Alternative building materials m 4

Faculty - Mr. ABHILASH B.L ALTERNATIVE BUILDING MATERIALS(15CV653)
Alternative Building Materials
ABHILASH B.L. M.Tech, IGBC-AP.
Assistant Professor,
Dept. of Civil Engineering,
VidyaVardhaka College of Engineering,
Mysuru – 570002.

• Use of arches in foundation,
• Alternatives for wall constructions,
• composite masonry, confined masonry, cavity walls, rammed earth,
• Ferro cement and Ferro-concrete building components,
• Materials and specifications, Properties, Construction methods, Applications.
• Top down construction,
• Mivan Construction Technique.
Module -4
Chapter-1 Alternative Building Technologies

Concepts of
• Filler slabs
• Composite beam panel roofs
• Masonry vaults and domes
Module -4
Chapter-2 Alternative Roofing Systems

• Arches are one of the efficient forms of structural systems. They are widely
used in buildings and bridges since ancient times.
• The behaviour of arches depends on the geometric characteristics (i.e. rise,
span, thickness and width), materials used for the construction, types of
loading and support conditions provided.
• Arches are constructed normally in masonry. Conventionally masonry arches
are constructed using Bricks or Stones in cement mortar.
• Plain cement arches can also be preferred in constructions.
• The effective use of Arches in construction for various purposes which lead
to the increase in strength of structures and reduction in the overall cost of
construction.
Arches

1. Arches in foundation

USES OF ARCHES IN FOUNDATIONS
• Arches have been used as an economic alternative to the conventional spread
footings of walls of residential buildings.
• The arch can be constructed using masonry, plain cement concrete and
reinforced cement concrete. Any shape of the arch can be chosen.
• Parabolic arches are preferable to other shapes as it is stronger than the
circular arches.
• The study carried out by Deodhar (1992) has shown that the load carrying
capacity of parabolic arches is twice that of circular arches.
• Arches are analysed as two hinged arches subjected to uniformly distributed
throughout the span. The uniformly distributed load that gets realised on the
arch is due to the brick masonry wall and the slab supported by the wall. The
thickness of the arch depends on the magnitude of load acting.

• (i) The spans and positions of the arches are fixed suitably based on the
positions of walls in building. span varies from 2m to 4.5m.
• (ii) Pits of suitable size are excavated for pillars at all junctions of arches. A
minimum pit size of 1mx1mx1m should be provided.
• (iii) Natural ground in between the pits is trimmed to the arch shape so that
crown of the arch is at the ground level. The rise of the arch should be as
high as feasible to keep the horizontal thrust low.
The step by step procedures of constructing arches in
foundations

• (iv) In the excavated pits, pillars (masonry or cement concrete or reinforced
cement concrete) upto springing level are constructed over 1:4:8 cement
concrete bed of thickness 100mm.These pillars supports the arches and
transfer the loads from arch to the soil.
• (v) Arch of designed thickness is constructed. If masonry is used then arch
is constructed by placing the masonry units radially on the prepared surface
starting from the springing level and proceedings towards the crown.
• (vi) Spandrel walls are constructed upto the crown level.

2. Alternatives for wall constructions

Wall - A wall is a structure that defines an area, carries a load, or
provides shelter or security.
There are many kinds of walls . . . !

Why Wall . ??

Types of walls two most simplest ways of categorising based on there
construction are :-
load bearing
non-load bearing

•Rammed earth is form of unbaked earth construction
•The processed soil compacted in layers to form a component of a building
structure is termed as rammed earth
•Formwork becomes essential for the construction of rammed earth elements
with an exception for rammed earth foundations
•This type of construction technique finds application in the construction of
walls
foundations
floors
built-in furniture etc.
Rammed earth construction

History of rammed earth construction
•Rammed earth has been used for the construction of walls since several centuries
•Construction of parts of great wall of China 3rd century
•Rammed earth buildings in Himalayan region of India and Tibet around 8th
century
•Thousands of years old buildings in middle east and Africa represent some of the
historical rammed earth constructions
•There are large numbers of modern rammed earth buildings which have been
built in the last three decades.

1841, Weilburg

Small metal formwork (900 mm length,
moveable)

Wooden formwork (longer dimension)

Longer formwork (no joints)

Characteristics of Cement Stabilised Rammed Earth Depend upon
•Density
•Moisture content during testing
•Clay fraction/soil grading
•Percentage of cement
Rammed Earth.mp4

Cavity walls
consist of two "skins" separated by a
hollow space (cavity). The skins are
commonly masonry, such as brick or
concrete block. Masonry is an
absorbent material, and therefore will
slowly draw rainwater or even
humidity into the wall, as well as from
the inside of the house as from outside.

Advantages of Cavity Walls.
1. Cavity walls are best for damp prevention than solid building walls.
2. They work best as heat insulators; it can decrease heat transmission from the
outside environment.
3. Sound waves travel faster in solid walls as compared to hollow walls. Hence,
the cavity walls are also best for sound insulation.
4. The construction cost of the cavity wall is about 20% less than the
construction of solid walls. Hence, they are also economical.

Disadvantages of Cavity Walls.
1. Highly skilled labour and masons are required for cavity wall construction.
2. Require standard supervision during its construction.
3. A vertical damp proof course is also necessary for it.

Composite wall.
A wall built of a combination of two or more masonry units of different
types of materials that are bonded together, one forming the facing of the
wall and the other the backup.

Confined masonry
Confined Masonry is a construction system where the walls are built first, and
the columns and beams are poured in afterwards to enclose (confine) the wall

ICF – Insulated concrete formwork
Concrete Insulated Walls Insulating concrete
form-work (ICF) is a cost effective, flexible,
modular, permanent concrete form system. The
basic unit of this system are expanded
polystyrene (EPS) forms that are filled with
concrete and steel reinforcement.
There are two types of forms: planks and blocks

Compressed Agricultural Fibre is made of
STRAW BALES.

Straw board photograph
straw board specimens

New straw board
office building
straw board office building
indoor scene

FerroCement / FerroCrete/ FerroConcrete
building components

Ferro cement building components
• Ferro cement is a composite material composed of a mortar reinforced with
light steel fabric/mesh, used to form thin sections. (Ferro cement should not
be confused with ‘Ferro concrete’, a name given to early reinforced concrete.)
• The construction process consists of forming the shape of the required
structure with a mesh of fine reinforcement, such as chicken wire or
expanded metal.
• Multiple layers may be used to achieve the required density of steel and the
whole may be stiffened with a few standard reinforcing bars.
• A stiff mortar is then applied to both sides of the layer of reinforcement
known as the ‘armature’) and finished to the required thickness.

TOP DOWN CONSTRUCTION
Top down construction is the reverse method of bottom-up
construction in which the permanent structure is built from top to
bottom of the basement along with deep excavations.

CONSTRUCTION PROCEDURE:
1. Construct the perimeter wall, Construct piles. Place the steel columns
or stanchions where the piles are constructed.
2. Cast the floor slab of first basement level.
3. Proceed to the first stage of excavation.
4. Start construction of the superstructure.
5. Cast the floor slab of the second basement level Proceed to the second
stage of excavation.
6. Repeat the same procedure till the desired depth is reached.
7. Construct the foundation slab and ground beams, etc. Complete the
basement
8. Keep constructing the superstructure till it gets finished.

ADVANTAGES OF TOP DOWN CONSTRUCTION:
1. Early restoration of the superstructure is possible even before the completion of
the building and the structures aboveground can be carried out simultaneously
with the structures below ground. This greatly reduces the time for construction.
2.Concrete diaphragm walls are more cost-effective when they can
simultaneously function as a groundwater cut-off and temporary soil retention
system during the excavation phase of the project, and then as permanent
underground walls with load-carrying capabilities for the finished structure.

3. Easier and economical construction of roof since it can be cast on prepared
grade rather than using bottom forms.
4. The structural slab act as an internal bracing for the support of
excavation, thus reducing the number of tiebacks required.
5. The virtually vibration-free operation minimizes the potential for ground
movement and its resulting detrimental settlement.
6. It requires less width for construction area. Reduced environmental pollution
associated with pre-construction earthworks
7. Eliminates the need to underpin adjacent structures

DISADVANTAGES OF TOP DOWN CONSTRUCTION:
1. Inability to install external waterproofing outside the walls.
2. Potential water leakage at the joints.
3. More complicated connections for the roofs, floor, and base slabs.
4. Access to the excavation is limited and limited space for the construction of
base slab.
5. Complex design involved.

Mivan Construction Technique

Factors Conventional Mivan
Speed of
construction
slower due to step by step completion of
different stages of the activities such as
erection of formwork, concreting and de-
shuttering and thereafter plastering and other
finishing activities.
wall and the floors are casted simultaneously in
one continuous operation and also the finishing
work can be started immediately
Quality Normal quality is obtained Superior quality is obtained
Aesthetics Partition walls are made up of bricks due to
which the column and the beam show
unsightly projections in room interiors.
Partition wall and the ceiling elements are casted
together due to which the interiors have neat and
clean lines without unsightly projections in
various corners. The wall and the ceilings also
have a smooth even surface.
External
finishes
It requires manual cement plastering which
needs to be repainted frequently.
Do not require manual cement plastering and
also have smooth finishing, so this will need no
frequent repainting.
Maintenance The maintenance cost is too high as it requires
frequent repairs of plasters of wall and
ceilings, painting of outer and inner walls due
to leakages.
The maintenance cost is negligible as the walls
and ceiling are made up of high quality concrete
which do not require frequent repairs.

Concepts of
• Filler slabs
• Composite beam panel roofs
• Masonry vaults and domes
Module -4
Chapter 2 - Alternative Roofing Systems

Filler slabs
• Filler slab is alternate slab construction technology where part of concrete
in bottom of slab is replaced by filler material.
• The basic principal of filler slab is that the concrete in bottom half of RCC
slab is structurally not required (concrete acts as compression material
which is required in top half portion of slab). So this portion concrete is
replaced by low cost, light weight filler material (like mangalore tile, clay
pots etc).
• Total concrete required in this technology is about 30% less than
conventional slab construction. Due to reduced concrete, self weight of the
slab is reduced and thus about 40% less steel is required, without
compromising strength of the slab.
• This technology was used by Architect Laurie Baker in Kerala extensively.

CONSTRUCTION OF FILLER SLAB

FILLER MATERIAL POINTERS
•Filler material should be inert. It should not react with concrete or steel
•It should be light weight, low cost and preferably locally available
•Size of filler material should be such that it fits in bottom half of the slab
and structural grid of reinforcement
•Using material with good thermal insulation properties like clay will
provide thermal comfort inside the room
•The filler material will be seen as part of ceiling so shape and finish of
the material should be as per desired aesthetics

Filler slab casting

SAMPLE FILLER SLAB

Different types of SMB Filler Blocks

Typical C/S of a Mangalore tile filler slab

Typical C/S of a stabilized mud block filler slab

Composite beam panel roofs
This concept is based on the efficiency of beam and slab construction. The
roofing consists of partially precast or cast-in-situ ribs/beams at certain
spacing covered with panels.

Composite reinforced tile-work panel roof

Masonry vaults and Masonry domes

Alternative building materials m 4

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