Concrete• One of the very important and widely used material in construction• The Grade of the concrete is specified by its 28 day’s cube strength (E.g. M20 means the cube strength is 20 N/sq.mm)• Concrete used on works is specified according to IS 456 (2000). 1
•Consists of Portland cement, water, and aggregate ( Fine&Coarse )•Cement, water and fine aggregate – mortar-Admixtures added for specific purposes like – Entrain numerous microscopic air bubbles – Retard the initial set of the concrete – Waterproof the concrete , etc. 2
Concrete chainCement supply sand supply Coarse aggregate Water supply supply Transporting, unloading and stacking Gauging Mixing Slump test Cube test Transporting Placing 3 Compaction Curing
PROPORTIONING CONCRETE MIXTURES• For successful utilization, the mixtures must be properly proportioned ( Mix design )Concrete Mix Design-IS 10262Designed to achieve a defined• workability• strength• durability 4
BATCHING AND MIXING OF CONCRETE MATERIALS • Batching is weighing or volumetrically measuring and introducing into the mixer the ingredients for a batch of concrete • A batch is the quantity of concrete mixed at one time More accurate to measure by weight• As per IS 4925 : 1968 - specification for concrete batching and mixing 5
Formwork systemIt is a mold used to shape the concrete and support theconcrete until it attains sufficient strength to carry itsown weight.
Introduction No desirable structure can be built without the use of formworks. Such is the importance of formwork that it constitutes 30% of Cost 60% of Time Construction Apart from that the quality of concrete finish and soundness of concrete depends very much on the formwork system.
Types of FormworkFormwork can be divided into two approaches : Traditional approach Systematic approach (System formwork)
Traditional formwork system in System formwork in ProgressProgress Collapsible A network ofWooden A network of type props wooden H-beamsposts wooden beams (CT props) to support the(ballies) to support the sheathing. sheathing Pictures and sketches taken from L&T- DOKA formwork manuals
Column FormworkPictures and sketches taken from L&T- DOKA formwork manuals
Wall FormworkPictures and sketches taken from L&T- DOKA formwork manuals
Beam Forming SupportPictures and sketches taken from L&T- DOKA formwork manuals