Composite action of ferrocement slabs under static and cyclic loading

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Composite action of ferrocement slabs under static and cyclic loading

  1. 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME57COMPOSITE ACTION OF FERROCEMENT SLABS UNDER STATICAND CYCLIC LOADINGDr. T.Ch.Madhavi*,Shanmukha Kavya .V**, Siddhartha Das**,Sri Prashanth .V**, Vetrivel .V***Prof & HOD, Civil Engg, SRM University, Ramapuram Chennai-600 089, India.**BE (Final Year), SRM University, Ramapuram, Chennai-600 089, India.ABSTRACTFerrocement is a composite material that can be used for construction of certainstructures such as ships, water tanks, boats and other similar structures, where we need notuse lot of resources such as coarse aggregates. This paper presents the flexure studies on ferrocement slabs, where the number of reinforcing weld mesh layers are varied as 2 layers, 3layers and 4 layers. 6 slabs are cast, 2 each for each type of reinforcing, i.e., 2 slabs of 2layers, 2 slabs of 3 layers, 2 slabs of 4 layers, using custom made moulds. They are tested forstatic and cyclic loading conditions of flexure testing after 28 days of curing. After the tests,the results are tabulated and represented graphically and analysed. It is found that, increasingthe number of layers of mesh increases the flexural strength of the ferro cement slabs. Also,as the number of layers increase, the crack propagation is slow.Key Words: Ferro Cement Slabs, flexure, Static loading, cyclic loadingINTRODUCTIONFerro cement is a composite material made up of cement mortar and reinforcement inthe form of layer of mesh. Ferro cement consists of closely spaced, multiple layers of mesh orfine rods completely embedded in cement mortar. A composite material is formed thatbehaves differently from conventional reinforced concrete in strength, deformation, andpotential applications, and thus is classified as a separate and distinct material. It can beformed into thin panels or sections with only a thin mortar cover over the outermost layers ofreinforcement. Compared to other cement concrete structures, those made of ferrocement arelight weight, tough, durable, crack resistance and can be made into virtually any shape1. OverINTERNATIONAL JOURNAL OF CIVIL ENGINEERING ANDTECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 4, Issue 3, May - June (2013), pp. 57-62© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2013): 5.3277 (Calculated by GISI)www.jifactor.comIJCIET© IAEME
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME58the years, applications involving ferrocement have increased due to its properties such asstrength, toughness, water tightness, lightness, ductility and environmental stability.Ferrocement may be cast in various shapes and forms even without the use of form work andare aesthetically very appealing. Ferrocement has a very high tensile strength to weight ratioand superior cracking behaviour in comparison to reinforced concrete2. Hence, Ferrocementis an attractive material for construction of shell, folded plate, ribbed slab and housingcomponents. The slenderness of these elements may adversely affect their performance underworking loads. Hence, there is a need to study their (a) first crack strength and (b) load-deflection (P-d) behaviour. While (a) and (b) characterize the serviceability behaviour offerrocement elements, it is equally important to predict their flexural strength.Wail N. Al-Rifaie3et al studied the structural behaviour using two ferrocementchannel-like beams to form I-cross-section beam and indicated that ferrocement can be usedin construction of buildings. Y. Yardim et al4(2008), investigated the performance ofinverted two-way ribs precast ferrocement thin panel as permanent formwork and found thatthe thin panel with suitable ribs layout and support distance can be used as permanentformwork. Jalal .A. Saeed et al4tested ferrocement one way slabs with openings subjected totwo point loads taking into consideration number of mesh layers and size of the openings asvariables. The results showed that by increasing number of mesh layers the slabs flexuralstrength increased and size of the openings have negative effect on flexural strength of theslabs. Essam Eltehawy observed the influence of using Ferrocement in enhancement of themechanical properties of reinforced concrete slabs subjected to impact, penetration and fire.Deeptha Shri. S (2012) studied the flexural behaviour of self-compacting concrete (SCC)ferrocement fiber reinforced slab panels.EXPERIMENTAL INVESTIGATION6 ferrocement slabs of dimensions 600 mm x 300 mm and 25 mm thickness andwelded mesh in 2, 3 and 4 layers are tested under static and cyclic loading. OrdinaryPortland cement, River sand and potable water are used. Welded wire mesh of 3mm diameterand 25 mm x 25 mm spacing is used. Chicken mesh is used on either sides of the layerformed. Normal binding wire is used to tie up the welded wire mesh with each other andchicken mesh to form the core of the slabs. 1:3 cement mortar with a water cement ratio of0.48 was prepared.Fig1 Reinforcement of slab Fig.2 Reinforcement placed in the mould
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME59Fig 3. Test Setup Fig 4. Failure of slabThe slab is placed under 2 point load with dial gauge fixed to it as shown in fig 3 andtested till failure as shown in fig 4.RESULTS AND DISCUSSIONSThe deflections were measured at the mid-span and the first crack and ultimate loads arenoted.Static loadingFirst Crack LoadingIn static loading, the slab with 3 layer shows 68.75% increase in first crack load fromthe slab with 2 layers. Similarly the slab with 4 layers has increased by 87.5% . Hence the 3layer slab shows considerable increase over the 2 layers slab as shown in table 1 below.Table1: First Crack and Ultimate loads under static loadingSl.No.Specimen First CrackLoad(kN)% increasein firstcrack loadUltimateLoad% increasein Ultimateload1 2 Layer 3.2KN - 5.6kN -2 3 Layer 5.4KN 68.75 % 8.4kN 50 %3 4 Layer 6KN 87.5 % 9.7kN 73.21 %Ultimate LoadThe ultimate failure is a bit low for the 2 layer mesh slab, 5.6 kN. But the ultimatefailure is relatively high for both 3 layer and 4 layer mesh slabs i.e, 8.4 kN and 9.7 kNrespectively. This shows an increase of 50% over 2 layer slab. The 4 layer slab shows anincrease of 15.47% ultimate strength than 3 layer slab and 73.21 % over the 2 layer slab.
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME60Fig 5. Load Deflection Curves Fig 6. Load Deflection Curves(Static load) (Cyclic load on 2 layer slab)Load deflection CurvesThe load deflection curves were plotted for FC/2L, FC/3L and FC/4L as shown in fig.5. The curves are almost linear for all the 3 slabs in static loading. But towards failure, thereis a sudden increase in deflection. Hence the deflection increases gradually for lesser loads.And as the loads increase, deflection increases.Cyclic LoadingFirst Crack loadIn cyclic loading, the slab with 3 layer shows 46.15% increase in first crack load fromthe slab with 2 layers. Similarly the slab with 4 layers has increased by 89.47%. Hence the 4layer slab shows considerable increase over the 2 layers slab.Ultimate loadThe ultimate failure is a bit low for the 2 layer mesh slab, 3.9 kN. But the ultimatefailure is relatively high for both 3 layer and 4 layer mesh slabs i.e, 4.3 kN and 8.2 kNrespectively. This shows an increase of 10.25% over 2 layer slab. The 4 layer slab shows anincrease of 15.47% ultimate strength than 3 layer slab and 110.25 % over the 2 layer slabTable2: First Crack and Ultimate loads under cyclic loadingSl.No.Specimen First CrackLoad(kN)% increasein first crackloadUltimateLoad(kN)% increase inUltimate load1 2 Layer 1.3 - 3.9 -2 3 Layer 1.9 46.15 % 4.3 10.25 %3 4 Layer 3.6 89.47% 8.2 110.25 %02024202464202468642024688.205101520250 5 10DeflectioninmmLoad in kN
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME61Fig 7. Load Deflection Curves Fig 8. Load Deflection Curves(Cyclic load on 3 layer slab) (Cyclic load on 3 layer slab)CRACK PATTERNSThe cracks under flexure loading were observed to be parallel to each other, and theywere in the plane perpendicular to load application. The cracks appeared on the face of theslab which was opposite to the face of load application. It is also observed that in the 4 layermesh slab, the first crack appeared very later, and the increase in the cracks, upon applicationof load was slow.CONCLUSIONS1. Increasing the number of layers of mesh increases the flexural strength of theferrocement slabs.2. Slabs with highest number of layers of wire mesh have highest flexural strength underboth types of loading.3. The flexure strength under static loading increased by 50% % for 3 layer slab, from 2layer slab. It further increases by 15.47 % for 4 layer slab over 3 layer slab.4. The percentage increase of flexural strength of static loading condition of 4 layer slabover 2 layer slab is 73.21%5. The flexure strength under cyclic loading increased by 10.25 % for 3 layer slab, from 2layer slab. It further increases by 90 % for 4 layer slab.6. The percentage increase of flexural strength of cyclic loading condition of 4 layer slabover 2 layer slab is 110.25%7. As the number of layers increase the crack propagation is slow, and the crack spacing isleast for 4 layer mesh slabs, which ultimately leads to better load bearing capacities.8. It was also seen that, as the number of layers increases, it is difficult to pack them intolayer into same thickness020242024642024670051015202530350 2 4 6 8DeflectioninmmLoad in kN0202420245420240024681012141618200 2 4 6deflectoninmmload in kN
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME62REFERENCES1. Anitha .M et. al. Coimbatore, India (2012). “An experimental investigation on theflexural behaviour of SCC ferrocement slabs incorporating fibres”, International Journalof Engineering Science and Technology,Vol. 4; No. 5; pp 2146-2158.2. Ezzat. H. Fahmyet. al. Cairo, Egypt (2009).“Ferrocement sandwich and cored panels forfloor and wall construction”, “our world in Concrete and structures”.3. Dr.Wail N. Al-Rifaie andMuyasser M. Joma’ah, Tikrit, Iraq (2010). “Structuralbehaviour of ferrocement system for roofing”, “Diyala Journal of engineering sciences” ,pp-237-2484. Y.Yardim et. Al (2010), “Performance of Precast Ferrocement Panel for CompositeMasonry Slab System”, “International Conference on Construction and BuildingTechnology”, 2008, ICCBT 2008 - B - (36) – pp397-408.5. Jalal .A. Saeed, PaymanH. Mohammad , and lbrahimH. Aziz, (2008). “Behaviour andflexural strength of ferrocement one way slabs with square openings”, “Journal ofZankoy Sulaimoni”, Vol. 1 No.1.6. K. Sasiekalaa and R. Malathy, “Flexural Performance of Ferrocement LaminatesContaining Silicafume and Fly Ash Reinforced with Chicken Mesh”, InternationalJournal of Civil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012,pp. 130 - 143, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.7. Mohammed Mansour Kadhum, “Effect of Dynamic Load: Impact of Missile onMechanical Behavior of Ferrocement – Infrastructure Application”, International Journalof Civil Engineering & Technology (IJCIET), Volume 4, Issue 2, 2013, pp. 295 - 305,ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

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