GEOPOLYMER BASED FAL-G CONCRETE

Transcription

1 GEOPOLYMER BASED FAL-G CONCRETE Tarun Syal, Dr. Sanjeev Naval, PhD Scholar, IKG Punjab Technical University, Associate Professor, DAV Institute of Kapurthala Engineering & Technology, Jalandhar Simarpreet Singh Batra Assistant Professor, Amritsar College of Engineering & Technology, Amritsar Abstract-- FaL-G is the innovative cementitious binder that has the ability to offer structural concrete with sound microstructure properties. FaL-G is the product name given to a cementitious mixture composed of Fly ash (Fa), Lime (L) and Gypsum (G). It is low-cost environmental-friendly and very useful material in construction industry. Since it is manufactured using industrial wastes and by-products, the environmental impacts are mitigated. Due to the differential basic strengths, FaL-G cement has to be added around 1.5 times to that of OPC by weight, to develop a concrete or mortar of equal grade strengths, keeping the quantity of other aggregates same. The use of alkali materials and Alumina Silicates known as Geopolymers can be used in FaL-G products for better qualities. In this paper the effect of Geopolymers on workability and compressive strength of FaL-G concrete has been studied and is observed that full replacement of cement with 55% FaL-G and 45% Geo-polymer resulted in 14% increase in slump value with 18% decrease in compressive strength. On the other hand 33% increase in compressive strength and 8% increase in slump value (which can further be increased by use of plasticizers) is observed by partial replacement of cement with 25% FaL-G and 50% Geo-polymer in concrete. Keywords: Concrete, Fal G Concrete, Geopolymer Concrete, Compressive Strength I. INTRODUCTION A. Fal G Concrete FaL-G is the product name given to a cementations mixture composed of Fly ash (Fa), Lime (L) and Gypsum (G). It is low-cost and environmental-friendly material very useful even in rural housing industry. It gains strength like any other hydraulic cement, in the presence of water, and is water resistant when hardened. The FaL-G binder, innovated by the authors in 1989, is a cementitious blend of fly ash, lime and gypsum. Though FaL-G has the versatility to serve both brick and concrete segments, for over 8 years FaL-G technology has been confined mostly to brick, except for a few concrete applications. "FaL-G is a ground blend of fly ash (Fa), lime (L) and Gypsum (G) in suitable proportions which, upon hydration, yields strengths in the range of kg/cm2, rendering a totally water impervious hard matrix, with the formation of mineralogical phases during hydration similar to those of Ordinary Portland Cement (OPC).Gypsum and fly ash are industrial byproducts that are generated by the phosphorus 479

2 fertilizer industry and by thermal power plants respectively. Lime Pozzolanic binders are known for very slow setting and progressive strength gain over ages.the proportions of lime and gypsum are dependent upon the chemical constituents and the behaviour of fly ash. The technology is thus coustom built, with process parameters to yield a product of superior technology virtues. whenever lime is in short supply, Portland cement can be used as source of lime. (Al) in a source material of geological origin or in byproduct materials to produce binders. Because the chemical reaction that takes place in this case is a polymerization process, the term Geo-polymer is used to represent these binders. B. Geo Polymer Concrete There are two main constituents of geo-polymers, namely the source materials and the alkaline liquids. The source materials for geo-polymers based on alumina-silicate should be rich in silicon (Si) and aluminium (Al). These could be natural minerals such as kaolinite, clays, etc. Alternatively, by-product materials such as fly ash, silica fume, slag, rice-husk ash, red mud, etc. could be used as source materials. The choice of the source materials for making geopolymers depends on factors such as availability, cost, type of application, and specific demand of the end users. The most common alkaline liquid used in geopolymerization is a combination of sodium hydroxide (NaOH) or potassium hydroxide (KOH) and sodium silicate or potassium silicate. An alkaline liquid could be used to react with the silicon (Si) and the aluminum Fig. 2 Manufacturing of Geo-Polymer Water, expelled from the geo-polymer matrix during the curing and further drying periods, leaves behind nano-pores in the matrix, which provide benefits to the performance of geo-polymers. The water in a lowcalcium fly ash-based geo-polymer mixture, therefore, plays no direct role in the chemical reaction that takes place; it merely provides the workability to the mixture during handling. However, a small proportion of calcium-rich source materials such as slag may be included in the source material in order to accelerate the setting time and to alter the curing regime adopted for the geo-polymer mixture. In that situation, the water released during the geo-polymerization reacts with the calcium present to produce hydration products. It is recommended that the alkaline liquid is prepared at least 24 hours prior to use. The sodium silicate solution is commercially available in different grades. The sodium silicate i.e., SiO2 = 29.4%, Na2O = 14.7%, and water = 55.9% by mass, is generally used. The sodium hydroxide with 97-98% purity, in flake or pellet form, is commercially available. The solids must be dissolved in water to make a solution with the required concentration. 8 Molar solution of Sodium 480

3 Hydroxide is adequate for most applications. The mass of NaOH solids in a solution varies depending on the concentration of the solution. The use of alkali materials and alumino-silicates to form a cement is broadly referred to as 'geo-polymer' technology, coined by French researcher Davidovits, but is also known as alkali-activated cement and inorganic polymer concrete in various parts of the world. Geo-polymer technology provides comparable performance to traditional cementitious binders, but with the added advantage of significantly reduced Greenhouse emissions, increased fire and chemical resistance and waste utilization. Although Zeobond is the first mover and world leader in modern large-scale commercial geo-polymer production, industrial geo-polymer applications date back half a century in some East European high-rise buildings. II. LITERATURE REVIEW Geo-polymer concrete is the result of the reaction of materials containing alumino-silicate with concentrated alkaline solution to produce an inorganic polymer binder. As per the study carried out by James Aldred et al. [1], the proprietary geo-polymer concrete used by wagners in Australia for both precast and in situ applications complies with the relevant performance requirements of the Australian Standards and thus can be used as an alternative to Portland cement based concrete. With the ongoing research in the field of polymer concrete attempts have been made to improve the properties of polymer concrete by making use of various materials. Similar attempt has been made by J.M.L Reis [2] who studied the change in properties of polymer concrete when different fibers like coconut fiber, sugarcane fiber etc. was used in polymer concrete and concluded that chopped coconut fiber and sugarcane bagasse fiber increased both fracture toughness and fracture energy of polymer concrete. But flexural strength of polymer concrete was slightly decreased by sugar cane bagasse and banana pseudo stem fiber. Geo-polymer, an inorganic alumina silicate polymer is synthesized predominantly from silicon and aluminum materials or from byproduct materials like fly ash. Gypsum used as ingredient of geo-polymer concrete also contributes for strength acceleration in the early stages of hydration in addition to increasing setting time of cement (N. Bhanumathidas et al. [3]). Mohammed Rabbani Nagral et al. [4] found out that maximum strength of geopolymer was obtained at 90oC for 12 hours of curing period while studying the effect of curing temperature and curing hours on the properties of geo-polymer concrete. M.S.H Khan et al. [5] in his studies found out that geo-polymer concrete with steel furnace slag aggregates offered higher compressive strength, surface resistivity and pulse velocity than that of geo-polymer concrete with traditional aggregate due to incorporation of calcium and magnesium into the geo-polymer structure as well as better bond between steel furnace slag aggregates and geo-polymer matrix. Lateef N. Assi et al. [6] studied the properties of flyash based geo-polymer concrete and concluded that the resulting concrete has the potential for high compressive strength and the compressive strength is directly affected by the source of fly ash. Lateef Assi et al. [7] further investigated about the ambient conditions which can improve the early and final compressive strength of fly-ash based geo-polymer concrete and results showed that early and final compressive strength gains, in case of absence of external heat, can be improved by using Portland cement as a partial replacement of fly ash. The oldest and simplest bond test, which is the standard concentric pull out test, is usually used as a 481

4 comparative test for different concretes in order to assess the bond with deformed bars and Zohra Dahou et al. [8] carried out pull out tests and developed empirical models correlating the steel-concrete bond strength to the mean compressive strength of concrete for both OPC and geo-polymer concretes. Geopolymer concrete when incorporated with fly-ash that is considered to be waste material can improve the properties of concrete as studied by various researchers. Hence Fly-ash based geo-polymer concrete can be extensively used in construction industry both precast and in-situ (B. Vijaya Rangan [9]). Polymer concrete has shown the advantages over conventional Portland cement based concrete like 292% increase in tensile strength and 285% increase in compressive strength as research carried out by Abhishek Jain [10], polymer concrete can be considered to be the future of construction industry. FaL-G is the cementitious blend of fly ash, lime and gypsum, where, for rapid setting and hardening, lime is replaced by moderate doses of OPC.FaL-G cement is an innovative breakthrough, free of clinkerisation or sintering thereby to result upon saving high energy input, comprising of fly ash, lime and gypsum in a physical blend, which sets hydraulically with its neat strength in the range of kg/cm2 in comparison to that of neat OPC at kg/cm2. (Gunther Erlenstaedt et al. [11]). Though FaL-G has the versatility to serve both brick and concrete segments, for over 8 years FaL-G technology has been confined mostly to brick, except for a few concrete applications (N. Banumathidas et al. [12]). Fly-ash being most important ingredient in the FaL-G technology is a byproduct in coal combusted thermal power plants and has the potential to be used as Pozzolanic material (N. Bhanumathidas et al. [13]). In an attempt to compare compressive strength of FaL- G concrete, RadhaKrishna et al. [14] concluded that the FaL-G masonry blocks are suitable to be used as masonry blocks and FaL-G concrete is suitable for making roller compacted concrete. Niranjan PS [15] carried out experimental investigation on FaL-G paste and concluded that the strength of FaL-G paste increases with age and adequate to use it in making deferent composites. FaL-G paste can also be used as controlled low strength material as it has good relative flow area and adequate strength development with age. Further research in improving fly-ash based geopolymer concrete resulted in use of crumb rubber partially replacing sand and it was found that an appropriate amount of rubber may be replaced with an equal volume of fine aggregates in rubberized geopolymer concrete without significant reduction of the compressive strength (Yeonho Park et al. [16]). In the current study attempt has been made to study the effect of Geo-polymer based FaL-G concrete in terms of workability and compressive strength. III. MATERIALS & METHODOLOGY A. Materials The various Materials used in the present study are Cement(Ultra Tech OPC 53 Grade), Fine Aggregates, Coarse Aggregates, Super plasticizer (Fosroc Conplast SP 430 G8M ), Gypsum, Lime, Fly Ash, Sodium Silicate Solution, Sodium Hydroxide Solution and Water The various properties of different materials used were determined as per relevant Indian Standard Codes and are given in Table 1. TABLE 1 PHYSICAL PROPERTIES OF INGREDIENTS 482

5 B. Methodology The experimental program consisted of the six different mixes are as under: basic materials viz. cement, sand, aggregates, water and super plasticizer. 75% with FaL-G cement (70% fly ash, 2% lime, 3% gypsum) to make a concrete mix called FaL-G concrete in cement route. - polymer as well as cement in the concrete mix. This mix is known as geo-polymer concrete in cement route. -G concrete mix is made by the addition of 60% fly ash, 30% lime and 10% gypsum called Fal G concrete in lime route. -polymer concrete mix is experimented by the addition of 29% of sodium silicate solution, 13% of sodium hydroxide solution and 58% of fly ash. -polymer concrete in lime route or the combination of geo-polymer and FaL-G concrete. In this mix, 20% lime is added, 25% fly ash is added, 10% gypsum is added, 33% sodium silicate solution is added and 12% sodium hydroxide solution is added. 1) Mix Design: Concrete mix design is the process of choosing suitable ingredients of concrete and determining their relative quantities with the object of producing as economically as possible concrete of certain minimum properties, notable workability, strength and durability. M30 grade of concrete is prepared as per IS 10262: 1982 assuming Moderate Environment Condition in which w/c ratio is.45 and mix proportion in ratio 1:1.2:2.4 (cement: fine aggregates: coarse aggregates).in all the mixes there is a replacement of cement with FaL-G mix. In all the mix proportions content of fly ash, lime and gypsum is kept constant as 60%., 30%and 10%. Six mixes were prepared with different percentage of cement. 2) Test Procedure: A suitable FaL-G concrete mix was prepared with different proportions of fly ash, lime and gypsum. In case of geo-polymer concrete, the concrete mix was prepared with different proportions of sodium silicate solution and sodium hydroxide solution. The geo-polymer concrete mix gives higher strength after 28 days testing. The various standard cubes made by varying quantities of FaL-G, cement and Geo-polymer were tested after 7days and 28 days of curing. TABLE 2 MIX PROPORTIONS FOR THE EXPERIMENTATIONS FOR ONE MOULD 483

6 IV. RESULTS Concrete Cubes with different Mix Proportions of Cement, FaL-G and Geo-polymer were tested to determine the Slump value as per IS 1199:1959 and Compressive Strength as per IS 516:1959 at 7-days and 28-days respectively. The observations are recorded in Table 3. The Fig. 3and 4 show the variation of Slump value and 28-days compressive strength for different Mix Proportions respectively. TABLE 3 SLUMP AND COMPRESSIVE STRENGTH OF DIFFERENT MIX PROPORTIONS Fig. 3 Slump Value variation for different Mix Proportions Fig days Compressive Strength variation for different Mix Proportions V. CONCLUSION Based on the findings of the study the following conclusions may be drawnconventional cement for FaL-G concrete and Geopolymer concrete respectively as compared to the conventional concrete. at 7 days has been observed when there is 25% FaL G, 25% cement and 50% of geo-polymer which indicates that geo-polymer is quite better binder than cement. -G and geo-polymer could be used as an alternate building material. As the final setting time of the geo-polymer concrete is quite lesser than the ordinary Portland cement concrete. So, this can also be used for increasing the construction speed. -G mix provides strength with time. But FaL-G is quite durable than OPC. As the lifetime is specified for cement but it is quite difficult to specify the lifetime of the FaL-G. - G mix provides only 40-45% strength as compare to cement mix. While geo-polymer mix provides the double strength with the small addition of cement in it. So geo-polymer concrete has the efficiency to gain the ultra-high strength in the less time period. mer based FaL-G may prove to an alternative to conventional concrete MIX 1 MIX 2 MIX 3 MIX 4 MIX 5 MIX 6 SLUMP VALUE (mm) MIX 1 MIX 2 MIX 3 MIX 4 MIX 5 MIX 6 28 DAYS COMPRESSIVE STRENGTH 484

7 VI. REFERENCES [1] James Aldred, John Day, Is geo-polymer concrete a suitable alternative to traditional concrete?, 37th Conference on Our World In Concrete & Structures, Singapore: August 2012 [2] J.M.L. Reis, Fracture and flexural characterization of natural fiber-reinforced polymer concrete, Construction and Building Materials, vol. 20, pp , 2006 [3] N. Bhanumathidas, N. Kalidas, Dual role of gypsum: Set retarder and strength accelerator, The Indian Concrete Journal, pp. 1-4, March 2004 [4] Mohammed RabbaniNagral, TejasOstwal, Manojkumar V Chitawadagi, Effect Of Curing Temperature And Curing Hours On The Properties Of Geo-Polymer Concrete, International Journal of Computational Engineering Research (IJCER), vol. 4, pp. 1-11, Sep [5] M.S.H. Khan, Arnaud Castel, A. Akbarnezhad, Stephen J. Foster, Marc Smith, Utilisation of steel furnace slag coarse aggregate in a low calcium fly ash geo-polymer concrete, Cement and Concrete Research, vol. 89, pp , 2016 [6] Lateef N. Assi, Edward (Eddie) Deaver, Mohamed K. ElBatanouny, Paul Ziehl, Investigation of early compressive strength of fly ash-based geo-polymer concrete, Construction and Building Materials, vol. 112, pp , 2016 [7] LateefAssi, SeyedAliGhahari, Edward (Eddie) Deaver, Davis Leaphart, Paul Ziehl, Improvement of the early and final compressive strength of fly ashbased geo-polymer concrete at ambient conditions, Construction and Building Materials, vol. 123, pp , 2016 [8] ZohraDahou, Arnaud Castel, Amin Noushini, Prediction of the steel-concrete bond strength from the compressive strength of Portland cement and geopolymer concretes, Construction and Building Materials, vol. 119, pp , 2016 [9] B. VijayaRangan, Geopolymer concrete for environmental protection, The Indian Concrete Journal, vol. 88, pp , 50-59, April 2014 [10] Abhishek Jain, Polymer Concrete: Future of Construction Industry, International Journal of Scientific Research, vol. 2, pp , Nov [11] Gunther Erlenstaedt, N Kalidas, N Bhanumathidas, Fal-G : The Breakthrough Hydraulic Cement, National Conference on Cement & Building Materials from Industrial Wastes (Jawaharlal Nehru Technological University, Hyderabad; July 1992) [12] N. Bhanumathidas, N. Kalidas, FaL-G : The Technology from Brick to Cement Concrete, Course Material for Training on FaL-G Technology At NirmithiKendras, AP State ousingcorpn. Ltd.June 19-25, 2007 [13] N. Bhanumathidas, N. Kalidas, Fly Ash Characterisation for Use as a Pozzolanic Material, II International Symposium on Concrete Technology for Sustainable Development, Hyderabad (Feb 27-Mar 03, 2005) [14] RadhaKrishna, P.S. Niranjan, P. Prithvi Raj, VittaSanket Kumar, An Experimental Study on FaL- G Mortar and Concrete, in the Proc. of Int. Conf. on Advances in Architecture and Civil Engineering (AARCV 2012), 21st 23rd June 2012 [15] Niranjan PS, Radhakrishna, An Experimental Investigation on FaL-G Paste, International Advanced Research Journal in Science, Engineering and Technology, vol. 2, pp , March 2015 [16] Yeonho Park, Ali Abolmaali, Young Hoon Kim, MasoudGhahremannejad, Compressive strength of fly ash-based geopolymer concrete with crumb rubber 485

8 partially replacing sand, Construction and Building Materials, vol. 118, pp , 2016 [17] Indian Standard Codes, IS 383:1970, IS 516:1959, IS 1199:1959, IS 1727:1967, IS 2386(Part 3):1963, IS 4031(Part 11):1988, IS 10262:1982, Bureau of Indian Standards. 486