NewCrete M
Synthetic Fibers
For Secondary Reinforcement of Concrete
Polyssive Ltd.
P.O.Box 3862 , Haifa , 34608 , Israel
Phone : 972 4 8344882 , Fax : 972 4 8241890
E mai : polysi-3@012.net.il
Description
NewCrete M fibers are 3 - 12 mm long by 12 micrometer diameter monofilament polymer fibers especially processed for use in most concrete mixes of nominal aggregate sizes of 5 mm to 30 mm to reduce the occurance of plastic shrinkage cracking and crazing , reduce plastic shrinkage and segragation and to enhance the barrier properties , the surface properties and wear life of the concrete.
They are especially treated to enhance the wetting and dispersibility with the cement paste , as well as to improve their UV and chemical stability in the concrete.
Manufacture and Quality control
The fibers are manufactured in a continuous process by spinning of polymer continuous filaments yams. The undrawn spun yarns are Draw - twisted , Seized , Redrawn , Relaxed and cut to 3 - 12 mm nominal length.
The manufacturing process is subjected to control checks on:
Spinning parameters: denier uniformity and yam properties. Draw - twisting:
Draw - ratio and yam Humidity. Seizing : chemicals uptake. Redrawing and cutting : cut - length uniformity.
Quality assurance checks are conducted on the spun and drawn yarns , including : Denier , Uster , Mechanical properties , Yam viscosity , chemicals uptake , cut - length uniformity.
Materials Delivery and storage
Fibers shall be measured by weight. When approved by the purchaser , fibers may be packed in premeasured , self - disintegrating bags , which are added unopened to the truck drum or central mixer. The specially designed cellulose fiber bag disintegrates and disperses its content , 300 gm , of NewCreteM fibers throughout the mix. Upon purchaser request , the fibers are also available in 2.5 and 5.0 Lbs bag sizes to suit 5 and 10 Cubic yards capacity trucks.
Larger quantities of fibers are available in standard PE bags for addition in the batching plant through a dispensing system.
Boxes of fibers must be stored on a clean surface , in dry conditions under cover and away from humidity and possibility for damage.
The bags and cardboard boxes bear the manufacturer’s and product name and batch number.
Desighn Data
* General
NewCrete M fibers are satisfactory for use with concrete mixes of nominal aggregate size of 5 mm up to 30 mm to reduce the occurrence of plastic shrinkage cracking and crazing , and enhance the surface properties of the concrete.
The fibers are not a substitute for conventional structural steel reinforcement or normal good curing procedures for concrete.
The addition of fibers at the recommended dosage of 0.300 Kg/QMeter does not normally require adjustment to the concrete mix design.
Mixes containing the product should be properly designed and placed.
The basic workmanship should comply with the relevant requirements.
It is essential that normal good curing procedures for concrete are followed.
* Air content and compaction factor
Tests conducted in accordance with procedures , indcate that the presence of fibers does not affect the air content or the ompaction factor of concrete.
* Workability
Tests show that fibers increase the apparent cohesiveness and reduce the slump of a concrete mix.
The slump test may be used as a general indicator of uniformity of concrete mixes containing fibers. Care is required when interpreting the value obtained since it may suggest a misleading low workability.
The placeability of the fiber dosed concrete and its compactability under vibration is much better than indicated by the lower consistency in the slump test.
It is recommended to use in addition to the slump test (ASTM C143) , the time of flow through inverted cone.test (ASTM C955). This test has been developed especially to measure the workability of Fiber Reinforced Concrete , effectively measuring the mobility or fluidity of the concrete under internal vibration.
Addition of water must not be added to increase the slump of fiber concrete mixes.
* Distribution of fibers
When installed in accordance with this Certificate , tests show that the fibers are uniformly and rapidly dispersed throughout the concrete mix without balling or agglomeration.
* Bleeding and plastic settlement
Tests show that the presence of fibers in a concrete mix reduces the amount of bleeding. Fiber dosed concrete generally has better surface integrity than that made from conventional (undosed) concrete with the same mix design.
* Plastic shrinkage cracking
The reduction in plastic shrinkage , bleed water migration and segregation together with early strength gain , contribute to reduce both the occurance and degree of plastic cracking.
Plastic shrinkage tests conducted on both concrete rings and slab speciemens indicate that the presence of the product significantly reduces the amount of plastic shrinkage cracking when compared to concrete made from conventional (non-fibrous) mixes.
* Stiffening times
Penetration resistace measurements show that addition of fibers decrease the nitial and final setting times should be considered when scheduling concrete construction operations , especially the mixing , placing , compaction and presence of cold joints.
* Water absorption and permeability
Water absorption and permeability tests conducted on concrete cores indicate that fibers reduce the flow rate of water absorption and its permeability.
Hence fibers increase the barrier properties of the concrete and increase its penetration resistance to be - icing salts , chlorides and carbon dioxide that corrode the steel reinforcement.
* Resistance to feeze/thaw
Freeze / thaw resistance tests conducted , indicate that fiber dosed concrete has a greater resistance to frost attack than similar concrete made with
conventional mixes.
Fibers may be considered as a substitute for proper air - entrainment to obtain freeze / thaw resistance properties.
These tests also indicate that fiber dosed concrete has a greater erosion resistance than conventional concrete.
* Resistance to abrasion
Abrasion resistance tests conducted , indicate that fiber dosed concrete has a greater surface abrasion resistance than conventional (undosed) concrete.
* Resistance to impact
It has been shown by impact resistance tests that concrete uniformly distributed with fibers has a significantly greater impact resistance than undosed concrete. These results also indicate that the degree of spalling and damage to arrisses of joints may be lessened.
* Changes in length on wetting and drying
Tests show that the changes in length on wetting and drying depend on the concrete mix proportions and density , and are unaffcted by the presence of the fibers.
* Strength characteristics
Compressive strength cube tests conducted indicate that the fibers , when used in recommended dosage rate of 0.300 Kg/Qmeter increase the early strength gain of concrete.
The fibers have no significant effect on the 28-day compressive strength of concrete cubes.
The fibers have no significant effect on the flexural strength of concrete and all normal reinforcement is still required as for conventional concrete.
* Bond strength of concrete to steel
Standard test method for comparing concretes on the basis of bond developed with reinforcing steel , shows that standard dosage of the fibers improves the bond of concrete to steel substaantially.
* Performance in relation to fire
The results of tests indicate that when concrete containing fiber reinforcement is subjected to fire , the structural integrity will be the same as for the concrete without fibers.
Fire will destroy fibers located close to the surface , resulting in an increase in porosity of the concrete surface.
Melting of the fibers will release steam pressure , enhancing the fire resistance of concretes containing higher dosages of fibers.
* Surface appearance and hardness
The fibers generally improve the surface quality of concrete using conventional mixes by reducing the number of bleed holes.
Consequently this improvement in near surface absorption of the fiber dosed concrete causes both water and dirt to be absorbed more slowly and evenly into the surface , and also results in a more uniform appearance.
The fibers are compatible with the concrete and are not visible , yielding a smooth , non-hairy surface.
Tests indicate that the presence of fibers does not affect the surface hardness of concrete.
* Durability
Test data indicate that the presence of fibers in conventional concrete mixes reduces the amount of plastic shrinkage cracking and bleeding in its plastic state and improves the resistance to impact surface abrasion , water absorption and permeability and freeze / thaw resistance of the hardened concrete.
Fibers dosed concrete is generally more durable than concrete made from conventional (undosed) mixes of same mix design.
Installation
* General
Newcrete M fibers may be added to all normal concrete mixes strictly in accordance with this specification and the purchasers instructions.
* Mixing
The fibers are added to concrete mixes at the rate 0.300 Kg/Qmeter.
The fibers may be added at either a conventional batching / mixing plant , or may be added by hand to the ready - mix truck on site.
In the plant : fibers can be added to the aggregate in the weigh hopper , added to the aggregate on the belt or added directly to the truck at the batch plant.
When adding to the ready mix truck on site : the content of each bag of fibers (self disintegrating paper) is added via the hopper , the concrete should be mixed for at least 4 minutes at approximately 75 revolutions per minute to ensure a uniform mix dispersion.
In special applications the concentration of the fibers could be higher , without any noticeable mixing problems.
* Placing
Newcrete M fibers require no special handling in the field : Fiber dosed concrete mixes will flow around reinforcement , into restricted areas and against mould faces in the same manner as conventional concrete of similar mix proportions.
Normal methods of placing concrete are compatible with Newcrete M fibers containing concrete , Whether discharging directly fron the chute or pumping.
Concrete reinforced with Newcrete is very easy to pump and the fibers lessen the danger of segregation.
Newcrete M entrained concrete usually assists normal mix placement by giving the material a more plasticised effect , thereby improving handling characteristics.
Fiber dosed concrete mixes may be hand tamped or vibrated by conventional screeding means to provide the necessary levelingand compaction.
* Curing
It is essential that all normal good curing procedures for conventional concrete are strictly followed.
Due to the effect Newcrete M has on water migration , it is recommended sufficient time is allowed before power floating procedures are adopted.
* Finishing
Finishing should be done by using standard techniques:
Placed concrete mixes containing the fibers may be floated and trowelled using all normal hand or power tools , to provide a smooth , fiber - free surface appearance.
Almost all concrete surface treatments and finishes , including pattern stamping , exposed aggregates , brooming and trowling are compatible with the fibers reinforced concretes.
All forms of sawcutting equipment can be used with fiber-reinforced concrete. Low volume fiber reinforced concrete is sawcut in a similar fashion to nonreinforced concrete.
Joints are needed because The use of Newcrete M fibers does not change the natural shrinkage behavior of the concrete. The fibers will help to reduce the intermediate cracking that often takes place between joints due to plastic shrinkage.
Inspections and quality control
The manufacturer should afford the inspector all reasonable access , for making necessary checks of the production facilities and for securing necessary samples to determine if the materials comply with the requirements of this specification.
* Sampling
Samples of batch mixed or continuosly mixed fiber reinforced concrete shall be obtained in accordance with specifications.
* Workability and air content tests
Make tests for workability and air content at the time of placement a often as necessary for control check purposes , and always when speciemens for test on hardened concrete are made.
Measure slump , time of flow and air content according to specifications.
If the measured parameters fall outside the permitted limits , in two different portions of concrete , the sample fails to meet the requirements of this specification.
* Acceptance testing of hardened fiber reinforced concrete
The flexural toughness parameters , or first - crack sterngth , or both are being used according to the purchaser requirements.
Test results should equal or exceed specified values defined for each method
According to the test age.
Ordering information
The purchaser shall specify the following:
* Type of cement , otherwise the cement shall be Type 1.
* Type of fine and coarse aggregate , otherwise shall be normal weight.
* Slump or time of flow at the point of delivery , or the point of placement.
Slump shall be specified when it is antucupated to be 2 in. (50 mm) or more , and time of flow shall be specified when slump is anticipated to be less than 2 in. (50 mm).
* Air content , when air entrainment is required , based on air content of samples taken at the point of discharge , or the point of placement.
* when the purchaser requires , the manufacturer assumes responsibility , should give consideration to requirements for workability , placeability , durability , sureface texture , and density.
* Requirements for flexural toughness , or first crack strength , or both , determined in accordance with method C 1018 or method C 78 respectively , using samples obtained at the point of discharge , or the point of placement. At the option of the purchaser , compressive strength (method C39) shall be
specified when the flexural requirements are considered inadequate for ensuring the quality of the matrix of the fiber reinforced concrete.
Test shall be performed after standard moist curing of 28 days.
* Minimum cement content in Kilograms per cubic Meter.
If admixtures are required , the type , name , and dosage to be used. The *
Cement content shall not be reduced when admixtures are used.
* The manufacturer shall , at the request of the purchaser , fumish statement prior to the actual delivery of the concrete giving : the sources , specific gravities , sieve analysis and saturated surface - dry weights of fine and coarse aggregates , the dry weights or cement and mineral admixtures , the type , dimensions and weight of fibers , the quantities , type and weight of chemicals and the amount of mixing water per cubic meter that will be used in the manufacture of the concrete.
Product specification
NewCrete M is composed of 3 - 12 mm long by 12 micrometer diameter flat monofilament fibers made from 100% Nylon 6.6 polymer.
The fibers specific properties are:
Specific Gravity - 1.16 gm / Cu cm
Dtex Per Filament – 1.5
Tenacity – 3.0 gm/dtex (350 mPa)
Elongation at break - 80%
Modulus - 20 gm/dtex (4,200 mPa)
Thermal Stability – melting point : 264 Deg.C
Water absorption - 4.5 - 8.0%
Color - White transparent
The product is for use as additive in plain concrete mixes of nominal maximum aggregate sizes of 5 mm to 30 mm to assist in controlling plastic shrinkage cracking and crazing , and enhance the hardened surface properties of concrete.
NewCrete M fibers are not a substitute for conventional structural steel reinforcement or normal good curing procedures for concrete.
Technical investigations
The following is a summary of the technical investigations carried out on Newcrete 19:
* Plastic Shrinkage Cracking
Test method
Procedure was following AcI544.2R-9 and the ’’Resistance to plastic cracking (rings)’’ FCB (Trodheim) Norway test method:
In a direct comparison between Newcrete and the commercial Nycon fibers , six mixes were prepared and tested for the restraint ring plastic shrinkage cracking.
Concrete mix proportions (Kg / Qmeter):
Crashed aggregates- 800
Fine crashed aggregate- 300
Sand- 600
Cement- 400
Water- 223
Fibers- As specified according to sample
Results :
Table I - Qantity and type of fibers
Mix # Fiber Type Fiber length Content (Kg/Qm)
1 no fibers
2 NewCrete 19 12 0.4
3 NewCrete M 12 0.3
4 Nycon 19 0.6
Table II - Slump and Crack Reduction Results
Mix# Slump Air% TOTAL Inside Outside Reduct.*
1 175 1.7 1669.0 559.0 1100.00 0
2 150 1.5 235.5 55.5 180.0 86.0
3 165 1.6 193.7 38.4 155.3 88.4
4 145 1.5 271.1 99.9 171.2 83.7
Conclusion
The addition of 0.300 Kg / Qmeter NewCrete M of 12 mm cut lenth is equivalent to 0.4Kg / Cubic meter NewCrete 19 and 0.6 Kg/ Cubic meter Nycon Caprolan RC .
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