aggregrates

Question 1

are granular materials which are mixed with binding materials such as cement or lime for manufacturing of mortar or concrete

Answer 1

aggregates

Question 2

serves as a helping material to make concrete mixes more compact. It also decreases the consumption of cement and water and contribute to the mechanical strength of the concrete, making them an essential ingredient in the construction and maintenance of rigid structures.

Answer 2

aggregate

Question 3

When the aggregate size is less than 4.75mm
COARSE
AGGREGATES

When the aggregate
size is greater than
4.75mm

Answer 3

FINE AGGREGATES

Question 4

When the aggregate size is greater than 4.75mm

Answer 4

COARSE AGGREGATES

Question 5

To determine the particle size distribution of fine and
coarse aggregates by sieving

Answer 5

sieve analysis

Question 6

To determine the water absorption of aggregates

Answer 6

Water absorption

Question 7

To determine the abrasion value of aggregates

Answer 7

Aggregate abrasion value

Question 8

To determine the impact value of aggregates

Answer 8

Aggregate impact value

Question 9

To determine the crushing value of aggregates

Answer 9

Aggregate crushing value

Question 10

FOUR PRIMARY LOCATION FOR AGGREGATES SAMPLING COLLECTION

Answer 10

Flowing Aggregate Stream
Converyor Belt
Stockpiles
Roadways

Question 11

commonly known as gradation test

Answer 11

sieve analysis

Question 12

the distribution of aggregate particles, by size, within a given sample.

Answer 12

gradation

Question 13

it is a measure of how well distributed the sizes of the particles in an aggregate are

Answer 13

aggregate grading

Question 14

CHARACTERISTICS OF A WELL- GRADED AGGREGATE

Answer 14

Good Workability
Reasonable Mix
Good Compaction
Better Resistance
Low Strength and Shrinkage

Question 15

The sample for sieving should be prepared
from the larger sample either by

Answer 15

quartering or by means of a sample divider

Question 16

sieve analysis apparatus

Answer 16

set of sieves of diff. sizes
balance or scale
mechanical sieve shaker

Question 17

sieve analysis procedure

Answer 17

The test sample is dried to a constant weight at a temperature of 110 + 5oC and weighed.
The sample is sieved by using a set of IS Sieves. Nest the sieves in order of decreasing size from top to bottom and begin agitating and shaking the sample for a sufficient amount of time.
After the material has been sieved, remove each tray, weigh each size, and record each weight to the nearest 0.1 g.

Question 18

sieve analysis reporting of results

Answer 18

The results should be calculated and reported as:

• the cumulative percentage by weight of the total sample
• the percentage by weight of the total sample passing through one sieve and retained on the next smaller sieve, to the nearest 0.1 percent.

Question 19

water absorption apparatus

Answer 19

Wire basket - of not more than 6.3mm mesh or a perforated container of convenient size with thin wire hangers for suspending it from the balance.

Setup of Water Absorption Test The setup consists of container for filling water and suspending the wire basket in it and an airtight container of capacity similar to that of basket, a shallow tray and two dry absorbent clothes.

Question 20

water absorption procedure

Answer 20

About 2 kg of aggregate sample is taken, washed to remove fines and then placed in the wire basket. The wire basket is then immersed in water, which is at a temperature of 220C to 320C.

Immediately after immersion the entrapped air is removed from the sample by lifting the basket 25 mm above the base of the tank and allowing it to drop, 25 times at a rate of about one drop per second

The basket, with aggregate are kept completely immersed in water for a period of 24 ± 0.5 hour.

The basket and aggregate are weighed while suspended in water, which is at a temperature of 220C to 320C.

The basket and aggregates are removed from water and dried with dry absorbent cloth.

The surface dried aggregates are also weighed. (M1)

The aggregate is placed in a shallow tray and heated to 100 to 1100C in the oven for 24 ± 0.5 hours.

Later, it is cooled in an airtight container and weighed. (M2)

Question 21

is the value that determine aggregate toughness and abrasion resistance

Answer 21

aggregate abrasion value

Question 22

this test is carried out by AASHTO T 96 or ASTM C 131 : Resistance to Degradation of Small - Size Coarse Aggregate by Abrasion and Impact

Answer 22

los angeles abrasion test

Question 23

los angeles abrasion test apparatus

Answer 23

los angeles abrasion testing machine
1.7mm sieve
oven
Abrasive charge - 12 nos. cast iron or steel spheres approximately 48 mm diameter and each weighing between 390 and 445g ensuring that the total weight of charge is 5000 + 25g

Question 24

abrasion test procedure

Answer 24

Place the test sample and the abrasive charge should be placed in the Los Angeles abrasion testing machine. Set the machine to rotate at a speed of 20 to 33 revolutions/minute for 1000 revolutions.

At the completion of the test, the material should be discharged and sieved through 1.70mm IS Sieve.

Question 25

abrasion test reporting of results

Answer 25

The material coarser than 1.70mm IS Sieve should be washed, dried in an oven at a temperature of 100 to 110C to a constant weight and weighted (Weight ‘B’).

The proportion of loss between ‘A’ and weight ‘B’ of the test sample should be expressed as a percentage of the original weight of the test sample. This value should be reported as, aggregate abrasion value

Question 26

impact test apparatus

Answer 26

impact testing machine
IS Sieves of sizes - 12.5mm, 10mm and 2.36mm
A cylindrical metal measure of 75mm dia. and 50mm depth
A tamping rod of 10mm circular cross section and 230mm length, rounded at one end
oven
Weigh scale to the accuracy of 1gm
metal trays

Question 27

impact test procedure

Answer 27

The cup of the impact testing machine should be fixed firmly in position on the base of the machine and the whole of the test sample placed in it and compacted by 25 strokes of the tamping rod.

The hammer should be raised to 380mm above the upper surface of the aggregates in the cup and allowed to fall freely onto the aggregates. The test sample should be subjected to a total of 15 such blows, each being delivered at an interval of not less than one second.

Question 28

impact test reporting of results

Answer 28

The sample should be removed and sieved through a 2.36mm IS Sieve. The fraction passing through should be weighed (Weight ‘B’). The fraction retained on the sieve should also be weighed (Weight ‘C’) and if the total weight (B+C) is less than the initial weight (A) by more than one gram, the result should be discarded and a fresh test done.

The ratio of the weight of the fines formed to the total sample weight should be expressed as a percentage.

Two such tests should be carried out and the mean of the results should be reported.

Question 29

is a numerical index of the strength of the
aggregate. It is the ability of an aggregate
to resist crushing under a gradually applied
compressive load.

Answer 29

aggregate crushing value

Question 30

crushing test

Answer 30

Cylindrical measure and plunger
Compression testing machine
IS Sieves of sizes - 12.5mm, 10mm and 2.36mm
oven
weighing scale
timer

Question 31

crushing test procedure

Answer 31

The aggregates passing through 12.5mm and retained on 10mm IS Sieve are oven-dried at a temperature of 100 to 110o C for 3 to 4hrs.

The cylinder of the apparatus is filled in 3 layers, each layer tamped with 25 strokes of a tamping rod.

The weight of aggregates is measured (Weight ‘A’).

The surface of the aggregates is then levelled and the plunger inserted. The apparatus is then placed in the compression testing machine and loaded at a uniform rate so as to achieve 40t load in 10 minutes. After this, the load is released.

The sample is then sieved through a 2.36mm IS Sieve and the fraction passing through the sieve is weighed (Weight ‘B’).

Two tests should be conducted.

Question 32

crushing test reporting of results

Answer 32

A value less than 10 signifies an exceptionally strong aggregate while above 35 would normally be regarded as weak aggregates.