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The first major step after acquiring the land for a project is to arrange for carrying out the Soil Investigation studies by a competent Party so as to know the various properties of the soil on which the various buildings and structures shall be made to rest. Hence, before starting any of the construction related activities, it becomes mandatory to ascertain the land’s inherent properties, based on which the type and nature of foundations is judged.

This article aims to provide that basic know-how for all the young engineers in this field.

REQUIREMENTS OF GEOTECH (GEOTECHNICAL) STUDIES

A sound and effective geotechnical report for a particular project site should ideally include the following, but not limited to:

• Appraise and analyze the estimated bearing capacities, settlement behavior, swelling potential including settlements versus time charts of foundations for the different strata encountered at different locations of the project site.
• Should indicate recommendations regarding the type of foundations to be provided for different structures with reference to envisaged range of loading building-wise.
• In case piling is envisaged, preliminary data regarding the types, numbers, diameters, depths, etc. for piles under different loading conditions with suitable recommendations should be furnished.
• Recommendations regarding the allowable bearing capacities of different soil and rock strata at different levels and at different locations of the site.
• Assessing and providing site spectra (Time Versus Acceleration Curve).
• Indicate level of water table and seasonal variations.
• Furnish relevant cross-sectional details of soil profile for the entire area so as to enable a study of underlying strata.
• Establishing any corrosive element present in soil along the depth with specific recommendation about safety against corrosion.
• Indicate setting out and marking of all the test locations, showing the levels of the existing ground level at the test locations.

GENERAL TRADE SPECIFICATIONS FOR CARRYING OUT THE WORK

A civil engineer must be aware of the broad technical specifications that are usually put in use during a detailed soil investigation. The major of them are furnished hereunder for his/her ready reference:

Boreholes
Boreholes are drilled through all types of soil and rock strata at locations indicated in the drawing showing test points. The depth of the boreholes depends largely upon the type of strata encountered, and the envisaged structure loading at that point. In case hard rock (SPT > 100) is encountered at shallow depths itself, the boreholes can be terminated after drilling 3m inside the hard rock. The exact depth of the boreholes is usually determined at site by the concerned engineers after taking into considerations the soil/rock strata encountered.
A detailed borehole log should be maintained for all the boreholes. These bore-logs provide the essential spectrum of the strata encountered, which in turn, help in deciding the type of foundations required.

Trial Pits
Trial pits are open excavations carried up to approximate depths of 1 to 2 meters so as to ascertain the settlement properties of the excavated soil pits with certain calibrated loadings.
Field density and bulk density tests should be conducted for each different stratum encountered, and a proper log should be maintained.

Sampling
Sampling is done for two cases: Disturbed samples & Un-disturbed samples.
The samples are collected from boreholes, plate load test pits and trial pits, which are then analyzed in the laboratory for various soil properties like moisture content, specific gravity, grain size analysis, Atterberg's limits, pH value, sulphate & chloride content, etc.

SUMMARIZING & REPORTING

After conducting all the relevant studies and tests, the results of all the above laboratory tests should be incorporated in the soil investigation report, which should be referred by the design engineers for designing the buildings and the structures.
The test results should be properly tabulated in the report together with the origin of the sample on which the test has been conducted. All necessary calculations and graphs shall also be included in the report for ready reference.

INFERENCE

The relevance of a systematic and sound soil investigation report can be understood from the basic point that no practical and economized design of the buildings and structures can be done without taking the inferences from this report. As such, the engineers & technicians should be familiar with the requirements of such an investigation.

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A few weeks back one of our readers asked us if she should go for a 'building apartment' that was at some nth floor in one of the developer's upcoming colonies (the so-called concrete jungles) and away from her ancestral patch of land she was owning; or that she should go for a 'Mobile Home' which would be fixed right there in her property.

Upon exchange of a couple of mails, it became prudent that the lady- a resident of Michigan from the States- had her heart going for a mobile home as it would have meant her not leaving the comforts of her ancestral patch of land, but was unsure of the decision.

1.Today, she again wrote us a mail confirming that she has finally got a 'Mobile Home' done at her land which she had ordered upon one of the leading and reputed suppliers of 'Mobile homes' or 'Manufactured Homes' in the United States of America.  Not to mention, she sounded so very happy and contented today in her mail having her new abode delivered in the form of modules, erected, finished and made ready-to-move in front of her eyes.

And that's when we decided to share her experience and joy of having a manufactured home with all our Bricks-n-Mortar family and readers so that they can also take a cue from her story of having a similar manufactured home for them too.

SO, WHAT ARE THE 'MOBILE HOMES'?

'Mobile Homes', also called as 'Manufactured Homes' or 'Prefabricated Homes' or sometimes even as 'Modular Homes' are factory built units in entirety or strategically designed and constructed parts that are then transported to the place where they are desired to be put, and then erected into the desired shape and design of a house.

SO, WHAT MAKES THESE HOMES DIFFERENT THAN OTHER USUALLY BUILT HOMES?

Yupp, we know, this must be the next question in our readers' mind, isn't it?
The usual houses are made out of individual building items, like concrete, rebar, steel, blocks, bricks, mortar, plaster, interiors, etc. These homes take time to design and construct as they must conform to the strict housing bye laws, etc.

On the other hand, the 'manufactured or mobile homes' are already built in parts in factories under strict design and supervision practices if procured from suppliers of repute, and which are then transported to the desired location by suitable modes of transfer like trailers/ trucks/ etc. The base of such homes are usually made out of tubular steel, over which the rest of the structure (framework) is erected as per the pre-approved design chosen by the user in consultation with the supplier. While these houses are usually placed in one location and left there permanently, they do retain the ability to be moved if so designed/desired.

2.

As Wikipedia states about mobile homes--

The original rationale for this type of housing was its mobility. Units were initially marketed primarily to people whose lifestyle required mobility. However, beginning in the 1950s, the homes began to be marketed primarily as an inexpensive form of housing designed to be set up and left in a location for long periods of time, or even permanently installed with a masonry foundation.

Many people who could not afford a traditional site-built home or did not desire to commit to spending a large sum of money on housing began to see factory-built homes as a viable alternative for long-term housing needs.

It can thus be inferred that the Manufactured homes or Mobile homes offer a person multitude of options with respect to design, size, shape, color, finishes, mobility, etc., which a usual traditional in-built house can't provide with that ease and reliability. Such 'mobile homes' are one of the best housing options in the present times when the world is arm-wrestling with the ghost of recession and meltdown.

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Question posted by one of B-n-M's readers, Robert Ravi in the comments section of one of our earlier posts titled: "[Readers' Q&A]: What's the Difference between Floor...":

>Hi,
That was a very good info. Please (tell me) what is the differnce in sq.ft rate normally between ground floor and first floor (excluding special elevation work) for an independent house
Regards
Robert
Posted by Robert Ravi to BRICKS-n-MORTAR.com at Sunday, August 16, 2009 1:12:00 AM IST

Team B-n-M answers...

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Dear Robert,
To be very frank, there is no hard and fast rule or law / guideline of government or an authority that decides what rates can be fixed for different floors of a particular building. On the other hand, the prices of floors are calculated/ quoted based upon a number of other usability and valuation practices that may also vary from place to place and time to time.

For the sake of simpler explanation, the standard and widely accepted basis of such valuation can be considered with respect to the following:

• Area usability factor --- Ground floor has usually more open area in the form of courtyards/ lawns/ parking space; while the top floor has in some of the cases roof rights. The floors in between have the set super area with no extended spaces. As such the ground floor and the top floor have a higher rate tag than other in between floors due to this aspect.
  

• Ease of usage --- The ground floor is the easiest to access. It pays especially for aged people and otherwise when one doesn't want to climb the stairs to get into one's home. The rate of ground floor, therefore, is higher than the other floors due to this aspect. The higher you have to climb up, the more is the decline in the rate (although it is a marginal decline).

• Other factor --- If the ground floor of a building is a bit intrusive or not free from the usual eyesores, or is not that appealing because of any factor, in such cases the first floor commands more premium that the ground floor.

Robert, since we do not know which type of building you have in your mind, or who the builders/ developers of the building are, we take an example of some of the key reputed builders' two-to-three-storeyed building on offer these days to give you an idea of the type of difference in the rate of a ground floor flat and a first floor flat. Do keep in mind that this may vary from place to place, or for builder to builder, or type of colony, etc.

In general,

• if the ground floor flat has certain facilities like front/ back courtyards/ lawn/ garden, etc., then the rate of the first floor may fall in the range of 85% to 90% as compared to that of the ground floor.
  

• On the other hand, in case there are only two floors in the building and the first floor has also got full or part roof rights, then the rates of the either of the floors shall not vary much.

Hope this gives you some insight and may help you in taking the appropriate decision. For any other information/ clarification, do let us know.

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Found this post interesting? Then check out other related posts : PropertyTalk

>>

Alternatively, write us at: team@bricks-n-mortar.com describing your requirement/ doubt/ clarification/ inquiry/ etc.

Stumbled upon this very useful website information wherein the Delhi Government's e-dept has uploaded various lists having important telephone numbers along with respective postal addresses.

A must in every Indian netizen, I say!

Contributed by PSood in reference to: Important Telephone Numbers (view on Google Sidewiki)

BRICKS-n-MORTAR.com invites Corporates, Companies, Product launchers, Project owners, Building material suppliers, Equipment suppliers and all related sector representatives to advertise on this blog which endeavors to cater to the requirement of the common man's Civil Engineering related queries and doubts, etc.

The Ads / contextual posts / introductory product reviews / etc. can be mutually drafted and finalized with the location of ad placement given prime importance.

Contact 'Team B-n-M' for details and further action.

Thanks & regards,
Team B-n-M

B-n-M

Question posted by one of B-n-M's readers, Muthiah in the comments section of one of our earlier posts titled: "[Readers' Q&A]: Difference between types of cement":

Hi!

Wan i know the difference of OPC and PPC cements

-Muthiah

Team B-n-M answers...

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Dear Muthiah,
This is a very common question people ask. As a quick reference, you can also go through the above-mentioned earlier post and its comments section to get the answer in brief.  Further, let us explain again for easy understanding of yours and all our other interested readers...

OPC (Ordinary Portland Cement) is the basic form of cement with 95% of it being the clinker and 5% being gypsum which is added as an additive to enhance the setting time of the cement to a workable 30 minutes odd or so.  This cement is the standard norm being manufactured and sold by cement manufacturers around the world. As the Understanding-Cement website puts it: "In particular, 'Ordinary Portland Cement' is the normal, grey, cement with which most people are familiar".

However, with changing times and with enhanced energy requirements and associated environmental implications that came along with, the thermal (coal based) power plants the world over started producing multitude of coal ash (commonly known as 'Flyash or Fly Ash'), which is a waste product otherwise, in the form of finely divided residue resulting from the combustion of ground or powdered bituminous coal or sub bituminous coal (lignite) and transported by the flue gases of boilers fired by pulverized coal or lignite.

Then, with the bitter fact the world faced about the disposal of fly ash becoming a serious problem in itself, and on the other hand this fly ash being found to have certain useful cementetious properties, the worldwide statutory and academic bodies allowed addition of up to 35% of fly ash in making the type of cement, commonly known as the Pozzolanic Portland Cement (PPC). This way, the waste product which could have become a serious environmental hazard, has now become a sought-after raw material for manufacture of modern day large-scale produced cement known as the Pozzolanic Portland Cement (PPC).

One common question relating to use of OPC / PPC that people usually ask us is:

Is PPC good to use for the construction of my house/ factory/ repair works/ heavy engineering works?

Some people have presumption that since PPC uses a waste product as an ingredient, it makes it less good than the good old OPC. However, on the other hand PPC has certain distinct advantages over OPC, as listed below:

• Low heat of hydration reducing chances of surface cracks
  
• Longer setting time making it more workable than OPC
• Ultimate strength higher than OPC
• Lower porosity imparting the concrete more water tightness
• Lower manufacturing cost compared to OPC
• Waste utilization making it more environmental friendly
  

Thus, it can be safely inferred that PPC (Pozzolanic Portland Cement) can be used invariably for all common uses that OPC (Ordinary Portland Cement) can be used including one's construction works, concrete works, repair works, finishing works (plastering, flooring, etc.), and the likes.

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