Developments in concrete technology

I have recently attended few lecture series of Mr.C.M.Dordi,Chief of QA of Ambuja Cements on developments in concrete technology It may not be of much interest to lay men on most of the details,I will just give a hint of changes that is taking place in concrete technology for the benefit of my readers who are basically laymen finding ways and means of building their dream house in Kerala.

Mr.Dordi is a highly qualified and experienced Engineer who previously worked with Tata Electric at Mumbai for.their 500 MW power projects.

Original 1:2:4 concrete is now giving way to much more capable stronger concrete.This 1:2:4 concrete is referred to as M20 concrete by engineers.As the strength and quality of concrete improves this M no.goes up.For Burj Building which is supposed to be the tallest building in the world M80 concrete was used.When the concrete become better it is called HPC(High performance concrete).Instead of having just fine aggregates(sand),coarse aggregates(metal in our usual language) ,cement and water,this HPC has the following components

1.Cement of better strength (above 60 grade)

2.Water in calculated quantity(not as you please)

3.Fine aggregates

4.Coarse aggregates

5.Cement adhesives

6.Fly ash

7.Micro silica

8.Fibers

If you use optical fibers in concrete you can even get transparent or translucent concrete.As technology advances there will be two type of cement.One high setting cement of the order of grade 60 or above.Two,cement for plastering of low grade as plastering does not require high grade cement.

Very soon,you will have plaster mix coming in bags just like you buy cement.So ,you will not have to arrange for river sand .There will be ready mix concrete which can be made to remain not setting even as long as 56 hours so that concrete workers can go on week end holidays and come back to resume concrete work.

As the use of high performance concrete increases steel reinforcement can be reduced as concrete itself will be more stronger.Even with high performance concrete water curing after concrete laying  will be very important.

Immediately after laying of concrete the reactions taking place will generate temperature as high as 25 degree centigrade.So when you do concreting at high atmospheric temperature,it is better to cover concreted surface immediately after concreting with a plastic sheet when it is real hot atmospheric conditions to prevent hair line cracks forming on concreted surface.You can remove the plastic sheet next day morning when you are ready for water curing.

Water curing with plenty of water is essential  for three days immediately after laying of concrete.Any carelessness in this case for those critical three days cannot and will not be compensated by curing after three days though concrete gradually attains higher and higher strength with curing going on for about 56 days

Nalukettu house-features

I get enquiries for design and construction of Nalukettu house quite often.Many of those who desire to build a Nalukettu house do not really know merits and problems associated with a Nalukettu house.But still prefer to have a Nalukettu house possibly due to desire to have a traditional design house or simply to show off as one of the major requirement when building a house in Kerala these days is to announce to neighbours and relatives about the newly acquired  financial status of the owner of the house.

One of the major differences between present day houses and houses of yester years is that for present day houses security and privacy are  major concerns.Again lighting and ventilation is not required to be generated through natural means these days as Electricity is available.In olden days there was no Electric supply and hence house has to be designed to provide lighting and ventilation through natural ways.

Nalukettu type houses provide natural lighting and ventilation .Security was not a major concern in those days partly due to large number of inmates in the house due to joint family living and also due to lesser wealth stored in the building..

Poomukham

Typically A nalukettu house has got a Poomukham in the centre of the portion of front side of building.This is where the master of house used to relax by sitting in a  chair which provides facility to recline in the chair.So the master of the house will be partly lying and partly sitting.All his visitors are not supposed to sit in his presence.So they come and stand in front of Poomukham  at Ground level and talk to master of house with fear and reverence.As all sides of Poomukham except entry to house portion is open,master of house will get sufficient wind and breeze while relaxing in his “Charu Kasera”.

Such a master of house cannot be seen these days and hence Poomukham in the same manner is not required now.

Chuttu verandah

Connected to  poomukham as a continuation of the open space,there will be verandah going around the house.If not exactly going round the house at least it will go around front and one side of the house.This Chuttu verandah with typically about four to five feet width can have Charupady which is wooden seating arrangement .Usually this Charupady is built in Teak wood with seating and reclining portion both in Teak wood with reclining portion possibly with wooden hand carvings.

This Charupady must have been a later addition as originally no body was allowed to sit at same level of master of house.Now a days, to save money and reduce cost people have started using granite slab instead of wooden seating of Charupady.Wooden reclining portion of charupady is also  being  substituted  with concrete reclining portion.But these substitutes lack elegance and in my opinion you should go for  teak wood that too Kerala Plantation teak preferably the Nilambur variety for the best finish.

Charupady will be useful to have informal discussions with relatives and friends  as the position of charupady allows both natural ventilation and light.

Nadumuttom

Lot of people have a mistaken notion that  a house with Nadumuttom is called Nalukettu.Even though Nadumuttom is central and essential for Nalukettu house,Poomukham and Chuttu verandah also are essential features of Nalukettu house.Nadumuttom is normally a square gap not less than ten feet by ten feet size  preferably at exact centre of the house.Even if that is not possible due to other construction requirements,the centre of Nadumuttom should be in line with centre line of Poomukham and front door opening.In the traditional arrangement where slope roofs of rooms around Nadumuttom slope down on all four sides to Nadumuttom,there has to be at least four feet wide passage like a verandah around Nadumuttom.

In the present day adaptation of this arrangement Dining room ,Family living space and Formal living space are provided at three different sides of Nadumuttom thereby allowing visibility and access to Nadumuttom from these three  living spaces.At least on one side of the house close to these common spaces,Chuttu verandah comes up.So naturally you will have to place bed rooms in the other side leaving rear space for Kitchen and front space for formal living connected to Poomukham and front door.

Naturally the plinth area of house with Nalukettu arrangement goes up.Even with 3000 sft plinth area you cannot have more than three bed rooms at Ground level in this arrangement.Nalukettu houses are mostly single storey.

Closing top of Nadumuttom

This was not a problem for yester year people  as they kept Nadumuttom top open .That opening was required for light and ventilation.As I told you earlier security was not their problem in those day houses.From about sitting height there was not even any brick work as they used to have wood work with ample gaps for light and air around all rooms.Now we cannot even think of such open type bed rooms and other living spaces.Check my blog entry on Krishnapuram palace at Kayamkulam.The entire palace is an open building with free flow of light and air  and the major component of house construction was thick size wood.We cannot even think of using such quantity and quality wood these days for house construction.Krishnapuram palace is a Pathinaru kettu house(House with four Nadumuttom) used by the King for his leisure days.Protected by armed soldiers ,King was not worried about any intruder entering his house without his knowledge and permission.

But now  a days you have to close top of Nadumuttom with concrete slope roof at a higher level to allow air inside through side openings at higher level possibly with grills or brick work with small gaps.

In conclusion I can say that it is not advisable to go for a nalukettu house unless of course budget is not your problem.