### EXPERIMENTAL COMPARISON BETWEEN FLEXURAL CRACKS BEHAVIOR OF SELF-COMPACTING CONCRETE AND NORMAL CONCRETE BEAMS

#### Abstract

Eight reinforced concrete rectangular beams were designed and tested to study the effect of using self-compacting concrete (SCC) and normal concrete (NC) on the flexural cracking behavior under two concentrated load. All beams have the same longitudinal and vertical steel ratio and gross section area of (15000) mm2. The tested beams were divided into two groups; the first group consists of four self-compacting concrete beams (SCC) while the second group consists of four normal strength concrete (NSC). Each group was divided into two series according to clear span to effective depth ratio (ln/d), each series includes of two compressive strength (f_c^' ). It was found that the beams which made from SCC was more stiffer as compared with the beam which made from NCC with same of the clear span to effective depth ratio, longitudinal steel ratio, vertical steel ratio and relative compressive strength. The first crack in the SCC beams about 26.95% from the ultimate load while the first crack in the NSC beams about 20% from the ultimate load, the ACI 318-08 equation is conservative as compared with the experimental study, the max crack width of SCC beams is lesser than the NC beams, the number of crack in SCC beams is lesser than the NC beams, the Z factor value in different exposure in ACI formula is more conservative than obtained from experimental study, the experimental cracking moment of SCC beams are greater than the experimental cracking of NSC. As compared with theoretical cracking moment predicated from cracking moment predicated from ACI formula, the maximum crack width of SCC increased about 20.833%, 26.16% when the clear span to the effective depth ratio (ln/d) increase from 8.4 to 10 at compressive strength (f_c^') 23.81 and 17.9 MPa respectively while the maximum crack width of NSC increased about 8.1%, 11.42% when the clear span to the effective depth ratio (ln/d) increase from 8.4 to 10 at compressive strength (f_c^') 22.41 and 16.2 MPa respectively and the ultimate load capacity of SCC increased about 9.433%, 14.285% when the compressive strength (f_c^') increased from (17.9) to (23.81) MPa at clear span to effective depth ratio (ln/d) (8.4),(10) respectively while the maximum crack width of NSC increased about 2.56%,5.714% when the compressive strength (f_c^') increased from (16.2) to (22.41) MPa at clear span to effective depth ratio (ln/d) (8.4),(10) respectively.

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