WATERPROOFING MATERIALS IN BUILDING LIM TZE LIANG UNIVERSITI TEKNOLOGI MALAYSIA

Transcription

1 WATERPROOFING MATERIALS IN BUILDING LIM TZE LIANG UNIVERSITI TEKNOLOGI MALAYSIA

2 UNIVERSITI TEKNOLOGI MALAYSIA PSZ 19:16 (Pind. 1/97) BORANG PENGESAHAN STATUS TESIS JUDUL: WATERPROOFING MATERIALS IN BUILDING Saya SESI PENGAJIAN : 2004/2005 LIM TZE LIANG (HURUF BESAR) mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) * ini disimpan di Perpustakaan Universiti Teknologi Malaysia dengan syarat-syarat kegunaan seperti berikut: 1. Tesis adalah hakmilik Universiti Teknologi Malaysia. 2. Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi pengajian tinggi. 4. ** Sila tandakan ( ) (Mengandungi maklumat yang berdarjah keselamatan atau SULIT kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972) TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan) TIDAK TERHAD Disahkan oleh (TANDATANGAN PENULIS) (TANDATANGAN PENYELIA) Alamat Tetap: 12-1, TAMAN SAKEH JAYA, ENCIK BACHAN SINGH JALAN SAKEH, Nama Penyelia 84000, MUAR, JOHOR. Tarikh: 14/3//2005 Tarikh: 14/3/2005 CATATAN: * Potong yang tidak berkenaan. ** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD. Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM).

3 Saya akui bahawa saya telah membaca karya ini dan pada pandangan saya karya ini adalah memadai dari segi skop dan kualiti untuk tujuan penganugerahan Ijazah Sarjana Muda Kejuruteraan Awam (Pengurusan Pembinaan). Tandatangan : Nama Penyelia : ENCIK BACHAN SINGH Tarikh : 14/3/2005

4 WATERPROOFING MATERIALS IN BUILDING LIM TZE LIANG A report submitted in partial fulfilment of the requirements for the award of the degree of Bachelor of Civil Engineering (Construction Management) Faculty of Civil Engineering Universiti Teknologi Malaysia MARCH, 2005

5 ii Saya akui karya ini adalah hasil kerja saya sendiri kecuali nukilan dan ringkasan yang tiap-tiap satunya telah saya jelaskan sumbernya. Tandatangan : Nama Penulis : LIM TZE LIANG Tarikh : 14/3/2005

6 Untuk insan-insan yang sabar dan sentiasa mendoakan kejayaan ini... iii

7 iv AKNOWLEDGEMENT First and foremost, I would like to extend my heartiest gratitude to Mr. Bachan Singh, as my supervisor during this Projek Sarjana Muda. He gave me the chance to finish the study and with his guidance, the study can finish smoothly. Besides that, his patience and encouragement leads me to complete this study in time. In addition, I would like to thank all the staff from the contractor firms and consultant firms for their kind advice and assistance in giving the information of waterproofing materials in building. Not forgetting my parents and sisters, for their full support and coaching throughout this research. Lastly but not the least, to all my friends for their support, advice and their help when the time I need them.

8 v ABSTRAK Pengkalisan air untuk sesebuah struktur bangunan adalah satu elemen yang kritikal dalam proses merekabentuk dan pembinaan. Oleh kerana kesan air yang akan merosakkan struktur bangunan, pengawasan yang teliti harus diberikan dalam proses pemilihan kualiti bahan-bahan kalis air untuk melindungi bangunan. Bahan- bahan kalis air mempunyai jangka hayat yang lebih pendek berbanding dengan jangka hayat sesebuah bangunan. Peruntukkan yang kurang telah menghadkan penggunaan bahanbahan kalis air dalam perindustrian bangunan. Kajian ini bertujuan untuk mengkaji penggunaan bahan-bahan kalis air, mengenal pasti faktor-faktor yang mempengaruhi pemilihan bahan-bahan kalis air dan mengenal pasti jenis bahan-bahan kalis air yang sentiasa diguna. Sebanyak dua puluh dua borang soal selidik diedarkan kepada golongan profesional yang terdiri daripada arkitek, pengurus projek, jururunding dan kontraktor. Data yang diperolehi akan dianalisis dengan kaedah purata index. Pengetahuan mengenai konsep dan objektif kalis air telah dikaji melalui bab kajian literatur. Membran kalis air akan dipakai di bahagian luaran struktur bangunan dan memerlukan pengorekan tambahan di sekitar asas bangunan. Ini merupakan satu faktor yang mungkin akan menghadkan penggunaannya untuk projek infill dan perbandaran. Untuk bahagian dinding dalam bangunan, bahan kalis air diguna dengan tujuan menahan air dan sistem ini membenarkan air untuk meagalir melalui bangunan sebelum ia ditolak dalam bahagian dalaman. Kesimpulannya, kos adalah faktor utama yang mempengaruhi pemilihan bahan kalis air yang berkualiti dan asphalt adalah bahan kalis air yang sentiasa dipakai dalam industri pengkalisan air.

9 vi ABSTRACT Waterproofing a building structure is a critical element of its design and construction. Because of the damaging effect of water, particular attention should be given in selecting quality waterproofing material to provide the proper in-place performance. Waterproofing material s life is shorter than building s life. Tight budget limits the extensive use of waterproofing in building industry. This study is to study the usage of waterproofing materials, identify the factors involved in decision making to waterproof a building and identify the types of waterproofing materials that we frequently used. The questionnaires were sent to a total of 22 samples from 4 categories of respondents namely the architect, project manager, consultant and contractor. The data is analyzed using average index. The conceptual knowledge such as definition and objectives of waterproofing had been studied through the literature review. Waterproofing membranes are applied to the outside, or "positive" side, of the structure. This requires additional excavation around the foundation, a factor that may limit its use with infill and urban projects. On the other hand, "negative-side" waterproofing, applied to the interior of the wall, is used primarily for water-holding purposes. By design and necessity such systems allow the water to infiltrate the structure before it is blocked from the interior space. The conclusion from the analysis found that cost is the main factor affecting the selection of good waterproofing materials and asphalt is the major material that is used in the waterproofing industry.

10 vii CONTENTS CHAPTER ITEM PAGE TITLE DECLARATION DEDICATION ACKNOWLEDGEMENT ABSTRAK ABSTRACT CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF APPENDIX i ii iii iv v vi vii - ix x xi xiii CHAPTER 1 INTRODUCTION 1.1 Introduction Research background Aims and objectives Scope of study Methodology 4

11 viii CHAPTER 2 LITERATURE REVIEW 2.1 Definition of waterproofing The need to waterproof Problems of waterproofing in building Penetrating damp Hydrostatic pressure Degree of water tightness Requirements by building regulations Waterproofing forms of construction Design requirements and design criteria of 15 waterproof in building Pre-design considerations Application of waterproofing in building industry Positive side waterproofing Negative / blind side waterproofing Nature and characteristics of waterproofing materials Rubberised asphalt sheet membranes Bentonite clay Asphalt Mastic PVC or high density polyethylene (HDPE) sheet membranes Summary 29 CHAPTER 3 RESEARCH METHODOLOGY 3.1 Introduction Data collection Primary data collection Secondary data collection 31

12 ix Data analysis Limitation of the study Expected Result Further recommendation study 33 CHAPTER 4 DATA ANALYSIS AND RESULT 4.1 Introduction Description of data obtained The factors involved in decision making to waterproof a building The types of waterproofing materials that are frequently used 46 CHAPTER 5 CONCLUSION AND RECOMMENDATION 5.1 Introduction An overview of the study Conlusion Consideration of selection of waterproofing materials during design stage Further recommendation study 60 REFERENCE 61 BIBLIOGRAPHY 62

13 x LIST OF TABLES TABLE NO. TITLE PAGE 2.1 Guide pf level of protection to suit basement use (BS 8102:1990) Breakdown of various groups responding Sample item and mean scores Arrangement of relative importance between eight factors Sample item and mean scores Arrangement of relative frequently usage between five materials 54

14 xi LIST OF FIGURES FIGURE NO. TOPIC PAGES 1.1 Flowchart of research methodology 2.1 The best way to avoid water penetration Forms of waterproofing structure classification Positive side waterproofing to foundation walls and basement slabs Negative side waterproofing to interior slabs Blind side waterproofing to foundation walls and basement slabs Bentonite panels can be nailed to concrete foundations and are overlapped at the joints between panels and basement slabs Asphalt used as external tanking applied to face of wall Number of years of the respondents involved in the usage of waterproofing materials Mean of cost by 4 categories of respondents Mean of life expectancy by 4 categories of respondents Mean of site condition by 4 categories of respondents Mean of side of application by 4 categories of respondents Mean of functionality by 4 categories of respondents Mean of ease of application by 4 categories of respondents Mean of protection during construction by 4 categories of respondents 43

15 xii 4.9 Mean availability in local condition by 4 categories of respondents Comparison of total mean Mean of rubberised asphalt sheet membrane by 4 categories of respondents Mean of bentonite clay by 4 categories of respondents Mean asphalt by 4 categories of respondents Mean of mastic by 4 categories of respondents Mean PVC / HDPE sheet membrane by 4 categories of respondents Comparison of total mean of 5 major types of waterproofing materials 53

16 xiii LIST OF APPENDIX APPENDIX NO. TOPIC A Example of questionnaire

17 1 CHAPTER 1 INTRODUCTION 1.1 Introduction Waterproofing a building structure is a critical element of its design and construction. Water may permeate the concrete or masonry barrier of the basement area via capillary action. It is possible that water could enter into the basement at any location, depending on the porosity of the cement and saturation of the exterior sub terrain. Water infiltration and leakage damages a building s structure and its contents. Because of the damaging effect of water, we must pay particular attention in selecting a quality waterproofing material to provide the proper in-place performance. The most common sources of water leakage are through structural defects such as cracks and voids, or through construction and control joints. Below-grade areas are susceptible to fluctuating water tables while horizontal decks are susceptible to ponded water. (Binsacca, R., 1999) Anyone who has had damage from water leakage knows that it is a costly and time-consuming process to repair. An effective and inexpensive way to avoid the problem is through proper design and careful selection of the waterproofing materials.

18 2 1.2 Research background Out of 10 waterproofing works, we found 9 instances that need retrofitting and remedial works. 10 years warranty was given to the building but usually the system meet its failure in the time of 5 years only. (Teh Cheng Eng, Managing Director of Econpile (M) Sdn. Bhd. specialist foundation and civil engineering contractor) Price is the prime concern in choosing a product. Quality and workmanship are also important considerations. Timely delivery and stock availability are important as Malaysia construction projects depend on tight schedules. Seventy percent of waterproofing material sells directly through agents or distributors to end users who are architects, contractors and developers. (Binsacca, R., 1999) I ask early if the owner willing to pay $2 per square foot for a basic waterproofing system. If not, damp-proofing around 80 cents a foot. Architects want to extend the life of the building and serve clients as best they can but $2 a foot sometimes a hard sell. (Hardwood, T., 1998) In most cases, waterproofing membranes are applied to the outside, or positiveside, of the structure. This requires additional excavation around the foundation, a factor that may limit its use with infill and urban projects. Negative-side waterproofing, applied to the interior of the wall, is used primary for water-holding purposes, though it is increasingly called upon when positive-side waterproofing is not possible. By design and necessity such system allow the water to infiltrate the structure before it is blocked from the interior space. (Binsacca, R., 1999) Under normal conditions, architects appreciate the standardisation of off-theshelf waterproofing specs, which free from the detailing the system on paper. Bituthene or equal is a typical spec for architects simply looking for language to plug into the spec sheet. (Binsacca, R., 1999)

19 3 Lolly columns that pass through a basement floor slab and conduits that pass through foundation walls will result in a natural path for water seepage. A waterproof bond between the concrete or masonry and a dissimilar material will rarely exist. The foundation and basement are surrounded by soil, water can leak or seep into a building through cracks or holes, or through mortar between blocks. ( The statements mentioned above can be summarised as: i. Waterproofing material s life is shorter than building s life ii. Tight budget limits the extensive use of waterproofing in building industry iii. Infill development and urban projects limit the use of positive-side waterproofing Therefore, this research topic is aimed to provide a better and more scientifically based understanding of the role of waterproofing materials to assist the prevention of moisture from penetrating sub-grade walls and slabs. The significance of the research topic is to provide a review of the development of waterproofing materials in implementing waterproofing system in building industry with some case study reference in the current market in Malaysia. 1.3 Aims and objectives The study has set the objectives as follow: i. To study the usage of waterproofing materials ii. To identify the factors involved in the selection of waterproofing materials iii. To identify the types of waterproofing materials that are frequently used

20 4 1.4 Scope of study This study focuses on: i. A questionnaire was prepared to elicit responses from participants in Klang Valley to gauge how strongly they felt about certain factors or issues. ii. The main group headings were identified, consisting of the architect, the project manager, the consultant and contractor from contractor firms and consultant firms in Klang Valley. 1.5 Methodology This section gives a brief summary of methods used when conducting the research / study. Different methodology was used to accomplish and achieve the objectives of the dissertation.

21 5 LITERATURE REVIEW IDENTIFY TITLE OF STUDY IDENTIFY OBJECTIVES AND SCOPE OF STUDY PRIMARY DATA SECONDARY DATA QUESTIONNAIRE CONTRACTOR CONSULTANT REFERENCES, ARTICLE, MAGAZINE, NEWSPAPER, JOURNAL, INTERNET, ETC DATA COLLECTION DATA ANALYSIS CONCLUSION/ RECOMMENDATION Figure1.1 Flowchart of research methodology

22 6 CHAPTER 2 LITERATURE REVIEW 2.1 Definition of waterproofing According to Cambridge International Dictionary of English, waterproofing can be defined as treatments to surface with a substance, which will prevent water from going through it. Waterproofing means that no openings are present that permit leakage or passage of water and water vapour; the material is impervious to water and water vapour, whether under pressure or not. Waterproofing prevents the entrance of water that is under pressure by forming a continuous membrane around walls, through concrete footings and under concrete floor slabs. (Merritt, F.S. & Ricketts, J.T., 1994 : 3.16) 2.2 The need to waterproof Waterproof materials effectively prevent the entrance of water in any portion of a structure that is below grade, walls must be designed to resist lateral pressure and floors must be designed to resist upward thrust. Waterproofing provides protection against penetration through the exterior enclosure of buildings of groundwater and rainwater.

23 7 Water may leak through cracks, expansion joints or other openings in walls and roofs, or through cracks around windows and doors. Also, water may seep through solid but porous exterior materials, such as masonry. Whether thrust against and into a building by a flood, driven into the interior by a heavy rain, leaking from plumbing, or seeping through the exterior enclosure, water can cause costly damage to a building. Consequently, designers should protect buildings and their contents against water damage. The water proof membrane must prevent the water from entering pores and voids in the structure of building Problems of waterproofing in building Buildings, after all, are essentially climate filters: for people, their belongings, their goods and their accessories. They provide a variety of functions in terms of shelter for protection and privacy, and an enclosure of space, as well as being climate barriermodifier. (Oliver, A., 1998 : 219) Building can also be considered as a third skin (Holdsworth & Sealey, 1992). The first skin is our own skin; our clothes comprise the second skin. The building skin is meant to keep us warm in the cold and cool in the hot as well as dry in the wet. Unfortunately, because they are relatively crude structures, buildings often do not perform as well as expected. It is not surprising therefore that one of the crucial technical performance indicators of any building is its ability to resist leaks. Next to structural adequacy, water exclusion is probably the most important requirement of any building.

24 Penetrating damp One of the major problems with penetrating damp is that the source of a leak may be in a different place from where it is manifesting itself. Thus tracing a leak can often be difficult and time-consuming. The effects of penetrating damp are primarily chemical, physical and electrical: Chemical: loss of adhesion; sulphate attack resulting in cracking of finishes; efflorescence, rusting and corrosion of unprotected metalwork Physical: water staining, streaking and damage to finishing; saturation of furniture and soft furnishings; differential moisture movement of finish or background Electrical: damage to electrical circuits and switchgear may be rendered unsafe Hydrostatic pressure Hydrostatic pressure will force water into the pores of masonry or concrete surfaces where it can chemically attack cementitious materials and cause them to deteriorate. Static water will exert a pressure of 2990 N/m 2 of wall or floor surface plus 20.6 N/m 2 for every foot below groundwater table or the surface of seawater, rivers, or lakes Degree of water tightness It is fundamental to the success of any belowground structure that the designer and the client have a clear understanding of each others requirements and limitations. The designer should explain to the client the options of various grades and the cost

25 9 implications of increasing performance level requirements. The client, on the other hand, must share with the designer his expectations on the use to which the building will be put, whether there are any acceptable limitations on this use and the extent to which the financial emphasis will fall upon either initial cost or future maintenance. The following checklist may provide a useful framework for designer / user discussion: a. The consequences of any leakage or condensation or dampness b. The feasibility and form of remedial works c. The scope for testing during construction d. The risk of aggressive groundwater penetrating inadequately water-tight construction and causing damage e. The risk of changes to the surrounding groundwater regime f. The need and / or ability to incorporate movement joints within the structure g. The need or ability to provide particular floor or wall surface treatments in response either to the users wishes or to meet some risk of perceived by the designer h. The impact of the chosen waterproofing material and the consequential risk attendant upon less than adequate workmanship The balancing of cost against risk in choosing whether construction cost or future maintenance cost will assume priority or in choosing whether the building contract will place greater or less emphasis on a performance requirement Requirements by building regulations The constructional requirements of Uniform Building By-Laws 1984 (Amended 1999), Part IV Constructional Clause 84 states that:

26 10 (1) Suitable measures shall be taken to prevent the penetration of dampness and moisture into a building. (2) Damp proof courses where provided shall comply with BS 743 (materials for Horizontal D.P.C.). (3) Every brick or masonry wall of a building founded on strip footings shall be provided with a damp proof course which shall be a. At a height of not less than 150 millimetres above the surface of the ground adjoining the wall; and b. Beneath the level of the underside of the lowest timbers of the ground floor resting on the wall, or where the ground floor is a solid floor, not higher than the level of the upper surface of the concrete or other similar solid material forming the structure of the floor. (4) Where any part of a floor of the lowest or only storey of a building is below the surface of the adjoining ground and a wall or part of a wall of the storey is in contact with the ground a. The wall or part of the wall shall be constructed or provided with a vertical damp proof course so as to be impervious to moisture from its base to a height of not less than 150 millimetres above the surface of the ground; and b. An additional damp proof course shall be inserted in the wall or part of the wall at its base. (5) Where the floor or any part of the walls of a building is subject to water pressure, that portion of the floor or wall below ground level shall be waterproof.

27 11 Water-rain or building run-off Gravel backfill Soil Foundation wall High water table Water enters the wall system and spreads through the naturally-occurring voids and cracks Eventually moisture fills the voids in the wall system and reaches the interior surface either as seeping water or excessively moist, damp air During periods of higher-than-normal ground water levels, water will apply pressure against the structure in all directions, including upward from beneath the floor slab. Water enters through the floor cracks and floor slab perimeter joints Floor Perimeter drain system Normal water table Base Footing Water-rain or building run-off Soil Water and moisture are prevented from entering the wall system cracks and voids by the installation of a waterproof membrane adhered to the exterior surface Foundation wall A fabric-faced drainage composite protects the membrane High water table Installing a waterproofing membrane system beneath the structural floor slab provides complete protection for the entire underground structure even during periods of higher-thannormal ground water Floor Gravel fill at perimeter drain system Normal water table Mud slab Footing Figure 2.1 The best way to avoid water penetration is through proper desigcareful selection of the waterproofing system (Source: Grace Construction Products, 2004)

28 Waterproofing forms of construction BS 8102:1990 Code of Practice For Protection of Structures Against Water From The Ground contains recommendations for either minimising or preventing the entry of water to the inner surfaces of buildings and identifies three different types of construction. These are set out below and illustrated in figure. Tables relate form of construction to performance for different uses. a. Type A (tanking protection). Constructed from concrete or masonry and offering no protection against the ingress of water and water vapour by the nature of its design. Protection is therefore totally dependent on a continuous barrier system applied to the structure b. Type B (structurally integral protection). Designed and constructed in reinforced or prestressed concrete either to BS 8110 (to minimise water penetration) or to BS 8007 (to prevent water penetration) dependent on the chosen grade of building use. Transmission of water vapour may not be wholly prevented c. Type C (drained protection). Constructed from structural concrete (including diaphragm walls) or masonry to minimise the ingress of water. Any moisture which does finds its way into the building is channelled, collected and discharged within the cavity created through the addition of an inner skin to both walls and floor. Vapour transmission may be prevented by ventilation of the cavity and by providing an effective damp-proof membrane over the under drained floor. For those seeking maximum assurance this combination of construction and waterproofing is considered the most effective and trouble free.

29 13 Table 2.1 Guide pf level of protection to suit basement use (BS 8102:1990) Grade Basement usage Performance Forms of construction level 1 Car parking; plant rooms Some seepage Type B. reinforced (excluding electrical equipment); workshops 2 Workshops and plant rooms requiring drier environment; retail storage areas 3 Ventilated residential and working areas including offices, restaurants etc., leisure centres 4 Achieves and stores and damp patches concrete design in tolerable accordance BS 8110 No water Type A. penetration but Type B reinforced moisture vapour concrete design in tolerable accordance with BS 8007 Dry environment Type A. Type B with reinforced concrete design to BS 8007 Type C with wall and floor cavity and DPM Totally dry Type A. requiring controlled environment Type B with reinforced environment concrete design to BS 8007 plus a vapour proof membrane Type C with ventilated wall cavity with vapour barrier to inner skin and floor cavity with DPM

30 14 Structural wall Floor finish Concrete base slab Hardcore Type A (tanked protection). The structure itself does not prevent water ingress. Protection is dependent on a total water or water and vapour barrier system applied internally or externally Type B (structurally integral protection). Example of a detail of a concrete structure designed in accordance with BS 8007 to be no waterproof but or vapour proof. An external or internal vapour proof membrane could be applied External wall Drained cavity (ventilated Drained tiles Concrete base slab Interior wall Damp-proof membrane Screed Type C (drained protection). The drained wall and floor construction provides a high level of safeguard. Provision of a ventilated cavity and horizontal damp proof membrane prevents moisture ingress Figure 2.2 Forms of waterproofing structure classification (Source: BS 8102:1990)

31 Design requirements and design criteria of waterproof in building A quality waterproofing system consists of three key elements: a. A waterproofing membrane which prevents the passage of liquid water in the presence of hydrostatic pressure b. A prefabricated drainage composite which protects the membrane while reducing hydrostatic pressure c. Accessory products which compliment, attach and detail the waterproofing and drainage courses Pre-design considerations Before any design is carried out for building works below ground level a thorough site investigation should be made including the exploration of water levels. Almost all basement structures are likely to be subjected to water pressure at some period of their life. Even when the site examination indicates dry conditions, the risk of waterlogging at some future time should be considered. In permeable subsoil groundwater requires time to drain away and if there is a pump failure, working space around basements under construction can soon become inundated with surface water. It is, therefore, recommended that basements should included provision for resisting a pressure equivalent to 1 m head of water at least. 2.5 Application of waterproofing in building industry The problem of water intrusion into a structure can be addressed via three general avenues:

32 16 a. Positive side waterproofing: waterproofing systems should be placed on the same side of the structure as the source of the water. This is known as positive side waterproofing. Placing the waterproofing on the positive side prevents water from passing through the structure. This protects structural elements from damage due to water infiltration b. Negative side waterproofing: some new structures, and many existing ones, have waterproofing placed on the inside or negative side of the structure. These systems may prevent water intrusion into the interior of a structure, however they allow the damaging effects of water to continue unabated within the structural members c. Blind side waterproofing: in some instances it is impossible, economically or practically, to waterproof the positive side of a structure after the concrete has been poured. This includes under slabs and against foundation walls cast against soil retaining systems such as timber lagging. However, waterproofing systems may be installed on the positive side before the concrete structure is poured. This technique is known as blind side waterproofing and requires specially designed systems to provide proper waterproofing Positive side waterproofing The advantages of placing the waterproofing material on the outside face as shown in figure are that the structure itself provides the necessary resistance against the pressure of water on the material and that the material keeps the water out of the structure. Faults due to poor workmanship or to settlement are, however, difficult to locate and remedy, because the point at which the water enters the internal face may be a considerable distance away from the fault in the material. In spite of this the advantages of the external membrane are such that it is usual to adopt this method in all new buildings.

33 17 The material to the floor is laid on a blinding layer of concrete and is usually protected immediately by a fine concrete screed. The concrete floor slab which is then laid must either be thick and heavy enough to resist the upward pressure of any subsoil water or be suitably reinforced to fulfil the same function. The vertical material to the walls should be protected externally by a protective skin. This is usually brickwork, but the requirements of the job may necessitate the use of thin in-situ reinforced concrete or precast concrete walling. The material may be applied either direct to the retaining wall or to the protective skin, according to the circumstances of the job. When working space is available behind the wall, the wall is first built and the material then applied direct to the face of the wall which, if of brickwork, should have the joints raked out to form a key. If of concrete, it should be treated in some way to give a rough surface for the same purpose. Where possible the excavation on the outside of the wall should be sloped back to avoid the use of timbering, but if strutting is essential this must be arranged so that the position of the struts can be changed to permit the material to be applied at the strut points. The protective skin would most suitably be brickwork built up as the installation of the material is carried out, so that the struts may be repositioned to bear on the brick skin and thus avoid possible damage to the material. When no space at the back of the wall is available, for example in underpinning work or on a confined site where the basement extends to the boundary of the site, the material is applied to the protective skin. In these circumstances, temporary support to the soil face behind the protective skin must be maintained until the new retaining wall has been constructed, and the waterproofing work must be carried out in short lifts as each section of the wall rises. In the case of a reinforced concrete wall which is cast direct against the material, care must be taken that the material is not damaged or pierced by reinforcing bars or tamping rods. In some circumstances when the basement wall is of concrete, even when working space is available behind the wall, it may be cheaper to build up the brick skin

34 18 as a thin, self-supporting wall, stiffened by piers at intervals, to which the material can be applied. The concrete wall can then be cast between the protective skin and inside formwork. Surface treatment Drainage or protection Drainage or protection Waterproofing membrane Mud slab Surface treatment Aggregate Concrete Termination Reinforcement Reinforcement Fillet Figure 2.3 Positive side waterproofing to foundation walls and basement slabs (Source: Grace Construction Products, 2004)

35 Negative / blind side waterproofing Application of the waterproofing material to the inside face of the structure is largely confined to existing buildings where it would normally be required as a dampproofing measure rather than as a tanking against water under pressure. When used as tanking, it gives no protection to the structural elements and there is the danger that the membrane may be forced away from the surfaces, by water pressure, unless it is adequately loaded. These loaded coats will reduce the usable volume within the basement. But, in certain circumstances, as for example in large deep town centre basements, access to the external face of the perimeter wall is not possible and site restrictions make high standards of workmanship difficult to achieve or the chosen method of construction may be such that watertightness cannot be assumed, for example diaphragm or contiguous piled walls particularly at the junction of the base slab and the wall, in either of these case, complete watertightness may be neither economically nor practically possible for installation of positive side waterproofing and the designer, after establishing the intended use or possible future use of the basement areas, should adopt the negative / blind side waterproofing method. Service pipes and drainpipes must often pass through the tanking and some provisions must be made to prevent water entering at these points. The usual method when the water pressure is not high is to form a sleeve round the pipe and extending an equal distance on both sides of the line of the tanking.

36 20 Termination Drainage or protection Fillet Surface treatment Waterproofing membrane Concrete Figure 2.4 Negative side waterproofing to interior slabs (Source: GraceConstruction Products, 2004) Soil Termination bar Soil retention system (timber logging) Waterproofing membrane Drainage composite Steel solder pile One-sided wall framing system Concrete slab Compacted soil or mud slab Waterproofing membrane Figure 2.5 Blind side waterproofing to foundation walls and basement slabs (Source: Grace Construction Products, 2004)

37 Nature and characteristics of waterproofing materials Waterproofing materials providing protection against penetration of water under hydrostatic pressure and water vapour. To resist hydrostatic pressure, a membrane should be made continuous in the walls and floor of a basement. It also should be protected from damage during building operations and should be laid by experienced workers under competent supervision. Most of the materials come with accessories, including fasteners used to apply sheet membranes, surface-preparation solutions, and slender tapes used to waterproof tight areas, corners, or seams. There are several important elements to consider when selecting a quality waterproofing material. A quality waterproofing material should provide: a. Full-adhesion to substrate: waterproofing systems should be fully-adhered to the structural substrate to prevent the lateral migration of water between the waterproofing material and the substrate. A fully-adhered system will localise water entry into the structure if a leak develops. Otherwise, water will migrate freely within the system making it difficult to determine the source of the leak b. Factory-controlled uniform thickness: waterproofing systems should be manufactured in a factory-controlled environment to ensure a consistent uniform thickness. Variations in thickness may lead to variable performance c. Flexibility over cracks: waterproofing systems should be flexible enough to withstand typical substrate movements under a wide range of temperature and environmental conditions d. Resistance to high hydrostatic pressure: waterproofing systems should have the ability to bridge substrate cracks while under high hydrostatic pressure to avoid rupture and leakage

38 22 e. Positive drainage and protection of the waterproofing: a quality system should include prefabricated drainage composite to both protect the waterproofing from damage and to minimise hydrostatic head pressures f. Complete system approach: the components of the waterproofing system should be provided by a single manufacturer to ensure complete system compatibility and performance g. Ease of application: the waterproofing system should be easy to install at the job site. A simple installation will minimise applicator error. Also, the system should be able to be covered immediately to avoid damage and eliminate job site delays h. Chemical resistance: waterproofing systems should be resistant to chemicals which may originate from sources within and around the building structure. Chemical exposure may lead to premature deterioration of the waterproofing system i. In-place testability: waterproofing systems should be tested for watertightness prior to placing the overburden, particularly on horizontal decks. Flood testing is the most common method on horizontal decks. Walls may be visually inspected j. Track record: the waterproofing system should be proven by time k. Corporate support: the waterproofing system should be backed by a company dedicated to the industry and which provides quality products and a high level of service to all those involved in the construction process Rubberised asphalt sheet membranes The self-adhering rubberised asphalt membrane is the most commonly used waterproofing material (Teh Cheng Eng, 2004). This membrane forms a tough, flexible, thick and waterproofing material. Its rubber-like properties provide a self-healing characteristic which help ensure waterproofing integrity.

39 23 It is an elastomeric sheet membrane designed to waterproof masonry, concrete and wood surfaces, vertically and horizontally, above and below grade. The membrane is cold applied to a primed surface and when firmly pressed against the primer will adhere tenaciously to the substrate to assure water will not migrate beneath the membrane in the event of physical damage. This material is formulated for application on dry, cured concrete walls and when the temperature is above 40 F. That means the membrane may not be applied for up to as many as 30 days after the concrete is poured, depending on the speed at which the concrete cures (dictated by outside temperatures and the nature of the concrete mix). Once the forms are stripped away, the surface accepting the membrane must be made smooth and monolithic to prevent spalls, tie wires, honeycombs or other irregularities from interrupting the membrane s continuous seal. This additional step further slows the protected construction schedule and adds cost. Once laid, the membrane must be protected from direct sunlight, rain and other environmental conditions which degrade it until the backfill, wearing slab or other covering is provided. Special primers and formulations are increasingly available for colder conditions, as well as for use with unusual soil conditions. But for the most part, the membrane is best reserved for moderate climatic conditions and on smooth surfaces Bentonite clay Bentonite, technically referred to as sodium bentonite, is a clay formed from decomposed volcanic ash, with a high content of the mineral montmorillonite. The clay is mined, dried, ground, and sized to provide a finely divided, free-flowing material that will swell to form a waterproof barrier the consistency of heavy grease when in contact with water. It can absorb large amounts of water, which causes it to swell many times

40 24 its original volume, forming a waterproof barrier. The dried, finely ground particles are usually applied as a waterproofing membrane in three ways: a. Bentonite panels Panels consist of a biodegradable paper covering over bentonite clay particles. It is used on vertical walls and under structural slabs. The panels are ready to apply when received on the job and can be applied at all temperatures and over moist substrates. They can be nailed to green concrete walls. A hydrated sodium bentonite gel is used to fill gaps around pipes and fittings. If the backfill contains rocks that may pierce the panels, they should be covered with a protective material. b. Sprayed bentonite One method consists of spraying the clay mixed with a modified asphalt which acts as a binder adhering the clay to vertical surfaces. The standard membrane is built up to 9.5 mm with a clay content of 7.32 kg/m 2. One advantage of the sprayed-on system is that it will stay in place fir several weeks before backfilling is started. c. Bentonite-sand mixture Bentonite clay mixed with sand is used for waterproofing the underside of a horizontal concrete slabs on grade. The mix is carefully measured and spread over the area to be covered with concrete. It is then covered with a polyethylene sheet to protect it from the moisture in the concrete. The reinforcing is placed on top and the slab is poured. If too much bentonite is used, damaging up-lift forces may be created when water contracts the mixture and the clay expands could crack the slab. Bentonite panels enclosed between layers of geotextiles are the most practical and expensive version of the product since the carpet-like sheets are difficult to puncture and are flexible enough to go up over lagging and other uneven surfaces. But, the cardboard that encases some panelized versions will degrade over time, causing the bentonite to erode and leaving the walls completely exposed.

41 25 Bentonite s chief advantage is that it can be put over a concrete surface almost immediately after the forms are pulled, which helps speed the construction schedule. It also does not have the climatic limitations of rubberized asphalt, though the material or cardboard panels should not be exposed to rain or snow. The disadvantage of bentonite is somewhat permeable, allowing moisture vapor to migrate through walls and condense on interior surfaces. The vapor can cause damage and odor over time. Concrete foundation Bentonite panels Figure 2.6 Bentonite panels can be nailed to concrete foundations and are overlapped at the joints between panels (Source: William P.Spence, 98)

42 Asphalt Asphalt is a bituminous found in many parts of the world and is a smooth, hard, brittle, black or brownish-black resinous mineral consisting of a mixture of various hydrocarbons. Asphalt can be hot / cold-applied to the structures by brush, roller or spray. These are effective only for situation in which hydrostatic pressure is not a factor. A waterproofing system that will resist hydrostatic pressure consists of alternate layers of hot mopped asphalt over layers of mineral or glass fibre felts in much the same way as laying a built-up roof. The number of layers of felt and asphalt depends on the hydrostatic conditions. Manufacturers of these systems have established specifications for various conditions. Liquid asphalt has two major advantages over its competitors: it is highly elastic, allowing it to bridge cracks and accommodate movement, and it embodies "self-healing" properties, meaning the material will ooze around and seal a puncture from a nail or sharp object. Applying two layers, with a sheet of fibrous matting in between, creates a stronger barrier. Asphalt is most suited to a horizontal application since the hot liquid, mopped onto a vertical surface, can drip, posing a safety hazard.

43 27 Protective skin of brickwork Concrete can be hacked or covered with spatter dash to provide key for asphalt 20 mm vertical asphalt in three layers 2-coat angle fillet 30 mm horizontal asphalt in three layers extended to ensure proper junction with vertical asphalt Figure 2.7 Asphalt used as external tanking applied to face of wall (Source: Foster,1995)

44 Mastic Mastics are urethanes modified with various polymers to make them flexible. It is dispensed from a caulking gun with sort of clay-like consistency. There is a variety of solvent-based mastic waterproofing compounds. They are available as a thick mastic, a semisolid mastic and a spray mastic. They give waterproofing properties to interior and exterior above-grade and below-grade surfaces. They are used on metal to prevent corrosion. These are cold-applied, usually by rolling or troweling them onto the surface. They dry to create a hard surface, often eliminating the need for protective board. Mastics are easy to apply, but there is evidence that they become brittle and lose their effectiveness more quickly than asphalt. Both types of fluid membranes are suitable for rough surfaces and tough-detail areas, such as tight interior corners, penetrations, and other conditions that are difficult for sheet membranes to accommodate. But while the thickness of a sheet membrane is factory-controlled, spray-and trowel-applied systems rely on the installer to achieve the desired thickness PVC or high density polyethylene (HDPE) sheet membranes This membrane is a composite sheet consisting of PVC / HDPE, adhesive and coating. It can be used in all horizontal sub slab and below grade split slab positive side waterproofing where concrete is cast directly against membrane. The membrane can be fixed directly to plaster or brickwork using plastic fixing plugs. PVC is a high polymer resins and not affected by aging, mildew or corrosion. It remains flexible at low temperatures and has good abrasion and tear resistance. It is bonded and laps are sealed with a special adhesive. Some forms of PVC membrane can

45 29 be formulated to be resistant to gasoline and oil. The seams can be welded with hot air or bonded with an adhesive specified for that purpose. The single-ply sheets, including PVC and high-density polyethylene are less common usage in the industry. That's because the materials and their application is expensive, especially if there are a lot of details or horizontal-to-vertical transitions to coax the sheets through. In most cases seams must be heat welded, though installation varies. 2.7 Summary Recent regulatory policies have banned or severely limited the use of solver based waterproofing products, including mastics and primers used prepare the foundation for waterproofing. Land-use covenants and infill urban sites often restrict excavation or the ability to install standard, positive-side systems. Tight budgets and construction schedules may discourage the use as well. All these factors have caused a shift in the industry toward new products for special conditions, a variety of primers, sealants and other compounds to ease application and non- or low-voc mixtures to meet the environmental standards and reduce odor and flammability.

46 30 CHAPTER 3 RESEARCH METHODOLOGY 3.1 Introduction This study identifies the factors that are related to decision in selection of waterproofing materials. The conceptual knowledge such as definition and objectives of waterproofing had been studied through the literature review. The comparisons have made among five major categories of waterproofing materials and some recommendations had been made to implement the usage in building industry. This section gives a brief summary of methods used when conducting the research / study. Different methodology was used to accomplish and achieve the objectives of the dissertation. 3.2 Data collection Primary data collection Questionnaire will be carried out on different architects, project managers, contractors and consultants in Malaysia. Respondents are required to give their opinion

47 31 on the statements by indicating whether a particular statement is very important, important, less important or unimportant/irrelevant. They are also required to indicate their occupational background. Non-random sampling will be used in this questionnaire Secondary data collection Desk studies will be throughout the preparation of the dissertation. The resources of the desk studies would be the books in the libraries, articles from magazines as well as the World Wide Web (www). The literature reviews will also be used as to elaborate some conceptual theories and waterproofing problems as well as solutions in building industry in Malaysia Data analysis The data collected from the questionnaire will be analysed via computer package Statistical Package for the Social Science Programmes (SPSS). The answered questionnaire will then be checked to ensure it has been completed. Subsequently the data will be coded and entered into the programme for processing. The analysis technique will be carried out by using average index (mean, standard deviation & percentage). Descriptive statistic will compare the mean score within the different category. The findings of the research will be discussed in the form of table, graph and explanation in the following chapter.