GOVERNMENT POLYTECHNIC, JUNAGADH

CIVIL ENGINEERING DEPARTMENT

SUBJECT : BUILDING MATERIALSSUBJECT CODE : 3330601

• PROJECT ON : CEMENT GRADES

• SUBMITTED BY : MAHIDA ZAHIR GULAMJILANI• COURSE DIPLOMA IN CIVIL ENGINEERING• ENROLLMENT NO : 146190306036• SEMESTER 3rd SEMESTER

• SUBMITTED TO : FACULTY : N. D. VINZUDA SIR ( Lect. In civil )• YEAR : 2015

HISTORY OF CEMENT• Cement was first discovered by an English mason named Joseph

Aspdin in 1824 .• He called it Portland cement for the reason that the cement he

discovered resembled the limestone found in Portland .• The approximate composition of Portland cement is given below

• Lime ( CaO ) 60 – 70 %• Silica ( SiO2 ) 20 – 25 %• Alumina (Al2O3 ) 5 – 10 %• Ferric oxide ( Fe2O3 ) 2 – 3 %

LIMESTONE LIMELIMESTONE MINE

ALUMINA

FERRIC OXIDE PORTLAND CEMENT

• The raw materials used for the manufacture of Portland cement are limestone ( provides CaO ) and clay (provides SiO2, Al2O3 and Fe2O3) which are finely powdered and mixed in the ratio 3 : 1 by mass.

• The mixture is again ground to a fine powder and water is added.

• The finely ground powder called slurry is heated to 1773 k in a rotary kiln.

• On heating lime, silica, alumina and ferric oxide react togather and produces a mixture of dicalcium silicate and tricalcium aluminate called clinker.

• The clinker is cooled and a small amount of gypsum ( 2-5 % ) is added to it ,

to delay the setting time of cement .

• The mixture off clinker and gypsum

is then ground to a fine powder which is called cement .

• It is stored in tall structures called silos . GYPSUM

SILOS

• The cement is then packed in waterproof bags and sold in markets .

• When cement is mixed with water , it becomes hard over a period of time. This is called setting of cement .

• Gypsum is often added to Portland cement to prevent early hardening or ‘’ flash setting ‘’ , allowing a longer working time.

•WHAT ARE DIFFERENT GRADES OF CEMENT ?

• In actual practice different types of works have different requirements , like rapid hardening , more strength , resistant against frost or sulphate actions, etc.• One type of cement cannot satisfy different requirements.• Hence different standards are required to satisfy different situations.• Nowadays Portland cement has become very popular as a bindings materials

for construction work.• Lime also possesses binding properties but its properties are not standard.• Portland cement is mostly used for general purpose of construction.• Selection of proper cement suiting the requirement brings economy.• But in such case the product has to be reliable so far as its standard and

properties are an concerned.

• In order to provide different standards of cements, Indian standard institute decided to give different grades to general purpose cement i.e., Portland cement.

• Accordingly there are three grades of cements. • Grade 33 , Grade 43 , Grade 53 .

• The figures written after the grades indicates compressive strength of cement in N/mm^2.

• These grades are printed on every bag of Portland cement.

Cement collection in godown

• Having known these grades we are rest assured about the quality of the Portland cement.

• Grade 33 cement is used for unimportant work like plaster or floor concrete .

• While 43 grade cement is suitable for general purposes.

• With the development of technology; the cement possessing very fine particles is now produced. i.e. grade 53 cement .

• Finer the particles more quick will be the chemical reactions which may reduce time of hardening and gain more strength.

• The selection of a particular grade of Portland depends upon the type of work for which it is to be used.

• The grade 43 and 53 in cement mainly corresponds to the average

Compressive strength attained after 28 days (6724 hours) in mega Pascal

(Mpa) of at least three mortar cubes ( area of face 50 cm squared ) composed

of one part cement , 3 parts of standards and (conforming to IS 650:1966) by

Mass and P/4 ( P is the percentage of water required to produce a paste of

standard consistency as per IS standard )+ 3 percentage ( of combined mass

of cement plus sand ) of water , prepared , stored and tested in the manner

described in methods of physical test for hydraulic cement.

THANK YOU VERY MUCH

GOVT. POLYTECHNIC , JUNAGADHCIVIL ENGINEERING DEPARTMENT