Filler Slab

Filler slab roofs: An alternative roofing technology

A.   INTRODUCTION TO RCC FILLER SLAB

Filler slab technology is a simple and a very innovative technology for a slab construction.

The reason why, concrete and steel are used together to construct RCC slab, is in their individual properties as separate building materials and their individual limitation. Concrete is good in taking compression and steel is good in tension. Thus RCC slab is a product which resists both compression as well as tensile.

Fig 1: Simply supported slab cross section

Knowing this much if we want to move further to understand the “Filler slab” technology, we will have to further study the cross section of a typical simply supported RCC Slab. Under its own load and applied load, the slab will try to bend as shown in the Figure 1.

Fig 2: showing unwanted tension concrete

If we refer Figure 2, which indicates the neutral axis and also tension concrete in the bottom fibers of the slab which is in tension but the top fibers will be in compression.  Knowing this much is the key to understand the filler slab technology. Tension in a slab is on the bottom fiber and compression on the top fiber. That means if we want to optimise the structure we can remove concrete from the tension zone where it is not much needed. That’s the key behind filler slab construction.

This is a very cost effective roofing technology. Knowing the way slab is constructed on site (w.r.t. Gujarat, India), it is not easy to remove, the concrete from the tension zone, hence we try and replace (partially); that part of concrete using light weight and low cost filler material. This method of construction is called filler slab.

Filler slab technology is being used across India, but substantial amount of work on the successful promotion and transfer of this technology was done by Ar. Laurie Baker in South India. It is one place where filler slab has crossed the boundary of research and controlled implementation to being one of the regular options of construction by both government and private sector and also architects and designers have been promoting this technology.

These filler materials are so placed as not to compromise the structural strength, stability and durability, resulting in replacing unwanted and non-functional tension concrete, from below and thus resulting in economy of high energy material consumption and respective cost savings and decreased dead load of the slab.

An internal cavity can be provided between the filler material which adds an extra advantage; other than cost savings and energy savings; improved thermal comfort for the interiors. Also an added advantage of lower dead weight transferred to the supporting elements and finally onto the foundation to further adds up cost saving in design of these elements.

These filler materials are so placed as not to compromise the structural strength, stability and durability, resulting in replacing unwanted and non-functional tension concrete, from below and thus resulting in economy of high energy material’s,  consumption and considerable cost saving and decreased dead load of the slab.

B.    MATERIALS SELECTION AS PER NEED AND DESIGN

Light weight, inert and inexpensive materials such as low grade Mangalore tiles, Burnt Clay Bricks, Hollow Concrete blocks, Stabilized Mud blocks/ Hollow Mud blocks, Clay pots, Coconut shells etc. can be used as filler materials. These materials are laid in the grids of steel reinforcement rods and concreting/concrete topping is done over them.

fig 3: Filler material arrangement

The following points to be kept in mind for filler material selection:

• Filler material should be inert in nature. It should not react with concrete or steel in RCC slab constructed.
• Filler materials water absorption should be checked for as it will soak the hydration water from concrete.
• Filler material should be light in weight, so that overall weight of the slab reduces and also the dead load onto the foundations is reduced.
• Filler material should be low cost so that it cost is much lesser then the cost of the concrete it replaces. This is very important to achieve economy.
• Filler material should be of a size and cross-section, which can be accommodated within the spacing of the reinforcement and also thickness wise could be accommodated within the cross section of the slab.
• Moreover the Filler slab also provides insulation (compared to a conventional RCC slab) from the hot climate outside the building, providing thermal comfort to the user. 
• Filler material texture should match with the desired ceiling finish requirements so as not to provide an ugly ceiling pattern.

C.    INSTALLING FILLER MATERIAL IN THE SLAB

Size of the filler material will be very crucial. It is must to decide the filler material before the slab is designed. The dimension of filler material will help decide the spacing of reinforcement and accordingly the depth of the slab and other structural details will be worked out.

Also, filler material should be properly soaked in water so that it does not absorb any water from the concrete. While installing the filler material, one will have to decide the concreting sequence of the slab i.e. from where the concrete will be started and how will it progress to cover the whole slab.

Filler materials like Manglore tiles/Clay tiles can be installed in two layers (2 nos. one over the other) entrapping an air cavity between the two tiles. A sketch showing cross section of a filler slab with manglore tile is shown below. This will improve the thermal properties of the slab.

Figure 3: Filler slab section - Manglore tile filler material.

D.    ADVANTAGES OF FILLER SLAB TECHNOLOGY:

• By adopting RCC filler slab construction compared to a RCC solid (conventional) slab in case where manglore tiles are used as a filler material, you can save on approximately 19% of the total concrete and including the cost of filler material, you can save around 5-10% of your concrete cost.
• Another advantage is, if the filler material is just a waste i.e. for ex temporary manglore tiles that are removed from the roof to construct a pukka roof, you can save upon nearly 15% on your roof concrete construction cost.
• Building a 25 sq. m slab can save you approx. Rs. 5000 from your concrete cost.
• Filler slab technology can also be applied to mass housing projects and township projects to gain high cost saving and also saving in high energy consuming materials.
• Another advantage can be of a better thermal comfort if a cavity is kept between the filler material or the filler material itself has a cavity. For example tow manglore tiles/Clay tiles can be kept one over the other to form an air cavity thus keeping the interiors of your house remain cooler in summer and warmer in winters.
• Filler slabs can be kept exposed (with proper workmanship) to create aesthetically pleasing ceiling with a view of filler material from below and thus the cost of plastering and/or painting also can be avoided.
• RCC being made of cement, steel, sand and aggregates, is a very high energy intensive material. So reduction in concrete quantity compared to conventional slab construction, adds this technology to the list of sustainable and environment friendly technologies and corporating green building features.

E.    COST SAVINGS

Material saving assuming a 100 mm thick slab 2.54×3.86 m, and calculating the material and cost savings as per market material rates of Ahmedabad, Gujarat, August, 2011 and comparing the savings

 for 1 m3 : RCC Filler slab vs. Conventional Solid RCC Slab.

• 1.61 bags (19% saving)                       =         Rs 418/ m3 saving in cement cost.
• 0.09 m3 less sand (19% saving)            =          Rs 21/ m3 saving in sand cost.
• 0.18 m3 less aggregates (19% saving)  =       Rs 127/ m3 saving in aggregates cost.
• 10 kg less steel/m3 of slab casted       =       Rs 500/m3 saving in reinforcement cost.

The table below shows the consumoption of materials and cost savings for 1 m3 quantity of the slab:

Table 1: Cost saving/cu.m of concrete slab

The figures in the table seem less as the slab taken for calculation is a small size slab. Elaborating this savings, assuming a normal MI

G house area of 100 sq.m ground area and of two stories. Assuming the slab area comes to be 160 sq.m. for this house, the total savings in concrete cost can be Rs. 30,000. Also if the filler material is not a virgin material for the slab construction, you can save about Rs. 90,000 from your concrete cost.

E.    EMBODIED ENERGY SAVINGS

The table below shows the embodied energy calculations for a 200 sq.m house slab. Slab dimensions to be same as above in D.   Cost Savings.

Cost Comparision: Conventional RCC solid slab v.s. RCC Filler Slab

Source:http://sepindia.org

How solar power works

Enjoy a clean, safe energy system

Solar power can be used in your home with any surplus exported to the electricity grid. It emits no fumes, pollution or carbon dioxide.

Did you know that a solar power system can help you:

• save money on your energy bill
• generate your own electricity
• get paid for any excess power you export back to the grid (if eligible)
• add value to your home
• reduce your greenhouse gas emissions

While the technology driving solar power is complex, the process of converting sunlight to electricity is simple. Here's how it works.

The sun’s energy

The sun's energy is available to everyone. Solar power is still generated on cloudy or overcast days, however at a reduced output. At night, when solar panels typically can’t produce enough electricity to meet your household needs, power is automatically drawn from the electricity grid.

Solar panels

These roof-mounted panes contain photovoltaic cells, also known as solar cells. When sunlight falls on the cells they convert the sun’s energy into DC (direct current) power. Solar panels typically produce energy for at least 25 years.

An inverter

Connected by a cable to the solar panels, the inverter converts the DC power to 240V AC (alternating current), the type of electricity used in your home. On some inverters the digital display provides statistics on how much power is being generated throughout the day.

A bi-directional electricity meter

Measures in half-hour blocks both the power you use and the power sent back to the grid. The power you don’t use can be sold back to the grid if you’re eligible. This is called the feed-in tariff, a rebate which depends on your electricity retailer and state.

The electricity grid

Any surplus energy your home generates is fed back into the grid for others to use; when you need additional power, the grid provides this.

source: http://www.energyaustralia.com.au/residential/products-services/solar-power/how-solar-power-works

EVERY RULE HAS A REASON ..

IF YOU ARE AN OWNER OF AN OLD HOUSE AND WANTS TO REDEVELOP IT..
IF YOU HAVE A LAND AND WANTS TO DEVELOP IT..

THEN YOU PROBABLY MUST BE THINKING......

WHY DO THE PROJECT TAKES A LOT OF TIME TO GET A LIFE FORM??

WHY THE EQUATION " RULES = MANDATORY " TO BE STRICTLY FOLLOWED BY THE DEVELOPER/BUILDER??

WHY THERE ARE BUILDING BYLAWS AND REGULATIONS IN EVERY CITY, IN EVERY MUNICIPALITY ??

WHY DO WE HAVE TO GO THROUGH ALL THE PROCEDURE OF SANCTIONING THE BUILDING PLAN AND GETTING A COMPLETION CERTIFICATE FROM THE LOCAL MUNICIPAL AUTHORITY ??

ALL OF THE ABOVE AND MANY MORE SUCH QUESTIONS..

THEN FOR YOUR KNOWLEDGE, LET ME TELL YOU..
YES..
THERE IS A REASON !!

IN ONE LINE..
SAFETY, COMFORT, AESTHETICS, STRUCTURAL STABILITY, ENVIRONMENT FRIENDLY, AND SO ON.. 

IF YOU THINK THESE ABOVE MENTIONED CRITERIA MATTERS, THEN YES THERE IS A REASON!!

THOUGH IT IS A TIME TAKING PROCESS IN OUR COUNTRY, IT HAS MANY LEVELS AND MANY DEPARTMENTS ARE INVOLVED IN ONE SINGLE PROJECT. MAY IT BE WATER SUPPLY DEPARTMENT TO MEET YOUR DAILY WATER REQUIREMENTS, OR FIRE DEPARTMENT TO ENSURE YOUR SAFETY OR DRAINAGE DEPARTMENT TO ENSURE THE WASTE WATER DISPOSAL..
THERE IS ELECTRICITY DEPARTMENT, TO ENSURE PROPER ELECTRIC SUPPLY AND FOREST DEPARTMENT & ENVIRONMENT DEPARTMENT TO MAKE SURE THAT YOU DON'T HARM THE ENVIRONMENT BY CREATING ANY SORT OF POLLUTION..
ALL OF THESE COMBINED AND A FEW MORE IS A DEPARTMENT RUN BY THE RESPECTIVE MUNICIPALITY, WHO MAKES SURE YOUR PROJECT IS  MEETING ALL OF THE ABOVE REQUIREMENTS..

ALSO THERE IS PLANNING DEPARTMENT, SURVEY DEPARTMENT, URBAN LAND-SELLING DEPARTMENT TO LOOK AT THE PROJECT AT A BIGGER SCALE, AT A REGIONAL LEVEL..
THE REGION INCLUDES NEARBY VILLAGES, AGRICULTURAL AREA, NATURAL RESOURCES, URBAN AREA, ROADS AND CONNECTIVITY; ETC.
AN APPROVAL FROM THEM IS THE FOREMOST NECESSITY, TO MAKE SURE YOUR PROJECT IS NOT AFFECTING ANY PART OF THE RESPECTIVE REGION AT LARGE.

AND IF YOUR PROJECT AREA IS BIG ENOUGH TO CALL IT A TOWNSHIP OR CAMPUS, THEN THERE ARE MANY MORE DEPARTMENTS TO GUIDE YOU THROUGH THE WHOLE PLANNING PROCESS..

SO OVERALL.. YOUR ONE STEP MAY OR MAY NOT AFFECT THESE MANY THINGS AND NOW YOU MUST BE REALISING HOW IMPORTANT THESE RULES AND REGULATIONS ARE..

SO WATCH OUT FOR THE STEP YOU ARE TAKING AND MAKE SURE YOU ARE FOLLOWING THE RULES..
BECAUSE,

EVERY RULE HAS A REASON..

VASTU SHASTRA AND PLANTS..

According to the essence of Veda,

It is ten times a better deed to dig up a tank than to dig up a well in a good site...
It is again ten times a better deed to beget a good son than digging up ten tanks...
It is again ten times a better deed to plant and grow a good tree than to beget ten good sons... 

Vastu Shastra or Vast Veda is nothing but the Science of Construction. Its an ideal way to construct a structure for the benefit of the users and benefit of the environment as well.

In the world of concrete jungle, losing our lives to work pressure, keeping up the busy daily routine, we somewhere want to have a peaceful life, close to nature. Some of us live in a small apartment now a days, some lives in a big house with surrounding open space. We may not build our homes according to Vastu rules completely. But there are certain Vastu principles that we can still try to follow and make our life peaceful.

Plantation within and surrounding the house is one of the way..

There are certain Do's and Don'ts to be followed while planting a tree. Some of them are mentioned below..

Plants should be planted during auspicious constellations. 

• It is ideal to plant during the bright half, i.e., close to full moon. 
• Saplings should first be planted in clay pots and only later placed in the ground. This enables them to grow better. 
• Trees should not be planted directly in front of the house’s main entrance. 
• There should be an even number of trees on one’s property, not an odd number. 
• Trees should be planted on the south or west sides of the house. Ideally, they should be planted on both these sides rather than on only one side. 
• It is not good to plant a tall tree on the north, northeast, or east sides of a building. 
• Smaller trees may be planted on the east or north sides, but no trees should be planted in the northeast corner. 
• Tall trees should not be too close to a building as they block the sunlight. 
• A tree’s shadow should not fall on the house. 
• Large trees should not be located too near the house as their roots can damage the foundation and compound wall. Also, the roots of large trees absorb sunlight quickly, meaning these positive rays will not be received by the building. 
• Do not allow tree branches to touch the house. 
• Stone sculptures and rock gardens should be located on the southwest side of the house because they are heavy. 

In addition the appearance of the house surrounded by greenery is quite appealing to the eyes and adds beauty to the house.

By planting and growing plants, and trees, the family will be benefited.

The text written by MAYA however warns that there are certain trees that are beneficial and certain other trees which are maleficent to the welfare of the family.
Good Trees:

1. Tulsi: It is always good to grow a Tulasi plant on one’s property. Tulasi should be located on the north, northeast, or east sides of the house, or in front of the house. 
2. Coconut tree 
3. Neem tree 
4. Betal tree 
5. Sandalwood Tree 
6. Lemon Tree 
7. Pineapple 
8. Bilva 
9. Almond 
10. Mango 
11. Jackfruit 
12. Amla 
13. Katha 

Bad Ones for House:

1. Thorny Plants: Thorny plants should not be planted near the house. Thorny plants other than Roses have a negative energy. Ideally all thorny plants should be pulled up and destroyed. 
2. Cactus: Cactus should not be planted at all. 
3. Creepers: Creepers or other plants should not be grown by using the building or compound wall as support. Creepers should only be grown in a garden, and they should have their own independent supports. 

Banyan and Pipal (Aswatha) are sacred trees; they should usually only be planted near a temple or at a sacred place.
So plant more trees and make your life peaceful and happy..

For Indoor Plants:

• Tulsi or basil plant is considered as a very powerful and auspicious plant. It can be grown either in the front or the back of the house. It should be ideally located at the North, East or Northeast side of the house.
• Vastu Shastra suggests having cascading, crawling, tree-like plants in the living room. They are usually used to minimise the imbalance of protruding or sharp columns, corners or pillars. Thorny plants are best avoided in any room of the house.
• Tall and fully grown plants are ideal to be kept in the bedroom of the house to rectify or neutralise the sharpness of corners.
• The money plant can be placed inside the house to bring in good luck and prosperity.
• Avoid keeping the plants at the Northeast corner of the house. Keeping plants along the North and East walls is also not recommended by the Vastu Shastra experts.
• Bonsai and plants bearing red flowers are also not suitable to be kept inside the house.

Source:

1. http://www.vasthusastra.com/vasthuplantsandtrees.asp
2. http://www.astrojyoti.com/vastutreesnplants.htm
3. http://en.wikipedia.org/wiki/Vastu_shastra
4. http://homeneeds.sulekha.com/vastu-tips-for-keeping-indoor-plants_448977_blog

Geoffrey Bawa

Highly personal in his approach, evoking the pleasures of the senses that go hand in hand with the climate, landscape, and culture of ancient Ceylon, Geoffrey Bawa brought together an appreciation of the Western humanist tradition in architecture with needs and lifestyles of his own country. Bawa has exerted a defining influence on the emerging architecture of independent Sri Lanka and on successive generations of younger architects. His ideas have spread across the island, providing a bridge between the past and the future, a mirror in which ordinary people can obtain a clearer image of their own evolving culture. In 2001, Geoffrey Bawa recieved the prestigious Chairmans Award from the Aga Khan Award for Architecture for his lifetime achievement.

Bawa’s early work included office buildings, factories and schools and was influenced by the ‘Tropical Modernism’ of Fry and Drew and ultimately by the work of le Corbusier. Typical of projects from this period are the remote Strathspey Tea Estate Bungalow at the foot of Adam’s Peak, and the classroom extension for Bishop’s College in Colombo.

In the classroom block for Bishops College the interiors were protected by perforated external wall panels which were supported on a concrete portal frame and inserted between the exposed beam-ends to give an impression of extreme lightness and delicacy.A heavy horizontal eaves beam was hung out to protect the facade and to mask the pitched roof, thus accentuating the horizontality and modernist credentials of the design.

Lunuganga Estate was the country home of the renowned Sri Lankan architect Geoffrey Bawa. Started in 1947, the garden led Bawa, a lawyer called to the Bar at the Inner Temple in 1940, to decide to become an architect. As he went on to become Sri Lanka’s and one of Asia’s most prolific and

influential architects, the garden at the Lunuganga estate remained his first muse and experimental laboratory for new ideas. He continued to change and experiment with its spaces and structures throughout his life until his final illness in 1998. Left to the Lunuganga Trust on his demise in 2003, the gardens are now open to the public and the buildings on the estate are run as a country house hotel.

33rd Lane Colombo, 1960-1970

The house in 33rd Lane is an essay in architectural bricollage. In 1958 Bawa bought the third in a row of four small houses which lay along a short cul-de-sac at the end of a narrow suburban lane and converted it into a pied-à-terre with living room, bedroom, tiny kitchen and room for a servant. When the fourth bungalow became vacant this was colonised to serve as dining room and second living room. Ten years later the remaining bungalows were acquired and added into the composition and the first in the row was demolished to be replaced by a four-storey tower.

At Heritance Kandalama Bawa created an austere building that derives its beauty from the surrounding landscape. The simple geometry and lack of decoration help to highlight the natural environment.

When he first built the hotel, he told the staff that one day it would peer out from under a canopy of lush vegetation. The staff didn’t fully grasp what he was describing. Ten years later, after Bawa was long gone, the staff say he had described the hotel exactly as it is today.

Bawa’s buildings are not just bricks and mortar, but the expression of intangible emotions. Heritance Kandalama is the living embodiment of Geoffrey Bawa’s architectural vision.

Source:
http://www.geoffreybawa.com/
http://www.greatbuildings.com

Green Buildings

The concept of a Green Building brings about a picture of a structure that co-exists with its surrounding habitat such that it becomes a part of that habitat contributing to its growth.

The question arises..........

W H Y  A T A L L  A  G R E E N B U I L D I N G ? ?

There is a simple answer.... It cannot always be about us... We have to take responsibility of our surroundings, our habitat and our world....because we only have one home...

We are now sitting on a time bomb...where the so called growth of the human being has resulted in large scale depletion of fossil fuels, extinction of species, water scarcity, atmospheric imbalances , global warming and so on and so forth...... 
S U S T A I N A N C E  can only occur when in an organisation or an enterprise each and every organisation has a symbiotic relationship with one another. We had to be thoughtful 

What is a green building in true sense.....

Green building (also known as green construction or sustainable building) refers to a structure and using process that is environmentally responsible and resource-efficient throughout a building's life-cycle: from siting to design, construction, operation, maintenance, renovation, and demolition. 

This requires 

• close cooperation of the design team, the architects, the engineers, and the client at all project stages. 
• The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort.
• Although new technologies are constantly being developed to complement current practices in creating greener structures, the common objective is that green buildings are designed to reduce the overall impact of the built environment on human health and the natural environment by:
• Efficiently using energy, water, and other resources
• Protecting occupant health and improving employee productivity
• Reducing waste, pollution and environmental degradation