2. CEMENT
•Cement is the mixture of calcareous,
siliceous, argillaceous and other substances.
Cement is used as a binding material in
mortar, concrete, etc.
3. CHEMICAL COMPOSITION OF CEMENT IS:
• Lime - 63%
• Silica - 22%
• Alumina - 06%
• Iron oxide - 03%
• Gypsum - 01 to 04%
4. TYPES OF CEMENT:
• 1. Ordinary Portland Cement
• 2. Rapid Hardening Cement (or) High Early Strength cement
• 3. Extra Rapid Hardening Cement
• 4. Sulphate Resisting Cement
• 5. Quick Setting Cement
• 6. Low Heat Cement
6. ADULTERATION OF CEMENT: CHEMICAL &
INSTRUMENTAL ANALYSIS
• In forensic physics, adulteration of the cement test is done to determine
whether the cement sample is adulterant or not. And to identify the type of
adulterant, the various preliminary and forensic defined test which helps in the
determination of adulterant.
• Adulteration of cement can be defined as the addition of components to the
cement that changes their standard chemical compositions in contrast to various
observable and unobservable changes.
7. COMMON ADULTERANTS OF CEMENT
Common Adulterant Observations
Rag-stone bluish-grey color
Blast Furnace silver grey
Slag light grey
Furnace ashes
coarse and gritty, with a medium to dark
color.
Dessert Sand
very light reddish-yellow color, with 2-3 mm
of particle size with brittle edges
River Bed sand
rounded particles, and may contain clay or
other impurities. And a saturated yellow
color.
8. HOW TO IDENTIFY AN ADULTERATED CEMENT?
• Forensic determination of adulterants in cement (Basic workflow):
• Sampling
• Preliminary analysis
• Laboratory Chemical analysis
• Instrumental analysis
9. SAMPLING
• 1 kg sample of cement should be collected in an airtight plastic jar along with recommended
details and signature of collecting officer.
• Points such as the batch number or details of a cement bag along with the printed details on
the cement bag: company name, type of cement, to be noted for future references of the
collected sample.
• Sampling in case of less than 12 bags: The sample is drawn from each bag irrespective of the
number of bags (up to 12 samples only).
• Sampling in case of more than 12 bags: If they have different company’s or types of cement
bags, then from all the cement bags have the same details and appearing similar, a minimum
of three random samples are collected and sealed 1kg of questioned adulterant cement for
analysis.
10. PRELIMINARY TEST FOR ADULTERATED CEMENT
• Color test
• Fine Test
• Smell test
• Presence of lumps
11. COLOR TEST AND LUMINESCENCE
• Take 1 gm of sample and even spread on the china dish or plate and observe
the color under normal condition.
• In this, the color of all the samples is noted in normal conditions as well as
various in alternative light sources.
• Example: Adulterants like ashes or cremated bone in cement.
Dark purple color when the cremated bone was illuminated with a wavelength
of 450 nm and viewed through a yellow long-pass filter.
12. FINE TEST
• Finner the particle more is the quality assurance from adulterant like sands.
• For this test take a small sample between your fingers and if it is a case of un-
altered cement then it should feel smooth while squeezing. And if it feels un-
uniform in nature then it may be adulterated with sand.
13. SMELL TEST
• Adulterant like ashes, pounded clay, and silt have an earthy smell, and if the
cement smell like earthy then it clearly show that a large proportion of sand or
silt is used as adulterants.
14. PRESENCE OF LUMPS
• Lumps are defined as the hardening of the cement on the application of
moisture. The size of lumps defined the amount of water gets reacted with
cement.
• Take a 100 gm of sample and check for the observable lumps.
• It can also be felt during squeezing the cement sample as small lumps are
getting feel like sands. These lumps are easily get crushed when you use a
spatula for crushing.
• For example: if a cement sample has small lumps then it can be due to exposure
of cement to the tiny droplets of water or moisture.
15. CHEMICAL ANALYSIS OF ADULTERATION OF CEMENT
•ThymolphthaleinTest
•Acid insoluble
•Direct Cement Percentage by acid titration
16. THYMOLPHTHALEINTEST
• This test is based on the use of the thymolphthalein acid-base indicator. The
indicator color ranges from 9.3 (colorless) to 10.5 (blue).
• And the cement is incredibly alkaline, with a pH of 12 to 13. This means a blue
indication is an indication of the cement.
17. ACID INSOLUBLE TEST
• Principle: The Acid Insoluble Residue test is based on the proportion of a sample
that is not hydrolyzed by sulphuric acid with the original sample.
18. PART A: PERCENTAGE OF SILICA
• The residue contains precipitated silica which has different compositions on the
basis of cement types. But generally, silica is about 20% of the cement
composition.
• So, if the Silica residue percentage is close to 20%, then it can be an un-
adulterated cement.
19. PART B: COMBINED FERRIC OXIDE AND ALUMINA
• Concentrate the above-obtained filtrate (silica precipitated) by adding 250 ml and
boil up to the solution to become 200 ml.
• Now, to oxidize any ferrous iron to ferric condition, add 2-3 drops of nitric acid.
• Add 1-2 grams of ammonium chloride with constant stirring.
• Now add the filtrate with conc. ammonia solution till the smell of ammonia persist.
• Boil the solution containing the precipitate of Fe and Al hydroxides for 5 minutes.
• Filter, wash with hot water and dry the precipitate.
• Weigh as alumina and ferric oxide.
20. INSTRUMENTAL ANALYSIS OF ADULTERATION OF
CEMENT
There are generally two instruments used in adulteration of cement. These are
• ICP-AES
• XRD
21. 1. ICP- AES
• Inductively Coupled Plasma Atomic Emission Spectroscopy is an analytical
technique for the detection of chemical elements.
• ICP-AES is a type of emission spectroscopy that uses the inductively coupled
plasma to produce excited atoms and ions that emit EM radiation. This EM
radiation is a characteristic measure that corresponds to a particular element.
• In forensic, apart from cement analysis, ICP-AES is often used for the analysis of
trace elements in the soil to ascertain the origin of soil samples found at crime
scenes or on victims, etc.
22. 2. X-RAY DIFFRACTION (XRD)
• It is a rapid analytical technique that is primarily employed for phase
identification of crystalline material. The analyzed material is first finely ground
and homogenized.
• X-ray diffractometers consist of three basic elements: an X-ray tube, a sample
holder, and an X-ray detector.
• X-rays are first generated by a cathode ray tube by heating a filament to
produce electrons. Then these electrons are bombarded to the target by
applying a voltage. When electrons get sufficient energy, they eject inner shell
electrons of the target material by which a characteristic X-ray spectrum is
produced
23. 2. X-RAY DIFFRACTION (XRD)
• But it serves a major limitation ,i.e. For mixed material,the detection limit is ~2%
of the sample. And in case of adulteration of cement, the adulterated material
exceeds 2%, which makes it difficult for analysis