fig1 illustrates a concrete admixture package 10 of the invention which comprises synthetic fibers 12 operative to dispense throughout a volume of fresh concrete upon agitation of the concrete and to reinforce the concrete when set ; and a closed non - soluble paper bag 14 enclosing the fibers 12 , the bag operative to disintegrate in agitated fresh concrete and uniformly distribute the fibers throughout the fresh concrete . as used herein , the term &# 34 ; effective amount &# 34 ; of reinforcing fibers means an adequate quantity of fibers per cubic meters of hardened concrete to impart an improvement in the early crack resistance of the resulting material . in most concrete operations , this means from about 0 . 1 lbs . to about 300 lbs . of fibers per cubic meter of concrete . for synthetic fibers , the effective amount is from about 0 . 2 lbs . to about 20 . 0 lbs . per cubic meter of concrete , preferably from about 3 / 4 to about 3 lb . per cubic meter . often , more than one bag of fiber material is added to a commercial concrete mixer . as a result , the total amount of fibers from the bags must &# 34 ; cumulatively &# 34 ; result in an effective amount . typically , one bag containing about 1 . 5 lb . of fibers is added to each cubic meters of concrete ( dry weight ). as used herein , the term &# 34 ; uniform distribution &# 34 ; or &# 34 ; relatively uniform distribution &# 34 ; means that the fibers are distributed in such a manner as that no clumps of fiber larger than 0 . 5 inches ( 1 . 27 centimeters ) in diameter can be detected in the mixture . as used herein the term &# 34 ; batch type concrete mixer &# 34 ; means any batch mixer suitable for thoroughly mixing cement and aggregates so as to obtain a homogeneous mass and coat all particles with cement paste . preferred concrete mixers are : ( 1 ) rotating mixers , consisting of a revolving drum or a square box revolving about its diagonal axis and usually provided with deflectors and blades to improve the mixing ; or ( 2 ) paddle mixers , consisting of a stationary box with movable paddles which perform the mixing . rotating mixers are most preferred for use in the present invention . many manufacturers have developed water soluble papers . for example , gilbreth company , philadelphia pa ., markets &# 34 ; dissolve &# 34 ;, which is a water soluble paper prepared by coating synthetic paper with polyvinyl alcohol . the resoluble papers comprise carboxy methyl cellulose and the sodium or potassium salt of carboxy methyl cellulose . ( see u . s . pat . no . 3 , 859 , 125 issued jan . 7 , 1975 to miller , et al .) these specialized papers would surely dissolve in the aqueous environment of a concrete mixing operation . however , these papers are very expensive and , without being bound by theory , it is believed that these papers would dissolve too rapidly and could produce a large clump of fibers within the mix which might resist distribution . furthermore , the alcohol coatings of the soluble paper have a detrimental effect on the resulting concrete as they tend to detrain air in the wet mix . applicants have discovered that a packaged material prepared from paper of a non - soluble , traditional variety abrades more slowly and , surprisingly , distributes the fibers very uniformly throughout the fresh concrete mixture . these non - soluble papers tend to disintegrate upon the wet abrasion found in the concrete mixer , they do not dissolve , because the cellulosic materials found within the paper are insoluble in water . the abrasion of the sand , gravel and other concrete components causes the paper to disintegrate , i . e . fragment into pieces which are unnoticeable to the human eye and have no detrimental effect on the properties of the finished concrete . preferred papers contemplated in the present invention include repulpable and beater paper , shopping bag kraft paper , and multiwall kraft paper . the most preferred papers are repulpable , beater papers . flexible paper container material are further described in kirk - othmer , encyclopedia of chemical techonolgy , 3rd ed . ( 1981 ), vol . 16 , page 801 , incorporated herein by reference . one paper which is particularly effective in the present invention is a 50 lb . white beater paper . this paper is fabricated from 100 % pine pulp , has a basis weight of about 50 lb ., a machine direction tear of about 109 , a machine direction tensile of about 16 , sizing of about 0 , a brightness ( tappi ) of about 80 . 0 , and a moistron moisture of about 5 . 6 %. these paper specification determinations are further described in kirk - othmer , encyclopedia of chemical technology , 3rd ed ., ( 1981 ), vol . 1b , pp . 771 - 780 , incorporated herein by reference . this paper can be fabricated into a bag or pouch . union camp corporation , wayne , n . j ., fabricates a 50 lb . white multi - wall beater paper bag which is most preferred in the present invention . bags or pouches can be fabricated in any shape , provided that they fit into the fill opening of a standard concrete mixture . a preferred embodiment of the present invention includes 1 . 5 lb . of a polypropylene fiber contained in a 15 &# 34 ;× 14 &# 34 ; flat pillow pouch fabricated from the 50 lb . white multiwall beater paper bag described above . the bag or pouch is typically placed inside the concrete mixer drum via the drum opening . this may be done before introducing the other concrete components , during the introduction of the concrete components , after the introduction of the concrete components , or any combination of the three . mixing times should be at least about 5 minutes . applicants have discovered that it is also helpful to seal bags of the present invention with a water soluble adhesive . these adhesives can be any water soluble or water miscible adhesive which imparts sufficient bond strength to prevent premature opening of the bag in transit . it is also important that the adhesive does not impart any deliterious qualities to the resulting concrete . a typical water soluble adhesive suitable for use in the present invention is a one - part acrylic copolymer emulsion adhesive . it has also been discovered that distribution of fibers can be improved by including a dispersant in the package along with the fibers . these dispersants can be water - reducing and high - range water - reducing dispersants selected from the group consisting of lignosulfonates ( e . g ., sodium lignosulfonate ), naphthlene sulfonate , malemine sulfonate , &# 34 ; superplasticizers &# 34 ; ( like those described in u . s . pat . nos . 4 , 518 , 725 to arfaei on mar . 21 , 1989 ; 4 , 657 , 593 to aignesberger et al . on apr . 4 , 1987 ; and 4 , 814 , 014 to guicquero on may 21 , 1985 , incorporated herein by reference ), and mixtures thereof . preferred dispersants are lignosulfonate and naphthlene sulfonate . liquid dispersants are added to the fibers by spraying or any other acceptable coating means . dry dispersants , in powder form , may be added directly to the bag containing the fibers . the ratio of dispersant to fibers is typically from about 1 : 1 to about 1 : 15 w / w . the preferred ratio of dispersant of fibers is from about 1 : 6 to about 1 : 9 w / w . the level of dispersant can vary based on the dispersant itself . a quantity of 1 . 5 lb . of collated , fibrillated polypropylene fibers which are 3 / 4 &# 34 ; in length and are weighed . the fibers are distributed by w . r . grace & amp ; co .- conn . under the name grace fibers ™. these fibers have the following typical properties : ______________________________________specific gravity 0 . 91absorption nonemodulus of elasticity 500 ksimelt point 160 ° c . ignition point 590 ° c . alkali , acid + salt resistance high______________________________________ the fibers are spray coated with naphthlene sulfonate dispersant solution , wherein the fibers are coated with 90 gm of dispersant . the coated fibers are manually packaged in a 14 &# 34 ;× 15 &# 34 ; 50 lb . white multi - wall beater paper flat pillow - type bag , manufactured by union camp corp ., wayne , n . j . the bag comprises one open end which has a lip coated with a water soluble pressure sensitive adhesive . the adhesive is protected by a cover strip to prevent contamination of the adhesive surface . after the bag is full , the cover strip is removed from the lip at the open end of the bag , exposing the adhesive . the adhesive lip is folded so that the bag is closed and the adhesive is contacting the bag fully . manual pressure is then applied to seal the bag firmly . finally , the bag is placed in a cardboard box for shipping . alternative method of preparing the improved concrete additive product of the present invention a quantity of 1 . 5 lb . of collated , fibrillated polypropylene fibers which are 1 / 2 &# 34 ; in length are weighed . the fibers are distributed by w . r . grace & amp ; co .- conn ., cambridge , mass . under the name grace fibers ™. these fibers have the following typical properties : ______________________________________specific gravity 0 . 91absorption nonemodulus of elasticity 500 ksimelt point 160 ° c . ignition point 590 ° c . alkali , acid + salt resistance high______________________________________ the fibers are manually packaged in a 14 &# 34 ;× 15 &# 34 ; 50 lb . white multi - wall beater paper flat , pillow - type bag , manufactured by union - camp corp ., wayne , n . j . the bag comprises one open end which has a lip coated with a water soluble , pressure - sensitive adhesive . the adhesive is protected by a cover strip to prevent contamination of the adhesive surface . 90 gm . of sodium lignosulfonate ( lignosite 458 . manufactured by georgia - pacific corp .) are added directly into the bag through the opening . the bag is fed into an automatic sealing / folding machine . the machine then removes the cover from the lip , folds the adhesive lip to close the bag , and applies enough pressure to seal the bag . the bag is then put into a cardboard box for shipping . method of using the improved dispersant - free concrete additive products of the present invention . a quantity of 1 . 5 lb . of collated , fibrillated polypropylene fibers which are 1 / 2 &# 34 ; in length are weighed . the fibers are distributed by w . r . grace & amp ; co .- conn ., cambridge , mass . under the name grace fibers ™. these fibers have the following typical properties : ______________________________________specific gravity 0 . 91absorption nonemodulus of elasticity 500 ksimelt point 160 ° c . ignition point 590 ° c . alkali , acid + salt resistance high______________________________________ the fibers are manually packaged in a 14 &# 34 ;× 15 &# 34 ; 50 lb . white multi - wall beater paper flat , pillow - type bag , manufactured by union - camp corp ., wayne , n . j . the bag comprises one open end which has a lip . the bag is fed into an automatic sealing / folding machine . the machine then applies the adhesive to the bag lip , folds the bag to close the bag , and applies enough pressure to seal the bag . the bag is then put into a cardboard box for shipping . the concrete additive product of example i is removed from the cardboard box . the bag is placed in a revolving drum - type rotating concrete mixer containing 1 m 3 of fresh ready - mix concrete mixture through the drum opening . the fresh concrete and bag are mixed for 5 minutes . no lumps of fibers greater that 1 / 2 inch ( 1 . 27 cm ) in diameter are observed in the resulting fresh concrete . alternative method of using the improved concrete additive products of the present invention the concrete additive product of example ii is removed from the cardboard box . the bag is placed in a revolving drum - type rotating concrete mixer via an automated magazine feed dispenser which introduces the bag to the other concrete components at a rate of one bag per 1 m 3 of concrete . water is added to the dry mix and the fresh concrete slurry is mixed by rotating the drum for 5 minutes . no lumps of fibers greater and 1 / 2 inch ( 1 . 27 cm .) are observed in the resulting fresh concrete .