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rajmane
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Joined: 26 Jan 2003
Posts: 160
Location: Chennai

PostPosted: Fri Nov 17, 2006 12:02 pm    Post subject: No Title Reply with quote

17-11-2006

Dear all

(1) I tend to agree with Shri Daljeet that  M20 is possible with : 1:1.5:3,  hand mixing, water cement ratio of 0.525 (=  5% of aggregates + 30% of  cement ), and 33 grade OPC cement. However, let us also consider the following aspects.

(2) Unless we have mentioned w/c ratio, we can not say that we have defined any concrete adequately. Again I say that unless all the three parameters of concrete (w/c ratio, cement content, concrete strength) as given in IS : 456-2000, are explicitly mentioned, concrete can not be taken to be suitable for structural use as per IS:456-2000.

(3) We must also remember that a given proportions can give a very wide range of concrete strengths depending upon the cement strength (cement grade can not define the actual cement strength).

Thanking you all, with regards

N P Rajamane Deputy Director and Head, Concrete Composites Lab,
Structural Engg Research Centre, CSIR, Taramani, Chennai 600113 (Ph :
22549152 (D), 22549150 (CCLab), Res: 224417882) Email :
rajmane[AT]ser..., rajamanenp[AT]yah...

PS : The above opinion is personal and it may not be necessarily the
view of SERC.

sidhudaljeet[AT]yah... wrote:

Quote:
Dear N P Rajamane
1:1.5:3 for M-20 was used for hand mixed non vibrator concretes with water cement ratio  based  on water (5% of aggregates + 30% of  cement ) Thus water cement ratio of 0.525. I think even today if you use hand mixed concrete and donut use vibrator 33 grade OPC cement and water cement ratio 0.525, M-20 would be a great achievement.
Daljeet
rajmane[AT]ser... wrote:

13 Nov 2004

Dear all

(1) I do not agree that nominal mixes are " The Nominal Mix for M20
concrete is 1:1.5:3, for M15 is 1:2:4". For RCC, we have to think of
durability which is ensured by suitable adoption of w/c ratio. In the
absence of inclusion of w/c ratio in defining the concrete mix or grade,
the concretes can not be taken as acceptable. Defining/describing the
concrete without w/c ratio should stop in the interest of the concrete
constructions, especially, when the cement is produced in modern cement
plants where high strength cements are easily and consistently produced
and made available to engineers without much effect on final price.

(2) I am very glad about the following observation by Shri Basu, Pranab:

"Design Mix is a design of concrete mix where all the actual design
requirements as per the actual materials and working conditions are
taken care of. The main design considerations are Structural Strength,
Standard Deviation in strength, Durability of structure (minimum cement
content), physical and chemical properties of building materials,
exposure of the structure, workability factor and above al the available
resources for commercial viability."

However, I wish to add that the words "Durability of structure (minimum cement
content)" should be replaced with "Durability of structure (minimum cement
content, max. w/c ratio, minimum grade, for a particular exposure condition)".

(3) Let us accept important observations of Prof. Kalgal. A given mix proportion can give a wide range strengths, say ranging even from as less as 10 MPa to as high as 100 MPa depending upon several factors such as type and strength of cement strength, w/c ratio, presence/absence of mineral and chemical admixtures, type of mixer machine, transportation, placing and curing operations, age, etc.

Yours sincerely

N P Rajamane Deputy Director and Head, Concrete Composites Lab,
Structural Engg Research Centre, CSIR, Taramani, Chennai 600113 (Ph :
22549152 (D), 22549150 (CCLab), Res: 224417882) Email :
rajmane[AT]ser..., rajamanenp[AT]yah...

PS : The above opinion is personal and it may not be necessarily the
view of SERC.

Akshaya.Das[AT]ake... wrote:

Quote:
Dear Sefian,

Here is some comment from a very experienced engineer in the
construction field. I thought to share this with you all.

Regards,

Dr A K Das

________________________________

Message From  Basu, Pranab
Sent: Friday, November 10, 2006 4:53 PM
To: Das, Akshaya
Subject: nominal mix design

I could not understand as to where from the discussion evolved? Unless
you know the purpose, you might not contribute significantly. However
like others, I can share my knowledge in the following manner.

1. First of all there is no terminology like Nominal Mix Design.
Nominal Mix is a recommendation by IS 456 based on statistical data from
several regions. Obviously the structural strength as well s the
durability factor remained in consideration.

The Nominal Mix for M20concrete is 1:1.5:3, for M15 is 1:2:4

2. Design Mix is a design of concrete mix where all the actual design
requirements as per the actual materials and working conditions are
taken care of. The main design considerations are Structural Strength,
Standard Deviation in strength, Durability of structure (minimum cement
content), physical and chemical properties of building materials,
exposure of the structure, workability factor and above al the available
resources for commercial viability.

Design Mix is always an economic option but require technical
competence.

I do not know how my vies can help one, if the problem or the issue is
not known.

-----Original Message-----
Message From  Das, Akshaya
Sent: Friday, November 10, 2006 4:31 PM
To: Basu, Pranab
Subject: FW: nominal mix design

Interesting discusiion!!!!!

Akshay

-----Original Message-----

Message From  rajmane[AT]ser... [mailto:rajmane[AT]ser...]

Sent: Friday, November 10, 2006 10:00 PM

To: Das, Akshaya

Subject: nominal mix design

10 Nov 2004

Dear all

I do not agree that nominal mix design of reinforced concrete M20 it is
1:2:3. For RCC. We have to always note that a design mix which should
satisfy both strength (used in design of structures) and durability
requirements (max. w/c ratio, minimum cement content, minimum grade, for
a particular exposure condition) as per IS:456-2000. When we say RCC, I
feel, we mean only structural concrete. Then durability requirements of
Codes have to be ensured.

N P Rajamane Deputy Director and Head, Concrete Composites Lab,
Structural Engg Research Centre, CSIR, Taramani, Chennai 600113 (Ph :

22549152 (D), 22549150 (CCLab), Res: 224417882) Email :

rajmane[AT]ser..., rajamanenp[AT]yah...

PS : The above opinion is personal and it may not be necessarily the
view of SERC.

dipeshtanuja[AT]red... wrote:


Quote:
Hi,


Quote:
Regarding nominal mix design of reinfirced concrete M20 it is 1:2:3 of

cement:sand:ageeregate with watercement ratio.

Quote:
On Thu, 09 Nov 2006 parikshit_pandya[AT]red... wrote :



Quote:
Quote:
Dear all,


Quote:
Quote:
what are the general thumb rules for nominal mix design?


Quote:
Quote:
Parikshit pandya




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PostPosted: Mon Apr 28, 2008 12:38 am    Post subject: No Title Reply with quote

3.Constitution of Council of Architecture.- (1) The Central Government shall, by notification in the Official Gazette, constitute, with effect from such date as may be specified in the notification, a Council to be known as the Council of Architecture, which shall be a body corporate, having perpetual succession and a common seal, with power to acquire, hold and dispose of property, both movable and immovable, and to contract, and may by that name sue or be sued.

(2) The Head Officer of the Council shall be at Delhi or at such other place as the Central Government may, by notification in the Official Gazette, specify.

(3) The Council shall consist of the following members, namely :-

(a) five architects possessing recognised qualifications elected by the Indian Institute of Architects from among its members :

(b) two persons nominated by the All India Council for Technical Education established by the Resolution of the Government of India in the late Ministry of Education No.F.16-10/44-E.III, dated the 30th November, 1945;

(c) five person selected from among themselves by heads of architectural institutions in India imparting full-time instruction for recognised qualifications;

(d) the Chief Architects in the Ministries of the Central Government to which the Government business relating to defence and railways has been allotted and the head of the Architectural Organisation in the Central Public Works Department, ex officio;

(e) one person nominated by the Central Government;

(f) an architect from each State nominated by the Government of that State;

(g) two person nominated by the Institution of Engineers (India) from among its members; and

(h) one person nominated by the Institution of Surveyors of India from among its members.

Explanation.-For the purposes of this sub-section,-

(a) " Institution of Engineers (India)" means the Institution of Engineers (India first registered in 1920 under the India Companies Act, 1913 (7 of 1913) and subsequently incorporated by a Royal Charter in 1935.

(b) "Institution of Surveyors of India" means the Institution of Surveyors registered under the Societies Registration Act, 1860 (21 of 1860).

(4) Notwithstanding anything contained in clause (a) of sub-section (3), the Central Government may, pending the preparation of the register, nominate to the first Council, in consultation with the Indian Institution of Architects, persons referred to in the said clause (a) who are qualified for registration under section 25, and the persons so nominated shall hold officer for such period as the Central Government may, by notification in the Official Gazette, specify.

(5) Notwithstanding anything contained in clause (f) of sub-section (3), the Central Government may, pending the preparation of the register, nominate to the first Council, in consultation with the State Governments concerned, persons referred to in the said clause (f), who are qualified for registration under section 25, and the person so nominated shall hold officer for such period as the Central Government may, by notification in the Official Gazette, specify.

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PostPosted: Mon Apr 28, 2008 12:40 am    Post subject: No Title Reply with quote

What could be the reason of water as well as wet sand is percolating
out of the building boundaries from all sides? Is it a serious warning for a disaster?

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PostPosted: Mon Apr 28, 2008 12:40 am    Post subject: No Title Reply with quote

What could be the reason of water as well as wet sand is percolating
out of the building boundaries from all sides? Is it a serious warning for a disaster?

What are the most popular cars? Find out at Yahoo! Autos

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PostPosted: Mon Apr 28, 2008 12:40 am    Post subject: No Title Reply with quote

What could be the reason of water as well as wet sand is percolating
out of the building boundaries from all sides? Is it a serious warning for a disaster?

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Jiyo cricket on Yahoo! India cricket

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PostPosted: Mon Apr 28, 2008 12:53 am    Post subject: No Title Reply with quote

I had the swirl and ache

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PostPosted: Mon Apr 28, 2008 12:53 am    Post subject: No Title Reply with quote

I craved strong  sweets, but those
Seemed strong when I was young;
The  petal  of the rose
It was that stung.

Now no joy but lacks salt
That is not dashed with pain
And weariness and  fault;
I  crave the  stain

Of tears, the aftermark
Of  almost too much love,
The sweet of bitter  bark
And burning clove.

When stiff and sore  and scarred
I take away  my hand

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PostPosted: Mon Apr 28, 2008 12:53 am    Post subject: No Title Reply with quote

The hurt  is  not  enough:
I long for  weight  and strength
To feel the earth  as rough
To  all my length.

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PostPosted: Mon Apr 28, 2008 1:03 am    Post subject: No Title Reply with quote

whereas  in stuctures designed based on Limit state the
load factors are clearly spelt out as 1.2 and 1.5 respectively.

Thus  for Truss members where DL+WLcasegoverns,
an increase of stresses are taken evn though
WL(=100-120) >> DL(=25 to 30Kg/cm2).
This can be seen in SP-38 at  clause 2.2

However for Tower structures, one can say that
wind load is main load vis-a vis DL. and no increase.

with regards

vikramjeet

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PostPosted: Mon Apr 28, 2008 1:35 am    Post subject: No Title Reply with quote

I had the  swirl and ache

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