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Horizontal And Vertical Extension of RCC Buildings

Ferrocement Technology

INTRODUCTION

Slide 1 INTRODUCTION- Many times extension of building is required to be

carried out

- Generally vertical extension of building are carriedout

- Sometimes horizontal extension of building are alsorequired to be carried out. But it has limitation many

times since horizontal space may not be available.

- Extension of building is a nuisance to the occupantsdue to construction activity like stacking of materials,

construction traffic and man-power movements and

site offices etc.

- With the advent of precast Ferrocement Technolgy,extension activity at site reduces by 50% since

precast works are carried out away from the site.

- Ferrocement being low self-weight material,horizontal and vertical extensions are most carried

out conveniently.

- Horizontal extension with Ferrocement is carriedout with cantilever upto 1.5 mtrs. without use of

columns.

- This is not feasible with R.C.C.

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FERROCEMENT HORIZONTAL EXTENSION

- Hollow cantilever beams about 1.5 mtrs. long withferrocement 2.5 cm thick on sides and bottoms are

manufactured on machinery set up.

- The reinforcement for beams are incorporated in theferrocement on sides and bottoms which acts as

formwork.

- The indigenous anchors as per reinforcement spacingof beams are provided at floor level at joints of

columns and beams of building.

- To this anchors cantilever hollow beams are weldedand attached to the building.

- In this hollow plane vibrated concrete is poured andthe beam is ready

- There are no props nor any formwork.- Similarly hollow ferrocement edge beam is

manufactured on machinery set up under controlled

conditions with flexure and shear reinforcement, is

connected to the end of cantilever beams.

- Plain vibrated concrete is placed in the hollow and thebeam is ready.

- There is no formwork nor any props to beams since itis strong enough to take construction load

- Ferrocement floor slab panels manufactured onmachinery set up are connected to building and

beams by welding and wiremesh lapping and matrix

applications.

- The horizontal floor is ready to carry out otherworks like walls,window, door, floor finishing etc

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Photo 2 -

Ferrocement slab panels 4 cm thk. connected to building and beams

Photo 1 -

Ferrocement hollow beams, cantilever as well as edge

beam . Bottom of beams is concreted on machinery set up.

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Photo 3 -

Extension of room by about 1.00 mtr. with Ferrocement beams & slabs

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FERROCEMENT VERTICAL EXTENSION

- Ferrocement Vertical Extension scores over RCCvertical extension since it has much low self-weight

than RCC

- Vertical extension one or two floors can be carriedout with ferrocement since generally there is reserved

strength in the column of existing RCC building.

- Otherwise Ferrocement columns, which are muchsmaller than RCC duly connected to the building at

floor levels at joints of beams and columns are

provided.

- Method of construction of beams shall be on samelines as for horizontal extension except that anchor

arrangement is not necessary.

- Box columns with ferroceent on periphery with mostreinforcement incorporated is manufactured on

machinery set up

- These boxes are anchored to the columns below withmore reinforcement provided, if necessary and in situ

vibrated concrete placed in the hollow. The column is

ready.

- Ferrocement grid beams of size of 5 to 15 cms to 10to 25 cms are connected to main beam. On these and

main beams slab panels are duly connected with

welding and wire mesh lapping and ferroceent joint

matrix application. The floor is ready

- Further construction is most convenient in two/threedays time since the area below is clear of props and

no shuttering which is provided with conventional

method.

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FEATURES AND ADVANTAGES

WHAT IS FERROCEMNT

- Ferrocement eliminates use of conventional formworksince surface of columns and beams with reinforcement

incorporated is thin ferrocement about 2.5 3 cms thk.- In the absence of formwork stripping operations

providing floors, walls, door, windows work can be

started soon.

- There is no activity of reinforcement placing at site forcolumns, beams and slabs

- There is no plaster application on ferrocement surfaces.- Ferroecment construction saves time of construction by

20% and cost by about 15%

- Ferrocement plated RCC member is systematically fiberreinforced at surfaces. Thus there will be no fiber in the

core body of plane concrete. There will be saving in

consumption of fibers.

- Thin section material consists of cement, wiremesh, light

structural steel, admixtures, fibers etc. with low water

cement ratio of around 0.35

- Prevents crack formation upto isotropic stage and furtherof width of microns with minimal depth

Isotropic material upto about 40% of yield and design

strength upto near to yield value.- Crack formation being in microns and of low

depthautogenous healing is fast and efficient.

- Prevents carbonation

- Efficient waterproof material

- Faces earthquake, cyclones and all disasters efficiently

- Durable material with least maintenance for decades

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FERROCEMENT IS A DURABLE MATERIAL

Photo 5 -A large barge constructed decades before in China (Courtesy Prof. AntoineE. Naaman, Michigan University)

Photo 4 -This Ferro-cement boat constructed in 1887 was observed to be serviceable

in 1967. At present it is in the lounge of a Cement Industry, Amsterdam

(Courtesy Prof. Antoine E. Naaman, Michigan University)

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FERROCEMENT IS CRACK-RESISTANT MATERIAL

The graph shows crack width of very low value in a Ferrocement waterstorage tank.(Courtesy Prof.Antoine E. Naaman, Michigan University)

The graph shows Ferrocement is isotopic upto about 40% yield. It shows no

collapse for large strains and very small crack width perhaps to trap water by

surface tension. (Courtesy Prof. Antoine E. Naaman, Michigan University)

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FERROCEMENT IS EARTH-QUAKE RESISTANT

MATERIAL

FERROCEMENT IS A FIRE RESISTANT MATERIAL

Photo 6 -

A Ferrocement Auditorium of capacity 250 constructed around 1997 inOascaco Mexico having dia. 24 mtrs. and ht. 12 mtrs. resisted earthquake of

Richter scale 7.2 and 7.4, 1998 and remain untouched (Courtesy Prof.

Antoine E. Naaman, Michigan University)

Photo 7Qualitative test by UNIDO (United Nations Industrial DevelopmentOrganis- ation) in about 1972 showed that the damage due to fire on a

Ferrocement boat was negligible.

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FERROCEMENT IS A CORROSION RESISTANT

MATERIAL

Photo 8

Most hard skin of the roof panel cast in the year 2000, could not be

removed by chiseling. Had to be removed by Cutting wheel carefullynot to damage the wiremesh. Most superficial line mapping on

pouring of water on the surface - disappearing within a minute or so.

Photo 9Closer view wiremesh reinforcement showing no corrosion of wires but

nominal brown colouration indicating no corrosion for future.

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Photo 10

Initial corrosion of reinforcement in RCC takes place due to reaction

with residue water used for mixing concrete for placing. This is not

due to any water or moisture from outside. In due course of time,

crack formation takes place in the cover and travels to the surface.

Water, moisture, gases etc. enter into cracks, and reach the

reinforcement and corrodes steel more and travel along the

reinforcement and deterioration starts. If column is treated with

ferrocement wrapping then such cracks and deterioration stops. With

any conventional method like polymers, cracks reappear and corrosion

phenomena is resumed.

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