ISSN (0970-2083)

EXPERIMENTAL INVESTIGATION ON FERRO CEMENT COLUMNS UNDER STATIC LOADING

M.Pavan Kumar1* and S Pradeep2

1M.Tech, Department of Civil Engineering, SRM University, Kattankulathur Campus, Chennai, Tamil Nadu, India

2Assistant Professor, Department of Civil Engineering, SRM University, Kattankulathur Campus, Chennai, Tamil Nadu, India

*Corresponding Author:
M.Pavan Kumar
M.Tech, Department of Civil Engineering
SRM University, Kattankulathur Campus
Chennai, Tamil Nadu, India
E-mail: pavan.muppa@gmail.com

Received Date: 17 June, 2017 Accepted Date: 24 November, 2017

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Abstract

The main objective of this research is to study the ultimate load carrying capacity of Ferro cement columns. The strength of mortar plays a vital role in affecting the performance of specimens. In this experimental work four columns were casted and tested in a column testing machine under axial loading. The results of solid Ferro cement column and hollow Ferro cement column were compared with the conventional RCC column, and it is evident that the ultimate strengths of solid Ferro cement column and Hollow Ferro cement column were increased up to 6.6% and 13.3%.

Keywords

Ferro cement, Hollow, Ultimate load, Mortar, Wire mesh

Introduction

Ferro cement is one of the earliest versions of reinforced concrete. However, its design has been mostly empirical, and formal design guides have not developed as they have been for more traditional reinforced concrete. IS 456-2000 gives detailed design guidelines for reinforced concrete structures. However Ferro cement is not specifically covered, and the design guidelines for Ferro cement produced by ACI Committee 549 (ACI 549) lacks detail in its use as a repair and strengthening the material. In the earthquake-resistant design of structures, over strength and ductility are key factors that influence safety. Ferrocement is the combination of cement mortar and thin layers of wire mesh. This study investigates the use of Ferro cement and its use as a construction material for new structures in seismically active zones. Ferro cement has been used as a strengthening and repairing material, especially for quick repairs and strengthening measures for civil engineering structures worldwide. The advantages of using Ferro cement wrapping are its adaptability, high strength to weight ratio, superior cracking characteristics, and good bond with existing concrete surface, improved ductility and impact resistance when compared to conventional strengthening materials such as steel plates. Ferro cement behaves as a similar elastic material over a wide limit because the uniformly distributed mesh reinforcement results in a better crack-resisting mechanism. (Ivy, 2013) Has experimentally investigated the circular columns using high-performance Ferro cement. By replacing the concrete cover with High-performance Ferro cement cover, the strength achieved is 30–59% higher than normal specimens. (Rajesh, 2003) Have conducted an experimental investigation on Ferro cement columns. From his study, it is evident that by using Ferro cement reinforcement as confining shell for reinforced concrete columns increase ductility and load carrying capacity. (Shinde and Bhusari, 2003) From their study on Ferro cement columns by changing the orientation of mesh resulted in the increase of strength which is 36% more in single layer compared to double layer. (Abdullah and Katsuki, 2003) In this study the researcher presents the behaviour of reinforced concrete columns strengthened with Ferro cement jacketing. Ferro cement usedas a strengthening agent for conventional RC columns showed very good results in ductility and stable during plastic hinge formation. (Mourad and Shannag, 2012) In this investigation researcher studied about repair and strengthening of Ferro cement jacketing to RC columns.Ferro cement jacketing to RC columns shows very good results in compressive strength and stiffness and it is about 28%- 33%. Similarly 15%-28% strength gained in repairing of RC columns with Ferro cement jacketing. (Yaqub, et al., 2013) Researcher conducted experimental study on post heated circular and square columns repaired with Ferro cement jacketing. By conducting various experiments optimal solution to regain the strength of post heated columns is by providing both the Ferro cement jacketing and fibre reinforced polymers will show better results in ductility, compressive strength, stiffness etc. (Rathish, et al., 2007) In this study researcher presents the seismic loading tests on RC and Ferro cement columns with jacketing. Energy dissipation capacity, ductility, stiffness had increased because of using Ferro cement as external confinement in columns. (Amrul, 2013; Mohammad and Reza, 2005) In this study by improving square Ferro cement jacketingthe ultimate load carrying capacity of columns were increased and failure at corners had minimised.

Experimental Program

Material properties and specifications

Ordinary Portland Cement (OPC) of 53 grade is usedfor test specimens for making both mortar and concrete which is confining to IS 12269. Specific gravity of ordinary Portland cement is 3.15.Fine aggregate is commonly used in the matrix and coarse aggregate is used in preparing concrete. Specific gravity of fine and coarse aggregates are 2.64 and 2.7. Aggregates having high hardness, large strength and containing sharp silica can achieve the best strength results. However, the aggregate should be kept clean, inert, free of organic matter and deleterious substances and free of silt or clay. Additionally, (IS 10262-2009) requires that 80%-100% of the weight of the aggregate should pass the IS Sieve No.7 (2.36 mm). The water used in Ferro cement should be fresh, clean and free from organic or harmful solutions.Welded wire mesh is used in this study which has a higher stiffness than woven mesh, which is why the welded mesh leads to smaller deflections in the elastic stage. The galvanized iron weld mesh is shown in (Figure. 1) having a diameter of 1.26 mm and spacing of 15 mm centre to centre. Welded mesh is more durable, more intrinsically resistant to corrosion and more stable in structures than woven mesh (Bo, et al., 2013; Kaish, et al., 2012).

icontrolpollution-welded-mesh

Figure 1: Welded mesh.

Mix proportions and design specifications

In this experimental study, M30 grade concrete mix is designed as per IS 10262-2009. 150 mm × 150 mm × 150 mm sized cubes were casted and tested to find the compressive strength. Two trial mixes were done to find the best grade of a matrix to cast Ferro cement columns. 70.6 × 70.6 × 70.6 mm sized cubes were casted and tested to find the compressive strength of matrix which is confining to IS 10080-1982. The details of mix proportions are shown in Table 1.

Variables Ferro cement RCC
Sand/Cement ratio 1:2 1:2.25 1:1.32:2.2
Water/Cement ratio 0.45 0.45 0.45
Volume of cement (kg/m3) 678 640 492.5
Volume of fine aggregate (kg/m3) 1357 1440 651
Volume of coarse aggregate (kg/m3) - - 1084
Volume of water (kg/m3) 305 289 197

Table 1. Details of mix proportions.

One square reinforced concrete column and three Ferro cement columns were casted. The detailing of reinforcement in columns is shown in (Figure. 2), and it consisted of four longitudinal 8 mm ribbed steel bars and seven 6 mm steel bar stirrups, with 190 mm spacing in between. The prepared reinforcement cage was held carefully in the moulds. Concrete spacers of 20mm size were used to maintain 20 mm concrete cover to the main reinforcement. One column had two-layers of galvanized iron welded mesh, and two columns had one-layer of mesh. The dimensions and skeleton of reinforcing mesh is shown in above (Figure. 1). One RCC column was casted and two Ferro cement solid columns, one Ferro cement hollow column (Syal and Rejivsyal, 1997; American Cement Institute; IS 456:2000). A total of 4 specimens which is having a dimension of 1000 mm height and a cross section of 110 × 110 mm were casted and tested as shown in (Figure. 3). These specimens are tested by using 500 kN hydraulic jack and proving ring which is arranged in a column testing machine. Deflectometers are arranged in center of the column on both sides of a specimen to find deflection. The testing frame is shown in (Figure. 4) (section along with the specimen).

icontrolpollution-reinforcement

Figure 2: Detailing of reinforcement in columns.

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Figure 3: Casted specimens.

icontrolpollution-column-test

Figure 4: Column test setup

Results and Discussion

The compressive strengths of concrete and mortar mix for 7, 14, 28 days are shown in (Figure. 5). All casted cubes of concrete and mortar are tested in compressive testing machine which has a capacity of 200 ton as shown in (Figure. 6). Total of 27 cubes (9 cubes for concrete and 18 cubes for mortar) were tested to find the compressive strength.To find the best matrix two trial mixes were used. Concrete achieved a strength of 32.4 N/mm2 and mortar mix achieved a compressive strength of 37.4 N/mm2 after curing of 28 days. Experimental results for cubes were shown below in Table 2.

icontrolpollution-testing-machine

Figure 5: Compressive testing machine.

icontrolpollution-compressive-strength

Figure 6: Comparing compressive strength of cubes for 7, 14, 28 days.

Variables Days of curing Collapse load (kN) Compressive strength (N/mm2)
RCC 28 734 32.6
Ferr cement (Trial mix-1) 28 170 34.1
Ferro cement (Trial mix-2) 28 187 37.4

Table 2. Compressive strength of cubes.

All the tested specimens with failure crack patterns are showed in (Figure. 7-9) respectively. Failure of Ferro cement hollow column is clearly shown in (Figure. 7) and the crack occurred at the top face of column, weld mesh buckles out. Similarly for conventional column the failure occurred at bottom face of column and spalling of concrete occurred as shown in (Figure. 8). Conventional column has achieved a compressive strength of 232 KN with a deflection of 1.62 mm. Failure of Ferro cement solid columns takes place along the periphery of specimen, diagonal cracks were observed and spalling of mortar takes place instead of buckling welded mesh are clearly shown in (Figure. 9). The collapse load thus determined for all columns were shown in Table 3. Load vs. deflection graphs were plotted for all the tested specimens are shown in (Figure. 10). Ferro cement hollow column carries a load of 272 KN with a deflection of 2.86mm. By increasing number of layers of weld wire mesh compressive strength increased and initial deflection got minimised. Cost analysis were carried out for all the casted specimens and shown in Table 4.

icontrolpollution-ferro-cement

Figure 7: Failure of ferro cement hollow column.

icontrolpollution-failure

Figure 8: Failure of a RCC column.

icontrolpollution-failure-ferro

Figure 9: Failure of ferro cements solid columns.

icontrolpollution-deflection

Figure 10: Load vs. deflection for RCC, ferro cement solid and hollow columns.

Specimen RCC Ferro cement Hollow Ferro cement (1 layer of mesh) Ferro cement (2 layers of mesh)
Dimensions (mm) 110*110*1000 110*110*1000 110*110*1000 110*110*1000
Reinforcement details #4,8Ǿ 1.26 mm GI mesh 1.26 mm GI mesh 1.26 mm GI mesh
Grade of mix M30 M30 M30 M30
Ultimate load (KN) 236 272 252 324
Deflection (mm) 1.62 2.86 2.12 2.28

Table 3. Comparison of collapse load for RCC and ferro cement columns

Variables   RCC Ferro cement
(1 layer of mesh)
Ferro cement hollow Ferro cement
(2 layers of mesh)
Weight (kg) Cost
(Rs)
Weight (kg) Cost
(Rs)
Weight (kg) Cost
(Rs)
Weight (kg) Cost (Rs)
Cement 5.96 38.4 7.75 49.6 2.7 17.2 7.75 49.6
Fine aggregate 7.88 2 17.5 5 6.05 1.6 17.5 5
Coarse aggregate 13.12 2.02 - - - - - -
Steel 2.45 118.6 4.8
(sq-ft)
86.4 4.8
(sq-ft)
86.4 9.7
(sq-ft)
172.8
Total cost   161.02   141   105.2   227.4

Table 4. Cost analysis for RCC and ferro cement columns

Conclusions

In the earlier studies the work on Ferro cement hollow column were not found. The main aim of this research is to know the performance of Ferro cement hollow column. The above results states that the optimal design of Ferro cement hollow column provides better compressive strength by comparing with conventional and Ferro cement solid columns with same sized specimens. Cost analysis is carried out for all tested specimens and Ferro cement hollow column has 34.66% and 25.5% reduction in cost while comparing to conventional column and Ferro cement solid columns.

1. The ultimate strength of solid Ferro cement column is increased by 6.6% more than that of the conventional column for the same size of the specimen.

2. The compressive strength of Ferro cement hollow column is compared with RCC column and achieved 13.3% higher strength.

3. Based on test results, by increasing layers of weld mesh the compressive strength of columns increased.

4. By comparing ferro cement solid column and ferro cement hollow column. Ferro cement hollow column will give higher compressive strength and lesser deflection.

5. Ferro cement hollow column has a 34.66% reduction of cost while comparing with conventional column.

References

Abdullah. and Katsuki, T. (2003). An investigation into the behaviour and strength of reinforced concrete columns strengthened with Ferro cement jackets. Cement and Concrete Composites. 25 : 233-242.

American Cement Institute (ACI) Committee 549R-97. state of the art report on Ferro cement.

Amrul, K.A.B.M. (2013). Ferro cement jacketing for strengthening of square reinforced concrete column under concentric compressive load. The 2nd International Conference on Rehabilitation and Maintenance in Civil Engineering. Procedia Engineering. 54 : 720-728.

Bo, L., Eddie, S.L., Bo, W. and Wang, Y. (2013). Experimental investigation on reinforced concrete interior beam–column joints rehabilitated by ferro cement jackets. Engineering Structures. 56 : 897-909.

IS 10262-2009. Concrete mix design.

IS 456:2000. Code of practice for plain and reinforced concrete.

Ivy, F.H. (2013). Behavior of reinforced concrete columns confined with high-performance ferro cement. ASCE. 139(4) : 574-583.

Kaish, A.B.M.A., Alam, M.R., Jamil, M., Zain, M.F.M. and Wahed, M.A. (2012). Improved ferro cement jacketing for the strengthening of square RC short column. Construction and Building Materials. 36 : 228-237.

Mohammad, T.K. and Reza, M. (2005). Seismic shear strengthening of R/C columns with ferro cement jacket. Cement & Concrete Composites. 27 : 834-884.

Mourad, S.M. and Shannag, M.J. (2012). Repair and strengthening of reinforced concrete square columns using ferro cement jacketing. Cement & Concrete Composites. 34 : 288-294.

Rajesh, D. (2003). Ferro cement compression members - An experimental study. Bridge and Structural Engineering Journal. 1-13.

Rathish, P.K., Oshima, T., Mikami, S. and Sumanth, C. (2007). Studies on RC and ferro cement jacketed columns subjected to simulated seismic loading. NIT Warangal. Asian journal of civil engineering (building and housing). 8 : 215-225.

Shinde, V.M. and Bhusari, J.P. (2003). Response of ferro cement on the behavior of concrete short column. Journal of Mechanical and Civil Engineering.  24-27.

Syal, I.C. and Rejivsyal. (1997). New trends in concrete construction with welded wire fabric as reinforcement. The Indian Concrete Journal. 71(7) : 367-371.

Yaqub, M., Bailey, C.G., Nedwell, P. and Javed, I. (2013). Strength and stiffness of post-heated columns repaired with Ferro cement and fiber reinforced polymer jacketing. The University of Manchester, Sackville Street Building, Oxford Road, Manchester, M13 9PL, UK, Composites: Part B 44 : 200-211.
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