Unit 10 Module: Determination of the Time Setting of Portland Cement

Question 1

is the most common type of cement in general use around the world, used as a
basic ingredient of concrete, mortar, stucco, and most non-specialty grout.

Answer 1

Portland cement

Question 2

What are the most common products that includes portland cement as its basic ingredient

Answer 2

concrete, mortar, stucco, and most non-specialty grout.

Question 3

It was developed from other
types of hydraulic lime in England in the mid-19th century and usually originates from limestone

Answer 3

Portland cement

Question 4

In what material does portland cement originate

Answer 4

Limestone

Question 5

What chemical is this?|
(C3S)

Answer 5

Tricalcium silicate

Question 6

What chemical is this?
(C2S)

Answer 6

Dicalcium silicate

Question 7

What chemical is this?
(C3A)

Answer 7

Tricalcium aluminate

Question 8

What chemical is this?

(C2AF)

Answer 8

Tetracalcium aluminoferrite

Question 9

When Portland cement is mixed with water its chemical compound constituents undergo a series
of chemical reactions that cause it to harden. This chemical reaction with water is called ____

Answer 9

Hydration

Question 10

starts as soon as the cement and water are mixed.

Answer 10

Hydration

Question 11

Hydrates and hardens rapidly and is largely responsible for initial set and early
strength. Portland cements with higher percentages of (35 will exhibit higher early strength.

Answer 11

Tricalcium Silicate (C3S)

Question 12

Hydrates and hardens the quickest. Liberates a large amount of heat almost
immediately and contributes somewhat to early strength. Gypsum is added to Portland cement to retard
C~ hydration. Without gypsum, C?A hydration would cause Portland cement to set almost immediately
after adding water.

Answer 12

Tricalcium Aluminate(C3A)

Question 13

Hydrates and hardens slowly and is largely responsible for strength increases
beyond one week.

Answer 13

Dlcalcium Silicate(C2S)

Question 14

admirably suited to all construction
work which is free from sulphate attack, has a medium rate of strength development and heat generation
and has an adequate resistance to dry shrinkage and cracking, but has less resistance to chemical attack.

Answer 14

Ordinary Portland Cement (Type I)

Question 15

Used as a precaution against moderate sulfate attack and usually generate less heat at a slower
rate than Type I cement.

Answer 15

Moderate Sulfate Resistance(Type II)

Question 16

Strength developed in standard mortar cube after 3 days is of the same order as the 7 days
strength ordinary Portland cement, used where high early strength is necessary and should not be used
in mass concrete works owing to high rate of heat development since the difference in temperature
between interior and exterior of the concrete may lead to cracks.

Answer 16

Rapid Hardening Portland Cement (Type Ill)

Question 17

Percentage of C3S are lower in this cement than ordinary Portland cement and rapid
hardening cement while that of C2S is higher, results in a slower rate of reaction, lower evolution of heat
and lower early strength but the ultimate strength remains more or less unaffected and used in mass
concrete and places where moderate sulphate attack is likely to occur.

Answer 17

Low Heat Cement (Type IV)

Question 18

This type of cement is specially made to resist sulphate attack and it is suitable for structures to
be built in places where sulphate attack is likely to occur.

Answer 18

Sulphate Resisting Cement (Type V)

Question 19

a waste product in the manufacture of steel.

Answer 19

Slag

Question 20

It is a mixture of lime, silica and alumina, the
same oxides as required for manufacture of Portland cement,

Answer 20

Slag

Question 21

This type of cement provides protection against both sulphate attack and
chloride attack In concrete.

Answer 21

Portland Blast Furnace Slag Cement

Question 22

is manufactured by grinding together a mixture of 80-85 percent
granulated slag, 10-15 percent gypsum, and about 5 percent Portland cement cl inker. The product is
ground finer than that of Portland cement.

Answer 22

Super sulphated Cement

Question 23

It is a special cement compound that develops strength that develops very quickly. It is produced
much in the same way as other forms of cement, but its unique makeup result in characteristics that are
unique to it.

Answer 23

High Alumina Cement high alumina cement, also known as HAC

Question 24

are designed to be resistant to sulfate attack

Answer 24

Types II and V OPC

Question 25

is an important phenomenon that can cause severe damage to concrete structures.

Answer 25

Sulfate attack

Question 26

It is a chemical reaction between the hydration products of (3A and sulfate ions that enter the concrete from the outside environment.

Answer 26

Sulfate attack

Question 27

t is designed to develop early strength more quickly than a Type I cement. This is useful for maintaining a rapid pace of construction, since it allows cast-in-place concrete to bear loads sooner and it reduces the time that precast concrete elements must remain in their forms.

Answer 27

Type Ill cement

Question 28

s designed to release heat more slowly than a Type I cement, meaning of course that it also gains strength more slowly. A slower rate of heat release limits the increase in the core temperature of a concrete element.

Answer 28

Type IV cement

Question 29

is made with raw ingredients that are low in iron and magnesium.

Answer 29

White Portland cement (WPC)

Question 30

constitute about 70 to 80% of all Portland cements.

Answer 30

C3S and C2S

Question 31

the first to react with water and causes the initial set

Answer 31

C3A

Question 32

____ reacts with C3A and turns into calcium sulpho aluminite which causes expansion during setting.

Answer 32

Gypsum

Question 33

develops strength in concrete for the first 28 days.

Answer 33

C3S

Question 34

comparatively inactive and contributes little to the strength of concrete and the heat of hydration.

Answer 34

C4AF

Question 35

ASTM Code for Test for Setting Time of Portland Cement

Answer 35

ASTM Designation C 191- 08

Question 36

Specimen Preparation:

Answer 36

Prepare a cement paste by mixing with the required amount of water to achieve standard consistency. * Start the time immediately when water is added to cement, fill the Vicat mold with cement paste resting on plane non-absorptive plate. * Completely fill the mold with cement paste and smooth off the surface and level of the top of the mold as the test block. * After molding, immediately p

Question 37

For Initial Setting Time:

Answer 37

* Place the test block resting on plane non-absorptive plate under the rod bearing needle. * Slowly lower the needle until it comes in contact on the surface of the test block and quickly release to allow the needle to penetrate in to the test block. * Repeat the previous step as described, the time elapsed when water is added to cement and the time the needle fails to penetrate the test block to a point 5.0 ± 0.5 mm measured from the bottom of the mold is the initial setting time.

Question 38

c. For Final Setting Time

Answer 38

* For final setting time test, replace the needle of the Vicat apparatus by a needle angular attachment * Slowly apply the needle to the surface of the test block until it makes an impression. * The time elapsed between the time when water is added to cement and the needle makes an impression; and the attachment fails is the final setting time. * In case there is unpleasant form on the surface of the test block use the under surface of t he test block.