UNIT 11 WATER AND DAMP PROOFING

Structure 11.1 Introduction Objdvea 11.2 Principles of Water Proofing 11.3 Procedure for Damp Proofing~ 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 WinStage 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 Surface Treatments 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 Hm- 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 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 , , 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.

112 PRINCIPLES OF WATER PROOFING Most of bebuilding 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 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.

113 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 fhofmoisture 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, papers, plaster, timber, ceiling plaster are indicative signs of dampness. Displacement of parapets, wall , floor tiles and cracking of glass dwalls, 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 & ~~mp~~ooting 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 fm gravel,m., sandy soil or a soil containing light clay, will usually keep the foundations fairly In coastal towns 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 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 structure during ,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 I unoccupied new buildings, this effect is felt more. The problem may, however, disappear 1 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 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 I 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 Msintenaoce Techniques 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 Qroof111g problems 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 Ma 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) Quality of Workmanship: The materials used in construction such as stone aggregate and sand should be free from defects. The quality of workmanship in I masonry, concreting, plastering etc. should be well controlled and supervised. 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 I 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 sometimes be 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 than 40 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 mm 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 mSsdoorways 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 ndconditions. 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 150 mm 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. Pmus concrete attracts moispe from wet soil. Even dense cement concrete Wedwith 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 raiu that 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$h pointing will offer a good protection. Sometimes the soffits of all horizontal courses are slightly throated. Cavity walls afford sound protection and ensure a dry interior even if mow material is used for outside. The application of a porous rendering on the external surface will do much to prevent direct penetration. A porous finish will absorb water in wet weather and will permit free evaporation when the weather improves. A dense impeqious rendering is less efficient than a porous one as it will more effectively prevent moisture drying out rather than prevent it getting in, and is also more liable to crack A porous rendering is less liable to crack and will not cause the entrapment of moisture within the wall. An external treatment unless it is porous will also be liable b aggravate dampness if it is due to raising ground moisture, indirect penetration of rain or due to diliquescent salts. A mortar of cement: 1ime:sand in the proportiom of 129or 1: 1:6 is usually recommended. a) Efflorescence: Where soluble salts are present in excessive quantities in the bricks or the moftar they absorb moisture either from the air or water during cmbruction. These are brought to the surface in solution and deposited in concentrated patches either as a white powder or as translucent crystals, as the moisture dries out. Tbis crystallbe growth either flakes off or is reduced to a powder which can be brushed off. Attempts to seal back efflorescence are not usually successful and it is advisable to allow tl$e efflorescepce 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 atin 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 ,.-'": Smds over all window and door openings instead of simple sun-shades. 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 executed junctions 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 I Repair & Preventive Techniques b) The damp plaster may be varnished over with a solution 120 grams shellac Maintenance dissolved in 1 litre 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) vatis the difference between dampness and leakage ? ii) What are the cailses for dampness ? iii) hat 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 anmake 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 Pmohg WATER PROOFING r-+ INTEG~L SURFACE TREATMENTS

I ~ermeabili~ 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 1 to 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 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 transverse joints 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 shortcomings of 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 generad y 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 reinfad 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/Laminates and 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 concretelplaster is 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) Polyurethane coatings 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 specifications to 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 rbpe

I kakages and dampness Mftclcnt drainage I oaur here avo~drleakages

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 aw~drmter of slab stagnattng levelled

after the&~"s - have stopped

' lncorrect Correct c) Proper construction of parapet wall. Water & Damp I'rclofi~rg

Col.for future expn. PC Cop~ng to be frn~shedIn cerr

and beams

('arrccl figure 113 d) Proper casting of terrace slab.

B K BAT COBA laid ,It0 proper slope seepage through Damntss face on the wall h'

e) Proper orientation of rain water down take pipe.

Parapet v(l" -FKColum~--l- --- belowWall I I Terrace L---- 1--1 RWDown-i takepcpe ; I .! crowed pcpc n dlitliG~t io mtnlacn and gels 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 pr

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

Load bcarlng wIIAu Dampness and fungus Incorrect gmwfh noticed on wall Correct

Flpm 11.7 h) Roper casting of verandah slab.

lncorreet Correct Rpre 11.8 i) Leakages through water closets.

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

Rpre 11.9

j) Ropr connection of toilet blocks.

M-:RCC Wall Proper connection of nahani trap. Water & Damp Proofing

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

Leakage through joint between wall plecc and Long G - hahanl r1a ht angle bend trap Incorrect Correct (a) Figure 11.11 Sinks and wash basins.

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

Copper plate l5mm lbmmth~eklead flqshlng \ f lred on one side only fborlng CCBA

Lt.w.~atten fcred on one scde only

Concrete cgp slldlng /suffe~entl~at top

cbcm th~cktl'oorlng f B B CCBA CC Slab

L T.W. Plate flied 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 fished 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 ad2 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 construction joints. 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 wterprooflweatherproof compound 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 i3 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 undergmd 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 construction joints 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 effective key 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

~Borrhd- - Pnrcnt lkitment PIgon lLl5r ~JmdamAlrTnaads 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 come 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 ,where exposure 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-and vapour 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 construction joints, 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 Maintenance Techniques 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 sysdwas 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 consequent @provement in density and sometimes, they are used in conjunction with I 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 figagents. A number of new products for water proofing is manufactured by various fm. 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. (-) 186 to 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 Maintenance Techniques 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.