Ferrocement Construction

WELCOME TO THE FERROCEMENT SITE BY HEMENT VAIDYA

This site is created in the view of providing exposure to the much hidden virtues of FERROCEMENT and unleashing the capabilities of this neglected bounty for building constructions as found by the strenuous efforts of Mr. HEMANT VAIDYA

Here's what I'm covering on this page at a glance 

 


Initially Created on : 6 th Sept. 1998, 

Moved to new domain on : 23rd June 2013 

About Me


A Brief Introduction to Ferrocement

What we call taday as R.C.C. construction material and Ferrocement, entered construction field simultaneously by mid-19th century. Mr. J.L.Lambot built a wire-reinforced boat in which reinforcement was in the form of a network of wires. However, since then, R.C.C. advanced as a fullfledged constructional material, time tested and design procedure formulated, though modified from time to time. On the other hand, ferrocement was forgotten almost for a century and took a small step in the middle of 20th century, when Mr. Pier Nervi devised the homogeneity property of ferrocement.

 Looking at the advantages and superiority of ferrocement over R.C.C., now the former should have squared up atleast a century lag over the later. But in fact only some stray items like tanks, domes, etc.came in its shape. The physical property studied by Mr. Nervi was lost and once again, ferrocement got cutoff from major construction field.

 The obvious reason was design system for building system was used as non vulnerable construction material.

 Whatever efforts were put in formulating these minor designs , they were on the basis of R.C.C. design, which is not considered as 'homogeneous' material as ferrocement is considered.

 It was only after 1990 that, Mr. Hemant Vaidya took up the thread left by Mr.Nervi and designed for the first time ever  FERROCEMENT BEAM  as homogeneous construction material. This beam was physically and structurally of ferrocement in words and spirit. This was a giant leap that removed all the hurdles in using ferrocement as fullfledged construction material.

Some comparison with conventional technology - RCC

Strength of ferrocement comes from its degree of homogeneity. To meet this most important qualification, following parameters are to be looked into: 

  • Volume Fraction: It is a ratio of mesh volume to volume of matrix. It is generally in percentage form.
  • Contact Area Factor: By simple mathematics it can be shown that for same value of bars of diameter 6 and wires of diameter 3, the later gives double contact area.This is the precise reason that Ferrocement uses small diameter wires/bars.
  • Mesh Area Across Section: Positioning of the wires whether horizontal, vertical or inclined plays decisive part in promoting homogeneity. 

 At this juncture, let's weigh pros and cons of RCC and ferrocement

 

 RCC

 FERROCEMENT

 1 Fullpledged design procedure. Mr. Hemant Vaidya has removed tha lacuna and now ferrocement has fullpledged design procedure
 2 Steel takes tension and concrete compression (in bending). Homogeneous
 3 Concrete below the neutral axis is redundant. Any extra matrixing aroun mesh is a waste.
 4 Moment of inertia has no place in design Its ductilty is overcome by providing moment of inertia.
 5 Hardly any scope for precasting  It can be prcast, cast in situ or partially both, called as  Stagewise Ferrocement.
 6 Bulky Strength to weight ratio higher
 7 Compaction can not be ensured. Surface to be matrixed is open for inspection.
 8 Curing period 4 weeks Curing required just for one week
 9 Minute cracking Micro cracking

 

 

Case studies or executed projects

Number of housing projects were undertaken and executed successfully, once design concept developed. To mention a few features are:

  • 300 sqm. industrial hall was covered with ferrocement roofing. It looks like corrugated channel with ridge-valeey type. The span of channel was 5500 mm.
  •  In Pune, at NICMAR 
    Two storeyed hostel building having 10 rooms on each floor is constructed by using Ferrocement flat floor slab and cone formation type Ferrocement roof slab. It may be mentioned that on toilet unit flat slab overhead tanks are mounted. For the same building, 1200mm wide cantilever type steps (without riser) are provided as staircase. Hollow Ferrocement circular columns were casted in position in corridors

Please have a look

 Picture 1

  • Please note the ferrocement projecting mid landing. Ferrocement beams,corridor,circular columns of Ferrocement, cantilever staircase steps from midlanding to floor slab can be easily seen
  • Class rooms of 60.0 sqm area are covered bye different Ferrocement covering shapes. Every class room is required to have Ferrocement beams of span 7000mm
  • Long corridors in front of all buildings along with entrance covered with Ferrocement dome are constructed. Here flat Ferrocement slabs, Ferrocement beams, columns and footings were designed.
  • A bunglow of 200.0 sqm ground floor and 170.0 sqm first floor was constructed by using Ferrocement concept in totality. Footing, lintels/chhajjas, toilet walls and loft over beam, flat floot slabs, staircases, cantilever and stringer beam type were the freely used items at this site.The essence of this constructions is that there no projections whatsoever of beams and columns within the building which is a normal eyesore look of the building! 
     Please have a look at next couple of Photographs 
  •  

    Picture 2

    Please note that this hall is showing floor slab soffit. Observe that no projections of beams or columns are appearing. 
    Picture 3. External View : Ferrocement Gallary.
     
    Soffit and beam is clearly seen. At the far end, first and second floor slab level clear nitch of Ferrocement 'I' section member is seen. The entire slab is made up of such sections. 
     
    Picture 4
     
     In the figure above,beam is already mounted in position and precast ferrocement planks are being placed. As a second stage monolithic ferrocementing was completed in 1995.
     
    Picture 5
     
     And here it is ! 

     THE LONGEST FERROCEMENT BEAM (lenght 7 meters) SO FAR DESIGNED AND PRESSED IN OPERATION !!

     
      On the strength of design concept developed, followed by executional skills gained, Mr. Hemant Vaidya has written the book namely Ferrocement Housing Prelude in 1994 which is a unique book in its own way that Ferrocement technique elaborates all housing components and allied jobs from view point of design and execution tips. 
     
     Previous page | Ferrocement Hollow Blocks 

    Ferrocement counterfort retaining wall

    Picture 6 

    This is counterfort retaining wall of length 80 ft and height 12 ft average constructed at Panshet, Pune, Maharashtra, India in the year 2006 for the first time ever with our tested structural design system.

    The history is that this wall runs through a natural valley because of which rubble retaining wall could not stand for gush of monsoon waters. RCC was costliest - even one ferrocement consultant had proposed a design that too was costly. Hence, our design system is most economical and simple, stands today for 7 years as can be seen in the picture taken in July 2013.

    Ferrocement lining to a natural drain

     

    Picture 7 

     It shows ferrocement lining to a natural drain of which banks are unstable due to salinity located at Kavthepiran, Distt Sangli, Maharashtra, India.

    A similar problem was tackled at Dudhgaon in the nearby area by concerned state government Department with rubble which collapsed.

    Our above experimental lining is standing for last 5 years and allowing the underground salinity flushed in the channel.

    An Expert from Hariyana Saline Soil Research Institute visited the site and was satisfied that it will serve the function.

    Stage Wise Ferrocement (SWF)

     Picture 8

    Precast ferrocement – ‘T’ sections are being placed across ferrocement beams. It is called stage wise ferrocement (SWF). This avoids shuttering for slab totally.

    Picture 9

    14 feet high ferrobrick column 1 feet  X 1 feet finished with ferrocement (not appearing in the image),jacketing size 1 feet 3 inch X 1 feet 3 inch and ferrocement beams mounted span 4.5 meters. 

     Picture 10 

     

    It is a farmhouse admeasuring 2200 square feet plinth and 400 square feet mezzanine floor. Precast slab panels, circular hollow columns in ferrocement can be seen.

     

    Picture 11

    1000 square feet ferrocement slab before casting. Cost of the total scheme is INR 66600/- in month of March 2013 i.e. INR 66.6/per square feet. For the sake of comparison RCC slab will consume steel worth INR 1, 35,000/- and cement 150 bags (for ferrocement slab 87 cement bags were consumed). 

     

    Precast Bearing cum Friction Ferrocement Pile

    gain it is a new concept world over. It was first executed in 2005. I call it Precast Bearing cum Friction Ferrocement Pile.
    Its salient features are on hollow 100 PVC pipe ferro-steel is wrapped.The specific friction effect was provided by inserting 60 pins by puncturing PVC pipe to accommodate coming out extra length @ longitudinally 300 mm and 45 degrees deflection.
    The rough size of the precast ferrocement pile 200-225 mm diameter in a trench of 300 mm diameter. The space between soil surface and FF pile PVC pipe hollow was filled with 1:2:4 concrete with fine aggregate only. Its height is about 3000  mm.
     
     
     
    The project was executed at Nikam Park in Kolhapur, Maharashtra, India.
     

    Ferrocement Hollow Blocks

    Walling shares for a substantial amount in a housing project. In the general useferrocement walls have their own limitations such as structural slenderness and thermal discomfort apart from high cost per square unit in comparison with other conventional walling materials such as bricks or concrete blocks. 
     Throughout the think tank period over a decade in Ferrocement concept I did not digest brick wall concept since these bricks eat away fertility of fields

     In the year 1999, I got the opportunity to experiment with  Ferrocement Hollow Blocks (FHB)  replacing bricks and retaining advantages of conventional ferrocement walling but without its the shortcomings.

    Picture 8.  A room with walls of Ferrocement Hollow Blocks 

    The photograph shows a prototype room of size 3.7 m X 3.7 m X 3.0 m (ht) constructed using FHBs. In fact, the construction is designed for ground + one and load bearing type having wall thickness of 150 mm. Presently, the ground floor construction is over.

    The FHB blocks in the walling have external dimensions as 450 mm long, 150 mm width and 150 mm height. Walls and bottom slab thickness are 20 mm and 15 mm respectively. The block is laid bottom slab top and getting mesh strands outcropping from walls embedded in mortar layer below. This arrangement makes the total wall act as Shear Wall that resists earthquake shocks effectively and weigh light.

    Moreover, this walling provides for thermal comforts since it's made of Hollows! The temperature control effect has actually been reported by the people living in such constructions. Additionally, it's also reported that this construction provides water leakage resistance.

    Just as a comparison, the FHB wall costs less than the 230 mm brick wall.

     

     

    Ferrocement Water Tank

    And is a water tank of capacity 100,000 liter - designed and constructed in the difficult topography of Bhimashankar (near Pune, India) using the ferrocement system developed by me. Size of the tank is 10m X 7m X 1.5m. The top of the tank is fully covered by precast ferrocement panels.

    The cost of project was about Rs.600,000 (2014-15 rates) evenly split between labor and material. Practically no shuttering was used. RCC would have cost double in the same place.

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