Hazards related to coir pith: Normally, coir pith is dumped as agricultural waste and become accumulated as a waste product in the form of heaps of coarse and fine dusts. It is estimated that at present there is an accumulated stock of 10 X 10 6 metric tons of coir pith in the southern states of India viz. Kerala, Tamil Nadu, Andhra Pradesh, Karnataka, and Orissa. Coir pith has been traditionally been disposed off by burning. This burning has resulted in various environmental problems, including carbon deposits and the warming of the atmosphere. During the rainy season, the tannins and phenols of the coir pith are leached out into the soil and into the irrigation canals, thereby making agricultural lands unproductive. Also, the water pollution caused by such leaching is harmful to the aquatic and soil biological life. Coir pith is a biomass residue generated during the extraction of coir fibre from coconut husk and is a by-product of the coir manufacturing industry. The Coconut husk contains 20% to 30% fibre of 60 to 300mm length. After grinding the husk, the long fibres are removed and used for various industrial purposes, such as rope and mat making. The remaining 70% material is composed of short and medium-length fibres as well as pith tissue, this is commonly referred to as waste-grade coir. The waste grade coir may be screened to remove part or all of the fibre, and the remaining product is referred to as coir pith. Introduction: Thermal insulation on roofs Heat exchange between a building and its surroundings occurs primarily through the ‘skin’ of the building e.g. roof, walls, fenestrations etc. Roofs and ceiling may amount to about 15 to 50% of the total heat gain depending upon the roof area and height of the building. Hence insulation in roofing play an important role in contributing to the energy loads of a building for achieving thermal comfort through air conditioning or other strategies. Improper thermal insulation on roofs may lead to excessive expenditure on air conditioning and also add to the global energy consumption when observed on a global scale. Many agencies have prescribed standards for the thermal conductance/resistance of roofing assemblies. ECBC prescribes such values depending upon the region, climate and usage of buildings. There are many technologies that provide such insulation. But the production of constituent materials of many such assemblies is from non-renewable sources and they generally also have a larger carbon foot print Most commonly constructed insulation and water proofing system in India, Brick Bat Coba (BBC): Roof slabs constructed by RCC need insulation for thermal comfort and waterproofing treatment to prevent leakage of water. Both these requirements are supposed to be fulfilled by BBC assembly. Drawbacks of brick bat Coba: The drawbacks of brick-bat coba are as follows: • Provides insufficient thermal insulation • It imposes unnecessary load on the parent slab • Damages the parent slab during repairs as bricks adhere to the parent slab • If rain water reaches the bricks through cracks, the bricks absorb the water. But they dry slowly, hence a reservoir of water is created inside, specially in regions of heavy rainfall • Needs excellent workmanship Aims and objectives: Aim: Incorporating coir pith for efficient thermal insulation and water proofing on terrace RCC slabs. Objectives: • To study the applicability of coir pith in a thermal insulation and water proofing assembly. • To compare the thermal performance of commonly used system i.e. brick-bat coba with thermal insulation and water proofing assembly using coir pith. • To study the water proofing performance of a thermal insulation and water proofing assembly of coir pith. Design of the study Brick-bat coba is the most commonly used system for thermal insulation and water proofing in India. There are many disadvantages in using brick-bat coba as a thermal insulation and water proofing system on terrace RCC slabs as mentioned. Coir pith shows potentially better thermal insulating and water absorbing properties than burnt clay bricks and can be a potential replacement for bricks in conventional brick-bat coba technology. A comparative study of thermal and water-proofing performance of Brick-bat coba (BBC) and a system cast by replacing bricks by coir pith blocks in brick bat coba (Coir Pith Block Assembly, CPBA) is carried out.. Limitations: • The research needed a detailed study about the thermal properties of coir pith. No such studies are available, and the laboratory testing of coir pith for its thermal properties was not possible due to the local unavailability of apparatus or a laboratory that could perform such tests. • There could be many different ways to use coir pith in thermal insulation and water proofing systems. But due to the limitations of the time for this study, the assembly casted by replacing bricks by coir pith blocks in brick bat coba was adopted. • It was not possible to calculate the exact thermal conductance/resistance of the two assemblies, that are compared, due to the time and availability constrains of apparatus and local laboratories. • The experiment is conducted on specimen size of 300x300mm, due to which the implications of the use of coir pit on larger scale cannot be conclusively found out. • Due to limitations of time, the specimens could not be tested in very harsh weather of summer or intense rains. • This use of this technology is restricted to south Indian coastal regions due cost implications • Coir pith blocks loosen up in the presence of excessive water. This problem was not explored to detail and remains a limitation of the product. • • • • • • • • • • • • • • • • • Comparative study of thermal performance of CPBA as compared to Brick-bat coba Analysis and discussion of resultant data Conclusion • Durability • Load bearing capacity • Water absorption capacity • Chemical reactivity • Fungal and bacterial infections • Theoretical comparison of thermal performance • Experimental comparison of thermal performance • Thermal insulation Experimental study of water proofing performance • Designing controlled space for experiment • Selecting instruments and sampling method • Performing experiment • Data collection Applicability of coir pith in thermal insulation and water proofing system • Casting of specimen assemblies • • Performing the experiment • Observations Durability Coir Pith contains three major constituents . • Cellulose: A polymeric chain of anhydrous glucose units, which exists mostly in crystalline form • Hemi Cellulose: Which is made up of mixed polymers of various pentose and hexose sugars and is amorphous in nature. • Lignin: A complex amorphous ploymer of phenyl propane which surrounds the cellulose in cell walls. Lignin is relatively inert to hydrolysis. Chemical composition of raw coir pith is listed below: Contents %(w/w) Cellulose……………………….35 Lignin…….……………………25.20 Ash…………….………………8.70 Moisture………….…………..11.90 Pentosans………….………….7.45 Fats and Resins…...…………..1.80 Other Materials….…………...10.06 Fixed Carbon………………….37.10 Coir Pith contains Lignin and cellulose in almost equal quantities around 25 to 35% . Highly lignified materials are extremely durable and do not degrade under normal atmospheric conditions. Coir Pith contains lignin in the same percentage as teak i.e. 30% lignin, Hence it is extremely durable like teak wood and does not degrade even in the presence of moisture or water. Applicability of coir pith in thermal insulation and water proofing system: Thermal Insulation Both Coir and Coir pith have similar chemical composition with slightly different physical appearance and properties. Coir Pith is more porous and has more water absorption capacity than coir. Following is the comparison of porosity and density of coir and coir pith: Coir Coir pith Porosity(%) 40 76.77 Density (g/cc) 1.44 0.1525 Coir has Thermal conductivity 0.075 W/mK . Considering the above factors where the porosity of coir pith is more porous and density of coir pith is less than coir, it can be concluded that the thermal conductivity of coir pith would be more and never less than coir. As there is data available on thermal conductivity of coir pith, for the purpose of this study we consider that the Thermal conductivity of coir pith as equal to that of coir i.e. 0.075W/mK Load bearing capacity For the purpose of our study we would be using coir pith blocks which are manufactured by compressing coir pith. As there are no available studies related to the compressive strength of the coir blocks, a laboratory testing was conducted to evaluate the compressive strength of the coir blocks. 0.000 5.000 10.000 15.000 20.000 25.000 30.000 35.000 0.0 10.0 20.0 30.0 40.0 50.0 Results: Load of failure (kN): 29.1 Stress (Mpa): 0.84 29.1kn=2967.37kg force ~ 3000kg force Considering the applicability of coir pith blocks on the terrace, there will be an absence of walls and other dead load and dynamic point loads, 3000kg force is satisfactory and applicable for terrace thermal insulation and water proofing system. Water absorption capacity In the absence of any study related to absorption capacity of coir pith blocks, water absorption capacity of coir pith block was experimentally compared to the water absorbing capacity of burnt cay brick Design of study Specimens of burnt clay brick bat and coir pith block having equal volume were selected. Coir block as wrapped in porous membrane to avoid loosening These specimens were placed in plastic troughs of equal size each. The weight of the two specimens and the plastic troughs was recorded. The experiment was carried out in a controlled atmosphere of humidity controlled room. Observations: It is clearly observed that coir pith block had absorbed 962gm and brick had absorbed 234gm of water for the same volume of specimen size. Hence, coir pith is a better absorbent of water than Brick. This property of Coir pith block will be helpful in absorbing any water that percolates into the system and shall obstruct the water from reaching the parent slab INCORPORATING COIR-PITH FOR EFFICIENT THERMAL INSULATION AND WATER PROOFING IN ROOF RCC SLAB 2013-2014