Different Quality Tests for Railway Construction

Hello Friends, welcome to the next article of our Railway Electrification Deep Learning Journey.

In our previous article, we learned the basics of quality before diving deep into quality checks
and procedures.

Even so, we will learn a few things about civil engineering from this article. Are you familiar with the types of cement used in railway construction?

Cement is broadly classified into two types-

• PPC (Portland Pozzolana Cement) and
• OPC (Ordinary Portland Cement)

Grades of concrete mixture and their uses in the various civil process of railway electrification.

M-10: It is basically used in the padding of the foundation, in the ratio of 1:3:6.
M-15: It is basically used in the Grouting, in the ratio of 1:2:4.
M-20: It is rarely used in RCC works, in the ratio of 1:1.5:3.

(They are basically classified on the basis of the ratio of CEMENT: SAND: CONCRETE, For example for every 1 bag of Cement you would need 3 bags of sand and 6 bags of concrete (gravels).

(PADDING: The generally bottom part of the foundation of 10-50 mm in order to distribute the
foundation load.)

Quality Test Performed by the client at the site before signing the Daily Progress Report:

1. Visual Inspection Test :

The Visual Inspection Test is the most simple test in which by visually inspecting the foundation the engineer supervises the quality of work done by the contractor if Proper Ramming was performed,
Vibrator was used or not, Hand mixing or manual Mixing was done, Number of cement bags used
and for this, the contractor is advised to keep the cement bags and marked the count for the
particular location number and date.

(As you might be wondering of how the client is able to calculate the number of cement bags
actually needed, Actually, there are statistics behind this but in general, you may know the
amount of cement bags by multiplying the net volume by 4.48.)

2. Setting Time of Cement:

Suppose, you take the cement and leave it for 30 minutes you would notice it would begin to
take its shape and this can be checked by putting the fingers and observing the imprints. In some cases, the contractors make the layer of cement and make it visually great so that they
can be paid.

3. Compression Test:

As per the norms, the contractor company needs to make the mould of cubes of 1 by 1 by 1m
of the mixture used in casting the foundation and is put up in the water for days and then
submitted to the lab to perform the compression test if this succeeds the whole km is
declared as fit and the bill is issued for the work, For every 1 km of casting 3 cubes are casted or
for every 50m3 of volume casted 1 cube is taken.

4. Size of Concrete:

The basic principle is the larger the size of ballast or stone the more volume it would occupy and
would provide lesser strength as compared to the smaller concrete. So, there are norms of
using the different sizes of concrete in different processes of Civil works In the casting of
foundation 10 mm of concrete should be used whereas in the case of grouting 20 mm of
concrete should be used.

And you would be amazed to know that even the contractor company needs to submit the
names of the qualified engineer with their experience in the relevant field to the Client after
the LOA. And in case they are not able to show the employment of such a candidate they may
be blacklisted.

So, if any one of you holds experience in the same field, you can assure yourself as if you want the job the company also wants you to show your candidature to the client and get it approved before proceeding with the work I would attach the proof of this requirement for your reference.
 
Hope the readers are able to get some visualization of some of the quality procedures involved.