Leads Institute of Technology & Engineering Subject Code : Name Of Subject :Building Construction Name of Unit : Concrete Topic : Plain Concrete & RCC

Plain and Reinforced cement concrete Portland cement, Test on cement & concrete

What is Concrete? Concrete is a mixture of cement, fine and coarse aggregate. Divided into two parts PCC and RCC Mixture of cement, sand and coarse aggregate without any reinforcement is known as PCC(Plain cement concrete). Mixture of cement, sand and coarse aggregate with reinforcement is known as RCC(Reinforced cement concrete).

Importance in Civil Engineering Concrete is widely used for making architectural structures, foundations, brick/block walls, pavements, bridges/overpasses, highways, runways, parking structures, dams, pools/reservoirs, pipes, footings, fences and poles and even boats. Concrete is used in large quantities almost everywhere mankind has a need for infrastructure.

Some Concrete Structures Burj Kalifa tallest Building in the world. Location: Dubai, United Arab Emirates Time to build: 6 years Cost: USD $1.5 billion Height: 829.8m (2,722ft) (228.8m higher than the second tallest building in the world) Floor count: 163 floors

World’s Tallest Bridge in The world. Location: Millau-Creissels, France Time to build: 3 years Cost: USD $524m (€394m) Height: 343m (1,125ft)

Three gorges Dam, World’s Largest power station. Location: Sandouping, Yiling, Hubei Time to build: 14 years Cost: USD $37 billion (¥180 billion) Original estimated cost: USD $6 billion (¥20 billion) Height: 181m (594ft)

What is cement ? Cement is a fine powder, When mixed with water and allowed to set and harden can join different components or members together to give a mechanically strong structure. The percentage of cement in concrete is around 15%,

Role of Cement in Concrete Cement is binding material in the cement concrete. It fills up voids existing in the fine aggregate and makes the concrete impermeable. It provides strength to concrete on setting and hardening. The role of cement is very important in the strength and durability of concrete.

Overview of Portland Cement Dry powder of very fine particles forms a paste when mixed with water chemical reaction-Hydration glue paste coats all the aggregates together hardens and forms a solid mass. OR Ordinary Portland Cement is a controlled blend of calcium silicates, aluminates and ferrate, which is ground to a fine powder with gypsum and other materials

Cement Types

Type I - Normal Type III - High Early Type IV - Low Heat of Hydration

Difference b/w Hydraulic & Non Hydraulic Cement Hydraulic cement, Portland cement Cement that hardens under water Made by heating limestone and clay in a kiln and pulverizing the result Non Hydraulic cement, Cement which cannot harden while in contact with water. Made by using materials such as non-hydraulic lime and gypsum plasters and oxychloride, which has liquid properties.

Tests On Cement There are many tests of Cement But in our studies: Consistency Test Initial setting time Final setting Time

Consistency Test Consistency means amount of water needed to prepare a plastic mix. Consistency test is done using Vicat's apparatus. The standard consistency of a cement paste is defined as that consistency which will permit the vicat plunger to penetrate to a point 5 to 7mm from the bottom of the vicat mould.

About Vicat’s Apparatus It consists of the following: Ruler starting from 40 mm(which is the height of the mould). The Mould. Non-porous plate. The plunger. Note: The depth is always measured from the bottom of the mould.

(Note):-For making the normal consistence of standard paste we use a plunger with 10mm diameter.

Why we do Consistency Test ? Consistency test is used to find the amount of water to be mixed with Cement. It is necessary to find the consistency because amount of water present in the cement paste may affect the setting time. Consistency of cement should be less than 30%

Initial & Final Setting Time Test On Cement Initial Set Time from moment water is added until the paste ceases to be fluid and plastic. Final Set Time from moment water is added for the paste to acquire a certain degree of hardness.

Initial & Final Setting Time Test On Cement The time of setting of the hydraulic cement Is done by using VICAT needle apparatus. Needle Sizes For Initial Setting Time 1mm x 1mm cross-section 50mm length For Final Setting Time 1mm2 cross-section and 1mm deep inner needle 5mm diameter outer metal attachment

Why Initial & Final Setting Time Is necessary ? It is very important to know the setting times. Knowing the initial setting time is important in estimating free time for Mixing, transporting, placing, compaction and shaping of cement paste

Why Initial & Final Setting Time Is necessary ? Knowledge of final setting time of cement is necessary as well : After initial setting of cement Concrete starts gaining strength and harden So we have to know approximate final setting time of cement. After final setting of cement Strength of concrete can also be calculated. Final setting time also affects the strength and durability of concrete.

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