UNIT 11 WATER AND DAMP PROOFING

Structure
11.1 Introduction
Objdvea
11.2 Principles of Water Proofing
11.3 Procedure for Damp Proofing~WaterProofing
11.4 Dampness and Leakage
1 1.4.1 Signs of Dampness
11.4.2 Detection of Dampaess
11.5 Causes of Dampness
11.5.1 Condensation
1 1.5.2 Rain Penchation
1 1.5.3 Built-in Water
1 1.5.4 Pipe Leakage
11.5.5 Spillage
11.5.6 Seepage
I 1.5.7 Rising Dampness
11.5.8 Hygroscopic Salts
11.6 Prevention of Dampness
11.6.1 Planning and W i n Stage
1 1.6.2 Constmction Stage
1 1.6.3 Remedial Meatjures and Treatment
11.7 Dampness in Old Structure and Remedial Measures
11.8 Water Proofing
1 1.8.1 Integral Water Proofing
1 1.8.2 SurfaceTreatments
1 1.8.3 Metallic Water Proofing
11.9 Different Methods of Waterproofing and Case Studies
1 1.9.1 Water Proofing Basements
1 1.9.2 Polyma Plaster for Roof and H m - PROOFSOL
1 1.9.3 Wat,er Proofing of Roofs -Nina Industries Method
11.9.4 \V&r Proofing by Algiproothg Method
1 1.9.5 Case Studies
11.10 Spectrum of New Water Proofmg MaterialslSystems
11.11 Summary
11.12 Answers to SAQs

11.1 INTRODUCTION
You have already learnt about strengthening of stone and brick masonry and about repair
of floors, in previous blocks. Now in this unit, dampness and water leakage in buildings
their causeslreasons and ways and methods to avoidlprevent them is dealt with.
Dampness and water leakages in buildings is a serious concern of Civil Engineers all over
the world. In spite of proper supervision during construction, buildings are still affected
by these problems. Building materials such as bricks, concrete, plaster, timber etc., have a
moisture content which under normal circumstances is no cause for concern. ?be rise in
moisture content of these materials to a level where it becomes visible or when it causes
deterioration is the real dampness.
Objectives
At the end of this unit, you should be able to:
know methods to detect dampness,
find the causes for dampness,
know the methods adopted to prevent dampness, and
Repair & Preventive understand the various types of water proofing methods.
Maintenance Techniques
Thus you will be able to guide the artisans to take care during construction to avoid
dampnegs and provide correct water proofing.
Definition
I
Dampness is defiid as presence of moisture in air or on surface or diffused I
tbrough solid. Any indication of slight wetness or moisture is termed as dampness.

1 1 2 PRINCIPLES OF WATER PROOFING

Most of b e building materials used in construction are exposed to water and are not
impervious and do allow water to enter into their systems. Sometimes the building
materiais may be good but the bondihi materials like mortar may be pervious and may
permit water inside. Cracks occur due to expansion and shrinkage of construction material
which in turn form voids which allow water to pass through. Some materials absorb water
from outside.
Thus the:basic principle involved to prevent dampness and avoid water proofing problems
is to make construction materials voidsfree and avoid voids formation after the
construction. If porous materials are unavoidable they have to be made impervious with
materials in the pore filling class or covered completed with impervious layers to repel
water. The pore filling materials fill in the voids, expand because of chemical reactions
and thus enSure water dghtness.

1 1 3 PROCEDURE FOR DAMP PROOFINGIWATER

PROOFING
a) The source of dampness involk,d is to be established.
b) If any hydrostatic pressure is involved including uplift pressure, measures to counter
this pressure are to be adopted.
c) The most common construction material, concrete must be fully compacted while
casting.
d) Decide whether water proofing is to be on the positive sidelface, i.e water face or on
the opposite si& depending upon the construction details.
e) Decide about the water proofing system-pore filling or repelliint.
f) Follow instructions by the manufacturer in respect of specific materialslfiystemsused.

11.4 DAMPNESS AND LEAKAGE

11.4.1 Signs of Dampness
In case of dampness it is very important to maintain a complete record from the period
when it is first noticed. If it can be established that the occurrence of dampness is related
to temperature or weather, this can help significantly in limiting the possible causes of the
trouble. Signs of dampness which are directly evident are
a) Stains on different surfaces of buildings.
b) Visible water such as a f h o f moisture or drops of water on a surface.
Bad smell, mould, insects, salts and other corrosion products also testify to the presence of
dampness. Detachment and falling of paint films, wall papers, plaster, timber, ceiling
plaster are indicative signs of dampness. Displacement of parapets, wall tiles, floor tiles
and cracking of glass d w a l l s , also take place due to dampness.
11.4.2 Detection of Dampness
There is no limit to the size of a dampness stain. One of the ways of telling whether a
dampness stain is still active is to remove any growth of mould or efflorescence after a
record hds been ma& of the condition and to see how much it returns before the next
inspection. This way it can somet-s be determined whether the dampness is decreasing
 or increasing. Similarly it can be useful to draw a pencil line around the outline of the Water & ~ ~ ~m
~ o o tpi n g
dampness stain and to date it.
The size of the stain depends on the material behind the surface. The shape of stain is not
only informative but can also be conclusive. 'rhe crescent shape in the comer of a surface
is conclusive evidence of condensation while the convex shape of a stain indicates that the
source of water is other than cbndensation.

11.5 CAUSES OF DAMPNESS

Dampness in buildings is generally due to bad design, faulty construction andor poor
materials used. Structures built on high ground and well drained soil are far less liable to
suffer from foundation dampness than those built on low-laying water logged areas where
a sub soil of clay or peat is commonly found through which dampness will inevitably rise
unless properly treated. A sub-soil through which water can easily pass such as f m
gravel, sandy soil or a soil containing light clay, will usually keep the foundations fairly
m.,
In coastal towns walls are particularly prone to seepage because of the high humidity and
salt particles in the atmosphere. Since salt absorbs water, the walls become damp. When
that happens, the plaster peels off, exposing the steel reinforcement. In course of time, the
steel is corroded, further weakening the structure. The sand mixed with cement for the
reinforced concrete is also sometimes salt-contaminated,endangering the life of the
structure.
Leaks generally occur from the sanitary fittings. In new constructions,leaks are due to
inadequate curing of the concrete, substandard quality of the concrete etc.
The various causes for dampness are explained below:
11.5.1 Condensation
The deposition of moisture from the atmosphere, either internal or external, on relatively
cold surfaces. Condensation takes place on surfaces at temperatures below the dew point.
Internal air should be allowed to circulate by providing proper ventilation especially in
closed rooms.
11.5.2 Rain Penetration
Penetration of rain water in a structure takes place due to usage of defective materials,
faulty designs, or construction techniques. AU constructional defects allowing penetration
of rain water in any part of the structure should be immediately rectified. The building
should be dried thereafter by natural ventilation, by keeping the windows open or by using
suitable heaters. Dehumidifiers may be used keeping the windows closed. Fast drying
methods which affect timber joints, plaster, paint and wall papers, etc., should be avoided.
11.5.3 Built-in Water
The presence of water which has been enclosed with the structureduring ,the construction
I process, such as water used in mixing concrete, mortar, plaster, water from atmosphere
like rain, snow, frost and dews. Large quantities of water used during construction
evaporate into the internal air of a building and become available for condensation In
I1 unoccupied new buildings, this effect is felt more. The problem may, however, disappear
completely within two years, excepting in the case of water entrapped within the roof of
the structure. The remedy lies in drying out the affected areas of the building and
providing good ventilation.
' 11.5.4 Pipe Leakage

I
The leakage of water from water supply line or drains and trenches. Leakage from a water
supply line or rainwater pipes or a drainage systems, if not attended to in time, proves to
be an effective source of dampness. Such leakages should immediately be repaired and
water collecting near the fault point drained off.
' 11.5.5 Spillage
I
The spillage of water from industrial and domestic activities is an active source of
dampness. similarly, waste waters are contributed by dwellings and industrial buildings
I
I
Rep& & Preventive als?. To check spillage of water, remedial measures like the provision of proper drainagc
MsintenaoceTechniques should be ensured.
11.5.6 1 Seepage
The passage of wateran or in the ground through structure wholly or partly laid
undergnbund. Seepage in buildings takes place due to passage of water wholly or partly
below the ground water. Proper care during construction can make the structure
~eepage~fiee. External and internal drainage systems should be fitted with all possible
care.
11.5.7 Rising Dampness
The sloy rise of water from the ground up into the wallslfloors due to defective or missing
damp-proofing coursesltreatments. In the absence of damp-proof course or presence of
defectivie damp-proofing material, dampness odcurs internally or externally. In such cases,
new course should replace the old one or building chemicals available in the
market $nay be groutedinjected to form a preventive layer.
11.5.8 Hygroscopic Salts
Hygroscopic salts assist in moisture migration and cause deterioration of the construction
materials. In porous construction materials, excess water, accelerates the reaction.
Excessive wetting of construction materials should therefore be avoided. Care should 4e
taken td ensure that factors responsible for it are checked in advance. AU kinds of
dampnetss due to salt should be dealt with by removing the stained plaster. Affected
mortar joints should be raked and redone properly with water proofing additives wherever
require&
Damp~wssassociated with hygroscopic salts can be attributed to the following:
i) Contaminated Sand or Gravel :Presence of salts contaminating sand/gravel
in mortar and concrete mixes.
) Calclum Chlorlde :'Ihe presence of calcium chlpide used as a quick setting
agent in concrete or mortar mixes:
iii) Composltlon of Floor :Magnesium oxychloride in floors which have broken
down into chlorides:
iv) Industrial Contamlnatlon :The presence of salts from industrial processes;
v) Animal Contamlnatlon :The presence of salts from animal waste (either in
stables or indirectly, from leaky drains);
vi) Flooding :Large deposits of silt and mud containing salts, brought in by
floods etc.

11.6 PREVENTION OF DAMPNESS

11.6.1 Planning and Design Stage
Careful consideration is required to study the various causes that lead to dampness and
water Qroof111gproblems at the planning and design stage itself.
i) Slte Investlgation: Preliminary investigation is necessary to fm the under ground
water table level, since this aspect determines whether any waterproofing treatment
is required or not for the basement floor.
ii) ARer Investigation: The plinth level of the building should be fixed so that it is
well above the adjoining M a and surface water level. As far as possible, the
basements should be avoided if the subsoil level is high. If it cannot be avoided,
the subsoil water level should be lowered.
iii) Deslgn In RCC : In RCC work, the designer must ensure avoiding of shrinkage
cracks. Congestion of reinforcement leads to corrosion because of voids and
consequent absorption of water. Effectivedetailingis required. Impermeable
concrete should be specified when the members are in contact with water and the
designer should take the uplift pressure from the subsoil into consideration.
1 11.6.2 Construction Stage Water &Damp Rwdlng
-

I i) Quality of Workmanship: The materials used in construction such as stone

aggregate and sand should be free from defects. The quality of workmanship in
masonry, concreting, plastering etc. should be well controlled and supervised.

I ii) Water Stops: Special attention is required in respect of water stops provided in
RCC members. Joints should be perfect with welding. It is preferable to do the
fabrication on ground and then erect it at site before concreting.
iii) Voids in Materials: When different materials are involved like concrete and
brickwork, brickwork and wood etc. there are possibilities of voids being created
due to reasons like thermal expansion, variations in the environmental conditions,
stresses, deflection etc. Once voids are formed, a path of least resistance for the
passage of water will result. Water entering through the voids corrode the
reirforcement and further deterioration of concrete takes place.
iv) Expansion/Construction Joints: The basic approach required is that of forming
proper bond to ensure voidfree joints and junctions. In case of construction joints,
the standard specifications of cleaning the surface and providing a layer of rich
cement sliury before laying fresh concrete should be strictly followed. The
importance and the necessity to thoroughly clean the joints and to ensure perfect
bond must be well understood and specifications meant for the purpose must be
scrupulously followed. In the case of expansion joints there should be cover over
the joints location and the gap filled up with proper sealants.
11.6.3 Remedial Measures and Treatment
The cure for dampness depends on a correct diagnosis. An experienced and
knowledgeable person can easily identify the cause and suggest suitable remedial
measures.
1) Treatment of Foundation on Poor Soils :Where the subsoil water is not properly
drained (in clay or peat soil) the structure should be disconnected from the face of the
ground excavation and a trench made all round for a width of about 60 cm taken down to a
point at least as low as the underside of the concrete footings. The bed of the trench
should be provided with a good slope at each end and the trench filled with coke, gravel, or
stone, graded with fines to fill the voids. An open jointed land drain may be laid at the
bottom to collect and drain out the sub-soil water. A water proof coat should be given
outside the structure foundations (on the external face of the walls) and continued through
the thickness of walls (under the walls over the foundation concrete) and under the floor.
A 75 mm layer of water proofed cement concrete can be laid all around. Dampness can
also sometimesbe reduced by leaving out an air gap around the external wall of the
foundations.
Where sub-soil drainage has been ignored and necessary precautions have not been taken,
water will stand above the foundations, and the warmth of the interior of the building
acting through porous concrete floors will set up suction of moisture which will eventually
give rise to dampness in the floors and the walls. Where the sub soil water is near the
ground surface and cannot be lowered by underground drainage owing to the flatness of
the ground or any other reasons, the height of the plinth should be kept sufficiently high.
2) Damp-proof Course: One of the following specifications may be adopted for a
damp-proof course, according to the type of the construction and the nature of the ground :
i) Two courses of dense bricks in 1:3 cement mortar :Bricks should have a water
absorption of not more than40 percent. It is advantageous to leave the vertical
joints unfilled as moisture rises through the mortar joints.
ii) A layer of well burnt brick soaked in hot tar and pitch will suit for low cost
buildings.
iii) Non-porous stone slabs 50 mm thick laid for the full width of the walls over a bed
of cement mortar.
iv) Two layers of non-porous slates laid to break joint, each layer being bedded and set
solidly in cement mortar 1:3.
v) 12 mm cement plaster 1:3 with water-proofing compound laid above the plinth
masonry with one or two thick coats of hot coal tar applied over the mortar after the
Rcpsdr Lprrmtlve dmtar.has fully dried. Dry sharp sand should be sprinkled over the hot tar. Five
MdatmamceTmbaiqo*a.
permt of Pudlo by weight of cement can be used for water-proofmg the mortar.
vi) 40 to 50 m m cement concrete 1:2:4 : Two coats of asphalt or hot coal tar should
be applied over the cement concrete when the concrete has been fully cured and
dri& Mastic asphalt in one or two layers is generally consider4 best where
h#draulic pressure is encountered. The asphalt used should not melt or soften in the
hDttest days and should not get squeezed out due to pressure of the masonry over it.
The danlp-proof course should be laid flush with the floor surface and should not be
carried m S s doorways or other openings. The upper layer of cement concrete floors
should be continued over such openings and should be laid at the same time along the
floors. The asphalt or tar layer should be laid under the &mete at the opening. Where
concrete is laid on bitumen or tar, the surface of the bitumen or tar must be sprinkled with
dry sand.
The position of the dampproof course is also an important factor and it should be laid at
such a h6ight that it is above the normal level to which water splashes from the ground
when it is raining. A damp proof course should not be less than 15 cm above the highest
level of tbe ground. In Northern India plinths are usually kept 45 to 60cm above ground
level for good buildings under n d conditions.
3) ~reatmenbof Floors: The floors should be laid an some clry ftlling. A hardcore filling
- of stones with smaller stones to fill in voids is quite suitable. The filling should be well
rammed but wt unduly consolidated. It is considered that a thin layer of cinders and coal
' tar well rammed under a tilkd floor prevents the rise of damp and "kalar" or
efflorescence. A Nling of 75 to 150mm of dry coarse sand under the floor masonry is
usually s-ed, but this is suitable for dry locations only. Where there is possibility of
moisture penetrating the floor, it will be necessary t? lay a liquid-proof membrane before a
concrete goor is laid. P m u s concrete attracts moispe from wet soil. Even dense cement
concrete W e d with water proofw compound is not a complete barrier to moisture; the
passage of water as liquid may be prevented, but moisture can still reach the top of the
concrete as vapour and condense there if an impervious finish covers the surface.
4) Treatment of Walls: Rain can penetrate through solid brick walls as there is a limit to
'
the amount of raiuthat a wall can keep out, moisture is conveyed from the exterior to the
interior dqe to the porosity of the bricks. More rapid penetration is through the mortar
joints, and an efficient pointing on the exterior will greatly resist the passage of water. Ttae
simple flu$h pointing will offer a good protection. Sometimes the soffits of all horizontal
courses are slightly throated. Cavity walls afford sound protection and ensure a dry interior
even if m o w material is used for outside. The application of a porous rendering on the
external surface will do much to prevent direct penetration.
A porous finish will absorb water in wet weather and will permit free evaporation when
the weather improves. A dense impeqious rendering is less efficient than a porous one as
it will more effectively prevent moisture drying out rather than prevent it getting in, and is
also more liable to crack A porous rendering is less liable to crack and will not cause the
entrapment of moisture within the wall. An external treatment unless it is porous will also
be liable b aggravate dampness if it is due to raising ground moisture, indirect penetration
of rain or due to diliquescentsalts. A mortar of cement: 1ime:sand in the proportiom of
1 2 9 or 1:1:6 is usually recommended.
a) Efflorescence: Where soluble salts are present in excessive quantities in the bricks or
the moftar they absorb moisture either from the air or water during cmbruction.
These are brought to the surface in solution and deposited in concentrated patches
either as a white powder or as translucent crystals, as the moisture dries out. Tbis
crystallbe growth either flakes off or is reduced to a powder which can be brushed off.
Attempts to seal back efflorescence are not usually successful and it is advisable to
allow tl$eefflorescepce to expand itself as the wall dries before attempting any
treatmebt at rendering or white washing the walls.
b) Lintels and Sills: All soffits or undersides of lintels and sills should be throated. The
mere drafting of a line does not constitute a throating; there should be deep and wide
chase a t in the soffit which should be returned at the ends of the sill. The top of a
window sill should be sloped outwards and weather bar or water bar (of metal) should
be fitted between the stpne sill and the wood sill (or window frame) which will stop
the passage of water passing between the sill and the wood frame.
 c) Widows: Shrinkage of unseasoned wood and importance of properly designed
window frames should not be ignored. Frames should be so rebated, and which shauld
be deep enough, as to exclude the weather and afford good protection. Double rebated
frames are better in severe weather condition. Widows opening outside are
prefereable. A "hood" of simple form with groove to serve as throating can be fmed
on the head of the window frame. Where the windows open Wide, the inner sill
should be made to slope outwards and a small hole kept in the centre passing under the
window frame through which any water that has penetrated inside the window can
flow out.
In places liable to heavy storms it would be advisable tn
window and door openings instead of simple sun-shades.
,.- '": Smds over all

d) Treatment at Roofs: The presence of mass vegetation or other growth on roofs is

direct evidence of a porous roofing material in which water u Jl collect and will not be
drained off. Overhanging trees will keep the roof wet and their fallen leaves will block
the downpipes. Cracked roofing tiles and broken pointing are conanon causes of
leakage. Cement grout poured into the joints and cracks is very hekk" 11. hisufficient
roof slopes or flat pitches which are too slow to drain off the rain-warn nuickly are
also one of the main causes of leakage.
i) Rainwater Down Pipes: It is important to provide sufficient number of
downpipes and of adequate size and it is more important to see quite often that
they are not choked up. All vertical pipes should be fried to stand well clear off
A the walls so that if any cracks develop in the pipes or if there is leakage in the
joints, the walls will suffer little damage. Tops of the downpipes should be very
carefully and properly fixed with the roof outlets so that there is no overflowing
of the rain water or leakage through the walls. The bottom end(shoe) of the pipes
should be so arranged that the water is not thrown back on the walls.
ii) Chimney Stacks: Defective or poorly executedjunctions of chimney stacks and
roofs are a very common cause of leakage in sloping roofs. A sufficient "tuck"
of lead flashings into the chimney brickwork should be provided with cement
fillets where necessary.
iii) Copings to Parapets :'Ihe top of every wall not protected tlom the weather by a
roof or overhanging eaves should be built as to prevent the penetration of rain
water through the wall. The top can be finished with one burse of hard, well
burnt bricks set on edge in cement mortar over two courses of slates or dense
tiles projecting over the wall.

11.7 DAMPNESS IN OLD STRUCTURES AND

REMEDIAL MEASURES
Before applying any remedial measures to a damp wall a very important fact should be
borne in mind that there should be a tlee escape for any water that has already entered the
wall. There are many water-proofing commercial products in the market such as cement
pa&, bitumen and tar paints. Silica solution is transparent and very effective in resisting
dampness. Internal treatment of affected walls would consist of removing the old plaster,
b applying a slurry coat of neat cement with a water proofing compound and then cement
rendering with a dense mortar of 1:2 with an integral water proofer added. Another
internal treatment for damp walls is the application of an impervious coating of some
material or a coating bitumen or tar followed with blending with sand and plastering. If
I the body of the wall and any external covering is in porous material the internal treatment
will be effective. Where evaporation from the outer surfaces is likely to be difficult, with
internal treatment the wall still remains wet and dampness may spread to the other parts or
rise to a greater height as more water is absorbed by the wall, and little benefit can be
expected from internal treatment.
The following methods are also used for preventing dampness in walls:
a) Two parts by weight of coal tar and one part by weight of pitch are put in a vessel
I and heated and stirred untill the mixture is sufficiently liquid, and which is then
I applied on walls. This has been found to keep out dampness very well.
I
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Repair & Preventive b) The damp plaster may be varnished over with a solution 120 grams shellac
Maintenance Techniques
dissolved in 1litre of nephtha. This almost immediately hardens. It is preferable
to remove the damp plaster and let the walls dry.
c) Spray Qr paint the walls with a solution of sodium silicate (water glass), followed by
a solution of calcium chloride, which forms an insoluble silicate.
Another way Of preventing internal dampness is by lining the walls with wooden boards or
lathing which are battened out of direct contact with the walls.
If dampness id confined to one position near ground floor level above damp-proof course,
it may be due to a hole or crack in the damp proof course.
SAQ 1
i) v a t is the difference between dampness and leakage ?
ii) What are the cailses for dampness ?
iii) h a t are the stages at which you have to take precautions to prevent
dampness ?

11.8 WATER PROOFING

Water proofing is the treatment of a surface or structure to prevent the passage of water
under hydrostatia pressure, since the presence of unwanted water inside a structure is a
visible annoying ttnd a damaging element. Water proofing has to be provided to avoid the
inconvenience caused by dripping ceilings, peeling of paints in walls, efflorescence etc.
Most water proofing systems are designed for application on exterior surfaces, since they
form a barrier to @eentrance of water. ?he walls and floors provide the support system to
counterbalance the hydrostatic head of water, conversely where reservoirs, tanks or pools
are waterproofed qo contain water, the water proofing linings are installed on the water side
of structures for siknilar reasons. In these instances, the waterproofing is said to be applied
to the positive sidd or positive face.
However, several waterproofing systems are designed to be applied on the side opposite
the potential source of water i.e., the negative side since the system also have the structural
ability to withstand the hydrostatic head of water.
Surface treatments gain further importance because of the tendency of concrete to develop
cracks, due to the eprpansion and contraction of the surface on account of temperature
fluctuations, shrinkage, or permeability of concrete caused by improper workmanship or
materials. I

Regardless of the reasons, once the concrete or plaster has already started leaking only
surface treatments a n make it waterproof, without breaking and redoing the substrate.
Surface treatments are also provided as a precautionary measure to avoid possible
problems that may occur later in the concrete or surface.
Water proofing treatments are broadly divided into two categories.
a) Integral water proofing
b) Surfacd treatments.
The various types of water proofing are illustrated in this chart.
 Water & Damp P m o h g
WATER PROOFING

INTEG~L
r-+ SURFACE TREATMENTS

I
~ e r m e a b i l i ~ Water I I I I
Reducers Repellanb BOqdingAgenFI Capillary Tar-felts Potymer protective
I Crystallization Sheeb Ccltings

Fine Pa~liculates Plasticizers Acceleraton Epoxy Bitumen Rubber~zea Silicons Polvwthmrj

densify cement gel

Brick bat Coba and Tiling

11.8.1 Integral Waterproofing

Waterproofing by this method normally involves the use of admixtures and additives like
plasticisers, superplasticisers, air-entraining agents, water proofing components, bonding
agents, etc., at various stages of the construction itself, or repairs. The use of these
products improves the workability of !he cement mix with a lower water cement ratio
naaking the concrete waterproof.

*
11.8.2 Surface Treatments
Surface treatments are normally done after the concreting and cementing work is
completed, or even after the completion of the building. The object is to treat the surface
subsequently,overcoming the defects, and making the surface Oater proof.
Surface treatments can be broadly classified in the following categories:
i) Brick Bat Coba and Tiling
The surface of RCC slab shall be wire brushed and cleaned of all dust and foreign matter
to lay brick jelly concrete. Brick aggregate shall be obtained from well burnt hard broken
brick? and shall generally be varying in sizes from 20 mrn to 5 rnm and well graded
(under-burnt brick shall not be used). Brick aggregate shall be soaked in water for a
sufficiently long period before mixing with lime. Brick jelly concrete shall be made in the
proportion-of 1 m3 of brick aggregate to 0.37 m3 of slaked lime. No sand shall be added.
The brick jelly concrete shall be used when it is quite fresh. Brick jelly concrete shall be
spread over the slab to the cross-section and the surface shall be formed to slopes as
required. It is intended that the finished thickness of brick bat coba at the lower ends of
the slope i.e., at the points where the thickness of coba is minimum, shall be about 20 mm
and 25 mm. Consolidation shall be done by beating the surface with wooden beaters
weighing 1to 2 kgs and beating shall be continued till the beaters rebound readily and do
not make any impression on the surface. During the process of beating, the surface shall
be constantly kept wet by sprinkling with a mixture of Gur and boiled solution of bael
fruit. This mixture shall be prepared atleast ten days before it is required.
After brick jelly concrete has hardened or after 6 days a layer of flat tiles (machine pressed
tiles) of approved thickness shall be laid in cement mortar 1:3 mixed with crude oil as
described below. The surface shall be roughened and cleaned of all dust and other foreign
matter. It shall then be wetted before applying the mortar.
The flat tiles shall be immersed in water for two hours before being used. The cement and
sand $hall be first mixed dry. The cement shall be weighed for each mix to ascertain its
weight in order to fix the quantity of non-volatile crude oil to be added, which should be
5% of the weight of cement. The dry mixture shall be worked up well with the required
quantity of crude oil and then water added and the mortar further well worked with the
trowel. The tile shall be bedded properly in this mortar with joints of about 8 mm to
10 mm width with their logitudinal lines of joints truely parallel and horizontal and at right
angles to the transversejoints by less than 5cm. Before the work dries up completely the
joints shall be raked out and pointed over with cement mortar 1:3, mixed with crude oil.
(with crude oil being 5% of the weight of cement) prepared as above. The joints shall be
Repair & Preventive well rapped over with thin bar trowel and the excess of mortar scrapped off until the
Maintem~c~Tdques surface of the pointing attains a black polish and become hard. The tile work shall be
cured for atleast seven days during which period shall be suitably protected from damages.
Nowadays instead of brick coba, well burnt brick bats are arranged over the concrete slab
of roof providing sufficient slope towards the roof drainage pipes and the Interspaces are
filled with CM 1:3 mixed with water proof111g chemicals marketed by different agencies
and the top plastered with the same mix and thread lined to avoid surface cracks.
ii) Tarfelts/Polyrners Sheets
This type of treatment involves the laying of factory-made sheets or felts, which are
available in tolls of specific widths. This is laid on the surface over a layer of molten tar,
or similar adhesive and over-lapped at the joints. 'Ihe entire surface is thus covered with
the sheets. Joints are a vulnerable part of this treatment, apart from the weak bond given
by the bitumen. Water which may enter from the joints/punctures, etc., may subsequently
cause blistering and puncture of the felts. The use of surface is also restrictive. Further,
bitumen, which is a petroleum bi-product, is devoid of necessary oils and plasticisers,
which reduces its effectiveness. Weathering, Ultra Voilet (UV)radiation and temperature
changes alsol cause deterioration and brittleness of the tarfelt, which results in cracking.
The built up membranes are essentially bitumen saturated felts and asphalt or coal tar
coatings to ppluce a layered system that protects a structure from water penetration.
In a built up membrane system, the felts are used as a reinforcement to stabilise bitumen
layers. They provide the strength required to span irregularities in the substrate and to
'distribute strains over a greater dimension.
Felts are bitumen saturated and include:
a) Organic felts made from wood fibre pulp to which scrap paper and small
percentage of rag have been added.
b) Inorganic glass fibre felts and glass mats. The organic felts are saturated with
coal tar pitch or asphalt. The glws mat felts are treated with asphalt or coat
tar. The remaining felts are saturated with asphalt.
Overheating bihunen during application results in the loss of oils by distillation and
produces a ttlin film, when applied, that does not provide adequate cementing action. 'Ihe
temperature range for heating coal tar pitch is 325' to 375' F and for asphalt 400' to 430'
F;underheating below this range results in a loss of application workability and cementing
capability.
Single Ply Materials
The problem associated with built up membrane systems gave rise to the development of
synthetic sheet single ply systems.
Sheet membranes are generally available in roll form in various lengths and in widths of
lm minimum and thickness of 30 to 60 mil. Joints in single ply systems are made by heat,
fusion, torching solvent welding, tacky tapes or adhesives.
Single ply Waterproofing materials are costly items and hence are used only in special
environment$like U.V., Ozone and high temperature etc.
a) weoprene :This is the oldest of the synthetic rubbers having been introduced
in the early 1930. It is based on polymers of chloroprene.
b) Ethylene-Propylene-Diene-Monomer(E.P.D.M.) :This synthetic product
is available since about 1963 when it was introduced to overcome some of the
shortcomingsof butly rubber.
c) Chlorinated Po$ Ethylene (C.P.E.) : These sheets are available with or
Without polyester reinforcement. 'Ihe weather proofing materials have been
exposed to extremes of weather in Arizona and Florida for over 10 years.
d) Polyisobutylene(P.I.B.): It is a waterproofing synthetic material generady
bonded to a non-oven synthetic felt reinforcement that permits installation
using asphalts or contact adhesives.
e) Polyvinyl Chloride (P.V.C.) Membrane: It is made of P.V.C resins and
plasticizers apd is available with or without reinforcement. It has been in use
44 for over 20 years. Some non r e i n f a d P.V.C will shrink as much as 5%. It
 is not compatible with tar or asphalt. Lap seams are made by solvent welding Water & Damp Proof&
and sealing.
f) Modifled Bitumen/Laminatesand Composites: In addition to synthetic
membranes described above, there are proprietory single ply membranes that
are made by the addition of rubberizing ingredients to asphaltic materials. In
the manufacture of modified bitumens, a synthetic polymer such as
polypropylene or styrene butadiene is blended with asphalt. The
manufacturing process is critical since good dispersion of rubber and bitumen
is essential, to obtain a good quality single ply membrane. Some products of
this marriage produce a tacky membrane which allows the materials to be self
adhering. Others produce combination laminates using polyethelene sheets
reinforcing materials and aluminium foil in the composites.
iii) Capillary CrystalIization
This process involves the application of liquid chemicals on the surface of the
concrete. These chemicals enter the pores of the cmcreteJplaster and there after
crystalise, thus reducing and seaIing the pores. One major limitation is that the
concretelplasteris prone to further damage, development of cracks, wear and tear
and possible leakage.
iv) Protective Surface Coatings
Waterproofing by the u!! of surface coatings is the latest type of treatment and is
gaining immense popularity, due to its effectiveness and ease of application apart
from the economy of use. However, proper care in selecting the adequate treatment
and its proper application play an important part in effective water proofing.
Protective coatings are generally based on epoxy, bitumen, rubberised silicons,
polyurethanes etc.
Liquid agplied systems are available in both single component types and two component
types. They are applied by brush roller, sqeegee, trowel or spraying to form a seamless
waterproofiing membrane. The single component types solidify through evaporation of a
solvent or water or by chemical cure. The two components type solidify by chemical cure.
The Unicormity of thickness and free'dom from bubbles and punching obtained with a
liquid system is a function of the quality of work involved and the surface roughness of the
substrate.
a) Epoxy coatings have very good bonding properties with the substrate, and
form an impermeable membrane over the entire surface. Despite their good
abrasion resistance properties and resistance to mild acids and chemicals,
epoxies, being rigid in nature, cannot withstand the expansion and contraction
of the surface and develop cracks. Epoxies are also not recommended for
external applications due to their weak resistance to Ultravoilet radiation.
They are also very expensive.
b) Bitumen based coatings are normally modified with polymers, oils and
plasticisers and can be considered as an economical method for water
proofing. The additives only give limited resistance to heat, W , etc and the
treatment tend to become brittle leading to crack formation.
c) Rubberised compounds have good elasticity, easily bond with the surface
and expand and contract without cracking. These compounds, however,
deteriorate fast with the effects of W and ozone, causing toss of these very
properties and rendering the system ineffective.
d) Silicon based emulsion and coatings are colourless coatings which do not
change the appearance of the surface, while making the surface water
'repellent. Their biggest drawback is the lack of crack bridging capacity.
Silicons are thus not suitable for flat terraces or horizontal surfaces. At the
most they may be used on vertical walls for water repellency.
e) Polyurethanecoatings are by far the most effective surface coatings
available. They allow for good adhesion to the substrate, formibg a
monolithic membrane, which is totally impervious to water and has the
elasticity to withstand expansion and contraction of the surface. W
resistance, resistance to mild acids, slats, etc., help polyurethane coatings to
withstand external forces for long periods.
1:.pa(r & &-el ezd.;vr 11.8.3 Metallic Waterproofing
M:~irknanceTechniques
Metallic wart em roof in^! is a system of waterproofing, the interior surface below grade
concrete wdlsand floors that may be subject to hydrostatic heads of watt%. It is usually
employed ib confined sites or where it is impossible to apply membranes on exterior
surfaces as when buildings adjoin one another. The system is built up to about 2mm to
4mrn thick and then covered with a ~rotectivecoat of mortar. This method of
waterproofing is based on the fact that when water enters the system, the powdered iron
expands and prevents the intrusion of water. The mechanical bond of the metallic water
proofing to the concrete substrate allows the system to be installed opposite sides from
which the hydrostatic water head exists.
Any waterproofing system has to be decided based on the following properties:
Liquid system with good bond and penetration,
Monplithic membrane formed over an unlimited area,
Water impermeable,
Good resistance to hydrolysis,
Goodl elasticity, preventing cracking and warping,
UV resistance,
Abrasion resistance permitting normal use and atmospheric corrosion,
Resi$tance to algae, mild acids and alkalies, and
Easy application and maintenance.
For a waterproofing treatment by surface coatings to be successful, it is essential that the
application be done with proper care. The substrate should be clean and dry. All algae
formations, loose particulates, dust, etc., should be wire brushed and removed before the
treatment is applied. Cracks and joints need to be properly detailed as per the
specificationsto avoid their re-opening. Application plays as iniportant a part in the
success of a treatment as the material itself.
The followit.lg sketches furnished below explain the incorrect and correct methodlway of
carrying o~d/~rovidiin~ a LeaWDamp Proof construction in buildings/structures:
a) Condrete slab is not cast properly and not provided with slope.

r Correct r b p e

I
k a k a g e s and dampness Mftclcnt drainage I
o a u r here a v o ~ d rleakages

Incorrect Correct
Figure 11.1

'b) Flat terrace slab with masonry parapet wall.

4 Seepage through
top t c parapet
Plastered top
of parapet

R I P Outlet
slightly
belo w to
Top prdlle a w ~ drmter
of slab stagnattng
levelled

after the&~"s
have stopped
-
' lncorrect Correct
c) Proper construction of parapet wall. Water & Damp I'rclofi~rg

P C Cop~ng Col.for future expn.

to be frn~shedIn cerr

and beams

('arrccl
figure 1 1 3
d) Proper casting of terrace slab.

B K BAT COBA laid

, I t 0 proper slope
seepage
through
Damntss
face o n the wall h'

e) Proper orientationof rain water down take pipe.

Parapet v(l"
-FK I
L----
- ---
Colum~--l below

RWDown-i
takepcpe ;
Wall

1--1
I

I
Terrace

. !
c r o w e d pcpc n d l i t l i G ~ t
i o m t n l a c n and g e l s
frequently block
l~~corrcct COI-I.FF~
figure 115

f) Proper sloping of the slablfloor to go into rain water down take pipe.
R.C.Coptng,

BKBAT CQBAIald
to p r

underscde of
slab
Iscorrect
 Repair & Preventive g) Proper casting of slab with full bearing.
,M&tenance Techniques

Load bcarlng wII

Au
Dampness and fungus Incorrect
Correct
gmwfh noticed on wall

Flpm 11.7
h) Roper casting of verandah slab.

lncorreet Correct
R p r e 11.8
i) Leakages through water closets.

Jo~ntrbetween
floor lnnh and
Jotnt khveen
floor lanrrh and\ I-"

R p r e 11.9

j) R o p r connection of toilet blocks.

M-: RCC Wall

 Water & Damp Proofing
Proper connection of nahani trap.

Leak l
through f?oorlng
and Na hanl trap 'm

Leakage through
joint between
wall plecc and
r1aht angle bend
-
Long G hahanl
trap
Incorrect Correct
(a)
Figure 11.11
Sinks and wash basins.

Figure 11.12
m) Detail of expansion joint (recommended).

Copper
plate l 5 m m l b m m t h ~ e klead flqshlng
\ f lred on one side only
fborlng
CCBA

Lt.w.~atten fcred on
one scde only

Concrete cgp slldlng

/ s u f f e ~ e n t l ~at top

cbcm th~cktl'oorlng
fB B CCBA
CC Slab

L T.W. Plate f l i e d on
ow sldc
--

Figure 11.13
Repair & Preventive
ilaintenanceTechniques 11.9 DIFFERENT METHODS OF WATER PROOFING
AND CASE STUDIES
11.9.1 Water Proofing Basements
This treatment is provided by the specialist agency. It is necessary to have a water free
surface to make the treatment effective. A levelling course of PCC 1:5:10 of 80 mrn thick
is laid over a well compacted layer of 150 mm thick sand. The waterproof treatnient is
provided above the levelling coufse as indicated below:
a) Cement slurry with special waterproofing chemical compound is applied over
levelling oourse.
b) CM 1:4 layer of 20 mm thick with waterproof compound is laid on the levelling
course.
c) Again cement slurry with waterproof compound is smeared.
d) Then 20 n)m stone aggregate is pressed in CM 1:4 of 25 mm thick mixed with
waterproof compound.
e) Another course of CM 1:4 20 mm thick, with waterproof compound is then laid.
f) One layer d 20130 mm thick shahabad stone slabs are provided with joints pointed
with cement mortar mixed with waterproof compound.
g) Cement slurry with waterproofing compound is again smeared.
h) A plastering course in CM 1:4 with waterproof compound 10115 mrn thick is then
provided.
i) Finally, the surface is finished with cement punning with waterproof compound.
The average thiclmess of this treatment is about 100 mm on the floor and 50 mm in the
walls. In walls, the treatment is the same except the layer of providing 20 mm stone
aggregates in CM is omitted. Before a day's works is commenced, cement slurry mixed
with special compound is poured in the joint over the previous day's work after cleaning
and washing.
11.9.2 Polymer Plasterlfor Roof and Floor - PROOFSOL
Concrete material made by partial substitution of binder in cement concrete by polymers is
known as polymer modifed mortar and concrete. Mostly polymers in dispersion form
(latex or emulsiod) are added to cement mortar or concrete during mixing. Polymer film is
formed in cured @lymer modified mortar and concrete and enhances cement aggregate
bond.
In polymer cement concrete, the chemicals are used in much larger amount and also the
polymers in the concrete may supplement the cement in binding the material aggregate.
The polymer latex film through its high tensile strength and elongation, effectively holds
propagating micro cracks and holds existing micro cracks together. An important aspect
of polymer latex modified concrete is its improved durability over conventional concrete.
This is partly due to reduced porosity as a result of lower water cement ratio and partial
filling of pores by polymer, but existing pores also tend to be sealed by a continuous
polymer film.
Admixture of PROOFSOL in concrete and mortar making is an additional safeguard to
render the concrete and mortar mix waterproof. 2% by weight shall be ample for all
normal concreting. PROOFSOL is marketed in the form of powder.
Where the surface of wall to be treated is fairly even, two coats of rendering suffice. If the
surface is very roqgh and uneven, three coats may be necessary. The first coat should be
10 rnm thick being applied to level up the surface.
All the joints in thp masonry should be thoroughly raked out. The surface of the wall may
be cleaned, washei3 down with water to ensure good key for the rendering. Before
applying backing eoat, the wall surface may be made uniformly moist but not dripping
wet. A thin coat of neat cement slurry of cream consistency should be applied over small
areas at a time just a little ahead with the application of first coat.
The first coat coaists of 1 part of cement mixed with 2% of PROOFSOL and 3 parts of
clean sand graded 3 mm down. The surface should be made even with a wooden float and
 as soon as it has hardened suficiently, the surface should be combed to provide good bond. Water & Damp Roofin;
It should be cured for 48 hours before the application of next coat.
I
In three coat work, the second one should be similar to the fist one. The finishing coat of
plqter should be 10 rnrn to 12 mm thick. It should consist of the same mix as the base
coat, its surface should be rendered even with a wooden float and then f i s h e d smooth
with steel trowel. The surface should be cured by keeping it continuously wet for about 12
days.
Generqlly, a 25 rnm thick plaster with the above water-proofing compound as per the
directions specified will yield good result.
Waterproofing Using Epoxy
The items in sequence are indicated below:
a) The surface shall be cleaned by wire brushing
b) Bond coat is laid using epoxy resin and epoxy harcbner in ;he propotion of 2: 1
and applying on the surface at the rate of 0.5 kglsqm
c) A coat of plaster is done within 2 to 2 112 hours with CM 1:4 a d 2 iO 10 mm
thick. Curing should be done for not less than 10 days.
d) Binder coat1DEBKOT as frnal coat is laid using as above i.e., 2:l and
applying on the surface 0.6 kglsqm with an inter layer of fibre glass fabric
*
pieces of specification 30 gmslsqm.
In case porous concrete grouting is to be done, it is essential to have grouting at the
constructionjoints. Grouting is to be done using lkg of epoxy resin, 550 gms of epoxy
hardner and 50 gms of dilutant mixed together, of grouting pressure of 8 kgtsqm or
refusal. Generally grouting along construction joints will be at 1.5 m etc.
11.9.3 Water Proofing of Roof - Nina Industries Method
This consists of providing average 110 mm thick cement base waterproof treatment with
brick-bat-coba bedding. The steps are
a) Cleaning the surface.
b) Giving a coat of chemical wash mixed with cement.
c) Providing all round terrace, small waterproof watts (roundings) as a
preliminary.
d) Providing 10 mm thick cement mortar pad with admixture.
e) Placing brick bats of varying sizes average 75 mm,to a proper slope and
grouting their joint with cement mortar and 2% proofsol.
f) Providing plain cement concrete paving smooth finished 25mm thick
with admixture of proofsol good for common use.
g) Providing all around the terrace, large water-proof watts (roundigs) in PCC
one foot high above the finished floor level.
h) Finishing and curing 14 days.
11.9.4 Water Proofing by Algiproofing Method
Algiproof is a wterprooflweatherproofcompound manufactured by Brahmavar Chemicals
Pvt. Ltd. Brahmavar, Karnataka for use as an intergral cement admixture in all concrete,
mortars, including guniting and cement pressure grouting work. Algiproof is essentially a
dry chemical powder and has to be dissolved in water to prepare the stock solution atleast
10-12 hours prior to its actual use and should not be directly used in dry powder form.
Before use, the solution has to be stirred well to get uniform smooth consistency and to be
free from undissolved particles.
Preparation
1 kilo of dry powder i 3 dissolved in 30 litres of clean water and stirred well for 10-15
minutes. In case of mechanical mixing, first water is added tO the mixing drum, then
algiproof stock solution followed in turn by aggregate sand and cement for concrete and
in respect of mortar sand and cement.
Repair & Preventive Use on New Works
Maintenance Techniques
The consreting or plastering works, as the case may be, are to be carried out as per sound
engineeing practices. Water cement ratio has to be strictly followed. All air voids are to
be removed by proper trowellinglcompactioa After the initial set has taken place, the
surfaces are to be trowelled again to obtain hard, dense smooth sukface. Sprinkling of
cement has to be avoided, which may result in cracks. As far as possible, the newly
concreted surface while it is green, cement sand algiproof plastering of CM 1:5,12 mm
thick (1 kg algiproof for every 10 bags of cement) is done. In case of water retaining
structures, rich mortar with CM 1:3 can be used. After initial set, the surface has to be
trowelled. Similarly, for new plaster, algiproof is used as admixture which will also act as
a dampproofing agent.
11.9.5 Case Studies
a) Waterproofing Deep Well
A facility known as Cast Cure Facility in which the two distinct operations of casting and
curing of the propellant will be carried out in one and the same facility. For this purpose, a
cast cure well is built with 7.5 metre internal diameter and about 6.5 metre deep clear from
the finished floor level. This is a RCC circular well with 60 cm thick RCC steining. The
sub soil water level in the vicinity is 1.5.M below ground level.
One of the stringent requirements of the cast cure facility is that the cast cure well should
be absolutely dry and free from any moistule as the presence of moisture will increase the
relative humidity during the curing of the propellant.
The u n d e r g m d structure was cast with usual RCC kerb like water supply wells in stages
above ground level and well sinking was resorted to duly employing compressors, and
well sinkers with helmets. After the sinking process was completed, the bottom of the
well was plugged with M-20 concrete for a depth of 2 m. This concreting operation for
plugging the bottom of the well was carried out under water, making use of a concrete
placing bucket with an openable bottom flap door. This door can be operated for opening
and closing fiom the ground level on top of the well. After the completion of concrete
plugging and curing, the water inside the well was pumped out and the raft slab above
plugging concrete was then completed. Necessary water stops were provided at the
constructionjoints to avoid seepage of water inside the well. Similarly, sufficient grooves
were provided in the inner face of the well steining to enable the plugging concrete to have
effectivekey with the steining (Figure 11.14).

Figure 11.14 :Cast Cure Station BuUding

 Inspite of the well sinking technique resorted to for the cast cure well and subsequent water & Damp Pmdislg
plugging the bottom and providing the raft slab, it was found that the subsoil water was
finding its way through the minute pores of the stening and other possible vulnerable
locations, when the ground water table rose to its peak.
In order to contain the water seepage problem, epoxy injection had to be resorted to. The
following procedure was adopted to arrest the seepage of water through the side wells
bottom slab.
1) The seepage water inside the well was completely removed.
2) One coat of epoxy primer was painted followed by one coat of epoxy plaster.
The surface was finished with a epoxy seal coat.
3) PVC nipples 10 mm dia were placed at regular intervals in the walls and the
junction of wall and base slab which was vulnerable.
4) Epoxy grout was pumped under pressure through the nipple till refusal.
5) All the surfaces were cleaned and found that no seepage was observed.
b) Clean Room Supply and Return Air Tunnels (Under Groundl
Clean air required for a clean room is suppIied and recirculated through an underground
supply air tunnel of size 4.99 x 4.2m and return air tunnel of size 6.41 x 4.2 metre. These
underground tunnels are of reinforced cement concrete construction as indicated in
- Figurell.15.

Epoxy bond coat

DobcdtoLS2OF 4
Hordner EH 408

~ B o r r h d- -
Pnrcnt lkitment
PIgon l L l 5 r ~ J m d a m A l r T n a a d s
Being an underground structure, the tunnels have been provided with 5 course hessain
based felt treatment to ensure water tightness of the tunnels. However, in c o m e of time,
the waterproof treatment was found to be not effective and water leakages were found
through the walls, ceiling and floors, thus affecting quality of conditioned air supplied to
the clean room.
The following methods to overcome the problem were examined.
i) / To treat the tunnel from outside by exposing the external surface of the tunnels.
ii) Carrying out the treahnent externally at locations ,whereexposure of tunnels or
structures are possible and treat the areas not accessable internally.
iii) By treating the internal surfaces after the removal of vapour barrier and IW acoustic
treatment.
The following procedure was adopted for the repair work:
i) Removal of existing acoustic treatment-andvapour barrier treatment.
ii) Removal of the bitumen used as an adhesive in vapour barrier treatment and expose
the RCC surface by removing the plaster by sand blasting method and chipping
method and cleaning loose particles and dirt.
iii) Epoxy injection grouting using epoxy resin Debeckot 505 C, Hardner EH 408 and
dilutent 'C' in 1000: 550:50 grams ratio (total 1.6 kgs per batch was carried out at
constructionjoints, at intervals of 1.5m horizontally and vertically and also at
vulnerable points shown dampnessAeakage. Using rotary electric drills 100 mm
deep holes were drilled in RCC and PVC pipes of length 125 mrn inserted into the
Repair & Preventive holes and fixed with epoxy putty with PVC pipe projection 50 mm outside the RCC
MaintenanceTechniques
surface. The epoxy putty was allowed to set for 10 hours. The grouting was carried
out at 8 kg/sq.cm pressure using an air compressor having a capacity of
12 kg/sq.mm. During the actual operation, as high as 14300 points at closer
intervals were grouted consuming 3300 kgs of grout material as large leakages had
been noticed during the course of work. The maximum consumption per point was
32 kgs and minimum was 30 grams and average was 230 grams per point.
During the repair work, flooding was done through trenches dug near the junction 4

of top of side walls and roof slab to create a near monsoon condition.
iv) Aftdr grouting points was completed, the bond coat of Dr. Beck's epoxy system
contisting of Debeckot 520F and Hardner EH 408 in 2:1 proportion added with
suitable thinner for brushability was carried out on RCC and plastering to the
required thickness in CM 1:4 to get the level surface to relieve the binder coat. The
plastered surface was cured for 10 days at tunnel ambient temperature.
v) Then a binder coat consisting of Beak's epoxy system resin Debeckd 520F and
Hardner EH 408 in proportion 2:1 was applied over the plastered surface. Over this
coat of epoxy layer, fibre glass tissue mat of 30 gms grade was applied to contain
the $poxy layer. The binder coat is air cured for 48 to 72 hours at tunnel
tewrature.
The s y s d was found to be quite effective as no leakage was found in the tunnel even
during heavy rains.

11.10 SPECTRUM OF NEW WATER PROOFING

MATERIALSISYSTEMS
Materials and Systems: A host of water proofing materials and systems have been
spawned fot. a market eager to find a panacea against water infiltration.
Most water proofing systems are designed for application on exterior surfaces, since they
form a barrier to the entrance of water. The walls and floors provide the support system to
counterbalace the hydrostatic head of water. Conversely where reservoirs, tanks or pools
are waterproofed to contain water, the water proofing linings are installed on the water side
of structures for similar reasons. In these instances, the waterproofing is said to be applied
to the positive side or positive face.
However, several waterproofing systems are designed to be applied on the side opposite
the potential source of water i.e., the negative side since the system also have the structural
ability to withstand the hydrostatic head of water.
The prime requirements are that the concrete may have to be impervious to water under
pressure or merely to resist absorption of water. It is doubtful whether there is any really
effective additive which will make concrete impervious. Practice has established that it is
preferable to expend the extra cost of additives to increase richness of mix and thereby
rechicing the water cement ratio. It is possible however to improve resistance of concrete
to absorptioo of water.
Waterproof&rsmay be obtained in powder, pastes or liquid form and can consist of pore
filling matenials or water repellant materials. They can be further subdivided into
chemically active and inert types.
The chief materials in the pore filling class are alkaline silicates notably silicate of soda,
aluminium and zinc sulphates and aluminium and calcium chlorides. These are all
chemically active and accelerate the setting time of concrete thus rendering it more
impervious at an early age.
The chief chlemically inactive pore filling materials are chalk, fullers earth and talc and
these are usqally very finely ground. Their action is chiefly as an aid to workability with a
I
consequent @provement in density and sometimes, they are used in conjunction with
calcium and aluminium soaps. I
Materials in the water repellant class are soda and potash soaps to which are sometimes
added lime, alkaline, silicates or calcium chloride. These are chemically active.
Chemically inactive materials in the water repellant class are calcium soaps, resins,
vegetable oils, fats, waxes and coal tar residues and bihunen Some of these may also act Water & Damp ~
as pore f i g agents.
A number of new products for water proofing is manufactured by various f m . The
names of few finns/manufacturers along with the name of the water proofing product is
furnished below:
1) Lloyed Insulations (I) P. Ltd.
Lloyd Felts - Hessian based bitumen Glass fibre based bitumen.
Polyurethene foam - Roofs, Vessels & Walls Lowest Thermal conductivity
and hence minimum thiclmess. wide tempratme range. (-) 186to llO°C light
weight no structural support. Excellent adhesion. Adaptability to irregular
profiles.
2) FERROSITE co.
Ferroseal - Watei Proofing
Ferngrout -Resin based cements POLY COAT - Single component High
polymer modifed used both for internal and external brush application 200 to
300 micron.
Non toxic - can be used for potable water-tanks.
3) ACRO Construction aids (Ltd),
ACROSEAL - Water proofing compound
ACROFEX - Modified polymer membrane
ACROCOTT - Water proofing sluny
4) Structural Water Proofing Co. P.(Ltd).
CICO AQUAKEM -Water Proofing.
CICO POLYGROUT - Two component
Water based epoxy sealer, membrane coating system both interior and
exterior
5) M.C. BAUCHEMIE (India) P. Ltd.
ROOFEX 2000 - One component modified polymer - free from tar bitumen
& solvent.
Paste like consistency, can be applied on cement surfaces with a brush. Over
one coat of primer primex 250. Can be used as a sandwich product. Because
of flexibility, can be used on arches, domes etc.
6) TERRY Agencies
PLAST FELT - Water proofing
Flexible at row temperatures
Stable at high temperatures
E!ongation 300 to 1000%
7) FOSROC Chemicals P. Ltd. Conplast
Water Proofmg
Polyurethane - membrane coating
Construction Chemicals.
8) ROFFE Construction Chemicals
Construction Chemicals.
%GQ2
i) What are the main types of Water Proofing?
ii) What are the types in surface treatments?
Repair & Preventive
MaintenanceTechniques

Dampness and water leakages in buildingslstructures will cause harmful effects such as
unsightly stains,bad smell, detachment of paint films, wall papers, plasters, corrosion of
reinforcemeets, effluorescence,decay of materials etc. They further cause severe
structural damage to the various components. The treatmentslprevention can be done by
using various integral water proofing and surface treatment materials. Wide variety of
materials available permit the use of specific treatments for any type of condition.

11.12 ANSWERS TO SAQs

SAQ 1
i) Dampness is the presence of moisture in air or on surface or diffused through
solids, whereas leakage in the dripping of water through the poreslvoids.
ii) The causes for dampness are mainly due to bad design and faulty
construction, and poor quality of materials. And also condensation, rain
penetration, spillage, pipe leakage, seepage etc. causes dampness.
iii) At planning design stage, and construction stage.
SAQ 2
i) Integral water proofing and surface treatments.
ii) Tarfelts and polymer sheets, Brick bat Coba, Capillary Crystalization and
Protective Coatings such as Epoxy, Bitumen, Rubberised products, Silicon8
and polyurethanes.