LIGHT WEIGHT CONCRETE WITH STEEL FIBER TO IMPROVE DUCTILE BEHAVIOUR

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 4, April 2018, pp , Article ID: IJCIET_09_04_109 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed LIGHT WEIGHT CONCRETE WITH STEEL FIBER TO IMPROVE DUCTILE BEHAVIOUR A Lakshmi Narasimha Sai Ravi Tej P.G. Student, Department of Civil Engineering, SRM institute of science and technology, Chennai, India N.A.Jabez Department of Civil Engineering, SRM institute of science and technology, Chennai, India ABSTRACT The density of concrete will be generally in the order of 2200kg/m 3 to 2600 kg/m 3. This heavy self weight made concrete uneconomical structural material and also it will affect the efficiency of concrete. If the self weight of concrete can be reduced, without affecting its mechanical properties. It will increase the efficiency and economy of concrete. The present investigation is aimed to achieve light weight concrete with characteristic strength of 20N/mm 2 and having low water absorption and good ductile nature. Hooked steel fibers of aspect ratio 60 are used to improve ductility, tensile and flexural properties of concrete. Light expanded clay aggregate (LECA) is used as partial replacement of coarse aggregate to reduce self weight of concrete. Aluminium powder is used as an air entraining agent which will incorporate non-coalescing air bubbles that will distribute the voids uniformly through out the concrete mass. Concrete mixes with different proportion of Hooked Steel Fibre and aluminium powder are prepared. A comparative study of ductile behavior is carried out between different concrete mixes using the concept of ductile ratio. The strength properties of different concrete mixes are obtained and the results are compared. Key words: Aerated Concrete, Density, Hooked Steel Fibre, Light Weight Concrete. Cite this Article: A Lakshmi Narasimha Sai Ravi Tej and N.A.Jabez, Light Weight Concrete with Steel Fiber To Improve Ductile Behaviour, International Journal of Civil Engineering and Technology, 9(4), 2018, pp INTRODUCTION Concrete is most commonly used durable and versatile construction material, composed of cement or other cementations material, aggregate and water. Concrete is manufactured with editor@iaeme.com

2 Light Weight Concrete with Steel Fiber To Improve Ductile Behaviour different composition of its ingredients basing on the requirement of strength and durability. It is preferred in many constructions. The primary use of structural light weight concrete is to reduce the dead load of structure which allows structural designer to reduce size of structural elements. If a concrete with low density and strength suitable for using it as a structural member is achieved then it will increase the progress of building, lower s haulage and handling costs. LIGHT WEIGHT CONCRETE (LWC) CAN BE ACHIEVED BY THREE DIFFERENT WAYS 1. By replacing usual mineral aggregate by cellular porous or light weight aggregate. 2. By introducing gas or air bubbles. 3. By omitting fine aggregate. Out of three main groups of light weight concrete, the light weight aggregate concrete and aerated concrete are more often used than no-fines concrete. In the present investigation a combination of one &two is used. Light weight concrete is prepared with partial replacement of coarse aggregate with LECA and using aluminium powder for air entrainment. Hooked steel fibres are incorporated in concrete to improve its mechanical properties Literature Studies Yiquan Liu, Bo siang Leong, Zhong-Ting Hu invistigated on concrete with lime and incorporating waste aluminum dust as foaming agent. Their studies concluded that the use of aluminum dust as a foaming agent may not achieve a very low density but it does not compromise mechanical properties.[1] Jong-han Lee, Baiksoon cho, Eunsoon chio studied on Flexural capacity of fibre reinforced with a consideration of concrete strength and fibre content. Hooked steel fibres were used in their investigation. Their energy absorption tends to increase with increase in fiber volume fraction. [2] 2. MATERIALS AND METHODOLOGY 2.1. Materials Ordinary Portland cement of 53 grade was used for this investigation. River sand was used as a fine aggregate in concrete. As river sand will be usually sharp, angular and certainly free from salts with suitable properties Basic Properties of cement and sand are as in table-2 & table-3 respectively. Coarse aggregate of angular shape and 20mm size were used. As the angular shape of aggregate helps in achieving good workability and boding of concrete mix. It is preferred to use angular coarse aggregate in concrete. It s basic properties are as in table -3 One fifth of coarse aggregate was replaced by Light Expanded Clay Aggregate (LECA) of size 15-20mm. The properties of LECA are as in table- 3. As the aggregate were cylindrical shaped complete replacement will not give bonding. The cement mortar in concrete will not bind to the aggregate properly. So coarse aggregate was partial replaced. This won t reduce the density to good extent. So, to reduce the density further with less effects in mechanical properties air entrainment is done using Aluminium powder (Al). Hooked Steel Fibre (HSF) are incorporated in concrete to produce materials with increased tensile strength, ductility, toughness and Improved durability properties. Hooked steel fibres of aspect ratio of around 70 were used editor@iaeme.com

3 A Lakshmi Narasimha Sai Ravi Tej and N.A.Jabez 2.2. Methodology In the present investigation seven groups of concrete were prepared. Mix design is done as per ACI codal provisions for concrete with characteristic compressive strength of 20 N/mm 2. Mix proportions of concrete was found to be 1.64 parts of fine aggregate,2.51 parts of coarse aggregate for one part of cement. Among the seven groups of concrete, the first one is conventional concrete and the remaining are Light weight concrete mixes coined with 20% replacement of coarse aggregate. This Six groups of LWC were prepared with different proportions of Hooked Steel Fibre (HSF) and Aluminium powder (Al). Hooked steel fibres were added in proportions of 0, 0.5 and 1 percent of total volume of concrete. Aluminium powder was added in proportions of 0 and 0.5 percent by weight of cement. Notations for various types of concretes are tabulated, As in table-1. Table 1 Notations for different concrete mixes Sl.No Type of concrete Replacement of coarse aggregate (%) Hooked steel fiber (%) Aluminum powder (%) Notation 1 Conventional concrete CON 2 Light Weight Concrete LWC-1 3 Light Weight Concrete LWC-2 4 Light Weight Concrete LWC-3 5 Light Weight Concrete LWC-4 6 Light Weight Concrete LWC-5 7 Light Weight Concrete LWC-6 3. EXPERIMENTAL WORK Basic tests were carried out to obtain the properties that are required for mix design. Concrete cubes were casted to obtain compressive strength and water absorption. Split- tensile strength and ductility ratio were carried out on cylinders. Ductility Ratio (DR) is used for comparing the ductile nature of different concrete mixes. DR is defined as the ratio of yielding stress to ultimate stress. Many investigations and studies says that materials will start yielding after obtaining a strain of so in the present investigation the stress at a strain of is assumed to be yield stress. It should be understood that by using the concept of DR only comparative study of ductile behaviour can be made between different types of concrete. Concrete prisms were casted to obtain the flexural property of concrete. This test is carried out by applying point loads at one-third distance from support to obtain pure bending condition. (Fig 4) Fig 1 compressive test Fig 2 Split Tensile test editor@iaeme.com

4 Light Weight Concrete with Steel Fiber To Improve Ductile Behaviour Fig 3 cylindrical specimen with strain gauge Fig 4 Flexural test 4. RESULTS AND DISCUSSION Basic properties of cement and aggregates were tested and tabulated, As in table-2 and table-3 respectively. This properties were found to be satisfied as per codal provisions. Table 2 Properties of Cement Sl.No Properties Test Results 1 Specific Gravity Consistency of Cement 31% 3 Initial setting time 27 mins 4 Fineness of Cement 6% Table 3 Properties of coarse, fine and light weight aggregates Sl.No Properties Fine aggregate Coarse aggregate Light Weight aggregate 1 Specific Gravity Fineness modulus Density and water absorptions of different concrete mixes were as in table 4. On replacing one fifth part of coarse aggregate with LECA, it was found that there was a decrease in density around twenty percent and water absorption increased by 18.5%. With introducing the HSF in concrete it was found that there was a slit increase in density and decrease in water absorption. By adding aluminium powder it was found that there is decrease in density and increase in water absorption. so, the voids formed by Al powder in specified proportion with the combination of LECA and HSF are not distributed uniformly and they might be coalescing. Table 4 Density and water absorption of concrete mixes Type of concrete Density of concrete (Kg/m 3 ) Water absorption (%) CON LWC LWC LWC LWC LWC LWC editor@iaeme.com

5 A Lakshmi Narasimha Sai Ravi Tej and N.A.Jabez There was a decrease in Compressive, tensile and flexural strengths of concrete with replacement of coarse aggregate (LWC-1). But when LWC was coined with HSF the strength properties were found to be improved (LWC-2 &LWC-3). A drastic decrease in strength properties were found when aluminium powder was added to the concrete (LWC-4). (as in table -5). Strength of concrete increased when 0.5% of HSF was introduced to LWC (LWC-5), but slit decrease in strength was found when HSF was 1% (LWC-6) compared to HSF 0.5% (LWC- 5). This may be because of increase in compositeness of material with more voids and HSF. Type of concrete Table 5 compressive, split tensile and flexural strengths of concrete Compressive Strength (N/mm 2 ) Split tensile Strength (N/mm 2 ) Flexural Strength (N/mm 2 ) CON LWC LWC LWC LWC LWC LWC Ductility Ratio of concrete for different mixes were tabulated (as in Table-6). when concrete was coined with HSF (LWC-2 & LWC-3) DR of concrete was found to be increased. When Al powder was added to concrete (LWC-4) there was drastic drop in DR of concrete. There was a increase in DR in LWC-5 & LWC-6 compared to LWC-4. Table 6 Ductility Ratio of concrete mixes Sl.No. Notation Ductility Ratio (DR) 1 CON LWC LWC LWC LWC LWC LWC Figure 5 Compressive strength of different concrete mixes editor@iaeme.com

6 Light Weight Concrete with Steel Fiber To Improve Ductile Behaviour Figure 6 Split tensile strength of different concrete mixes Figure 7 Flexural strength of different concrete mixes Figure 8 Ductility Ratio of different concrete mixes editor@iaeme.com

7 A Lakshmi Narasimha Sai Ravi Tej and N.A.Jabez 5. CONCLUSION Though the density of concrete is found to be reduced when coarse aggregate was replaced with LECA the strength of concrete is also found to be reduced. But when Hooked Steel Fibres are coined in the mix the strength of concrete is found to be improved. Among the different mixes, it can be concluded that LWC-2 (Light weight concrete with 0.5% HSF) is a better Light Weight Concrete having eighty eight percent of compressive strength and the density is found to be reduced by twenty percent when compared to Conventional Concrete. Split tensile and flexure of LWC-2 were found to be almost similar to that of conventional concrete. It can also be absorbed that LWC-3 has more split tensile and flexural strengths compared to conventional concrete this is because of Hooked Steel Fibres. Density of concrete was found to be reduced by 24.71% percentage when Aluminium powder was introduced in light weight mix. But the water absorption of concrete was almost doubled. So it can be concluded that Aluminium powder will not make voids non-coalescing. It only decreases the density by air entrainment. The Ductile nature of Light Weight Concrete was found to be improved with introduction of Hooked Steel Fibre in both cases (with and without Aluminium powder). It was also found that the Ductility ratio is more in LWC-2 & LWC-3 compared to conventional concrete. There is a scope for further investigation of Light Weight Concrete with LECA using Aluminium powder in less proportions. This may reduce water absorption and improve strength properties. However there will be increase in density with decrease in proportions of Aluminium powder. There is also a scope for further investigation with Photographic analysis for examination of voids distribution with different proportions of Al powder. REFERENCES [1] YiquantLiu, Bq SianGleolng, Zhong-TingHu,En-Huna Yanga, Auctoclaved aerated concrete incorporating waste aluminium dust as foaming agent, Construction and building materials, Volume 148, 1 september 2017, Page [2] Jong-Han Lee,Baiksoon Cho, Eunsoo Choi,Flexural capacity of fibre reinforced concrete with a consideration of concrete strength and fiber content, Construction and Building Materials, Volume 138, 1 May 2017, pages [3] Md Abdul Bashar Emon, Tanvir Manzur, Nur Yazdani,Improving Performance of Light weight Concrete with brick chips using low cost steel wire fiber, Volume 106, 1 March 2016, Pages [4] Delsye C.L. Teo, Md. Abdul Mannan, John v Kurian, Flexural Behaviour of Reinforced Lightweight concrete Beams Made with Oil Palm Shell (OPS), Journal of Advanced Concrete Technology, Volume 4 (2006), Issue 3, Page [5] M Carasana, F Tittarelli, L. Bertolini,Use of no-fines concrete as a building material : strength, durability properties and corrosion protection of embedded steel, Cement and Concrete Research, Volume 48, June 2013,Page [6] M.Shanmugaraja,Strength and durability of Fibre Reinforced Quarry Dust Concrete, International Journal of Innovations in Engineering and Technology (IJIET), Volume 6 Issue 2 December editor@iaeme.com