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)
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