FLEXURAL BEHAVIOUR OF GEOPOLYMER CONCRETE BEAMS USING GEOGRID

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 12, December 2017, pp , Article ID: IJCIET_08_12_026 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed FLEXURAL BEHAVIOUR OF GEOPOLYMER CONCRETE BEAMS USING GEOGRID Santosh Chaudhari, D Rajitha, K Chandra Mouli Department of Civil Engineering, CMR College of Engineering &Technology, Medchal, Telangana, India ABSTRACT Over the last few decades, there has been considerable research in the field of geopolymer composites in various parts of the world. Interest on geopolymer composites is growing because of the fact that, unlike Portland cements, they consume no energy and is not detrimental to the environment. Tremendous surge in research in this area has been observed since there is the immense utilisation of waste products like fly ash, blast furnace slag etc. for manufacture of geopolymers. Ordinary Portland Cement (OPC) became an important material in the production of concrete which act as its binder to bind all the aggregate together. This paper presents the study on Behaviour of geopolymer concrete beams, focused on the durability of concrete for three grades i.e., Ordinary, Standard and High grades have been arrived and compared with that of ordinary Portland cement concrete. Key words: Geopolymer, Geogrid, Concrete Beams. Cite this Article: Santosh Chaudhari, D Rajitha, K Chandra Mouli, Behaviour of Geopolymer Concrete Beams Using Geogrid. International Journal of Civil Engineering and Technology, 8(12), 2017, pp INTRODUCTION The term Geo polymer was coined by Davidovits in 1978 to describe a family of mineral binders with chemical composition similar to zeolites but with an amorphous microstructure. Two main constituents of Geopolymers are source materials and alkaline liquids. The source material should be rich in silicon (Si) and aluminium (Al). In this case, the source material used is fly ash. The chemical reaction which takes place in this case is a polymerization process. Unlike ordinary Portland pozzolanic cements, geopolymers do not form calciumsilicate-hydrates (CSHs) for matrix formation and, but utilise the polycondensation reaction of silica and alumina where adjacent hydroxyl ions from these near neighbours condense to form an oxygen bond linking the molecules, and a free molecule of water.the monomers so formed in solution can be represented in 2-dimensions by - Si O Al O - (poly[silalate]), or, - Si O Al O Si O - (poly[silalate-siloxi]), precursors to attain structural ; hence the term Geopolymer was initiated to represent the binders editor@iaeme.com

2 Behaviour of Geopolymer Concrete Beams Using Geogrid Geopolymer is used as the binder, instead of cement paste, to produce concrete. The geopolymer paste binds the loose coarse aggregates, fine aggregates and other unreacted materials together to form the geopolymer concrete. The manufacture of geopolymer concrete is carried out using the usual concrete technology methods. As in the Portland cement concrete, the aggregates occupy the largest volume, that is, approximately 75 to 80% by mass, in geopolymer concrete. The silicon and the aluminum in the fly ash are activated by a combination of sodium hydroxide and sodium silicate solutions to form the geopolymer paste that binds the aggregates and other unreacted materials. 2. LITERATURE REVIEW The application of geogrids in concrete constitutes a new dimension for using geosynthetics in infrastructure. In pavement applications, geogrids have been used to provide confinement, stabilization, and reinforcement of unbound and asphalt concrete layers, as well as interlayers to mitigate reflective cracking [1]. The compressive and the workability of Geopolymer concrete are influenced by the proportions and properties of the constituent materials that make the Geopolymer paste. Research result showed that the higher concentration (in terms of molar) of sodium hydroxide solution results in higher compressive of Geopolymer concrete [2].geopolymer is a new type of binder which should be distinct from alkali activated aluminosilicate, most researchers preferred the name geopolymer to name all the alkali activated siliceous-aluminous binders amongst the aluminosilicate materials, metakaolin and fly ash are the most favourable raw materials for geopolymer production [3].One Significant aspect of geopolymer concrete is that it is generally heat-cured. Whilst curing of geopolymer concrete at ambient temperatures has been carried out, it is not recommended by most researchers of GPC. At ambient temperatures the reaction of FA-based geopolymeric materials is very slow, and generally results in slower setting and development. Therefore heat-curing, in the form of either dry-heat or steam, is required to increase the kinetic energy and degree of reaction, subsequently increasing the density of the pore system and improving the mechanical properties of the resulting composite [4]. Chemical composition, fineness and percentage of amorphous or reactive silica present. It also depends on quality of coal used as fuel. The types and relative amount of incombustible matter in the coal determine the chemical composition of fly ash. Fly ash that results from burning sub bituminous coals is referred as ASTM Class C fly ash or high calcium fly ash. It is typically contains more than 20 percent of CaO [5]. Geo-polymers are members of the family of inorganicpolymers. The chemical composition of the geo-polymermaterial is similar to natural zeolitic materials, but themicrostructure is amorphous instead of crystalline. Unlike ordinaryportland / pozzolonic cements, geo-polymers do not form calcium silicate-hydrates (C-S-H) for matrix formation, but utilize the poly-condensation of silica and alumina and a high alkali content to attain structural [6].Claimed that to produce optimal binding properties, the low-calcium fly ash should have the percentage of unburned material (LOI) less than 5%, Fe2O3 content should not exceed 10%, and, reactive silica should be between 40 50%, and 80 90% of particles should be smaller than 45 μm.alkaline liquid plays an important role in the polymerization process [7]. Portland cement concrete industry has grown astronomically in recent years. It will continue to grow as the result of continuous urban development. However, Portland cement concrete posses problems such as durability and carbon dioxide emission. Many concrete structures have shown serious deterioration, way before their intended service life, especially those constructed in a corrosive environment [8] editor@iaeme.com

3 Santosh Chaudhari, D Rajitha, K Chandra Mouli 3. MIX DESIGN CALCULATIONS Mix design for G20 The unit weight of Geopolymer concrete is 2400 kg/m 3 The Mass of Combined aggregate as 0.80% of the mass of concrete i.e 0.80 x 2400 = 1920 kg/m 3 Mass of Fly ash and alkaline Liquid = = 490 kg/m 3 Considering alkaline liquid to fly ash ratio as 0.5 Mass of fly ash =(490)/(1+0.5 )= kg/m 3 Mass of alkaline liquid= = kg/m 3 Considering the ratio of NaOH to Na 2 SiO 3 as 2.5. the mass of NaOH solution =(163)/(1+2.5)=46.57 kg/m 3 Mass of Na 2 SiO 3 solution= = kg/m 3 Now calculating the total amount of mass of water and mass of solids in the sodium hydroxide and sodium silicate solution: Sodium Hydroxide solution (NaOH): 8M concentration (NaOH) solution consists of 26.23% of solids (pellets) and 73.77% of water. 8 X 40(molecular weight) = 320 grams of sodium hydroxide solids per one liter of sodium hydroxide solution. This solution comprises 26.23% of NaOH solids and 73.77% water by mass. Mass of solids = (26.23/100) x (46.57) = Kg Mass of water = = Kg Sodium Silicate Solution (Na 2 SiO 3 ) The water content in the silicate solution in observed as 55.9%. The Mass of Water = (55.9/100) x (116.43) = Kg Mass of solids = = Kg Total mass of water Mass of water in NaoH solution + mass of water in Na 2 SiO 3 Solution +Extra water = = Kg. Total mass of solids Mass of solids in NaOH solution + mass of solids in Na 2 SiO 3 solution + mass of Fly ash = = Kg. Ratio of water to Geopolymer Solids = (121.43) / (390.57)= editor@iaeme.com

4 Behaviour of Geopolymer Concrete Beams Using Geogrid Mix design for G40 Assume density of aggregate as unit weight of concrete = 2400 kg/m3. Mass of Combined aggregate = % (consider 0.77%) = 2400 x 0.77% = 1848 kg/m3 Now, mass of combined aggregate = 1848 kg/m3 Mass of Fly ash and alkaline Liquid = = 552 kg/m3 Let us take alkaline liquid to fly ash ratio as 0.4. Now the mass of fly ash = (552)/(1+0.4) = kg/m3 Mass of alkaline liquid = = kg/m3 Let us consider the ratio of NaOH to Na 2 sio 3 as 2.5 Now mass of NaOH solution = (157.21)/(1+2.5)=45.06 kg/m3 Mass of Na 2 sio 3 solution = = kg/m3 Now calculating the total amount of mass of water and mass of solids in the sodium hydroxide and sodium silicate solution Sodium Hydroxide solution (NaOH) Considering 16M concentration, where in the solution consists of 44.4% of solids(pallets) and 55.6% of water. Mass of solids = (44.4/100) x (45.06) = Kg Mass of water = = Kg Sodium Silicate Solution (Na 2 sio 3 ) The water content in the silicate solution in observed as 63.5%. So, the Mass of Water = (63.5/100) x (112.64) = Kg Mass of solids = = Kg Total mass of water Mass of water in NaoH solution + mass of water in Na 2 sio 3. Solution = = 96.58Kg. Total mass of solids Mass of solids in NaOH solution + mass of solids in Na 2 sio 3 Solution + mass of Fly ash = = Kg. Ratio of water to Geopolymer Solids: Ratio = (96.58) / (455.39) = Mix design for G60 Assume density of aggregate as unit weight of concrete = 2400 kg/m editor@iaeme.com

5 Santosh Chaudhari, D Rajitha, K Chandra Mouli Mass of Combined aggregate = % (consider 0.77%) = 2400 x 0.77% = 1848 kg/m3 Now, mass of combined aggregate = 1848 kg/m3 Mass of Fly ash and alkaline Liquid = = 552 kg/m3 Let us take alkaline liquid to fly ash ratio as Now the mass of fly ash = (552)/(1+0.35) = 409 kg/m3 Mass of alkaline liquid = = 143 kg/m3 Let us consider the ratio of NaOH to Na 2 sio 3 as 2.5 Now mass of NaOH solution =(143)/(1+2.5)=40.85 kg/m3 Mass of Na 2 sio 3 solution = = kg/m3 Now calculating the total amount of mass of water and mass of solids in the sodium hydroxide and sodium silicate solution. Sodium Hydroxide solution (NaOH) Considering 16M concentration, where in the solution consists of 44.4% of solids(pallets) and 63.5% of water. Mass of solids = (44.4/100) x (40.85) = Kg Mass of water = = Kg Sodium Silicate Solution (Na 2 sio 3 ) The water content in the silicate solution in observed as 63.5%. So, the Mass of Water = (63.5/100) x (102.14) = Kg Mass of solids = = Kg Total mass of water Mass of water in NaoH solution + mass of water in Na 2 sio 3. Solution = = 87.56Kg. Total mass of solids Mass of solids in NaOH solution + mass of solids in Na 2 sio 3 Solution + mass of Fly ash = = Kg. Ratio of water to Geopolymer Solids: Ratio = (87.56) / (464.41) = 0.19 It is clear that for Water/binder ratio & alkaline liquid/fly ash ratio are the governing factors in designing the geopolymer mix design for various grades. The water/binder ratios of 0.31, 0.21 & 0.19 and Alkaline liquid to fly ash ratios of 0.50 for G20(8M) and 0.40 &0.35 for G40 & G60 respectively with 16M concentration. (Note: the mix design for both ordinary Portland concrete and geo polymer concrete is same but the cement is replaced by fly ash, water is replaced by alkali activators) editor@iaeme.com

6 Behaviour of Geopolymer Concrete Beams Using Geogrid 4. EXPERIMENTAL RESULTS AND DISCUSSIONS Compressive Strength Results Strength Results Table 4.1 Test results of Portland cement concrete mixtures Grade of Concrete M20 M40 M60 Compressive ( days) N/mm 2 Compressive (28 days) N/mm Table 4.2 Test results of fly ash-based Geopolymer concrete mixtures Grade of Concrete G20 G40 G60 Compressive Strength ( days) N/mm 2 Compressive (28 days) N/mm No. of Beams No. of Days Table 4.3 Results of OPC beams (M20) Reinforcement Load at peak 1 7 With grid Without grid With grid Without grid Table 4.4 Results of GPC beams (G20) No. of Beams No. of Days Reinforcement 1 7 With grid 2 7 Without grid 3 28 With grid 4 28 Without grid Load at peak editor@iaeme.com

7 Santosh Chaudhari, D Rajitha, K Chandra Mouli No. of Beams Table 4.5 Results of OPC beams (M40) No. of Days Reinforcemen t 1 7 With grid 2 7 Without grid Load at peak With grid Without grid Table 4.6 Results of GPC beams (G40) No. of Beams No. of Days Reinforcement Load at peak 1 7 With grid Without grid With grid Without grid Table 4.7 Results of OPC beams (M60) No. of Beams No. of Days Reinforcement Load at peak 1 7 With grid Without grid With grid Without grid Table 4.8 Results of GPC beams (G60) No. of Beams No. of Days Reinforcement Load at peak 1 7 With grid Without grid With grid Without grid editor@iaeme.com

8 Behaviour of Geopolymer Concrete Beams Using Geogrid Crack Patterns for OPC and GPC Beams The crack patterns and failures modes are similar for both Ordinary Portland Cement concrete and Geopolymer Concrete beams with and without reinforcement of geogrids as shown in fig CONCLUSIONS Figure 4.1 Failure mechanism of OPC and GPC beams The compressive results achieved are almost same at 7 days and 28 days for GPC and OPC concrete, which indicates that GPC concrete behaves similar to OPC concrete. In geopolymer concrete the high grades mixes are less workable when compared with lower grade concrete. The load deflection characteristics, crack patterns and failure modes for of reinforced ordinary Portland cement concrete beams and Geopolymer concrete beams are almost similar. For geopolymer beams the transverse is slightly more when compared with Ordinary Portland cement concrete beams. Various possibilities could have caused the failure of concrete first followed by rupture of geogrids ribs. Geogrid reinforcement provide a ductile postcracking behaviour, high flexural and deflection when compared to beams without geogrids. The physical and mechanical properties of the geogrids have a great impact on the peak and postpeak behaviour of reinforced beams in flexure. Biaxial geogrids with ribs aligned in the both directions yield better post-peak flexural behavior in comparison to others in terms of load and deflection capacity. Biaxial geogrid normal reinforced beams attained a 20% increase in load capacity and along with substantial increase in post peak deflection. There is a clear correlation between concrete, tensile properties of the geogrid. In both ordinary Portland cement concrete and geopolymer concrete specimens with geogrid performs better when compared to the specimen without geogrids. As the of both ordinary Portland cement concrete and geo polymer concrete is comparatively same, So the conventional concrete can be replaced by geo polymer concrete considering the environmental conditions such as global warming, emission of CO2 etc. REFERENCES [1] Anurag Misra, Rohit Ramteke Madan Lal Bairwa, Study on Strength and Sorptivity characteristics on fly ash concrete. Journal of Engineering and Applied Sciences. 2007;2(5) editor@iaeme.com

9 Santosh Chaudhari, D Rajitha, K Chandra Mouli [2] Barbosa, V. F. F., K. J. D. MacKenzie, C. Thaumaturgo. (2000). "Synthesis and Characterisation of Materials Based on Inorganic Polymers of Alumina and Silica: Sodium Polysialate Polymers." International Journal of Inorganic Materials 2(4): [3] Bakharev,Chindaprasirt, P., Chareerat, T., &Sirivivatnanon, V. (2005). Workability and of coarse high calcium fly ash geopolymer. Cement and Concrete Composites, 29(3), [4] Davidovits, J. (1991). Geopolymers: Inorganic Polymeric New Materials. Journal of Thermal Analysis, 37, [5] Davidovits, J. (1994). Properties of Geopolymer Cements. Paper presented at the First International Conference on Alkaline Cements and Concretes, Kiev State Technical University, Kiev, Ukraine. [6] Davidovits, J. (2002, October 28-29). 30 Years of Successes and Failures in Geopolymer Applications. Market Trends and Potential Breakthroughs. Paper presented at the Geopolymer 2002, Melbourne, Australia. [7] Duxson P, Fernandez-Jimenez A, Provis J, Lukey G, Palamo A, van Deventer J, Geopolymer Technology: The Current State of the Art. J Mater Sci (Advances in geoploymer Science & Technology), : p [8] F. El Meski, Ph.D., P.E.1 and G. R. Chehab, Ph.D., A.M.ASCE 2, Behavior of Concrete Beams Reinforced with Different Types of Geogrids. DOI: /(ASCE)MT American Society of Civil Engineers. [9] M. Keerthi and K. Prasanthi, Experimental Study On Coir Fibre Reinforced Fly Ash Based Geopolymer Concrete For 10m. International Journal of Civil Engineering and Technology, 8(1), 2017, pp editor@iaeme.com