The code offers detailed instructions for waterproofing underground water tanks and swimming pools, emphasizing construction techniques, material selection, and repair methods to guarantee water impermeability. It is aimed at engineering and construction professionals engaged in the design and erection of concrete structures that retain water, preventing both leakage and groundwater intrusion.
Overview
The code offers detailed instructions for waterproofing underground water tanks and swimming pools, emphasizing construction techniques, material selection, and repair methods to guarantee water impermeability. It is aimed at engineering and construction professionals engaged in the design and erection of concrete structures that retain water, preventing both leakage and groundwater intrusion.
Audience
Contents
Structure
This section outlines the extent of the standard, focusing on waterproofing measures for underground water storage tanks and swimming pools to ensure impermeability and prevent leakage. It applies primarily to reinforced concrete structures designed for liquid containment, highlighting the necessity of impervious concrete through appropriate aggregate grading, concrete mix design, and thorough compaction. The section also references key materials standards like IS 5871 for bitumen mastic and IS 269 for cement, and the importance of employing waterproofing treatments such as bitumen felts and integral compounds.
Details the mandatory compliance with IS 3370 (Part 1) for design of concrete tanks and reservoirs, ensuring structural integrity and water-tightness. Emphasizes proper concrete mix, reinforcement detailing as per IS 432 and IS 1786, and the need for adequate cover. Discusses construction joint and expansion joint design, including spacing and detailing, to prevent ingress or egress of water. Includes relevant material specifications and a water-tightness formula for maximum crack width.
Specifies the standards for materials used, including steel reinforcement (mild, medium tensile, and high strength deformed bars) conforming to IS 432 and IS 1786, and cement types such as ordinary, low-heat, slag, and pozzolana cements as per IS 269, IS 455, and IS 1489 respectively. Aggregates must meet grading and physical property requirements in IS 383 and IS 2386. Lists specifications for bitumen-based waterproofing materials including bitumen mastic (IS 5871) and bitumen felts (IS 1322). Highlights workmanship clauses ensuring proper compaction and grading.
Focuses on approved waterproofing methods including membrane waterproofing using bitumen felts and glass fibre reinforced bitumen sheets, chemical injection for sealing cracks, and guniting for extensive leak repairs. Recommends protective brick walls over waterproof layers to prevent mechanical damage. Details specifications for materials and outlines quality control measures including final testing of waterproofing effectiveness. Illustrates typical waterproofing layer arrangement and emphasizes adherence to BIS codes for installation.
Describes crucial construction procedures such as concrete placement, compaction, and curing to achieve imperviousness. Stresses the use of properly graded aggregates and the application of internal vibrators or slow hammering for thorough compaction around reinforcement and embedded elements. Highlights the use of bitumen felts, mastic, and fibre-reinforced bitumen per relevant IS standards. Advises on maintaining water-tightness during construction and conducting regular inspections and defect rectifications.
Specifies testing protocols conducted immediately after formwork removal, emphasizing filling the structure with water and maintaining the water level for a minimum of 72 hours to detect leaks. Advises on preparation steps such as cleaning and sealing before testing, and outlines remedial actions if leaks are discovered. Provides a timeline and flow for testing and repair to ensure the structure’s integrity and compliance with water-tightness requirements.
Outlines various repair techniques according to leakage severity, including cementitious injections, surface treatments, guniting for multiple leak points, and chemical injections for severe crack sealing. Describes the procedures, material requirements, and application conditions for each method. Highlights the importance of integral waterproofing compounds and precautions against subsoil water ingress during structure emptying.
Frequently Asked
The standard recommends flexible and durable waterproofing membranes including bitumen felts conforming to IS specifications, glass fibre tissue reinforced bitumen membranes for enhanced strength and crack resistance, and coal tar pitch with bitumen felts. These membranes must be compatible with reinforced or plain concrete structures and can be supplemented by protective brick walls to improve durability. Proper installation following IS codes is crucial for effective waterproofing.
Construction joints should be positioned perpendicular to the member's length, with surfaces cleaned and roughened if hardened, then coated with a thin cement grout layer before further concreting. Continuous wet curing must be maintained except briefly before joint concreting to allow surface drying. Expansion joints are spaced at a maximum of 35 meters for underground or fully covered structures and 28 meters for partially exposed ones, designed as per IS 3370 (Part 1) with appropriate sliding cover slabs and bitumen felts to avoid leakage.
Concrete should undergo continuous wet curing during the initial days to minimize permeability. Before pouring at joints, remove laitance and loose materials by hacking and wire brushing, then wash and moisten the surface. A thin cement-sand grout layer matching or richer than the concrete mix should be applied without excess water. Proper compaction using vibrators or slow hammering ensures elimination of voids, especially around reinforcement and embedded fixtures. Slight drying of joint surfaces before concreting helps bonding and avoids honeycombing.
Chemical injection is suitable for sealing severe crack-induced leakages, especially in water-logged areas. It can be applied internally at any stage without excavation or backfill removal. After identifying leakage points and dewatering, injection ports are drilled at these locations, and chemical grout is pressure-injected to fill cracks and block seepage. This method is effective when minor treatments fail and allows remediation without dismantling the structure.
Testing is conducted immediately after formwork removal by filling the tank with water and maintaining the level for at least four weeks to avoid drying cracks. All preparatory steps such as cleaning and sealing must be completed before testing. The structure is observed continuously for leaks or dampness both inside and outside. If leakage is detected, remedial treatments like guniting or bitumen mastic application are undertaken. This ensures compliance with water-tightness criteria and early defect detection.
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