IRC 72 (1978) outlines best practices for utilizing, operating, and maintaining machinery, instruments, and devices essential in bituminous pavement works. It addresses an array of equipment such as rollers, bitumen heaters, manual mixers, paver finishers, transport vehicles, and inspection tools, crucial for civil engineers and contractors to optimize performance and durability of road construction equipment.
Overview
IRC 72 (1978) outlines best practices for utilizing, operating, and maintaining machinery, instruments, and devices essential in bituminous pavement works. It addresses an array of equipment such as rollers, bitumen heaters, manual mixers, paver finishers, transport vehicles, and inspection tools, crucial for civil engineers and contractors to optimize performance and durability of road construction equipment.
Audience
Contents
Structure
IRC 72 defines the standard dimensions and specifications for tools and equipment employed in the construction and maintenance of bituminous pavements. It includes detailed classifications and measurements (in millimeters) for both common and specialized tools, emphasizing compliance with IRC guidelines to assure compatibility and durability. Typical tool dimensions are provided as examples, such as shovels with steel blades and wooden handles ranging from 900 to 1100 mm in length.
This section describes key equipment used in bituminous roadworks, including general hand tools like shovels, rakes, and tampers; special apparatus for hot-mix construction such as hot mix plants, bitumen sprayers, paver finishers, and various rollers (vibratory, static steel wheel, and pneumatic tyred). It also highlights the importance of meeting ISI standards and maintaining equipment for consistent pavement quality.
Outlined are typical tools for cleaning road surfaces prior to bituminous application, including stiff bristle brooms, mechanical sweepers, compressed air blowers, shovels, scrapers, and water spray systems. The section stresses the necessity of a dust-free, dry surface immediately before bitumen application to ensure proper adhesion and performance.
Details the components and operation of hand sprayers used for minor works where pressure distributors are unnecessary. Equipment typically consists of a small hand or mechanically operated pump attached to a heated bitumen boiler, with a strainer to avoid nozzle blockages. Parameters such as nozzle diameter, spray pressure, and bitumen temperature ranges are provided for effective manual spraying.
This section references IS standards governing hot asphalt mixing plants, hand-operated drum mixers, and cold mixing plants. It describes the typical mixing process flow, emphasizing temperature control for hot mix plants, and suitability of hand mixers primarily for small repair jobs.
Discusses the use of vehicles such as tipper trucks with capacities between 5 and 7.5 tonnes designed with smooth, crack-free surfaces and thermal insulation to prevent bitumen cooling during transit. Also covers aggregate spreaders of towed hopper and tail board types, and paver finishers conforming to IS specifications, all vital for efficient material transport and laying.
Describes equipment used for uniform distribution of stone chips over bituminous surfaces, including towed hopper types and tail board spreaders. Key features such as adjustable gates and compatibility with bitumen distributors ensure effective and consistent chip spreading.
Details the machinery and manual tools employed to spread and lay bituminous courses, including tipper trucks, aggregate spreaders, paver finishers (with heated screed boards), and hand tools like drag brooms, shovels, and rakes. Also outlines the types of rollers used for different compaction stages, referencing IS standards.
Although IRC 72 lacks explicit formulas, it recommends tools such as 3-meter straight edges, camber gauges, dipsticks, and unevenness indicators to assess surface flatness and camber. The acceptable tolerance for unevenness is generally within 3 mm for surface dressing applications.
Focuses on maintenance routines for bitumen boilers, hand sprayers, drum mixers, and mixing plants. Daily cleaning, lubrication, inspection, and proper handling procedures are highlighted to extend equipment lifespan and ensure operational safety. A summary table outlines daily and periodic maintenance tasks.
Although IRC 72 lacks detailed safety clauses, recommended practices include maintaining bitumen heating below 180°C, using insulated containers, wearing appropriate personal protective equipment, regular equipment inspections, safe storage of bitumen, and ensuring proper ventilation to avoid hazards.
Describes equipment requirements for penetration macadam and built-up spray grout applications, such as maintaining spray pressure between 2 to 3.5 bar, nozzle sizes of 3 to 5 mm, and heating bitumen to 160–180°C. Continuous mixing is essential to prevent segregation in spray grout, with a formula provided for estimating bitumen volume based on area and thickness.
Frequently Asked
IRC 72 advises using three-wheel steel rollers weighing 8 to 10 tonnes for breakdown rolling of asphaltic concrete and bituminous macadam, while tandem rollers of similar weight are suited for final finish rolling. Pneumatic tyred rollers, with adjustable ballast weights, are recommended for intermediate rolling and surface sealing, ensuring proper compaction and pavement durability.
Per IRC 72 Clause 11.3, bitumen hand sprayers should be inspected and cleaned daily, including strainers and nozzles, to prevent clogging. Pumping should commence only when bitumen attains the correct temperature. The spray lance and hoses must be cleared of blockages, and hoses should be hung vertically after use to drain bitumen. Disconnecting hoses under pressure must be avoided, and monthly maintenance includes dismantling and cleaning the pumping unit and checking seals.
Effective upkeep includes daily cleaning of boilers before cooling to prevent bitumen hardening, lubricating wheels and pivots, verifying absence of water inside boilers, maintaining bitumen levels below the top by at least 15 cm, and stirring bitumen regularly. Drum mixers require daily cleaning and lubrication of bearings, with periodic inspection of bolts and hinges. Hand sprayers need frequent cleaning of nozzles and strainers, proper temperature control during pumping, and monthly checks of pump components to ensure longevity and safety.
IRC 72 and IRC:SP 11-1977 recommend the use of adjustable camber boards or templates to verify cross slopes, 3-meter straight edges with graduated wedges for checking surface flatness, and unevenness indicators that provide real-time irregularity measurements and mark defective spots. These tools help ensure the pavement surface meets quality standards.
According to IRC 72, insulated tank lorries equipped with oil-fired heating systems and capacities ranging from 5,000 to 15,000 liters are suitable for transporting hot bituminous mixtures. These vehicles feature power-driven or compressed air pumps to facilitate bitumen discharge and spraybar units with nozzles controlled by metering devices for uniform application, as specified in IS:2093-1974.
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