Engineering practice lecture no 06 Lecture-06.pptx
- 2. Ready Mix Concrete Ready mixed refers to concrete that is batched for delivery from a central plant instead of being mixed on the job site. Each batch of ready-mixed concrete is tailor-made according to the specifics of the contractor and is delivered to the contractor in a plastic condition, usually in the cylindrical trucks often known as "cement mixers."
- 3. Ready Mix Concrete ADVANTAGES: Better quality concrete Elimination of storage space at site. Elimination of Procurement/Hiring of labor and machinery. Wastage of basic material is avoided. Noise and dust pollution at site is reduced. Time required is greatly reduced.
- 4. Ready Mix Concrete DEMERITS: The transit time from the time of preparation of concrete to the delivery site, will result in loss of workability The formwork and placing arrangement must be prepared in advance in large area as the concrete can be bought in larger amounts. Traffic jam and failure of vehicles create problems.
- 5. Ready Mix Concrete Materials Required: Aggregates Cement Admixture Water
- 6. Ready Mix Concrete Mixing Process: Thorough mixing of material is essential for production of uniform concrete. The mixing should ensure that the mass becomes homogeneous and consistent. Following are the three types of mixing process of RMC Transit mixed concrete Shrink mixed concrete Central mixed Concrete
- 7. Ready Mix Concrete Mixing Process: In transit mix concrete, all of the raw ingredients are loaded directly into the truck mixer. No plant mixer is involved. Central mix concrete plants also known as batching plants include a stationary mixer that blends the concrete materials prior to discharge into the truck mixer. The truck mixer is used primarily as an agitator when the concrete is centrally mixed.
- 8. Ready Mix Concrete TRANSIT MIXER
- 10. Ready Mix Concrete Mixing Process: Shrink mix concrete is partially mixed in a central mixer and then charged into a truck mixer, where the mixing is completed. Shrink mix concrete is partially mixed in a central mixer and then charged into a truck mixer, where the mixing is completed. Shrink mix concrete is partially mixed in a central mixer and then charged into a truck mixer, where the mixing is completed.
- 11. Ready Mix Concrete: Manufacturing: After producing ready mix concrete, an utmost care must be given to the quality of concrete during transportation to the site Travel Distance: Larger travel time may hamper the quality of concrete. Transit Mixers: Every transit mixer should be in goof condition and checked before carrying. Weather Conditions
- 12. Difference between Ready Mix Concrete and Site Mixed Concrete Ready Mix Concrete Site Mixed Concrete Consistent Quality Quality is inconsistent Construction in double quick time Manual Mixing is time consuming Raw materials are chosen after strict quality checks Quality of raw materials is manually checked Large quantities of concrete can be ordered. Repeated mixing needs to be done for large quantities, Now wastage of materials at site. Everything is pre- mixed at plant. High wastage of raw materials.
- 13. Concrete Construction Columns and Beams: Columns are normally of either circular or rectangular cross section. In placing concrete into wall and column forms, care must be taken to avoid segregation of aggregate and paste that may result from excessive freefall distances.
- 14. Concrete Construction Slabs: There are a number of different types of structural systems used for concrete slabs. Such systems may be classified as one-way or two-way slabs, flat slabs and flat plate slab.
- 15. Concrete Construction One way Slab: One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. The ratio of longer span (l) to shorter span (b) is equal or greater than 2 are considered as One way slab because this slab will bend in one direction i.e in the direction along its shorter span
- 17. Concrete Construction Two way Slab: Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along with both directions, it is known as two way slab. In two way slab, the ratio of longer span (l) to shorter span (b) is less than 2. In two way slabs, the load will be carried in both the directions. So, the main reinforcement is provided in both directions for two way slabs.
- 19. Concrete Construction Flat Plate Slab: Flat plates are solid concrete slabs of uniform depths that transfer loads directly to the supporting columns without the aid of beams or capitals or drop panels. Flat plates can be constructed quickly because of their simple formwork and reinforcing bar arrangements.
- 22. Concrete Construction Flat Slab: Flat slabs include two-way reinforced concrete slabs with capitals, drop panels, or both. These slabs are very satisfactory for heavy loads and long spans. They are particularly economical for warehouses, parking and industrial buildings, and similar structures, where exposed drop panels or capitals are acceptable.
- 25. Concrete Construction Precast Concrete: Precast concrete is concrete that has been cast into the desired shape prior to placement in a structure. There are a number of advantages obtained by removing the concrete forming, placing, finishing, and curing operations from the construction environment.