Investigation of Ferro Cement Composite Beam Under Flexure

The definition of ferrocement is given by ACI Committee 549: ―Ferrocement is a type of thin wall reinforced concrete constructed of hydraulic cement mortar reinforced with closely spaced layers of continuous and relatively small size wire mesh‖. Mesh may be made of metallic or other suitable materials. The matrix may contain discontinuous fibers. This definition ignores as important type of reinforcement currently in use in ferrocement i.e. the combination of steel rods and wire mesh. India has been identified as a developing economy which tends to give rise to a lot of infrastructure developments especially the building projects. RCC is most widely used in all over world because of its high load carrying capacity but the cost of cement and steel is increasing day-by-day. So, we require a substitute to concrete which gives se strength as that of RCC with low cost. In ferrocement, hydraulic cement mortar with closely spaced small diameter wire meshes is used. To improve certain characteristics of ferrocement various materials such as admixtures, silica fumes, fly ash and fibres are used. Generally, the thickness of ferrocement ranges from 20 – 50 mm.

1. Ferrocement can be used in Agricultural work such as in storage bins, irrigation channels, pipes and pedestrian bridges. 2. It can be used in new structures and repair & rehabilitation works. It can also be used in case of marine for docks, submarine structures, etc. 3. It can be used in case of pothole repairs, lining of swimming pools and corroded steel water tanks. 4. Structural application of ferrocement were boats, tanks, silos, roofs and the high cost of traditional wooden or steel form work led to the idea of using ferrocement laminate as permanent forms in concrete construction.

concrete. 2. Increment in weight due to skeleton steel. 3. Liable to corrosion due to bad compaction. 4. Because of distinctive shapes trouble in construction. 5. Time consuming technique. 6. Frequently suffers from intense spelling of matrix cover. 7. Labour demanding therefore excessive Labour cost.

5. Reinforcing mesh: Reinforcing mesh is the essential components in ferrocement. Different kinds of wire mesh are available in market. Various steel meshes for ferrocement includes square welded or woven mesh, expanded Meta lathe sheet similar to those used in plaster, chicken wire mesh of hexagonal shape. The function of wire mesh is to hold the mortar and form in liquid state and in

1. Square woven wire mesh: In this type of mesh, wire is bent in a zigzag shape and grid is formed by interlinking the wires without welding the intersections. 2. Square welded wire mesh: In this type of mesh, wires are straight and grid is obtained by welding the perpendicular wires at intersections. 3. Chicken wire mesh: In this type of mesh, the wire meshes are in hexagonal pattern. After weaving the cold drawn wire, the hexagonal pattern is obtained. This type of mesh is also called as Aviary wire mesh. 4. Expanded metal mesh: The expanded metal mesh is not so strong compared to others. This is formed by cutting a thin expanded metal sheet so as to form diamond shape openings. Different types of meshes are shown in Figure 1.

FERROCEMENT COMPOSITE: -

1. Thickness 6 to 50 mm. 2. Steel cover 1.5 to 5 mm. 3. Ultimate tensile strength up to 34MPa. 4. Allowable tensile stress up to 10MPa. 5. Modulus of rupture up to 55MPa. 6. Compressive strength up to 28MPa to 69MPa.

The main ingredients of ferrocement matrix are OPC (Ordinary Portland Cement), fine aggregate, water and admixture. Various additives such as silica fumes, fly ash, super-plasticizers and air-entraining agents are used in various ferrocement applications such as water reduction, good workability and improved permeability. For increasing the cracking behaviour of matrix fibres may be used. Some factors that have an effect on the properties of mortar are – 1. Water / Cement ratio: The water / cement ratio usually ranges from 0.35 to 0.60 by weight. For high strength and low shrinkage, water / cement ratio is kept low 2. Sand / Cement ratio: The ratio of sand / cement must lie between 1 to 1.25 by weight. 3. Grade of Sand: For workable mix, proper gradation of sand is needed. Sand must be free from silt, organic materials and it must pass through 2.36-millimeter sieve.

FERROCEMENT

The cement used in the test was Ordinary Portland Cement (Grade 43) Birla Super Gold according to requirements of IS code IS 1489:1991. Tests on Ordinary Portland cement: - 1. Setting Time 2. Soundness 3. Fineness 4. Compressive Strength

Portable Municipal tap water was used as a hydration agent in concrete and mortar. The water was clean and free of any salts, silt, oil and organic matter.

Perma Plast Super PS 34 is used which is a multicomponent liquid admixture based on high molecular weight polymers and naphthalene formaldehyde. The Perma plast Super PS 34 is used so as to produce self-compacting flowing mortar and to get high early strength concrete or mortar. It is used in a specify range of 0.5 to1.5 % of weight of cement for initiating trail based on type of mortar required. 4. Fine Aggregates

For ferrocement channel section 200mm width 150mm height and 2000mm length are manufactured to cast channel section having varying thickness from 20-50mm. with different number of mesh layers.

This topic includes the information relating to test specimen from their specific dimensions to the process of fabrication.

In this study, four types of ferrocement channel sections are fabricated; total fourteen types of specimens are casted and tested. The four types of sections are as follows- 1. 20mm 2 layer (using welded and woven mesh) 2. 30mm 2 &4 layers (using welded and woven mesh) 3. 40mm 2 &4 layers (using welded and woven mesh) 4. 50mm 2 &4 layers(using welded and woven mesh) The thickness of channel section is increased from inner side of channel section keeping the outer dimension constant to be 200mm X 150mm.

Sectional Dimension: 200mm X 150mm X 2000mm Thickness of web: 20mm

: 13.4

Thickness of steel mesh: 1.6mm No. of Mesh layers: 2 Clear cover for ferrocement steel mesh: 4 mm Clear spacing between two steel meshes: 12 mm Diameter steel mesh: 1.6mm

In this topic, the specifics of the experiment and its setup procedure are detailed. 1. Universal Testing Machine Universal Testing Machine also known as UTM for short is a multifunction testing machine for various tests for compression, Tension, Flexure etc. The load in UTM is applied by hydraulic action. The UTM in Applied Mechanics Department of MIT College, Pune was utilized for experimental work conducted. The capacity of UTM was 100 tonne.

The deflection gauge used in the experimental work was readily available in Applied Mechanics Department of MIT College, Pune. It has a least count of .01mm or 10micron.

At the time of testing, the specimen was painted with white paint to facilitate the visual crack detection during testing process. The specimen was laid on a universal testing machine of maximum capacity of 100 kN where the test was conducted under a four-point loads system with a span of 1800 mm. one dial gauges with an accuracy of 0.01 mm were placed under the test specimen at the centre to measure the deflection versus load. Load was applied at 100 N increments on the specimen exactly at the centre. Concurrently, the beam deflections were determined by recording the dial gauge reading at each load increment. Cracks were traced throughout the sides of the specimen and then marked with white chalk markers. The first crack-load of each specimen was recorded. The load was increased until complete failure of the specimen was reached.

The flexural strength formula is given by –

Where, M = Bending Moment (N.mm) = PL/6 I= Moment of Inertia I=MomentofInertia= Moment acting on channel section, M =

Calculation of flexural strength: - Thickness of section, = 20mm, Outer Height of wed section, = 150mm Outer length of flange section, = 200mm, Inner length of flange section, b = 160mm Load acting on slab, =2800N I = Moment of Inertia = = = Moment acting on channel section, M = Flexural strength, f = Flexural strength of ferrocement channel section =

Calculation of flexural strength: - Thickness of section, = 20mm, Outer Height of wed section, = 150mm Outer length of flange section, = 200mm, Inner length of flange section, b = 160mm Load acting on slab, =3700N = = 55.09mm I = Moment of Inertia = = Moment acting on channel section, M = Flexural strength, f = Flexural strength of ferrocement channel section =

Calculation of flexural strength: -

Outer length of flange section, = 200mm, Inner length of flange section, b = 140mm Load acting on slab, =4550N = = 55.09mm I = Moment of Inertia = = Moment acting on channel section, M = Flexural strength, f = Flexural strength of ferrocement channel section =

Calculation of flexural strength: - Thickness of section, = 40mm, Outer Height of wed section, = 150mm Outer length of flange section, = 200mm, Inner length of flange section, b = 120mm Load acting on slab, =4300N = = 59.286 mm I = Moment of Inertia = == Moment acting on channel section, M = Flexural strength, f =

The test results of the samples at the age of 28 days from the day of casting are presented in following tables and graphs and compared with FEM results –

Figure 2.Maximum deflection using2-layer welded mesh.

Based on the experimental and FEM results following conclusions are made. 1. The load carrying capacity and flexural strength of ferrocement channel section reinforced with welded square mesh is found to be more than that of ferrocement channel section reinforced with woven square mesh. 2. Flexural strength and load carrying capacity increases when the number of mesh layers increases from 2 to 4 numbers. 3. The proposed finite element model can be used efficiently in characterizing the behavior of ferrocement channel section under the flexural behavior. 4. The increase in the thickness of ferrocement channel section shows an enhancement in the load carrying capacity and decrease in the deflection. 5. The experimental results are in good agreement with the FEM results.

1. Very limited research reports are available on the behaviour of ferrocement compound structural sections like I, C, T, L etc. 2. Introducing nominal size of reinforcement at top and bottom of section would increase the load carrying capacity of channel section. 3. Using the different type of mesh (expanded wire mesh, fibre mesh) change in behaviour

4. Flexure behaviour also can be check for Changing the loading condition as applying load on base and providing supports on web.

Alaa Abdel Tawab, Ezzat H. Fahmy, Yousry B. Shaheen, ―Use of permanent ferrocement forms for concrete beam construction‖, September 2012, Volume 45, Issue 9, pp 1319–1329 Anisha G Krishnan, Allzi Abraham,―Experimental Study on the Effectiveness ofFerrocement as a Permanent Form Work for Beams‖,Volume 5 Issue 9, September 2016 Dr. C. Rama Chandrudu, Dr. V. Bhaskar Desai (2012). ―Influence of Fly ash on Flexural Strength of Ferrocement in Chemical Environment‖ UNIASCIT, Vol. 2 (4), (Page 324329). Hassan M.H. Ibrahim (2011). ―Shear capacity of ferrocement plates in flexure‖, ElsevierEngineering Structures 33 (2011) pp. 1680–168. K. Kesava, K. L. A. V. Harnadh, K. Nehemiya (2017). ―Experimental Investigation of Flexural Behaviour of Ferrocement Trough Type Folded Plate‖, International Journal of Innovative Research and Advanced Studies (IJIRAS) Volume 4 Issue 2, February 2017. Laxmikant A Doddamaini, Vaijanath Hallali (2014). ―Generation of Strength Statistics for Concrete Beam with Alternative of Permanent Ferrocement form‖, International Journal of Engineering Research & Technology, Vol. 3 - Issue 10 (October - 2014)

PG Student, Civil Engg. Dept. JSPM‘s Imperial college of Engineering & Research, Wagholi, Pune