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FUTURE SCOPE OF GEOPOLYMER CONCRETE

FUTURE SCOPE OF GEOPOLYMER CONCRETE

1.    Geopolymer concrete is an innovative & eco-friendly construction material & is an alternative to Portland cement concrete. By the use of geopolymer concrete we can decrease global warming which is one of the big problem of world.

2.    Use of geopolymer reduces the demand of Portland cement which is responsible for high carbon dioxide  emission .

3.    Geopolymer concrete is made from utilization of waste materials such as fly ash, & GGBS(ground granulated blast furnish slag).

ADVANTAGES AND DISADVANTAGE OF GEOPOLYMER CONCRETE

Advantage of geopolymer concrete

·       It has high compressive strength than that of ordinary concrete

·       Very low shrinkage

·       Resistant to heat & cold

·       It is very strong chemical resistance

 Disadvantage of geopolymer concrete

·       Difficult to create .

·       Geoolymer concrete is sold only as a pre-cast or pre-mix due to its hot(heating) curing process.

GEOPOLYMER CONCRETE

GEOPOLYMERCONCRETE

 Geopolymer is a new development in the world of concrete in which cement is totally replaced by pozzolanic materials like fly ash and activated by highly alkaline solutions to act as a binder in the concrete mix. For the selection of suitable ingredients of geopolymer concrete to achieve desire strength at required workability, an experimental investigation has been carried out for the gradation of geopolymer concrete and a mix design procedure is proposed on the basis of quantity and fineness of fly ash, quantity of water, grading of fine aggregate, fine to total aggregate ratio. Sodium silicate solution with Na2O = 16.37 %, SiO2 = 34.35 % and H2O = 49.28 % and sodium hydroxide solution having 13 M concentration were maintained constant throughout the experiment. Water-to-geopolymer binder ratio of 0.35, alkaline solution-to-fly ash ratio of 0.35 and sodium silicate-to-sodium hydroxide ratio of 1.0 by mass were fixed on the basis of workability and cube compressive strength. Workability of geopolymer concrete was measured by flow table apparatus and cubes of 150 mm side were cast and tested for compressive strength after specified period of oven heating. The temperature of oven heating was maintained at 60 °C for 24 h duration and tested 7 days after heating. It is observed that the results of workability and compressive strength are well match with the required degree of workability and compressive strength. So, proposed method is used to design normal and standard Geopolymer concrete.

Use of concrete is globally accepted due to ease in operation, mechanical properties and low cost of production as compared to other construction materials. An important ingredient in the conventional concrete is the Portland cement. Production of Portland cement is increasing due to the increasing demand of construction industries. Therefore the rate of production of carbon dioxide released to the atmosphere during the production of Portland cement is also increasing. Generally for each ton of Portland cement production, releases a ton of carbon dioxide in the atmosphere . The green house gas emission from the production of Portland cement is about 1.35 billion tons annually, which is about 7 % of the total greenhouse gas emissions . Moreover, cement production also consumes significant amount of natural resources. Therefore to reduce the pollution, it is necessary to reduce or replace the cement from concrete by other cementitious materials like fly ash, blast furnace slag, rice husk ash, etc. Fly ash is a by-product of pulverized coal blown into a fire furnace of an electricity generating thermal power plant. According to the survey, the total fly ash production in the world is about 780 million tons per year but utilization is only about 17–20 % . In India more than 220 million tons of Fly ash is produced annually . Out of this, only 35–50 % fly ash is utilized either in the production of Portland pozzolana cement, workability improving admixture in concrete or in stabilization of soil. Most of the fly ash is disposed off as a waste material that covers several hectares of valuable land. The importance of using fly ash as a cement replacing material is beyond doubt ,replacing cement by fly ash up to 60 % known as high volume fly ash concrete. But it was observed that the pozzolanic action of fly ash with calcium hydroxide formed during the hydration of cement is very slow. The particles of size less than 45 μm are responsible for pozzolanic reaction. Higher size particles present in fly ash acts as filler. Therefore for complete replacement of cement by fly ash and to achieve the higher strength within a short period of curing. Fly ash when comes in contact with highly alkaline solutions forms inorganic alumino–silicate polymer product yielding polymeric Si–O–Al–O bonds known as Geopolymer . To produce concrete of desired strength, various mix proportioning methods are used on the basis of type of work, types, availability and properties of material, field conditions and workability and durability requirements. As geopolymer concrete is a new material in which cement is totally replaced by fly ash and activated by alkaline solutions. Chemical composition, fineness and density of fly ashes are different from cement. Similarly, in cement concrete, water plays main role during hydration process while water come out during polymerisation process as in case of geopolymer concrete. Therefore it is necessary to develop a new mix design procedure for geopolymer concrete to achieve desired strength at required workability. So, in the present investigation, geopolymer concrete mix design procedure is proposed on the basis of quantity and fineness of fly ash to achieve desired strength , quantity of water to achieve required degree of workability , grading of fine aggregate  and fine-to-total aggregate ratio by maintaining solution-to-fly ash ratio by mass of 0.35 , water-to-geopolymer binder ratio of 0.35 , sodium silicate-to-sodium hydroxide ratio by mass of 1  and tested after oven heating at a temperature 60 °C for duration of 24 h and tested after test period of 7 days.

OVEN CURING OF GEOPOLYMER CONCRETE

                             

IMPORTANT POINTS TO REMEMBER FOR SITE ENGINEER

There are many things which should be known by the engineer who are working on site the below mentioned points are the important points which to be remembered by a site engineer to complete the work in systematic way .

1. lapping should be provided in bar diameter upto 36 mm, bar having diameter more than 36 mm should not be allowed for lapping.
2. The minimum spacing between two chair should be 1m.
3. The bar used for preparing chair should have minimum diameter of 12 mm.
4. Dowels bar should have minimum diameter of 12 mm.
5. Minimum bar used for square & rectangle column should be 4 & for circular column should be 6.
6. The distribution bar used in slab should have minimum diameter of 8 mm.
7. The main bar used in slab should have minimum diameter of 8mm if we use HYSD bar & should have minimum diameter of 10 mm if we use mild steel bar.
8. The minimum thickness of should be 125 mm.
9. One metric ton of reinforcement require 8 kg of binding wire (8kg/m t . of  reinforcement)
10. The maximum diameter of bar used in slab should not exceed 1/8 of total thickness of slab.
11. Electric conduits & sanitary pipes shall not run in column .
12. Parapet wall height should not be less than 1.2 m.
13. Mason can cover 25 to 30 m^3 brick work in a day.
14. 1 cubic meter of cement is equal to 28.8 bags of 50kg weight.
15. Thickness of plaster should not be more than 12 mm.

GATE EXAM MAY BECOME COMPULSORY FOR ALL ENGINEERING STUDENT

GATE(Graduate Aptitude Test In  Engineering)

 as per AICTE meeting GATE is going to be

compulsory for all engineering students.The GATE exam will be as a EXIT EXAM for engineering students i.e only after clearing GATE student will get there degree.This decision will be for both private & government college engineering students.This exam will be conducted in the final year of B.Tech and student who will clear the exam will be considered as B.Tech Graduates & the student who will not clear the exam have to re-appear for the exam and have to clear it in order to get his/her degree.

   

 The reason to conduct EXIT EXAM(GATE)

• To change the engineering education system of India.
• This decision will help or make students concern & aware about there study.
• This will increase the Employability of Engineer ,at present only 15% of engineering graduates are able to get job,rest all remains unemployed which creates a big  question marks on engineering education so to fix these problems the AICTE has taken this steps. 
• This decision will definitely increase the employability of engineers and this will also make the students concern about there study .
• this step is taken so that no engineering student have to face problems in the placement.

This decision is taken because of private colleges ,which only takes admission of students and give degrees to them they donot take responsibilities of providing knowledge to student they only take responsibilities of giving degree to student after four year and they need money from student so this all things are responsible for producing less skilled engineer and polluting the engineering education system & this all things decreases the level of engineering.so, to overcome this all bad stuffs in engineering education system AICTE has taken this decision .This will give good qualified Engineers to India which will be very helpful for the development of country.This step will also help engineering education system to maintain  its level and dignity & every engineer will feel proud of being engineer.

HOW TO CALCULATE MASS OF CONCRETE TO PREPARE ONE CUBE OF 15 CM^3

The cubes are casted to perform different test on concrete.This is widely used in civil engineering & every civil engineer perform different test with concrete cube so the point is that if we have to prepare exact concrete so that we can prepare one cube then how should we do this so here we will know to calculate the exact mass of concrete for preparing one cube of (15 cm × 15 cm × 15 cm ) volume.Usually this calculation is done at the time of study of civil engineering in field it is not so important because the sample is taken from a big amount of prepared concrete as much is requires to cast the desired cube there is no need to calculate the exact volume or mass but this thing will be helpful for calculating quantity of concrete required for big works. so let us start

the first things we have to know is that the density of plane concrete i.e 2400 kg/m^3

now we have to calculate the volume of one cube in cubic meter
=15 cm × 15 cm × 15 cm  =3.375 cm^3 = 3.375 × 10^-6 = 0.00337 m^3
now after converting volume into meter cube we have to apply the formula of density
        DENSITY= MASS/VOLUME
from here
        MASS=DENSITY × VOLUME
as we have to calculate the mass of one cube so we found out the formula of mass now,
        MASS=2400 kg/m^3 × 0.00337 m^3
        MASS= 8.1 kg
In this way we can calculate the mass of one cube