 38 dyn/cm or more.    
   
   
       9 . Polypropylene fibers for cement reinforcement, comprising: 
 monofilament spun out of polypropylene resin, said monofilament having single yarn fineness of 200 dt or more with irregularities on their surfaces, and having undergone a surface modification treatment selected between oxidation treatment and fluorination treatment so that a monofilament surface has an index of wetting of 38 dyn/cm or more.    
   
   
       10 . Polypropylene fibers for cement reinforcement of  claim 8 , 
 wherein the oxidation treatment is selected between corona discharge treatment and plasma treatment so that a fiber surface has an index of wetting within the range of 40 to 90 dyn/cm after the treatment.    
   
   
       11 . Polypropylene fibers for cement reinforcement of  claim 8 , 
 wherein the fluorination treatment is conducted under fluorine gas in a concentration within the range of 5 to 40% by volume so that a fiber surface has an index of wetting within the range of 50 to 90 dyn/cm after the treatment.    
   
   
       12 . Molded cement, comprising: 
 cement composition having an adequate amount of polypropylene fiber of  claim 8  added to mortar mixture including cement, fine aggregate and water.    
   
   
       13 . Method of constructing concrete structure which comprises mixing a fixed amount of polypropylene fiber of  claim 9  to concrete mixture including cement, fine aggregate, rough aggregate and water.  
   
   
       14 . Method of spray concreting which comprises mixing an adequate amount of polypropylene fiber of  claim 9  to concrete mixture including cement, fine aggregate, rough aggregate and water, spraying the mixture on a formation surface in a fixed thickness.  
   
   
       15 . Polypropylene fibers for cement reinforcement of  claim 9 , 
 wherein the oxidation treatment is selected between corona discharge treatment and plasma treatment so that a fiber surface has an index of wetting within the range of 40 to 90 dyn/cm after the treatment.    
   
   
       16 . Polypropylene fibers for cement reinforcement of  claim 9 , 
 wherein the fluorination treatment is conducted under fluorine gas in a concentration within the range of 5 to 40% by volume so that a fiber surface has an index of wetting within the range of 50 to 90 dyn/cm after the treatment.