CONSTRUCTION CHEMICALS FOR WATERPROOFING IN CONCRETE STRUCTURES GUIDED BY PRESENTED BY DEEPTHY DAS Dr. A K VASUDEVAN S8 CA ROLL NO: 25

INTRODUCTION Permeability is one of the main factors that can affect the durability of the structure. Permeable structures can result for various reasons such as low cement content, poor compaction too much water during concrete mixing etc. The passage of water through cracks ,joints, voids, and inter connected capillaries in the mass concrete makes the concrete pervious, ultimately leads to poor protection of structures, increases the rate of alkali aggregate reaction and also accelerates the rate of corrosion in the steel.

CONTIN………………… The impervious property of concrete can be improved by addition of admixture in the green concrete or by surface treatments and the phenomenon is generally known as waterproofing. The products used in both the stages of concrete are known as construction chemicals or admixtures and waterproofing is one of the aspects in construction aid. These products are required for modifying the properties of concrete or mortar to make them more suitable for the work at hand or for the economy for such purposes are saving energy.

CONSTRUCTION CHEMICAL FOR WATER PROOFING Integral water proofing compounds Acrylic based polymer coatings Mineral based polymer modified coating Chemical DPC for rising dampness Water proofing adhesive for tiles, marble and granite Silicon based water repellent material Injection grouted for cracks Protective and decorative coatings Joint sealants

New Innovative Products Mainly Thermo set Polymer Chemical cross linkage Main characteristics of thermo set polymer are once they are fully cured they can be bonded to like material with an adhesive. The four common sub categories of thermo set roof membranes are Neoprene(CR) Chlorosulfonated Polyethylene (CPSE) Epychlorohydrine (ECH) Ethylene Propylene Diene Monomer (EPDM)

Thermo Plastic Membranes There is no chemical cross linking mainly seven type Poly vinyl Chloride (PVC) Copolymer alloy (CPA) Ethylene Inter polymer (EIP) Tripolymer Alloy (TPA) Nitrile Alloy (TPA) Chlorinated Polyethylene (CPE) Thermoplastic Olefin (TPO)

Types of Integral Water Proofers Water proofing admixtures can be broadly grouped as (a) permeability reducers (b) Water repellents or hydrophobic (water hating) agents. Permeability reducers are pore filling and porosive reducing materials which can be further classified into: (a)very fine particulate matters (b)workability and air entering admixtures (c) accelerators.

PERMEABILITY REDUCERS Ground Sand, lime stone (powdered),slag, colloidal silica, flouro silicates main product Powdered form. Plasticizers and workability agents obviously avoid the presence of large voids and higher water requirements as per their advocated use. The plasticizers generally work by giving better disperation of cement and simultaneously reducing the surface tension of the water/aqueous phase. This results into better wetting and proper hydration reaction at lesser water requirements

water proofers Water repellent coatings, which can be applied on the concrete surface to impart water proofing to the concrete structure. Thermoplastic PU has been used in the water proofing of below grade structures building foundation, basements, reservoirs, ponds, walkways, tunnels, earthen shelters, bridge, abutments, retaining walls, landfills and water canals. Acrylic co polymer emulsion based additive for cement based coatings when mixed with cement gives excellent water proofing, excellent adhesion to concrete substrate, steel, asbestos, excellent resistance to ultra violet rays, excellent breathing properties and helps in reducing corrosion of reinforcement. Styrene butadiene co polymer emulsion have also been used as water proofing coating for concrete, which also increase adhesion strength, chemical resistance and abrasion resistance.

APPLICATION PROCEDURES

METHOD OF THE APPLICATION Cementitious Substrate 

Application of 1st coat of Dr. Fixit New coat   Application of 1st coat of Dr. Fixit New coat

Application of 2nd coat of Dr. Fixit New coat

Application of Dr. Fixit Prime seal

Roller Application of Dr. Fixit New coat

Application of 3rd of Dr. Fixit New coat

Preventive measures New Structures (During Construction) Calculated quantity of BBR Microdite is mixed with the concreting mixture and the percentage is to be decided on the basis of the quality of sand; New roof-Bad quality of sand: Upton 0.6% (300 gms. per bag of cement).Good quality of sand: It can go down up to 0.2% New bathroom-2% New toilet-First coat with 2% & second coat with 20% w.r.t. cement after a minimum time interval of 4 hours or more. Aggregate mixture: 5% Microdite w.r.t. mortar + cement. Fixing of tiles: Using cement paste prepared with 2% of Microdite. 

Continue…………. 4.New water tanks-Either uses the product during construction as a pre-mix or after construction as a coating.  5. Crack filling- In new structures if care is taken to mix BBR Microdite in plastering mixtures, concrete mixtures etc. during construction no problem of crack formation would arise in the future.  6.POP - Suggested dose of Microdite: 2% w.r.t. white cement (100 gms. of Microdite + 5 kgs. of white cement + 5- 6 liters. of water).

Restoration (Cure) of Old Structures 1.Old roof two coat of microditemixture. 2% of microdite. Coverage area 400-500sq.ft 2. Old flooring-Concentration of Microdite mixture for soaking: (1:5:7; i.e.1 kg. of Microdite+5 kg. of cement+7 liters. of water) Percentage of Microdite in cement paste:2% (20 gms. for 1 kg. of cement)

4. Crack – filling Hairline Cracks Hairline cracks get filled automatically when the coating is given in the usual way using Microdite-Cement-Water mixture. Cement can be substituted by synthetic primers to avoid curing. Suggested percentage of Microdite: 2-5 % Bigger Cracks: For filling of smaller cracks, cement paste mixed with BBR Microdite can be conveniently. Microdite: 2 - 5%

THE LATEST TRENDS IN WATERPROOFING The following methods can be used to achieve this: 1.Use of Water tight concrete For any kind of structure and especially for structural elements like foundations, slabs and shear walls, the main aim of waterproofing is to prevent the passage of water through the concrete. Quite simply this can be achieved by blocking the capillaries in concrete. Blocking pores/capillaries in the concrete can be done using the following methods: Using high performance PCE polymers Use of materials like Silica-fume or Aluminosilicate slurries in concrete Use of highly specialized latest generation Integral waterproofing compounds that work on process of Dynamic SynCrystallization (DySC) technology

Figure 1: Mechanism of action for PCE Polymers Using PCE polymers Figure 1: Mechanism of action for PCE Polymers

Use of Condensed Silica Fume or Aluminosilicates in concrete Again it is well-known that Condensed Silica Fume or Aluminosilicates are extremely fine materials that function both as micro fillers as well as pozzolanic materials that hydrate in the presence of the Calcium Hydroxide in Concrete. The combined effect of these materials as micro fillers and hydrating materials help close capillaries in concrete, thereby rendering it waterproof

Using Integral Waterproofing Compounds working by Dynamic syncrystallization Figure shows the progressive refinement of pore volume in concrete by DySCTechnology. This shows that progressive crystallization reduces overall pore volume of the concrete thereby rendering concrete waterproof. Shows progressive pore volume reduction using DySCTechnology Shows pore volume of a product using DySC Technology

2. Liquid Applied Membranes

BASEMENT WATERPROOFING Shovel a trench below the level of your basement all the way down to the concrete footings. Do this around the entire perimeter of your foundation. Apply a Portland cement-based waterproofing seal with a trowel and fill in small cracks or holes in your foundation. Reseal any mortar joints between cinder-block walls. Let the cement dry before proceeding Fill the pump sprayer with the urethane sealant. Saturate the foundation walls with the sealant by spraying it thoroughly with the pump sprayer. This will prevent additional cracking in the foundation. Place a layer of tar paper around the base of the foundation's perimeter.

5. Pour a few inches of washed gravel into the trench 5. Pour a few inches of washed gravel into the trench. Lay out a line of the plastic piping with holes, placing it on top of the gravel. Extend the piping around the perimeter of the foundation. 6. Fill the trench with the washed gravel up to a few inches from the top. This should equal at least 3 feet. 7. Cover the gravel with another layer of the tar paper. Wrap it around the gravel 8.Shovel topsoil over the top of the sheeting. Slope the soil using the shovel and a rake to angle it away from your house.

MARKET SIZE The market size for waterproofing material and compounds is estimated to be around Rs.600-800 cores per annum. Out of this chemical waterproofing will be around Rs.100 cores and the rest comprises of large group of products. With the introduction of newer products like APP modified SBS, EPDM, TPO and PVC membrane the market is ready to grow at a rate of 35-50% in the near future APP/SBS modified membrane has already been accepted as a durable waterproofing system and this enjoys a market share of Rs.250 cores.

CASESTUDY Waterproofing and Restoration Of 8000m2Hyperbolic Parabola Shell Roofs In Nepal Type of the Structure: Framed Type of roofing: Shell (Hyperbolic Parabola) Structure Year of Construction: 1950 Year of Completion: 1956 Year of Repair/Rehabilitation: 2001 Grade of Concrete: M20 Rebars: Mild Steel

Phosphate based rust remover cum passivator RUSTICIDE was used to clean the corroded reinforcement. Alkaline pure acrylic based Corrosion Inhibitor POLYALK FP was used for passivating the reinforcement from further corrosion and to maintain passive layer around the reinforcement. Spalled concrete cover was replaced with Polymer Modified Mortars with a polymer content of 20% in the mix. POLYALK EP which is an acrylic polymer admixture used for bonding and for modifying the properties of normal cement mortar viz. adhesion, impermeability, resistance to attack of ambient conditions, flexural and tensile strengths was used. The modifications with acrylic polymer in the mortar mix minimize the shear development at the interface due to volume change (with temperature and moisture change) and creep.

The expansion joint was filled with wooden planks covered by a metal plate over which a layer of tar felt with 5mm down aggregates was laid. A high performance two polysulphide sealant SUNJOINTSEAL was used in all the expansion joints of the school building. The works were completed in June 2001 and since then, till date there is no major leakage in the structure unlike the earlier scenario and will never be for many years to come either. Waterproofing and structural repair & rehabilitation job undertaken of the Laboratory Higher Secondary School was the first of its kind in Nepal. The rehabilitation techniques using equipment like mechanical stirrer, sophisticated sprays and advanced wire brush cleaners, moisture meter, feeler gauge etc. were new to most of the practitioners from civil engineering

CONCLUSION At present there are about 100 types of construction chemicals available in the market and the range continues to expand as there is constant spree for quality enhancement. In order to enhance the life of concrete structure the use of construction is of great importance. The construction chemicals are basically inorganic or organic materials or minerals, which when added to the concrete admixture enhance the life of concrete imparting them special properties as well result in the delay in the initiation of corrosion of steel rebar. Several construction chemicals are also available for waterproofing which effectively reduce water ingress, avoid water retention in concrete and also help in reducing wetting. Use of nano modified additives is of great help in enhancing the waterproofing of the concrete.  

REFERENCES I.Supradip Das“Emerging trends in construction chemicals and waterproofing” civil engineering &construction review vol: 25 no: 02 feb2012 II.Col Harry Sidhu“The Essentials Of Waterproofing” Civil Engineering &Constructionreview vol :25 no:02 feb2012 III.M.S Shetty Concrete Technology IV.Sunny Surlaker“Waterproofing Best Practices” New Building Material AndConstruction World Vol 17 Issue 10 April 2012 V.Sanjay Bahadur“Waterproofing” New Building Material And Construction World Vol 17 Issue 10 April 2012

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