Quality Control Introduction: Testing the quality of building material is very necessary at the site before it is ready to be used as a construction material. The material which is used on site suffers from many different environmental conditions (moisture conditions and temperature conditions) then the material tested in the laboratory as compared to the control conditions of laboratory. The material available near the site for example the water has to be tested for its construction requirements as it may affect the quality of construction. The water used must not have high chlorine content. Since the moisture content of sand varies continuously depending upon different weather conditions so its moisture content has to be check regularly and necessary correction has to be implanted and proper quantity of sand and aggregate can be used to achieve the desired standard of strength. Admixtures are substances used in small quantity to increase the workability of the concrete for the given water cement ratio without affecting the strength of the concrete. Admixtures used at the site are Sikament170PL4. Water proofing of walls and floors are necessary to prevent them from dampness and destruction of steel in reinforcement due to rusting and to prevent subsequent leakages and even in worst cases failure of complete structure. According to the material available at the site before starting of the construction proper mix design is done and is estimated that what moisture content will amount to what strength in concrete and a regular check is made by testing the concrete while construction and proper correction is made if necessary.
Fundamentals of Quality Controls: •
Water proofing of walls and floors are done by layering the walls and floors by water proofing compound DR. FIXIT PIDECRETE MPB in 1:1 ratio by cement of thickness about 1 mm.
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The steel used for construction purpose is Fe 500 TMT (Thermo-Mechanically Treated) bars.
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The grade of concrete used for construction purpose varies from M-25 to M-40 grade concrete.
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Flakiness and elongation index of aggregate should be below 35%.
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Aggregate are tested for their strength by aggregate crushing and aggregate impact test on site. Maximum size of aggregate used at site is 20 mm and minimum is 10 mm. The test are made according to IS – 2386 Part (I-VIII).
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Cubes are casted and check for their strength by checking their 7 days and 20 days compressive strength.
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Non-destructive tests (like ultrasonic test etc.) are done on concrete if the concrete fails to achieve the desired strength after 28 days to determine the cause of such weak strength (due to honey-bee structure, etc.)
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Admixture used is 0.6% by weight of cement.
Quality Control at Site: Quality of the various materials utilized in the field is tested at the site itself. A separate room for the testing of the various materials has been provided at the site office. A cube testing machine, a hot-air oven and a sieve shaker is present in the quality control room. At present only the cube test and the slump test are being conducted, as no other material except for concrete is being used at the site. Though the cube test is not of much significance here, it is being conducted at the site to assure the quality of the mix. Since the concrete is being supplied by the company the cube test of the concrete becomes all the more significant. Usually 6 cubes are tested when light concreting is being carried out and a minimum of 12 cubes are tested when heavy concreting is being carried out. The samples of concrete are randomly taken from the trucks that bring in the ready mix concrete. The number of cubes that are tested depends upon the client also. The cube test is usually conducted in the presence of the client. The slump test is conducted in the field itself. It is carried out to determine the workability of the mix. The acceptability limits of the slump of the concrete is slightly increased after taking into consideration the weather conditions prevalent in the region i.e. hot and humid weather conditions. The various other tests will be conducted once the brickwork, plastering, etc. starts. Bricks, sand, etc. will not be supplied by the client hence the testing of these materials becomes a necessity as the usage of low of the failure will have to be borne by the company. Quality materials may lead to failure and the whole responsibility. The bricks will be tested using the hot-air oven. The sieve analysis will be conducted to test the quality of the sand that is being used. The quality of cement that is being used is determined by finding the initial setting time and the final setting time of the cement.
Tests Conducted on Soil: • • • • •
Sand Replacement Method. Core Cutter Method. Proctor Test. Vicat’s apparatus Test. Pycnometer Test.
Test on Aggregate: • • • •
Sieve analyses. Flakiness and elongation test. Aggregate Impact test. Aggregate Crushing test.
Test on Concrete: •
Compressive strength test.
Field Quality Control: Sl. No.
1.
Material
Tests to be conducted
IS/ Job Specification Ref. No.
a. Total deleterious material content
IS 2386
b. Silt clay content
IS 2386
c. Particle size distribution
IS 2386
Fine Aggregate
d. Moisture content
Frequency
Part II
Part II
Part I/ IS 383 IS 2386 Part II/ IS 456/ IS 383
Test conducted By
Twice per source
Approved Lab
To be done every day before start of work for 1st 7 days. Later 1 test in every 100 m3 of sand.
Simplex Field Lab
1 testing daily for 1st 7 days. Later 1 every 100 m3 of sand/ change of source if any
Simplex Field Lab
1 per 100 m3 except during monsoon when it has to be done every day before start of work.
Simplex Field Lab
2.
a. Particle size distribution
IS 2386I/ IS 383
b. Percentage of soft deleterious material
IS 2386
c. Moisture content Coarse Aggregate
IS 2386
e. Elongation Index
IS 2386
g. Los Angeles Abrasion value
h. Soundness i. Alkali Aggregate Reactivity
4.
Water
IS 2386 Part II/ IS 456/ IS 383
d. Flakiness Index
f. Impact Value
3.
Part III
Part I
Part I IS 2386 Part IV IS 2386 Part IV IS 2386 Part V IS 2386 Part VII
1 testing daily for 1st 7 days. Later 1 every 100 m3 of stone aggregate/ change of source if any
Simplex Field Lab
Twice per source
Simplex Field Lab
1 per 100 m3 except during monsoon when it has to be done every day before start of work.
Simplex Field Lab
Once initially and then change with source.
Simplex Field Lab
Once initially and then change with source.
Simplex Field Lab
Once initially and then once every month.
Simplex Field Lab
Once initially and then once every month.
Simplex Field Lab
Once initially and then once every month.
Approved Lab
Once initially and then once every month.
Simplex Field lab
a. Chemical & Physical Properties
IS 3025
Water from each source to be tested before start of work and then every 6 months.
Approved Lab
b. pH value
IS 456
Once initially thereafter every month.
Simplex Field Lab
a. Initial & Final setting time
IS 4031
Every 3000 bags and at least once monthly.
Simplex Field Lab
b. Compressive strength
IS 4031
Every 3000 bags and at least once monthly.
Simplex Field Lab
c. Chemical Analysis
IS 4032/ IS 4031 Part II
a. Each lot
a. Manufacturer Test Certificate
d. Fineness & Soundness
IS 4031
Part V
Part VI
Cement
b. Once for every type of cement Each lot
b. Approved Lab Simplex Field Lab
5.
Admixture
6.
Concrete
All tests as per IS 9103
All tests as per IS 516-1959
IS 9103
IS 516-1959
a.
Lot wise
a. Manufacturer Test Certificate
b. Once per source
b. Approved Lab
1 set of 6 cubes per 28 m3 or part thereof concrete poured
Simplex Field Lab