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Concrete is the most broadly utilized construction material in structural building because of its high structural strength and stability, using strength and high performance concrete has been expanding all through the world. Among the different techniques used to improve the strength and performance of concrete, utilization of Cement Replacement Material (CRM) like Meta-kaolin is a generally new approach. The understanding of fracture mechanism of reinforced concrete (RC) structure is vital and under this study its focusing to crack and deflection behavior for RC beam under static loading. An experimental investigation has been carried out on 7-RC beam to investigate the behavior of reinforced concrete beams with 10% of Nano-Metakaolin in flexural to study effect of utilizing Nano-Metakaolin, effect of flexural reinforcement ratios, effect of compression reinforcement ratios and effect of characteristic strength of concrete. It is found that partial replacement of cement with Nano -Metakaolin has a greater influence on the tested beams by 122,107,107&125% for initial crack, ultimate load, maximum defection and toughness, with minimum flexural reinforcement ratio 1.29%, and minimum compression reinforcement ratio 0.44. KeywordsFlexural Strength, Reinforced Concrete, Nano-Metakaolin (MK) Flexural Behavior Of Reinforced Concrete Beams With Nano-Metakaolin 232 believed that the term kaolin is derived from the Chinese Kaoling, which translates loosely to white hill and has been related to the name of a mountain in China that yielded the first kaolins that were sent to Europe. Kaolinite is the mineralogical term that is applicable to kaolin clays. Kaolinite is defined as a typical mineral, hydrated aluminum disilicate, Al2Si2O5(OH). Metakaolin (MK) is a supplementary cementing material that complies with ASTM C 618, Class N[1] pozzolan specifications and it is considered as a pozzolanic material which is without direct cementitious value, yet will, within the presence of moisture, reacts chemically with calcium hydroxide (CH) to form compounds possessing cementitious properties. It is acquired by the calcinations of kaolin at a temperature extending in the vicinity of 500°C and 800°C. The material is a fine, white, clay mineral MK has been known to enhance strength and porerefinement at relatively early ages [2]. II. PREVIOUS RESEARCH P. Dinakar et.al. [3], by utilizing Metakaolin and cement with low water/binder ratio of 0.3, high performance concretes can be produced. From results it can be realized that Cube Compressive strength, Splitting tensile strengths and elastic modulus results shown higher values at 10% replacement of cement by Metakaolin. Nova John [4], the outcomes appears by the partial replacement of cement with Metakaolin helps in achieving high strengths in concrete. At 15% replacement of cement with Metakaolin content improves the strength characteristics such as of Cube Compressive Strength, Split Tensile Strength and Flexural Strength. K.Srinivasu et.al.[5], Better Outcomes are accomplished by adding mineral admixtures like Metakaolin with silica fume, flyash and steel fibers in HPC. Water absorption is improved by use of Metakaolin in concrete which increases density. M. Nazeer, R. Arun Kumar [6], the impact resistance of both binary blended and ternary blended mixes shows remarkable improvement compared to concrete mix with cement as the only binder. III. EXPERIMENTAL PROGRAM Materials and Methods A) Materials 1. Cement The cement utilized during the investigation is 52grade Ordinary Portland Cement. The cement was purchased from single source. The specific gravity of the above cement was 3.15 and it is conforming to Egyptian Standard Specification [7]. 2. Aggregates Natural river sand was used as fine aggregate and broken granite stones of size 20mm was used as coarse aggregate. Fine aggregates confirm to Zone II grading with specific gravity 2.64 and bulk density of 1560kg/m respectively. The specific gravity of coarse aggregate was 2.83. 3. Water Potable water available in laboratory was used in this investigation for making concrete. 4. Nano Metakaolin Metakaolin is a dehydroxylated form of the clay mineral kaolinite. Metakaolin was ground in a heat-treated at 800 C for 2 hr high speed ball grinding mill and it was reduced to nano scale, and investigated using SEM Quanta FEG 250 at Suez and Sinai Metallurgical and Materials Research Center of Scientific Excellence (SSMMR-CSE), Suez University, Suez, Egypt , Fig. 1 a and b respectively. It was observed that the particles sizes were decreased after heat-treatment and also the layered were reached to a nano-scale. It was reported that the nano-layer thickness and the Sub micron layer is more useful for concrete properties Ehab M. Lotfy and Manar Abdelshakor 233 Fig. 1 a: Row Material Metakaolin Fig. 1 b: Nano Metakaolin Object and Scope: The experimental program included testing of 7-RC beams to investigate the behavior of reinforced concrete beams with Nano-Metakaolin in flexural to study: I. Effect of using Nano-Metakaolin. II. Effect of flexural reinforcement ratios. III. Effect of compression reinforcement ratios. IV. Effect of characteristic strength of concrete. Description of the tested beams: This study involved testing of seven concrete beams; two-span concrete beams with rectangular cross-sections of 100*200 mm, total length of 2050 mm and tested length of 1750 mm were tested. Table (1) shows the details of tested beams, All beams were divided into four groups of different reinforced concrete beams; group one contains control beam with reinforcement (As=2Φ12mm) and (AS =2Φ8mm) and ø6mm @20cm as shear reinforcement. Group two contains three beams with characteristic strength 25Mpa and 10% Nano-Metakaolin and different ratios of flexural reinforcement as shown in table (1). Group three contains two beams with characteristic strength 25Mpa and 10% Nano-Metakaolin and different ratios of compression reinforcement as shown in table (1). Group four contains a beam with characteristic strength 35Mpa and 10% Nano-Metakaolin and reinforcement (As=2Φ12mm) and (AS =2Φ8mm) and ø6mm @20cm shear reinforcement as shown in figs. (2-5). Table (1) Details of tested beams. Group No Beam No Dim. (mm) fcu Mpa Reinforcement Nano-Meta kaolin (%) width depth Flex. Rfmt Flex. Rfmt Ratio (%) Comp. Rfmt α=As /As G1 CB1 100 200 25 2Φ12 1.29 2Φ8 0.44 G2 B2 2Φ10 0.89 2Φ8 0.64 10 B3 2Φ12 1.29 2Φ8 0.44 10 B4 3Φ12 1.93 2Φ8 0.296 10 G3 B5 2Φ12 1.29 2Φ6 0.25 10 B6 2Φ12 1.29 2Φ10 0.69 10 G4 B7 35 2Φ12 1.29 2Φ8 0.44 10 Flex. Rfmt: Flexural Reinforcement Comp. Rfmt: Compression Reinforcement Flexural Behavior Of Reinforced Concrete Beams With Nano-Metakaolin 234 Fig.2 Details of reinforcement and dimensions in mm for group 1 Fig.3 Details of reinforcement and dimensions in mm for group 2 Fig.4 Details of reinforcement and dimensions in mm for group 3 Fig.5 Details of reinforcement and dimensions in mm for group 4 Ehab M. Lotfy and Manar Abdelshakor 235 Loading Arrangement: The load was applied by universal testing machine of 2000 KN. Full capacity through a loading plate and a spreader beam to give two-point loading (60 cm) as shown in Fig. 6 Fig.6 Loading Arrangement of tested beams IV. RESULTS AND DISCUSSION Table 2 demonstrates the actual fcu, cracking load, ultimate load, maximum deflection of tested specimens and type of failure. Table 2. The results of tested beams Group No. Beam No. Actual fcu (Mpa) Cracking Load (kN) Ultimate Load (kN) Max. Deflection (mm) Toughness (kN.mm) Type of failure G1 CB1 27 18 53 28 1081 flexural-shear G2 B2 31 14 37.7 28.8 876 flexural-shear B3 30.5 22 56.7 3

FLEXURAL BEHAVIOR OF REINFORCED CONCRETE BEAMS WITH NANO-METAKAOLIN