Cement

1. Salahaddin University- ErbilCollege of EngineeringArchitecture Engineering DepartmentConcrete Design3rd Year Dr. AliIzzadinMarouf Architecture Engineering Department Concrete Design Third Year

2. Cement - Cement has the adhesive and cohesive properties necessary to bond inert aggregates into a solid mass of adequate strength and durability called hydraulic cement because water is needed for chemical process, in which the ce1nent power sets and hardness into one solid mass. - Portland cement is the most common type of cement in general usage. - Portland cement first patented in England in 1824 and it was named because of its similarity in colour to Portland limestone. - The common materials from which is made are limestone which provide CaO1 and clay or shales provide Si02 and Al2O3 Architecture Engineering Department Concrete Design Third Year

3. Reinforcement • Concrete is strong in compression, as the aggregate efficiently carries the comp load. However it is weak in tension as the cement holding the aggregate in place can crack, allowing the structure to fail. R. concrete solves these problems by adding steel reinforcing bar or plastic fiber to carry tensile loading. • Steel is used as reinforcement steel is high strength material, the useful strength of ordinary reinforcing steel in tension as well as compression the yielding strength is about 15 times the compressive strength also steel is high cost material cornpared with concrete. Architecture Engineering Department Concrete Design Third Year

4. Ex : The beam is subjected to a bending momnt M = 92 KN , n = 9 , calculate the stresses Architecture Engineering Department Concrete Design Third Year

5. Architecture Engineering Department Concrete Design Third Year

6. Doubly reinforced beams • A "doubly-reinforced" concrete means that beside the tensile reinforcement the concrete element is also reinforced near the compressive face for assisting the concrete to resist compression. The latter reinforcement is called compression steel. Used if: 1- A beam cross-section is limited because of architectural or other consideration. Concrete may not resist compression force alone, then used steel in compression zone. 2- To reduced long time deflection. 3- Resist negative moment at mid span. 4- To hold stirrups.  Architecture Engineering Department Concrete Design Third Year

7. Shear and diagonal tension in beams • Shear failure of reinforced concrete properly called diagonal tension failure (shear failure collapse) is likely to occur suddenly, with no advance warning of distress while for under reinforced beams flexural failure is initiated by gradual yielding of tension steel, so giving an1ple warning, therefore reinforced concrete beams are generally provided with special shear reinforcement to insure that flexural failure would occur before shear failure if the member should be severely over loaded. Architecture Engineering Department Concrete Design Third Year

8. Architecture Engineering Department Concrete Design Third Year