EXPERIMENTAL STUDY ON STRENGTH OF SLAG MORTAR BY REPLACING THE FINE AGGREGATE WITH EOF SLAG

Transcription

1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 12, December 2017, pp , Article ID: IJCIET_08_12_092 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EXPERIMENTAL STUDY ON STRENGTH OF SLAG MORTAR BY REPLACING THE FINE AGGREGATE WITH EOF SLAG Y. K. Sabapathy Professor, Civil Engineering Department, SSN College of Engineering, Tamil Nadu, India P. Sangeetha Associate Professor, Civil Engineering Department, SSN College of engineering, Tamil Nadu, India V. P. Haripriya Graduate Engineer Trainee, ICOMAT, Perungudi, Chennai, Tamil Nadu, India D. Revathy Research Assistant, Civil Engineering Department, SSN College of Engineering, Tamil Nadu, India D. Ravichandar Jindal Steel Limited - Salem Works, Tamil Nadu, India S. Sathyapriya Undergraduate Student, Civil Engineering Department, SSN College of Engineering, Tamil Nadu, India ABSTRACT Slag is an industrial waste product which is generated in substantial amounts from various steel industries all over the world. Various types of slag produced are dumped and used as landfill which proves to be hazardous to our environment. To avoid, this researchers are encouraged in finding a solution to use this waste product as an effective construction material. The main objective of this experimental investigation is to study the influence of using Energy Optimization Furnace (EOF) slag on the strength properties cement mortar. The use of slag as replacement to the natural river sand is advantageous from the environmental point of view. Three different ratios of cement: Sand/Slag ratios such as 1:2, 1:3 and 1:4 for five slag varying percentages- 0%, 25%, 50%, 75% and 100% were employed. Compressive strength, crushing strength and durability of masonry mortar were studied. The tests concluded that the editor@iaeme.com

2 Experimental Study on Strength of Slag Mortar by Replacing the Fine Aggregate with EOF Slag EOF slag can be used in building construction as an effective replacement for natural sand. Key words: Slag, Steel, Mortar, EOF, Masonry, Compression, Durability Cite this Article: Y.K. Sabapathy, P. Sangeetha, V.P. Haripriya, D. Revathy, D. Ravichandar, S. Sathyapriya. Experimental Study on Strength of Slag Mortar by Replacing the Fine Aggregate with EOF Slag. International Journal of Civil Engineering and Technology, 8(12), 2017, pp INTRODUCTION The use of cement mortar is inevitable when building masonry walls. Cement mortars need to be of good strength in bonding the masonry units and should also be durable when used for wall plastering especially when used for finishing the exterior wall surfaces. River sand which is conventionally used as fine aggregates in making concrete and mortars is fast depleting due to rapid urbanization and growing construction activities around the world. The fine aggregates constitute the majority of the masonry mortar and it has a substantial impact on the properties of the mortar in both fresh and the hardened state. The strength of any masonry structure mainly depends upon the strength of the mortar which in turn is dependent on the type of fine aggregate utilized. Mortar is effective in governing uniform stress distribution fixing the distortions in masonry and repairing distortions due to shrinkage and thermal expansions (El- Sayed Sedek Abu Seif, 2013) [1]. In the process of iron and steel manufacturing, various by- products are generated in large amount. The by-products include blast furnace slag, converter slag and electric arc furnace slag. The slags being produced in enormous amount have been widely employed in the construction industry for various uses such as mineral admixtures in concrete and Portland cement, for roadbeds, embankments, unconfined construction fill, skid resistant asphalt aggregates and also in environmental applications (Sang- Woo Kim., et.al, 2016) [2]. The EOF slag used in this experimental investigation is a new type of slag produced as a waste from the Energy Optimization Furnace used to manufacture steel. The influence of strength properties of mortar when natural sand is replaced with EOF slag was taken as the main objective of this study. Slag mortar cubes and brick masonry prisms were made for three different cement and slag/sand ratios- 1:2, 1:2.5, and 1:3 with five percentages of replacement of slag with fine aggregates- 0%, 25%, 50%, 75%, and 100%. Tests such as compression test, masonry prism test, water absorption test were conducted on all the specimens with three different curing regimes such as 3 days, 7 days and 28 days respectively. The test results from the study inferred that the use of EOF slag improves the bonding and crushing strength of mortar till a certain limit. In addition to this, the EOF slag in mortar reduced the water absorption capacity till an optimum level of replacement which is considered as an important property of any masonry mortar. 2. LITERATURE REVIEW Energy Optimization Furnace (EOF) is a new type of furnace used in making steel and this type of furnace is slowly evolving in the steel industries. Much of the earlier research works have been conducted in the various other categories of steel slags other than EOF slag as aggregates both in concrete and mortar. Earlier researchers investigated the effective way to use the granular slag as a replacement for fine aggregates. All the basic tests for mortar were conducted such as the compressive strength, masonry crushing and adhesion strength and editor@iaeme.com

3 Y.K. Sabapathy, P. Sangeetha, V.P. Haripriya, D. Revathy, D. Ravichandar, S. Sathyapriya water absorption for durability. It was concluded from the results that 50% to 75% of replacement of slag with natural sand increased the compressive strength and the bonding strength of the mortar considerably (Nadeem and Pophale, 2013) [3]. The possible use of granulated blast furnace slag as a substitute for fine aggregates in cement mortar was investigated (Natraja et. al, 2013) [4]. In this study 1:3 cement mortar mixes was adopted with sand and slag percentages of 0% to 100%. Three different water-cement ratios such as 0.4, 0.5 and 0.6 were adopted. Standard mortar cubes were cast and tested. The test results inferred that 50% to 75% of replacement of slag with fine aggregates proves to be optimum. Experimental investigation had been done on the use of GGBS in varying proportions in mortar for varying curing periods. The results concluded that curing regime has a significant improvement in strength showing that 3 to 7 days curing was the most favourable curing period for all mortar mixes. (Fathollah Sajedi, 2012) [5]. The influence of iron slag as a replacement for fine aggregates on the strength properties of mortar was investigated (Tamara Humam and Rafat Siddique, 2014) [6]. It has been reported that iron slag is sound in mechanical properties. The results show that 40% of replacement of fine aggregates with iron slag gave the most optimum strength. Apart from steel slag, the influence of industrial waste on the strength properties of the mortar was investigated (L. Baali et. al, 2007) [7]. This industrial waste is used as a replacement for fine aggregates with varying percentages of 0% to 100%. Standard mortar cubes and beams were casted and tested; the test results of which inferred that up to 25% of fine aggregated can be replaced with this industrial waste. 3. MATERIALS The materials used in this experimental study are as follows. Ordinary Portland cement of grade 53 with a specific gravity of 3.15 confining to the Indian standards IS (1987) [10] was used as the binding material. Potable water confining to IS 456: 2000 [11] was used. Natural river sand used as fine aggregates confirmed to the Indian standard IS 2116:1980 [12] was used with the cement in the preparation of mortar. The EOF slag brought from Jindal Steel Works, Salem was used as the replacement for the natural river sand with varying percentages accordingly. The chemical composition of the EOF slag [8] is shown in the Table 1. Table 1 Chemical composition of EOF Slag Compounds LOI CaO FeO SiO 2 MgO Al 2 O 3 MnO P 2 O 5 TiO 2 Na 2 O K 2 O % EXPERIMENTAL PROGRAM 4.1. Gradation Test Gradation test or sieve analysis is done to evaluate the particle size distribution of a granular material. The properties of the mortar are affected by gradation. With effective gradation, it is possible to achieve high bulk density, high physical stability, low permeability and optimum workability. The gradation test for the EOF slag is done as per IS 383:1970 [13]. Figure 1 shows the graph of the gradation test. It can be inferred from the graph that the particle size distribution of EOF slag is in close proximity to natural fine aggregates editor@iaeme.com

4 Experimental Study on Strength of Slag Mortar by Replacing the Fine Aggregate with EOF Slag Figure 1 Sieve analysis graph of EOF slag 4.2. Specific Gravity Specific gravity is an important parameter which indicates the suitability of the aggregates to be used in the mortar or concrete mix. If the value of specific gravity is very low, it signifies that the aggregate is very weak and porous. The specific gravity of both natural river sand and EOF slag was performed as per IS 2386(Part III) 1963 [14]. The values of the specific gravity of natural river sand and EOF slag were found to be 2.60 and 2.65 respectively. These values indicate that the slag is in close proximity to natural river sand and can be effectively used in the construction of structural elements Test for workability The flow table test is used to determine the workability of the mortar. Workability is the combination of properties such as consistency, plasticity, cohesion and adhesion which are greatly determined by the aggregate grading, water and air content. A workable mortar is the one which spreads easily and adheres well to the masonry units and assists in the progress of alignment of masonry structures. The test is conducted as per IS [15] for three different ratios 1:2, 1:2.5 and 1:3 for five percentage of replacements 0%, 25%, 50%, 75% and 100% Compression Test Compression test is used to evaluate the engineering quality of the material to be utilized in the structural elements. The mortar cubes for the three different ratios 1:2, 1:2.5 and 1:3 with a water-cement ratio of 0.6 for five varying percentages of replacements of slag namely 0%, 25%, 50%, 75% and 100% were casted as per IS [17]. The mortar cube specimens were allowed for 3 days, 7 days and 28 days curing before being tested. The mortar cubes were casted for the standard size of 70.6 mm and tested using the Universal Standard Testing machine as per IS 4031 (PART 7) [16] Masonry Prism Test Mortar is the primary load bearing material which resists the compressive forces in a building. For instance, the masonry walls and masonry columns are subjected to vertical forces for which the mortar joints should be strong to protect it from failure (Narendra Taly., 2010) [9]. Therefore this masonry prism test is performed to evaluate the strength of masonry mortar in compression. Standard bricks of dimension 210 x 10 x 10 mm were used in the test. Each prism consisted of two bricks connected by 10 mm mortar with three different ratios of 1:2, 1:2.5 and 1:3 with varying slag replacements of 0%, 25%, 50%, 75% and 100%. The prisms were tested after 7 days time in Universal Testing Machine editor@iaeme.com

5 Y.K. Sabapathy, P. Sangeetha, V.P. Haripriya, D. Revathy, D. Ravichandar, S. Sathyapriya 4.6. Water Absorption Test Water absorption test is used to measure the capillary forces exerted by the pore structure causing fluid to be drawn into the body of the material. The amount of water absorbed by mortar mixes depends on the water tightness of the mixes. As a general rule, a mortar should be characterized by low water absorption and high water vapor permeability, so that the water which enters the mortar can easily and quickly evaporate. The water absorption test was done as per the standards specified in ASTM C 1403 [18]. All mixes were subjected to water absorption test at the end of 28 days curing period after de-molding. The mortar cubes were placed in hot air oven at C for 24 hours. The oven dried cubes were taken out and cooled in ambient room temperature. Before testing the initial weight of the cubes were measured and noted as W 0. The cubes were placed in a container having 3mm of water. After placing the specimens their weights are taken at 0.25 hours, 1 hour, 4 hours and 24 hours respectively. The amount of water absorbed A t is calculated Scanning Electron Microscope Analysis (SEM) The SEM analysis of the slag mortar is shown in figure 2. The Scanning Electron Microscope analysis of the EOF slag provided necessary information about the mineral morphology, crystal size and chemical composition of the mortar matrix. Figure 2 shows the SEM images of the slag mortar The SEM analysis shows the microstructure of the binder conglomerates of the mortar matrix. These images reported that the slag has a good compactness and low amount of pores. This increased compactness results in enhancing the strength properties of the slag mortar. Also the SEM images reveal that the surface of the slag mortar is rough, platy with crystalline morphology. 5. RESULTS AND DISCUSSION 5.1. Workability The graph of the flow table test is shown in figure 3. From the graph, it can be inferred that the flow value peaks at 50% of the replacement for all the three ratios. During the experiment, the mortar was workable when replaced with 25% to 50% of the fine aggregates with slag editor@iaeme.com

6 Experimental Study on Strength of Slag Mortar by Replacing the Fine Aggregate with EOF Slag Figure 3 Workability test graph Beyond 50% the graph shows a steady declination irrespective of the mix ratios which is due to the considerable effect of shape and size of slag particles in the mortar. The reduction in workability is attributed to the fact that sand has been replaced by a finer material. Therefore higher the percentage of slag, lower the workability level Compressive Strength Test The compressive strength test was conducted as per the IS standards and the graphs of 3, 7 and 28 days for three ratios and five percentages of replacements are presented below. Figure 4 Bar graph showing varying compressive strength of 3, 7 and 28 days The bar graph shows the variation of compressive strength of slag mortar with respect to 3, 7 and 28 days curing periods as shown in figure 4. It can be inferred from the graphs that irrespective of the mix ratio the compressive strength is maximum for 50% replacement of fine aggregates with slag. This shows that the level of bonding of slag, cement and sand was reasonably higher. Beyond 50% replacement, the graphs show a meager declination indicating that the increasing percentage of slag decreases the strength of the mortar considerably. Of all the three ratios the compressive strength peaks at 50% replacement for 1:3. Therefore more the cement content the better the bonding strength. The failure of slag mortar is due to the property of volumetric expansion. The volumetric expansion of slag is due to the presence of editor@iaeme.com

7 Y.K. Sabapathy, P. Sangeetha, V.P. Haripriya, D. Revathy, D. Ravichandar, S. Sathyapriya calcium in slag. This causes the material to become weak under the compressive load and develop cracks Masonry Prism Test Figure 5 Masonry Prism test graph The graph of the masonry prism test is shown in figure 5. From the graph, it can be inferred that the crushing strength is maximum for 25% replacement of fine aggregates. Beyond 25% there is a declination for the ratios 1:2.5 and 1:3 indicating that with the increase in the percentage of slag the mortar strength decreases and becomes ineffective in taking up the applied load. This is due to the combined influence of the bricks on the bonding capacity of the slag mortar when used as mortar joints Water Absorption Test The mortar specimens were tested for water absorption capacity as per ASTM standards. Figure 6 shows the bar graph of the varying water absorption rates of all the three ratios during the different time intervals. It can be inferred from the graph that 50% replacement was found to be optimum for all for all the three ratios. Figure 6 Bar graph of varying water absorption rates editor@iaeme.com

8 Experimental Study on Strength of Slag Mortar by Replacing the Fine Aggregate with EOF Slag The low water absorption rate can be attributed to the fact that slag is rich in calcium hydroxide which results in the formation of C-S-H hydration compounds makes the slag mortar matrix dense. The C-S-H gel thus formed is the main constituent in enhancing the durability and strength of mortar. Thus the formation of denser pore structure resulted in lower permeability. Also, the slag particles are much smaller than the cement particles thereby filling the voids between cement and sand in the mortar. 6. CONCLUSIONS In this experimental work, the effect of EOF slag when used as fine aggregates in mortar has been studied and the following conclusions were made: 1. The compressive strength of the EOF slag mortar increases as the percentage of slag replacement for fine aggregates is increased up to an optimum point beyond which the compressive strength shows a steady declination. Therefore it can be concluded that there is an optimum level for the use of EOF slag which will result in high strength. 2. The compressive strength of slag mortar when replaced by 50% was found to be optimum and yielded the maximum strength for all the three ratios and for all the three curing periods studied in this work. 3. The masonry crushing strength of slag mortar when replaced by 25% was found to be ideal for all the three ratios of cement: slag/ sand studied in this experimental work. 4. The rate of water absorption of slag mortar was found to be the least for 50% replacement of EOF slag by natural fine aggregates. REFERENCES [1] El- Sayed Sedek Abu Seif. Performance of cement mortar made with fine aggregates of dune sand, Khagarga Oasis, Western Desert, Egypt: An experimental study. Jordan Journal of Civil Engineering, 7, pp [2] Sang- Woo Kim, Yong- Jung Lee, Kil- Hee Kim. Bond behaviour of RC beams with Electric Arc Furnace Oxidising slag aggregates. Journal of Asian Architecture and Building Engineering, 11, 2016, pp [3] Mohd Nadeem, Arun D. Pophale. Granular slag- Potential Sustainable Material Alternative to Fine Aggregate in Construction Application. Gazi University Journal of Science, 2, 2013, pp [4] MC Natraja, PG Dileep Kumar, AS Manu, MC Sanjay. Use of Granulated Blast Furnace Slag as Fine Aggregate in Cement Mortar. International Journal of Structural and Civil Engineering Research, 2, 2013, pp [5] Fathollah Sajedi. Effect of Curing Regime and Temperature on the Compressive Strength of Cement- Slag Mortars. Construction and Building Materials, 36, 2012, pp [6] Tamara Humam, Rafat Siddique. Properties of Mortar Incorporating Iron Slag. Leonardo Journal of Sciences, 23, 2013, pp [7] L. Baali, A. Naceri, R. Mehamed Said. Mechanical Response of Mortar made with Natural and Artificial Fine aggregates. Asian Journal of Civil Engineering (Building and Housing), 1, 2008, pp [8] Y. K. Sabapathy, V. B. Balasubramanian, N. Shiva Shankari, A. Yeshwant Kumar, D. Ravichandar. Experimental Investigation of Surface Modified EOF Steel Slag as Coarse aggregates in Concrete. Journal of King Saud University- Engineering Sciences, 4, 2017, pp [9] Narendra Taly. Design of Reinforced Masonry Structures, 2nd ed. New York: Mc Graw Hill, editor@iaeme.com

9 Y.K. Sabapathy, P. Sangeetha, V.P. Haripriya, D. Revathy, D. Ravichandar, S. Sathyapriya [10] Bureau of Indian Standard Specification IS 12269: 2013, Ordinary Portland Cement, 53 Grade Specification. [11] Bureau of Indian Standard Specification IS 456: 2000, Plain and reinforced concrete- code of practice. [12] Bureau of Indian Standard Specification, IS 2116: 1980, Specification for sand for masonry mortars. [13] Bureau of Indian Standard Specification, IS 383: 1970, Specification for coarse and fine aggregates from natural sources for concrete. [14] Bureau of Indian Standard Specification, IS 2386 (Part III) 1963, Methods of test for aggregates for concrete. Part III Specific gravity, density, voids, absorption and bulking. [15] Bureau of Indian Standard Specification, IS , Specification of flow table for use in tests of hydraulic cements and pozzolonic materials. [16] Bureau of Indian Standard Specification, IS 4031 (Part 7) 1988, of physical tests for hydraulic cement. Part 7- Determination of compressive strength of masonry cement. [17] Bureau of Indian Standard Specification, IS , Specification for vibration machine. [18] ASTM C , Standard Test Method for Rate of Water Absorption of Masonry Mortars, ASTM International, West Conshohocken, PA, 2015, DOI: /C ,