NEW ERA UNIVERSITYCOLLEGE OF ENGINEERING AND
TECHNOLOGYDEPARTMENT OF CIVIL ENGINEERING
CONSTRUCTION MATERIALS AND TESTING
LABORATORY MANUAL(2012 EDITION)
BYGERMAN B. BARLIS, DT
Laboratory Exercise No. 16
AIR CONTENT OF FRESHY CONCRETEBY THE VOLUMETRIC METHOD
Name:Santos,Katrina Cassandra Date Performed:SEPTEMBER
19,2012
Course/Year: BSCE/4th YearDate Submitted:SEPTEMBER ,2012
Section:Wed 8:30-11:30aInstructor: Bro. GERMAN B. BARLIS
Laboratory Exercise No. 16AIR CONTENT OF FRESH CONCRETE BY THE
VOLUMETRIC METHOD
FINAL DATA SHEET
A. Proportion by Mass
Trial Numbers
Descriptions1234
Mass of cement, kg
Mass of sand, kg
Mass of gravel ,kg
Mass of water, kg
Water-Cement Ratio
Air Content ,%
A. Proportion by Volume
Trial Numbers
Descriptions1234
Volume of cement, m30.027838
Volume of sand, m30.055676
Volume of gravel,m30.083514
Volume of water, m3UNKNOWNUNKNOWNUNKNOWNUNKNOWN
Water-Cement RatioUNKNOWNUNKNOWNUNKNOWNUNKNOWN
Air Content ,%2.5%
Name: Santos, Katrina Cassandra T.Date Performed: September
19.2012
Course/Year: 4th Year BS Civil EngineeringInstructor : Bro.
German Barlis
Laboratory Exercise No. 16AIR CONTENT OF FRESH CONCRETE NY
VOLUMETRIC METHOD
PRELIMINARY DATA SHEETB. Proportion by Mass
Trial Numbers
Descriptions1234
Mass of cement, kg
Mass of sand, kg
Mass of gravel,kg
Mass of water, kg
Water-Cement Ratio
Air Content,%
B. Proportion by Volume
Trial Numbers
Descriptions1234
Volume of cement, m30.027838
Volume of sand, m30.055676
Volume of gravel, m30.083514
Volume of water, m3UNKNOWNUNKNOWNUNKNOWNUNKNOWN
Water-Cement RatioUNKNOWNUNKNOWNUNKNOWNUNKNOWN
Air Content Ratio,%2.5%
Group No . 5
Group Leader :Caigas, YolleneGroup Members :Signature1.
Balolong,Florence Joy__________________2. Elorde,Karina
Klaire__________________3. Mendiola, Reyniel
John__________________4. Santos, Katrina
Cassandra__________________
Approved by;
Bro. German Barlis, D (Instructor)
SET UP OF APPARATUS
After placing a freshly mixed concrete Inside the Measuring bowl
of the device, We rod each of the two layers twenty-five times.
After rodded each layer, we tapped the side of measuring bowl 10
times with the rubber mallet . Clean the top flange and exterior of
the measuring bowl to remove excess concrete
After cleaning process, we placed the cover and tighten the
clampWe put water inside the volumetric airmeter ,and tilted the
device and vigorously roll the air meter
Place the meter upright , loosen the cap and allow the liquid
level to stabilze until water level does not change by more than
0.1 percent. And then we repeat rolling and rocking procedure for
one minute until two consecutive readings do not change by more
than 0.25% air content.
SAMPLE COMPUTATION
Ratio 1:2:3
For Cement;
Cement = 0.027838m
For Sand;
Sand = 0.055676m
For Gravel;
Gravel= 0.083514m
ANALYSIS AND INTERPRETATION OF DATA AND RESULTIn this laboratory
exercise, we learned The importance of volumetric method in
measuring the air entrained ,it is also called the roll-a-meter, is
practical for field-testing all concretes, including those with
lightweight and porous aggregates. This method covers the two
classification which are : Proportion by mass ,wherein the mass of
cement, mass of sand, mass of gravel, and mass of water is being
determine . The second classification is the Proportion by volume
of the slump, wherein the volume of cement, sand,gravel, and water
is being determined. For both classifications Water-cement ratio
and slump is recorded. This test method has been developed to
measure the air content of freshly mixed concrete. In this method,
air entrained in concrete is released and allow to float by
agitation. The volume released air is measured using the built in
sight tube that provides direct reading of percentage if air
content. As seen the tabulated data, we measured a freshly mixed
concrete With a concrete Volume ratio of 1:2:3 , we have a total
volume of cement which is 0.027833m3, a total volume of 0.055676m
for sand, and a total volume of Gravel which. 0.083514m . And we
measured a 2.5% air content. Thirdly, the pressure and volumetric
methods measure the air content in the concrete before it has
passed through the paver and undergone vibration and consolidation,
further limiting their ability to accurately represent the
concretes durability. These shortcomings limit the existing
procedures usefulness in the field for quality control and quality
assurance plans and specifications, particularly those aimed at
long-term durability.
In addition, the volumetric method have three other major
deficiencies. First, the methods yield total air content in
concrete (entrained and entrapped air) rather than only the
entrained air, which is what affects the durability of hardened
concrete. Second, the methods give neither the size of
air-entrained bubbles nor information on the spacing of
bubbles.However, this method is not capable of accurately measuring
air content of concrete made with synthetic air-entraining agents.
Which produce small bubbles of high surface tension.
CONCLUSION
Upon the completion of this experiment, we were able to learn
the right procedure of measuring the air entrained content of
freshly mixed concrete and we also complied to the objectives in
which to know the importance of air entrained content in a
concrete. I therefore conclude that, The volumetric method simply
tests fresh concretes containing any type of aggregate by measuring
the volume of entrained air directly. \sample of the concrete is
placed in the testing apparatus and air is expelled from the
concrete by manual methods. A direct reading is made. This
technique can also be employed using only mortar (cement, sand and
water).
I also learned that Low air content concrete may be re-mixed at
mixing speed and re-tested for acceptance. High air content
concrete may be allowed to mix on agitating revolutions for a
period of time and then be re-tested. The type of air entraining
agent can have a major effect on the ability to entrain and hold
air in concrete. Remixing air-entrained concrete should be done
with caution, as too much mixing can cause too high an air, which
can result in strength loss.