IRC 23-1966 provides a tentative specification for the construction of two coat bituminous surface dressing on road pavements. It covers the selection and application of bituminous binders and cover aggregates, preparation of the road surface, and detailed construction methods including rolling and curing. This standard is essential for civil and highway engineers involved in road maintenance and surface treatment to ensure durable, uniform, and safe bituminous surfaces.
Overview
IRC 23-1966 provides a tentative specification for the construction of two coat bituminous surface dressing on road pavements. It covers the selection and application of bituminous binders and cover aggregates, preparation of the road surface, and detailed construction methods including rolling and curing. This standard is essential for civil and highway engineers involved in road maintenance and surface treatment to ensure durable, uniform, and safe bituminous surfaces.
Audience
Contents
Structure
The Introduction of IRC 23 sets the general scope for specifications, stating that provisions apply unless modified for unusual conditions. Key specifications include aggregate gradation for surface coats as per the following table for cover material:
| Sieve designation nominal size of aggregate | Specification |
|---|---|
| 1. For first coat 13.2 mm | Passing through 22.4 mm square mesh sieve and retained on 11.2 mm square mesh sieve. |
| II. For second coat 11.2 mm | Passing through 13.2 mm square mesh sieve and retained on 5.6 mm square mesh sieve. |
This ensures proper aggregate size for surface treatments. No specific formulas are provided in the introduction section.
Sources: TABLE: 3.2. Cover Material
The scope of IRC 23 specifies that the provisions of this specification apply generally unless special provisions modify them for unusual conditions. Regarding aggregate gradation for surface treatments, the key table is Table 3.2, which defines the sieve designation nominal sizes for cover material as follows:
| Sieve designation nominal size of aggregate | Specification |
|---|---|
| 1. For first coat 13.2 mm | Passing through 22.4 mm square mesh sieve and retained on 11.2 mm square mesh sieve. |
| II. For second coat 11.2 mm | Passing through 13.2 mm square mesh sieve and retained on 5.6 mm square mesh sieve. |
This ensures proper aggregate size gradation for the two coats in surface treatment as per IRC 23-1966 and its amendments. No specific formulas are provided in the scope section.
Sources: Clause None, TABLE: 3.2. Cover Material
For materials in IRC 23, key specifications include the gradation of aggregates for cover material as per the provided table. For the first coat, the aggregate nominal size is 13.2 mm, which must pass through a 22.4 mm square mesh sieve and be retained on an 11.2 mm square mesh sieve. For the second coat, the nominal size is 11.2 mm, passing through a 13.2 mm square mesh sieve and retained on a 5.6 mm square mesh sieve. Bituminous materials are also specified under Clause 3.1, though details are not provided here. These gradation requirements ensure proper texture and bonding in pavement layers.
Sources: TABLE: 3.2. Cover Material
As per IRC 23 Clause 3.1, bituminous materials must conform to Indian Standards IS 73, 215, 217, and 454. The choice of binder grade depends on climatic conditions. For two-coat bituminous surface dressing, tentative specifications are provided in IRC 23, though detailed formulas or tables are not explicitly stated in the retrieved context. Generally, these IS codes specify properties like penetration, softening point, and viscosity for bitumen. Surface dressing involves applying bitumen followed by aggregate in two coats to improve road surface texture and durability.
Sources: IRC 23, Clause 3.1
The key specifications for cover material as per IRC 23 are:
Cover material shall be crushed stone, crushed slag, crushed gravel (shingle), or other crushed stones with clean, strong, durable, fairly cubical fragments free from disintegrated pieces, salt, alkali, vegetable matter, dust, and coatings. Rounded gravel or waterborne shingle may be used if crushed gravel is not available at reasonable cost (Clause 3.2.1).
The nominal sizes for cover material are given in the following table (Clause 3.2):
| Sieve designation nominal size of aggregate | Specification |
|---|---|
| 1. For first coat 13.2 mm | Passing through 22.4 mm square mesh sieve and retained on 11.2 mm square mesh sieve. |
| II. For second coat 11.2 mm | Passing through 13.2 mm square mesh sieve and retained on 5.6 mm square mesh sieve. |
Application rate of 11.2 mm aggregate cover material is 0.09 to 0.11 m³ per 10 m² immediately after binder application, spread uniformly by hand or mechanical grit spreader (Clause 4.5.3).
Rolling with a 6 to 8 ton road roller follows immediately after spreading to ensure uniform surface (Clause 4.5.4).
Finished surface tolerance: no variation greater than 6 mm over 3 m length when tested with template and straight edge (Clause 4.5.4).
Opening to traffic depends on binder type: next day for straight-run bitumen or road tar; delayed until curing for cutback bitumen (Clause 4.7).
Sources: Clause 3.2, Clause 3.2.1, Clause 4.5.3, Clause 4.5.4, Clause 4.7
Key construction methods per IRC 23 include:
| Sieve designation nominal size of aggregate | Specification |
|---|---|
| 1. For first coat 13.2 mm | Passing through 22.4 mm square mesh sieve and retained on 11.2 mm square mesh sieve. |
| II. For second coat 11.2 mm | Passing through 13.2 mm square mesh sieve and retained on 5.6 mm square mesh sieve. |
Application of Cover Material: Immediately after binder application, spread 11.2 mm aggregate at 0.09 to 0.11 m³ per 10 m² uniformly by hand or mechanical grit spreader (Clause 4.5.3).
Rolling: Use a 6 to 8 ton road roller soon after aggregate spreading; ensure surface uniformity with max 6 mm variation over 3 m length (Clause 4.5.4).
Opening to Traffic: For straight-run bitumen or tar, open next day; if immediate, limit speed to 16 km/h till next day. For cutback bitumen, keep closed until cured (Clause 4.7).
Traffic Arrangements: Close road length equal to one day's work, provide diversions, barriers, signs, and keep diversions watered to control dust (Clause 4.2).
Surface Preparation: Prepare underlying course to uniform grade, patch defects, and rectify fatting-up before dressing (Clause 4.3).
These ensure quality and safety during surface dressing construction.
Sources: Clause 4.5.3, Clause 4.5.4, Clause 4.7, Clause 4.2, Clause 4.3, TABLE: 3.2. Cover Material
As per IRC 23, Clause 4.1, weather and seasonal limitations are recognized but not explicitly detailed; the specification applies unless special provisions modify for unusual conditions. Key points related to construction under weather constraints include:
No explicit formulas or tables for weather limitations are provided, but adherence to these procedural steps ensures quality under typical weather conditions.
Sources: Clause 4.1, Clause 4.2, Clause 4.3, Clause 4.5.3, Clause 4.5.4, Clause 4.7
As per Clause 4.2 of IRC 23, the arrangement of traffic during road surface treatment requires closing the road length equal to one day's work with suitable diversions. Safety measures include barriers, flags, diversionary signs, and warning red lights. All diversions must be watered to prevent dust on cleaned or painted surfaces. Traffic control devices such as barricades and watchmen should be used to ensure safety. Opening to traffic depends on the binder used: for straight-run bitumen or road tar, the road can open the next day with speed restrictions if opened earlier; for cutback bitumen, the surface must cure before opening (Clause 4.7). These provisions ensure safe and efficient traffic management during construction.
Sources: Clause 4.2, Clause 4.7
Key specifications and procedures for preparation of road surface as per IRC 23 include:
Surface Preparation (Clause 4.3): The underlying course must be prepared, shaped, and conditioned to a uniform grade and section. Depressions and potholes should be cut out, patched with new material, and thoroughly compacted. Areas showing "fatting-up" must be rectified.
Aggregate Screening (Clause 13.2): Aggregate must pass through a 13.2 mm square mesh sieve and be retained on a 5.6 mm square mesh sieve to ensure correct size.
Application of Bituminous Material (Clause 4.4.1): Bitumen heated to appropriate temperatures is sprayed uniformly. Application rates are 17.0 to 19.5 kg/10 m² for straight-run bitumen and 19.5 to 22 kg/10 m² for cutbacks and road tars.
Cover Material Application (Clause 4.5.3): Immediately after binder application, 11.2 mm aggregate is spread at 0.09 to 0.11 m³ per 10 m² uniformly.
Rolling (Clause 4.5.4): Rolling with a 6 to 8 ton roller is done soon after aggregate spreading. Finished surface must be uniform with max 6 mm variation over 3 m length.
Opening to Traffic (Clause 4.7): For straight-run bitumen, open next day; if immediate, limit speed to 16 km/h. For cutback bitumen, open only after curing.
Traffic Arrangements (Clause 4.2): Close road length equal to one day's work with proper diversions and safety measures.
These ensure a well-prepared, durable road surface ready for bituminous dressing.
Sources: Clause 4.3, Clause 13.2, Clause 4.4.1, Clause 4.5.3, Clause 4.5.4, Clause 4.7, Clause 4.2
For the first coat in two-coat bituminous surface dressing as per IRC 23, the nominal size of aggregate is 13.2 mm. According to the specification, the aggregate for the first coat should pass through a 22.4 mm square mesh sieve and be retained on an 11.2 mm square mesh sieve. This ensures proper aggregate size distribution for effective surface dressing (Clause 13.2 and Table 3.2). The second coat uses a smaller aggregate size of 11.2 mm, passing through 13.2 mm and retained on 5.6 mm sieves. These sieve specifications are critical for achieving the desired texture and bonding in surface dressing.
Sources: Clause 13.2, Table 3.2
For the second coat in two-coat bituminous surface dressing as per IRC 23, the nominal size of aggregate is 11.2 mm. This aggregate must pass through a 13.2 mm square mesh sieve and be retained on a 5.6 mm square mesh sieve, ensuring proper gradation for the second coat application. This specification is critical to achieve the desired surface texture and durability. No specific formulas are provided in the retrieved context, but adherence to the sieve size gradation is essential for quality control.
Sources: TABLE 3.2. Cover Material, Clause 11.2
As per IRC 23 Clause 4.7, the key specifications for opening to traffic after surface dressing are:
Additionally, Clause 4.5.3 specifies spreading 11.2 mm aggregate at 0.09 to 0.11 m³ per 10 m² immediately after binder application, followed by rolling with a 6 to 8 ton roller (Clause 4.5.4). The finished surface must be uniform with no variation greater than 6 mm over 3 m length when tested with a straight edge.
These ensure proper curing and surface integrity before traffic is allowed.
Sources: Clause 4.5.3, Clause 4.5.4, Clause 4.7
For wet aggregate in bituminous road construction as per IRC 23, the aggregate should preferably be hydrophobic with low porosity, and water absorption shall not ordinarily exceed 1%. Cover material gradation for first and second coats is specified as follows:
| Sieve designation nominal size of aggregate | Specification |
|---|---|
| 1. For first coat 13.2 mm | Passing through 22.4 mm square mesh sieve and retained on 11.2 mm square mesh sieve. |
| II. For second coat 11.2 mm | Passing through 13.2 mm square mesh sieve and retained on 5.6 mm square mesh sieve. |
Immediately after binder application, 11.2 mm aggregate is spread at 0.09 to 0.11 m³ per 10 m² uniformly, followed by rolling with a 6 to 8 ton roller. The finished surface must be uniform with max 6 mm variation over 3 m length. Traffic opening depends on binder type: next day for straight-run bitumen, delayed for cutback bitumen until curing. For wet aggregate process, refer to the appropriate IRC specifications as noted in Clause 4.8.
Sources: Clause 4.5.3, Clause 4.5.4, Clause 4.7, Clause 4.8, TABLE I, TABLE 3.2
Key testing procedures and quality control specifications from IRC 23 include:
| Sieve designation nominal size of aggregate | Specification |
|---|---|
| 1. For first coat 13.2 mm | Passing through 22.4 mm square mesh sieve and retained on 11.2 mm square mesh sieve. |
| II. For second coat 11.2 mm | Passing through 13.2 mm square mesh sieve and retained on 5.6 mm square mesh sieve. |
Application of Cover Material: Immediately after binder application, spread 0.09 to 0.11 m³ of 11.2 mm aggregate per 10 m² uniformly by hand or mechanical spreader (Clause 4.5.3).
Rolling: Use a 6 to 8 ton road roller soon after aggregate spreading; finished surface must be uniform with max 6 mm variation over 3 m length when tested with a straight edge (Clause 4.5.4).
Opening to Traffic: For straight-run bitumen, open next day; if immediate opening is needed, limit speed to 16 km/h until next day. For cutback bitumen, keep closed until cured (Clause 4.7).
Wet Aggregate Process: Refer to IRC specifications for wet aggregate process control (Clause 4.8).
Sources: Table 3.2, Clause 4.5.3, Clause 4.5.4, Clause 4.7, Clause 4.8
Frequently Asked
The retrieved context from IRC 23 does not specify the types of bituminous binders used for two coat surface dressing. Generally, in two coat surface dressing, bituminous binders such as cutback bitumen, bitumen emulsion, or straight run bitumen are commonly used depending on the project requirements and climatic conditions. However, for precise types and grades, the specific clauses of IRC 23 or related IRC guidelines should be consulted.
According to IRC 23, the cover aggregates for each coat must meet specific size and quality requirements. For the first coat, the aggregate size should be 13.2 mm nominal, passing through a 22.4 mm square mesh sieve and retained on an 11.2 mm square mesh sieve. For the second coat, the aggregate size should be 11.2 mm nominal, passing through a 13.2 mm square mesh sieve and retained on a 5.6 mm square mesh sieve (Table 3.2). The cover material shall be clean, strong, durable, fairly cubical crushed stone, slag, or gravel, free from disintegrated pieces, salts, alkali, vegetable matter, dust, and coatings (Clause 3.2.1). Immediately after binder application, 11.2 mm aggregate is spread at 0.09 to 0.11 m³ per 10 m² uniformly (Clause 4.5.3).
Sources: Table 3.2, Clause 3.2.1, Clause 3.2.3, Clause 4.5.3
Prior to applying bituminous dressing, the road surface must be thoroughly dry and cleaned of all caked earth and foreign matter as per Clause 7.3. Cleaning should proceed in stages: first with hard brushes, then softer brushes, and finally by blowing off fine dust using sacks or gunny bags. For stabilised soil or porous aggregate bases, a bituminous primer may be applied at 7.3 to 14.6 kg per 10 m². If the base is old bituminous surfacing, it must be mechanically swept and blown clean, supplemented by hand tools if needed, and kept dry. Any depressions or potholes should be repaired and compacted well in advance, and defective parts cut out and patched as per Clause 4.3. The edges of the surface to be treated should be defined by rope lines. Only after the prime coat has fully cured should bituminous material be applied, sprayed uniformly at specified rates using mechanical sprayers (Clause 17.0).
Sources: Clause 7.3, Clause 4.3, Clause 17.0
For the first coat, the recommended application rate of bituminous material is 17.0 to 19.5 kg per 10 m² for straight-run bitumen, and 19.5 to 22 kg per 10 m² for cutbacks and road tars, as per Clause 17.0. Immediately after, cover material of 13.2 mm aggregate should be applied at 0.14 to 0.15 m³ per 10 m² (Clause 13.2). For the second coat, it should be applied immediately after the first coat or soon after, depending on site conditions and binder type, with road tar requiring immediate application (Clause 4.5.1). The aggregate size differs for first and second coats as per Table 1 (Clause 3.2.3), but specific rates for the second coat's bitumen and aggregate are not detailed in the retrieved context.
Sources: Clause 17.0, Clause 13.2, Clause 4.5.1, Clause 3.2.3
As per IRC 23 Clause 4.7, the treated surface can be safely opened to traffic on the following day after rolling if straight-run bitumen or road tar is used as the binder. If immediate opening is necessary, traffic speed must be limited to 16 km/h until the next day. For cutback bitumen binders, the surface must remain closed to traffic until the binder has sufficiently cured to hold the cover aggregate in place. Traffic control measures such as barricading and watchmen should be used to ensure safety during curing.
Sources: Clause 4.7
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