Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012 439 SOME PROPERTIES OF FIBER REINFORCED NO FINE CONCRETE Hussam A. A. Rehman Assist. Lecturer Civil Engineering Department/Wasit University hussam4s@yahoo.com . ABSTRACT This work focus on studying the mechanical characteristics of polypropylene and carbon fiber reinforced no fine aggregate concrete, containing different percentages of fiber. This work was carried out using several tests. These tests were workability fresh and hardened density, compressive strength, splitting tensile strength and modulus of rupture. Tests were performed for specimens at ages of (7, 28) days. The test results indicated that the inclusion of fiber to the pervious concrete mixes did not affect the compressive strength significantly, while the splitting tensile strength and the modulus of rupture were improved significantly. Test results indicated that, the modulus of rupture of (5%) carbon fiber pervious concrete specimens are three times that of the control specimens, while the modulus of rupture of (5%) polypropylene fiber pervious concrete specimens are two times that of the control specimens. The percentage increase in tensile strength for polypropylene mixes containing fiber by volume fraction of (1%, 3%, 5%) were (93%, 101% and 129%) respectively and the percentage increase in tensile strength for carbon mixes containing fiber by volume fraction of (1%, 3%, 5%) were (170%, 177% and 220%) respectively. KEYWORDS: No fine concrete, Carbon fiber, Polypropylene fiber, Flexural strength. 7 28 5 Hussam A. A. Rehman Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012440 13593101129 13593 101129 1. INTRODUCTION No-fines concrete (NFC) is an open textured cellular concrete and it’s a type of light weight concrete ,obtained by eliminating either fines or sand from the normal concrete mix. The alleged advantages of this type of light weight porous concrete include its lower cement content (resulting in lower cost), lower density, lower thermal conductivity, no segregation and, better insulating characteristics, than conventional concrete. A limited number of researches have been carried out to investigate the mechanical properties of fiber reinforced no fine concrete (NFC). However there have been many works on the mechanical characteristics of fiber reinforced normal concrete. No-fines concrete consists solely of normal Portland cement, water and coarse aggregate. The compressive strength of no-fines concrete is considerably lower than that of conventional Portland cement concrete and varies between (4 to 25) MPa [1]. The ratio of modulus of rupture to compressive strength expressed as a percentage varies between 10.8 and 31.0 percent [2]. The principal advantages claimed for no-fines concrete are economy in materials, somewhat higher thermal insulating values, lower shrinkage, and lower unit weight. The major disadvantages are its low compressive, flexural, and bond strength, and higher permeability. The principal applications for no-fines concrete are for load-bearing cast-in-place external walls of single story and multistory housing, small retaining walls, and as a dam proofing sub-base material for concrete floors cat on grade. Fiber reinforced No Fine Concrete (NFC) has a little application in Iraq. However, light weight carbon fiber reinforced concrete with micro balloons as aggregate has been successfully used in the construction of AL-Shaheed monument in Iraq [3]. The Density of NFC depends on the properties and proportions of the materials used. Also it depends of the compaction procedure used in placement; generally the density ranges in1600-2000 Kg/m 3 [4]. The tensile and flexural strength is increases with increasing fiber content (2 to 10%) by volume. The handling and the fabrication create some problems at volume fraction above 10% [5]. 2. EXPERIMENTAL PROGRAM Ordinary Portland Cement and crashed coarse aggregate of (14 mm) MAS was used to produce structural no fine concrete, carbon and polypropylene fibers were also used in this study with different volumetric percentages to improve the flexural strength of no fine aggregate concrete. 3. MATERIALS 3.1 Cement Ordinary Portland cement (Type I) was used in all mixes throughout this investigation. It was stored in air – tight plastic containers to avoid exposure to atmospheric conditions. The percentage oxide composition indicated that the adopted cement conforms to the Iraqi specification No. 5/1984 [6], Table 1 and 2 shows the physical and chemical properties of OPC. 3.2 Coarse Aggregate Crushed gravel of two different maximum aggregate sizes (MAS) (10) mm from Wasit, Badra region is used. Table 3 shows the grading of these aggregate, which conforms to the Iraqi specification No. 45/1984[7]. The specific gravity, sulfate content and absorption of coarse aggregate are illustrated in Table 4. SOME PROPERTIES OF FIBER REINFORCED NO FINE CONCRETE 441Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012 3.3 Carbon Fiber The properties of carbon fibers, such as high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion, make them very popular in civil engineering and other fields. However, they are relatively expensive when compared to similar fibers, such as glass fibers or polypropylene fibers. Table 5 shows the general properties of the used carbon fiber. 3.4 Polypropylene Fiber The properties of polypropylene fibers, such as fiber shape and dimensions, tensile strength, density, Elastic modulus and elongation are illustrated in Table 6. 4. CONCRETE MIXES Concrete mixes with no fine aggregate as a type of light weight concrete should have a dry density less than (2000 kg/m³) and a compressive strength great than (15 MPa) to produce structural concrete. These mixes were obtained by several trial mixes. The mix proportions of all concrete mixes are shown in Table 7. 5. MIXING, CASTING AND CURING OF SAMPLES All concrete samples (cubes, cylinders and prisms) are casted in steel molds. They were cleaned and oiled before casting. The fresh concrete was placed inside the molds with approximately three equal layers and compacted by means of vibrating table. Care was taken to avoid segregation of mixes as shown in Plate 1. After the top layer had been compacted, it was smoothed and then the mold covered with wetted gunny sheets for 24 hours to prevent evaporation of water so as to avoid the plastic shrinkage cracks as shown in Plate 2. After 24 hours the specimens were demolded and completely covered with wetted gunny sheets until the day of testing. 6. TESTING PROGRAM 6.1 Unit Weight The unit weight of hardened concrete were measured according to ASTM C567 [8] specifications respectively. 6.2 Compressive Strength Compressive strength tests were conducted using (150) mm cubes using an electrical testing machine with a capacity of (2000 KN) at loading rate of (15 MPa) per minute. This test was determined according to B.S. 1881: part 116: 1984[9].The average of three cubes was adopted for each test. The test was conducted at ages of (7 and 28) days as shown in Plate 3. 6.3 Splitting Tensile Strength Splitting tensile strength test was performed according to ASTM C496/C496 M-04 [10] using of (150× 300) mm cylinder. The test was conducted at age of (7 and 28) days. The average splitting tensile strength of three cylinders was adopted, as shown in Plate 4. 6.4 Modulus of Rupture Modulus of rupture of concrete was measured on (100 ×100× 500) mm specimens according to ASTM C78-02[11]. The prisms were subjected to two- point loading. Specimens were tested at age of (7 and 28) days as shown in Plate 5. http://en.wikipedia.org/wiki/Glass_(fiber Hussam A. A. Rehman Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012442 7. RESULTS AND DISCUSSIONS 7.1 Unit Weight The 7 and 28 day air dry density of all types of concrete mixtures is presented in Table 8. Results show that the 7 and 28 day air dry densities of (NFC) mixes produced from local naturally aggregate are conformed to the requirement of ACI 213-R-87. For structural pervious concrete, the air dry densities should be ranged between (1821-1854) Kg/m 3 , however all concrete mixes conform to the requirements of (LWC) according to ACI limits the maximum density to 2000 Kg/m³. Results show that (NFC) mixes without fibers have higher density than fiber reinforced (NFC) mixes containing polypropylene and carbon. 7.2 Compressive Strength The compressive strength development for all types of mixes is presented in Figure 1. Test results illustrate that in general, reference pervious concrete and polypropylene and carbon fiber reinforced pervious concrete specimens exhibited continuous development in strength up to 7 and 28 days of curing. There is a considerable improvement in strength for mixes containing fibers. There was a slight increase in the compressive strength with increasing the fiber volume fraction, unless the fiber volume is so high leading the air voids content to become excessively high. The air voids tends to have a negative effect on the compressive strength. 7.3 Splitting Tensile Strength Results of splitting tensile strength of various types of reinforced fiber concrete mixes cured with per lab sheets up to 7 and 28 days are demonstrated in Figure 2. The incorporation of polypropylene and carbon fiber leads to higher splitting tensile strength compared to their corresponding reference concrete. The tensile strength of the fiber concrete mixes increases with the increase of fiber volume content. This is due to the nature of binding effect of fiber available in concrete matrix. The control batch specimens containing no fiber failed suddenly once the concrete cracked, while the fiber reinforced concrete specimens were still intact together. This shows that the fiber reinforced pervious concrete has the ability to absorb energy in the post- cracking state. The comparison of percentage difference in splitting tensile strength for both polypropylene and carbon fiber reinforced pervious concrete to its control batch is presented below, for example the percentage increase in tensile strength for polypropylene mixes containing fiber by volume fraction of (1%, 3%, 5%) were (93%, 101% and 129%) respectively and the percentage increase in tensile strength for carbon mixes containing fiber by volume fraction of (1%, 3%, 5%) were (170%, 177% and 220%) respectively. 7.4 Flexural Strength The influence of fiber content on the modulus of rupture for all types of fiber reinforced pervious concrete specimens is presented in Figure 3. Results demonstrate that all concrete specimens exhibited considerable increase in flexural strength with increasing fiber content. The modulus of rupture trend for carbon fiber varies as the volume fraction of fiber is increased. It is found that, the modulus of rupture increases as the fiber volume fraction is increased. The concrete specimens containing no carbon fibers are cracked and failed in a brittle manner when strain in concrete reached its ultimate value. However, fiber reinforced concrete also cracked at ultimate strain, but the section is still capable to carry the load well after the initiation of the first crack .Test results indicated that, the modulus of rupture of (5%) carbon fiber pervious concrete specimens are three times that of the control specimens, while the modulus of rupture of (5%) polypropylene fiber pervious concrete specimens are two times that of the control specimens. SOME PROPERTIES OF FIBER REINFORCED NO FINE CONCRETE 443Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012 8. CONCLUSIONS On the basis of seven mixes described in the text, using three variables: two types of fiber (polypropylene and carbon), three different percentages for each of fiber (1, 3 and 5 %), and these mixes are tested in compressive, flexural and splitting tensile strength at age of 7 and 28 days, main conclusions can be summarized, as follows: 8.1 Density Results show that the pervious concrete mixes without fibers have higher density than fiber reinforced pervious concrete mixes containing polypropylene and carbon. However, the air dry densities should be ranged between (1821 - 1854) kg. 8.2 Compressive Strength There was a slight increase in the compressive strength with increasing the fiber volume fraction, unless the fiber volume is so high leading the air voids content to become excessively high. The air voids tends to have a negative effect on the compressive strength. 8.3 Flexural Strength Test results indicated that, the modulus of rupture of (5%) carbon fiber pervious concrete specimens are three times that of the control specimens, while the modulus of rupture of (5%) polypropylene fiber pervious concrete specimens are two times that of the control specimens. 8.4 Splitting Tensile Strength The comparison of percentage difference in splitting tensile strength for both polypropylene and carbon fiber reinforced pervious concrete to its control batch. For example the percentage increase in tensile strength for polypropylene mixes containing fiber by volume fraction of (1%, 3%, 5%) were (93%, 101% and 129%) respectively and the percentage increase in tensile strength for carbon mixes containing fiber by volume fraction of (1%, 3%, 5%) were (170%, 177% and 220%) respectively. 9. RECOMMENDATIONS FOR FUTURE WORKS The work carried out in this work can be considered as a key for further work such as: 1. Studying the mechanical properties of polypropylene and carbon fiber with light weight aggregate concrete. 2. Studying the durability of fiber reinforced no fine aggregate concrete. 3. Studying the effect of addition pozolanic materials on the properties of no fine aggregate concrete. 10. REFERENCES 1. Schaefer, V.R., et al (2006), "An Overview of Pervious Concrete Applications in Storm Water Management and Pavement System", Iowa State University, Ames. 2. Malhotra, V.M., "No Fine Concrete-Its Properties and Applications", State of The Art Report, ACI Journal, November 1976, pp. 628. 3. Akihama, S. Sueenage T. and Banno, J. “Mechanical Properties of Carbon Fiber Reinforced Cement Composite and the Applications of Large Domes” Kajime Institute of construction Technology, Tokyo, Jpan, July 1984. 4. Tennis, P.D., Leming, M.L. and Akers, D.J., (2004) "Pervious Concrete Pavement", Old Ochard Road, Skokie: Portland Cement Association. Hussam A. A. Rehman Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012444 5. Saker S. and Bailey. M." Structural properties of Carbon Fiber reinforced cement" RIlEM Symposium on fiber reinforced and concrete, September 1975, pp.361-371. 6. Iraqi Specifications No. 5, “Portland Cement”, Baghdad, 1984. 7. Iraqi Specifications No. 45, “Natural Sources for Gravel that is Used in Concrete and Construction”, Baghdad, 1984. 8. ASTM Standards: C 567-02, “Standard Test Method for Determining Density of Structural Lightweight Concrete”, ASTM International. 9. 10. BS 8110:Part2, “Structural Use of Concrete: Code of Practice for Special Circumstances”, British Standard Institute, London, 1997. 11. ASTM Standards: C 496-02, “Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens”, ASTM International. 12. ASTM Standards: C78-84, “Flexural Strength of Concrete [Using Simple Beam with Third Point Loading”, ASTM International. Table 1 Chemical Composition of Cement Compound composition (Oxides) Chemical composition Percentage by weight Limits of IQS 5:1984 (7) Calcium oxide CaO 62.98 -- Silicon dioxide SiO2 21.45 -- Iron oxide Fe2O3 3.64 -- Aluminum oxide Al2O3 5.63 -- Magnesium oxide MgO 2.39 <5 Sulphur trioxide SO3 2.57 <2.8 Lime saturation factor L.S.F 0.73 0.66 – 1.02 Loss on Ignition L.O.I 2.19 <4 Insoluble residue I.R 0.4 <1.5 Tricalicum silicate C3S 42.94 -- Dicalicum silicate C2S 29.18 -- Tricalicium Aluminates C3A 8.76 -- Tetracalicum aluminates ferrite C4AF 11.06 -- SOME PROPERTIES OF FIBER REINFORCED NO FINE CONCRETE 445Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012 Table 2 Physical Properties of Cement Properties Test results IQS 5: 1984 criteria (7) Fineness using Blaine air permeability apparatus (m 2 /kg) 464 >230 Setting time using Vicat's Method Initial (hrs:min) Final (hrs: min) 1:45 3:45 >45 min <10 hrs Soundness using Autoclave Method 0.19% <0.80% Compressive strength 3 day 7 day 28 day* 26.7 38.9 45.6 >15 >23 ----- * The 28-day compressive strength is now a compulsory test in most international standards. Table 3 Grading of Coarse Aggregate of MAS (10) mm Sieve size (mm) % passing by weight Limits of the Iraqi specification No. 45/1984 (8) 14 100 100 10 93 85-100 5 22 0-25 2.36 5 0-5 Table 4 Other Properties of Coarse Aggregate of MAS (10) mm Physical properties Test results Limits of the Iraqi specification No. 45/1984 (8) Specific gravity 2.55 -- Sulfate content 0.06%  0.1% absorption 1.15% -- Table 6 Physical Properties of Carbon Fiber* Property Value Nominal diameter (mm) 0.13 Tensile strength (MPa) 4300 Fiber Length (mm) 10 Density (g/cm 3 ) 1.76 Elastic modulus (GPa) 238 Elongation (%) 1.8 * Provided by the Manufacturer Hussam A. A. Rehman Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012446 Table 7 Characteristics of Polypropylene Fiber* Properties Thick fiber Fine fiber Nominal diameter (mm) 0.98 0.022 Tensile strength (MPa) 240 400 Fiber Length (mm) 10 10 Density (g/cm 3 ) 0.88-0.92 0.91 Elastic modulus (MPa) 5100 8500 Elongation (%) 24.4 12 Shape Wavy Flat * Provided by the Manufacturer Table 8 Unit Weight of All Mixes. Mix Designation % of fiber by volume w/c ratio by wt. Unit weight Air dry Density (28 days) kg/m³ NPC 0 0.3 1890 PFC1 1 0.3 1848 PFC3 3 0.3 1833 PFC5 5 0.3 1821 CFC1 1 0.3 1854 CFC3 3 0.3 1846 CFC5 5 0.3 1830 Figure 1 Relationship between Compressive Strength and Percent of fiber by volume. SOME PROPERTIES OF FIBER REINFORCED NO FINE CONCRETE 447Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012 Figure 2 Relationship between Flexural Strength and Percent of fiber by volume Figure 3 Relationship between Splitting Tensile Strength and Percent of fiber by volume Hussam A. A. Rehman Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012448 Plate 1 No Fine Concrete Mixture. Plate 2 Curing of Concrete Samples with Wetted Gunny Sheets SOME PROPERTIES OF FIBER REINFORCED NO FINE CONCRETE 449Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012 Plate 3 Compressive Strength Test Machine Plate 4 Splitting Tensile Strength Test Machine Hussam A. A. Rehman Al-Qadisiya Journal For Engineering Sciences, Vol. 5, No. 4, 439-450, Year 2012450 Plate 5 Flexural Strength Test Machine Table 1 Chemical Composition of Cement Table 2 Physical Properties of Cement * The 28-day compressive strength is now a compulsory test in most international standards. Table 3 Grading of Coarse Aggregate of MAS (10) mm Table 4 Other Properties of Coarse Aggregate of MAS (10) mm