Properties of Coconut Fiber Concrete at Elevated Temperature and Against Aggressive Environment

: -Concrete is a Composite material which is composed of Cement, fine and coarse aggregate with some admixture(if needed) binded together with a definite proportion of water. Wide scale use of concrete in construction have anadverse effect on the environment due to extreme reduction of natural resources ( stones, deposits, and aggregates) resulting in ecological imbalance. Another adverse effect of this is on the price of construction which is eventually going up. Therefore,introduction of alternate waste material in place of natural aggregate in concrete production not only protects environment but also make concrete a suitable, economical and environment friendly. In this paper, we are using coconut fiber as apotential replacement of fine aggregate by 2% of its weight in cement. As coconut fiber is vastly available near coastal areas, use of it in concrete should lead to increase in strength of concrete resulting increased sustainability from chemical effects in extremely hot weather condition and adverse chemical environment. The following study shows the effect of extremely hot exposure condition and adverse chemical environment such as acid attacks, sulphate attacks, and chloride attacks on the coconut fiber concrete of M30 grade by testing for 7 and 28 days to determine its compressive strength and loss of weight at raised temperature, and against adverse chemical environment respectively.

calcium sulfate. The significance of this lies in the fact that those other sulfates as well as calcium sulfates react with the various products of hydration of cement and not only with Ca(OH)2 [3].

I. MATERIALS AND METHODS:-1).CEMENT-Cement
is a binding material used in building construction and civil engineering construction.It is made by grinding calcined limestone and clay to a fine power, which can be mixed with water and poured to set as a solid mass and adheres to other materials to bind them together. In this project work we are going to use Pozzolana Portland Cement (PPC) of brandBirla Cement.
• The physical properties of OPC as determined given in the table ( Fig.4 showing coarse aggregate lab work 4) WATER:-Water is used as a raw material during the manufacturing of various civil materials and in construction. It plays an important role in concrete preparation as binding the cement with other aggregate and play major role in the chemical process of releasing heat of hydration and hence imparting strength to it. The pH value of water used in concrete should always be greater than 6. In general, water fit for drinking is suitable for mixing concrete.

5)ADMIXTURE
: -admixture are natural or manufactured chemicals which are used to give special properties to fresh and hardened concrete. It increases the workability without increasing water content or to decrease the water content at the same workability. In this project we have used CONMIX SP 1030 admixture from Radhekrishna Chemical Company. Technical data of admixture is present in following Main Base Sulphonated Naphthalene Formaldehyde 3.
Specific gravity 1.2 at room temperature 6.
Shelf life 12 months in original packing

7)MIXING, CASTING AND CURING OF COCONUT FIBER CONCRETE:-
The coarse aggregate and fine aggregate were weighted,and the concrete mixture was prepared by hand mixing on a water tight platformand mixed thoroughly until a uniform color is obtained, later to it coconut fiber of 2% of weight of cement was added and mixed thoroughly. Then water is added carefully, making sure no water is lost during mixing process. Water is added in stages for hydration of the cement which was carried out with preventive measure in place to avoid bleeding which may affect strength formation of concrete. Cleaned and oiled cube mould of dimension 150×150×150 mm was placed on a vibrating table, then concrete mix was placed in three layer, each layer first went through vibration to release air formed during mixing and vibration were stopped as soon as the cement slurry appeared on the top surface of the mould. The specimen were allowed to remain in the steel mould for the first 24hrs at ambient condition of temperature 27˚± 2˚ C. After that specimen were demoulded with care to prevent edges from breaking apart and specimen were placed in the tank at the ambient temperature of 20˚C for 28 days for curing. The specimen shall not be allowed to become dry at any time until they have been tested. At the time before testing specimens are cured in air with a temperature of 20˚C and 50% relative humidity.
• Table 5. Details of test specimens II. TESTING METODOLOGY: -Three cubes were tested for compressive strength each at 7 days and 28 days of curing using Universal Testing Machine.

Testing at Raised Temperature: -
Coconut fiber concrete was heated in an electric furnaceat a heating rate of 10˚c/min to target temperature of 200˚C, 400˚C,600˚C,800˚C,1000˚C respectively. At each target temperature, the specimen were maintained for 2hrs by Type K thermocouple. After each exposure cycle, the specimens were allowed to cool at room temperature for 24hrs and then tested to assess the residual strength and weight loss.

Testing method for Adverse Chemical Environment: -
Six cubes of M30 coconut fiber concrete were immersed in 10% concentration of sulphuric acid, 10% sodium sulfate solution and 10% sodium chloride each for test period of 30 and 60 days. To avoid settling of solution, the solution was mixed every 7 th day. Once the test period is over, the specimens were taken out and left at room temperature for 3 days then kept in heat curing chamber for 2hrs to dry. Afterwards the specimens were tested for change in compressive strength and change in mass.

(1).COMPRESSIVE STRENGTH AT RAISED TEMPERATURE:-
Compressive strength of concrete is directly determined with the help of universal testing machine in concrete at NSIT, Bihta. As the temperature increases the compressive strength of the concrete decreases gradually upto temperature 400˚C, and the coconut fiber would have burnt at this point. After400˚C the rapid decrease in strengthwith increasing temperature is observed. Graph 1. Change in compressive strength of specimen at raised temperature (2). COMPRESSIVE STRENGTH AGAINST ADVERSE CHEMICAL ENVIRONMENT: -Three numbers of specimens in each acid, sulfate and chloride solution were tested for compressive strength after curing time and unit weight of specimens was noted before the test.

(3). LOSS OF WEIGHT DUE TO RAISED TEMPERATURE:-
As the temperature increases, there is an increase in the loss of weight probably due to the dehydration of the hydration products and the loss of water from the fine pores in the cement paste and aggregate particles.

(4). LOSS OF WEIGHT DUE TO ADVERSE CHEMICAL ENVIRONMENT: -
OPC (M-30) cubes were immersed in 10% concentration of sulphuric acid, 10% sodium sulfate solution and 10% sodium chloride for test period of 30 days and 60 days. All the exposed specimen recorded weight loss and it was observed that the weight loss in case of acid attack was more as compared to sulfate and chloride attack.  loss % in cocnrete due to aggressive environment 10% sulphuric acid 10% sodium sulfate 10% sodium chloride