NATIONAL SEMINAR ON CONSTRUCTION INDUSTRY INSPIRING THROUGH PRACTICE. IN CONCRETE MIX Dawa Tamang, Civil Engineer, M/s Penjor Construction Pvt. Ltd.

Transcription

1 IN CONCRETE MIX Dawa Tamang, Civil Engineer, M/s Penjor Construction Pvt. Ltd. Abstract An experiment was conducted using ground glass, an aggregate, in order to have a concrete mix to enable organizing the wasted material (glass) in a systematic manner as we are spoiling the environment. We need to reuse and recycle the materials from human beings who will be at a greater loss. With the pace at which the environment is for coming 4000 years rather we are being careless with the lives of humans. Key words: Solid Waste, Glass that takes 4000 years to decompose, new idea to use it in structures so that systematically we can utilize the waste. Introduction in some proportions, then you will have concrete. It is nothing but mixture of the above. The strength and durability of concrete depends upon the quality and quantity of the above-mentioned ingredients. The quantity of concrete and other cement products made, utilizing over 120 million tons of cement to cater to the tremendous infrastructural development that is taking place in India, is making the concrete industry one of the biggest in monetary terms. When one looks around, there is not a single structure that is not made of concrete. As we all go through the journals of modern concrete, most of the scholars point to the danger of raw materials running out. If statistics are the only thing to go by, the future seems problematic, especially, when people in developing countries believe that recycling costs more than investing in original products from the raw materials. This project is developed as an idea about using the material, which would take over 4000 years to decompose glass. 11

2 12 NATIONAL SEMINAR ON CONSTRUCTION INDUSTRY INSPIRING THROUGH PRACTICE The main idea of the project is to use crushed glass or ground glass of particular size, between 4.36 mm to 150 micron and replace them with sand. The initial idea was the data is only about replacing sand by ground glass of the size mentioned above. The data in the project used are not manipulated and it was noted the way it was read by the machines. A total of sixty-six cubes (150mm X 150mm X 150mm) and thirty-three cylinders (100mm x 200mm) were casted. The glass material that was used for the project was bought from the scrap dealers, bars (the unwanted bottles) and glass shops (the small unwanted pieces of glasses which were making its way towards some scrap dealers). Some of the tests were done on the aggregates like sieve analysis, bulking of the sand and ground glass and consistency test on the cement and cement with 150 micron of glass powder. The main reason for working with glass was the thought that glass will not absorb water, which might result in getting a concrete of high strength with lowest water cement ratio. Since the experiments were not done before, the sand was replaced with glass on M20 concrete. In this way, the result would determine whether the replacement of ground glass would help increase in strength or not. Making the or not - if the workability of the concrete increases, it can be concluded whether the glass aggregate absorbs water or not. With this notion in head, this project was done at the College of Science and Technology, Bhutan. Glass Glass is an inorganic product of fusion which has been cooled through the glass transition to a rigid condition without crystallizing Pure silica (SiO2) which has a glass melting point at a viscosity of 10 Pa s (100 P) of over 2300 C (4200 F). While pure silica can be made into glass for special applications (see fused quartz), other substances are added to common glass to simplify processing. One is sodium carbonate (Na2CO3), which lowers the melting point to about 1500 C (2700 F) in soda-lime glass; soda refers to the original source of sodium carbonate in the soda ash obtained from certain plants. However, the soda makes the glass water soluble, which is usually undesirable, so lime (calcium oxide (CaO), generally obtained from limestone), some magnesium oxide (MgO) and aluminum oxide (Al2O3) are added to provide a better chemical durability. The resulting glass contains about 70 to 74 percent silica by weight and is called soda-lime glass. Soda-lime glasses account for about 90 percent of manufactured glass. Every ton of waste glass recycled into new items saves 315 kg of carbon dioxide. This study used crushed glasses as aggregates. The glass, which included both

3 coloured and colourless, were crushed, and then sieved. The crushed glass, which fell between the sizes, IS Sieve 4.36 mm and 150 micron. The powdered which Experimental studies Bulking is governed by IS: 2386 (PART III) 1963 and the experiments were done according to the code. Ground Glass (the material which was retained between IS Sieve 4.56 mm and 150 micron) Bulk density =1.536 kg/litre % Void =29% Void Ratio =0.847 Bulking of the ground glass BulkingofGroundGlass %changeinvolume %ofwateraddedtothetotalweightofgroundglass Bulkingof GroundedGlass Figure 1 : Bulking of Ground Glass 13

4 tension keeps every particle away from each other such that no point contact is possible between the particles. This causes bulking. The extent of surface tension and consequently how far the adjacent particles are kept away will depend upon the percent of moisture content and particle size of The bulking of the aggregates increase with increase in moisture content till the saturation point and decreases after that showing no bulking at all. THE PROPORTION OF GROUND GLASS REPLACING SAND Sl. No. Group % by which ground glass used replacing sand Weight of ground glass used Kg Weight of sand used kg 1 A B C D E F G H I J K Table 1 : Proportion of Ground Glass Replacing Sand 14

5 SLUMP AND COMPACTION FACTOR The following table gives the data for the test and compaction factor: Slump test Compaction factor test Sl No. Date Group Slump (mm) 1 11/5/09 A /5/09 B /5/09 C Nil 4 14/5/09 D /5/09 E /5/09 F /5/09 G /5/09 H /5/09 I /5/09 J /5/09 K 125 Remarks True True True True True Collapse Collapse Collapse Collapse Collapse Collapse Empty container wt. (kg) Partially compacted concrete wt. (kg) Fully compacted concrete wt. (kg) Compaction factor Table 2 : Slump Test and Compaction Factor Test 15

6 COMPRESSIVE STRENGTH AND TENSILE STRENGTH TEST Compressive Strength Compressive strength after 7 days Group Maximum load Compressive Strength Average Compressive strength (mpa) Cube 1 Cube 2 Cube 3 Cube 1 Cube 2 Cube 3 A B C D E F G H I J K Table 3 : Compressive Strength After 7 Days Result 16

7 COMPRESSIVESTRENGTHINN/mm COMPRESSIVESTRENGTH IN7DAYS 0 A B C D E F G H I J K GROUPSOFCONCRETE Figure 2 : Compressive Strength After 7 Days Chart Compressive Strength after 28 Days Group Maximum load Compressive Strength Average Compressive strength Cube 1 Cube 2 Cube 3 Cube 1 Cube 2 Cube 3 A B C D E F G H I J K Table 4: Compressive Strength after 28 Day 17

8 CompressiveStrengthafter28Days CompressiveStrengthinMpa CompressiveStrength Group Figure 3 :Compressive Strength after 28 Days Chart Tensile Strength after 28 days Sl. No. Maximum load Tensile Strength Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 1 Cylinder 2 Cylinder 3 Average Tensile Strength A B C D E F G H I J K Table 5: Tensile Strength after 28 days 18

9 3.5 TensileStrengthafter28days TensileStrengthInMpa TensileStrength 0 Group Figure 4 : Tensile Strength after 28 days chart 19

10 Sampling Test on Concrete Cubes with 20% Ground Glass. Cube Nomenclature Load Compressive No. of withstood Strength Cubes in KN Percentage of cubes in their Cumulative respective Percentage Categories Percentage Categorization above and below M % 16.00% % 24.00% % 32.00% % 48.00% % 64.00% % 84.00% % % 48.00% 52.00% Table 6: Compressive Strength after 28 days data for 25 samples 20

11 Consistency Test with Glass Powder (size: below 150 micron) The test was done by adding the glass powder, which passed through IS Sieve 150 microns as you can see in the picture below. The consistency of the cement was found and replacing a certain amount of cement by the glass powder, the test on the consistency of the mixed material was found. The following table shows the amount and proportions by which the mixture of cement and glass powder was prepared: 26 Figure 5 : Glass powder below 150 Micron Size (image source - self) Sl. No. Amount of cement in % Amount of glass powder in % Consistency Found (%) Table 7 : Tabulation for Consistency 21

12 Conclusion NATIONAL SEMINAR ON CONSTRUCTION INDUSTRY INSPIRING THROUGH PRACTICE This project found that the strength of the M20 concrete was changed by addition of ground glass of the size IS sieve 4.36 mm to 150 micron. The compressive strength of the M20 concrete was found to increase till the 20% of the replacement of sand by ground glass of the size mentioned above. This could be due to improvement in the grading of total aggregates (grading in Fine trend was also observed in the tensile strength as well up to 60% replacement. After that, the tensile strength was increased and then decreased. This could be due to better interlocking at that percentage i.e. 70%. From these results we can replace sand up to a maximum of 20% to improve the strength characteristics of concrete. Therefore, from the perspective of strength, the ground glass of the size mentioned above can be used to increase the compressive strength. It was also found that after sand was replaced by more than 50% of ground glass, the compressive strength decreased and workability increased. And when the ground glass, of the particular size mentioned above, replaced sand by more than 70% the compressive strength fell below the standard value. Hence forth, it can be clearly suggested that, the compressive strength of the concrete can be increased without manipulating anything but the ratio of the sand and ground glass. According to our calculation, it was found that an increase of 20% in compressive strength and with the same, it was found that 25 to 30% of the cement was saved. Thus, using ground glass is not only increases the strength, it is also economic. For instance, say M-25 hollow blocks are charged Nu. 32 in the market, with just savings on cement bags consumed, hollow bricks could be sold at Nu. 24 to Nu It was also found that the 150 micron glass particles changed the consistency of the cement. From the consistency tests, it was observed that consistency decreased up to 20% to 30% of replacement and then it increased. This could be due to the interlocking of glass particles in cement. From the point of sustainable development, it can be suggested that 20% of the sand that we are using worldwide can be saved for future generations by using glass. aggregates, which would help remove the bulky part of the litter in the environment 22

13 References NATIONAL SEMINAR ON CONSTRUCTION INDUSTRY INSPIRING THROUGH PRACTICE 1. Concrete Technology ~ M.S. Shetty 2. version) 3. revision) 4. IS 2386 (PT1) : 1963 Methods of test for aggregates for concrete part 1 particle size and shape 5. IS 2386 (PT2) : 1963 Methods of test for aggregates for Concrete part 2 estimation of deleterious materials and organic impurities 6. IS 2386 (PT3) : 1963 Methods of test for aggregates for concrete Part 3 7. IS 2386 (PT4) : 1963 Methods of test for aggregates for concrete Part 4 Mechanical properties 8. IS 2386 (PT6) : 1963 Methods of test for aggregates for concrete: Part 6 9. revision) IS 5816: 1999 Method of test for splitting tensile strength of concrete 13. IS10262: 1982 Recommended guidelines for concrete mix design

14 NATIONAL SEMINAR ON CONSTRUCTION INDUSTRY INSPIRING THROUGH PRACTICE Mr. Dawa graduated from NIT Warangal in the year He then worked for Yalama Arts and Consultancy for nine months before joining PHPA-II. He worked in PHPA-II for four years and eight months in Power House Division. There he was assigned with tunneling, analysis of rates for main components, construction of RCC buildings, prefabricated buildings and road works. His days at PHPA were adventurous. He currently works for M/s Penjor Construction Pvt. Ltd. Mr. Dawa likes to do sketches, paint, read, write and design. He maintains his own blog at dawaknight. blogspot.com about his works and other topics of his interest. Till date, he has designed more than 30 RCC buildings, which were commercial and residential. He also designed few Rotaries for Paro and Thimphu, and did some consultation works for water supply and sewage network designs for Kholongchu Hydro Electric Project. He volunteers for Bhutan Toilet Organisation to design toilets for them. He also donates stationeries to community schools from the proceedings from his paintings. 24