Recommended Practice for Sealing of Joints in Concrete Pavements (Second Revision)

The Scope of IRC 57 covers specifications and standards for joint sealing in concrete pavements, including types of joints, sealing groove shapes, sealing details, preformed seals, and resealing old joints as outlined on page 2 of the code. Key formulas include the Movement Accommodation Factor (MAF), which quantifies sealant elasticity as:

MAF = [(Compressed Width - Original Width) / Original Width] × 100 = [(Expanded Width - Original Width) / Original Width] × 100

Typical MAF values are ±25% for polysulphide sealants and -50% to +100% for silicone sealants (Clause 6.10).

Table 2 specifies ASTM D 2628 requirements for preformed seals, including tensile strength (min. 13.8 MPa), elongation at break (min. 250%), hardness (55 ± 5 points), and other durability parameters.

Groove dimensions must conform to manufacturer specifications and be installed after cleaning (Clause 5.6).

A sample calculation for joint width considering thermal expansion (coefficient 10×10⁻⁶/°C, temperature differential 21°C) is provided in Annexure-I.

This scope ensures proper selection, installation, and maintenance of joint seals for durable pavement performance.

Sources: Clause 2, Clause 5.6, Clause 6.10, Table 2, Annexure-I

As per IRC 57 Clause 5.1, the key types of joints in concrete pavements are:

• Contraction joints: To control cracking due to shrinkage.
• Expansion joints: To accommodate slab expansion.
• Construction joints: For joining concrete placed at different times.
• Longitudinal joints: To divide pavement width and control cracking.

Regarding sealant groove shape (Clause 4), the shape factor (Depth/Width of sealant) is critical for sealant performance under slab movements. Recommended shape factors are:

A compromise ratio of 3:2 (Depth:Width) is often preferred in practice to keep sealant stress within allowable limits. These joints and sealant details augment IRC:15 provisions (Clause 3.2).

Sources: Clause 3.2, Clause 3.4, Clause 4, Clause 5.1

Key specifications for Joint Layout and Configuration per IRC 57 include:

• Groove Dimensions: As per Clause 5.6, joint groove sizes are specified in Figures 3, 4, and 5, with permissible deviation of ±1 mm in depth and width.

• Shape Factor of Sealant: Defined as Depth/Width of sealant, recommended values (Clause 4) are:

• Sealant Groove Shape: Important to accommodate expansion/contraction stresses (Fig. 1) to keep strains within permissible limits.

• Sample Calculation: Annexure-I provides a sample calculation for contraction joint width.

These ensure proper joint performance and durability under temperature variations and loading.

Sources: Clause 5.6, Clause 4, Annexure-I

Key materials and specifications for joint sealing in IRC 57 include two main categories: hot-poured and cold-poured sealants (Clause 6.7). Hot-poured types include rubberized bitumen (IS 1834), polymeric, elastomeric, and coal tar PVC sealants, all generally self-leveling. Cold-poured sealants include silicone and silicon types per ASTM 5893-96, with silicone being non-sag and toolable, and silicon self-leveling.

Preformed seals must meet ASTM D 2628 requirements (Clause 13.8), summarized below:

Movement Accommodation Factor (MAF) defines sealant elasticity, e.g., polysulphide sealants have ±25% MAF, silicone sealants range from -50% to +100% (Clause 6.10). Sealant grooves and installation follow manufacturer specs and cleaning procedures (Clause 8). Sealant surface is recessed 2-4 mm below pavement surface to avoid bulging.

These details ensure durable, elastic, and weather-resistant joint sealing per IRC 57 standards.

Sources: Clause 6.7, Clause 6.10, Clause 13.8, Clause 8

As per IRC 57 Clause 5.6, the joint groove dimensions must conform to the sizes shown in Figures 3, 4, and 5, with a tolerance of +1 mm in both depth and width. Clause 6.2 specifies a two-phase sawing process: an initial cut to 1/4 to 1/3 slab depth soon after concrete sets to induce cracking, followed by a second cut to widen the groove to final size before sealant installation. Temporary seals like jute rope protect the joint between cuts. Grooves must be cleaned by air blasting or water jets and may be sandblasted for better sealant adhesion. Chamfers of 3 mm width are required if rough arises develop. Spalled edges or defects must be repaired with epoxy mortar. Early-entry saws with skid plates are recommended for early cutting, with minimum cut depth of 10% slab thickness or 30 mm minimum. Annexure-I provides a sample calculation for contraction joint width based on thermal expansion and temperature differential. Sealant groove shape and seal properties are detailed in Clause 13.8 with ASTM test requirements.

Sources: Clause 5.6, Clause 6.2, Clause 13.8

Key formulas and specifications for sealant application per IRC 57 Clause 6.10 and related clauses are as follows:

• Movement Accommodation Factor (MAF) defines sealant's capacity to expand/contract without volume change:

  [ \text{MAF} = \frac{\text{Compressed Width} - \text{Original Width}}{\text{Original Width}} \times 100 = \frac{\text{Expanded Width} - \text{Original Width}}{\text{Original Width}} \times 100 ]

• Typical MAF values:

  • Polysulphide sealants: ±25% or more
  • Silicone sealants: -50% to +100% (can compress to 50% and stretch to 100% of original length)

• Sealant application:

  • Cold-applied sealants are applied by hand-held guns or machines per manufacturer instructions.
  • Sealant surface recessed 2 mm to 4 mm below pavement surface.
  • Avoid applying sealant during contraction phase to prevent bulging.
  • Sealant tooling should produce a parabolic cross-sectional shape.
  • No air bubbles should be introduced during application.
  • Sealant shelf life: not more than six months old.

• Groove dimensions vary by sealant type; silicone sealants prefer thin sections for curing.

• For resealing old joints, remove old sealant, clean grooves to 20-25 mm depth, apply primer, and reseal.

• Preformed seals must meet ASTM D 2628 requirements as per Table 2 below:

• Sealant types include hot-poured (rubberized bitumen, polymeric, elastomeric) and cold-poured (silicone, polysulphide, polyurethane) with specifications per IS, ASTM, or BS standards.

• Sealant groove cleaning and preparation are critical for proper adhesion and performance.

This summary covers sealant application procedures, material properties, and quality requirements as per IRC 57 Clause 6.10 and related clauses.

Sources: Clause 6.10, Table 2, Clause 2.5

Preformed seals per IRC 57 shall conform to ASTM D 2628 with key properties as follows (Table 2):

Movement Accommodation Factor (MAF) defines sealant elasticity:

MAF = ((Compressed Width - Original Width) / Original Width) × 100 = ((Expanded Width - Original Width) / Original Width) × 100

Typical MAF values:

• Polysulphide sealants: ±25%
• Silicone sealants: -50% to +100%

Sealant application requires recessed surface 2-4 mm below pavement, tooling to parabolic shape, and avoiding air bubbles. Manufacturer's certificate for shelf life (max 6 months) is mandatory.

Groove dimensions depend on manufacturer specs; installation preferably by machine after cleaning.

These specifications ensure durability and performance of preformed seals in pavement joints as per IRC 57 Clause 7 and 6.10.

Sources: Clause 6.10, Table 2, Clause 7

As per IRC 57 Clause 6.4 and 6.3, debonding strips and backer rods are used to prevent sealant adhesion to the bottom of joint grooves and to stop sealant flowing through the groove bottom. The debonding strip is typically rectangular, about 5 mm thick, and paper-backed to reduce sealant absorption. Backer rods are round, closed-cell foam without paper backing. Materials include polyethylene foam (for cold-pour sealants), cross-linked polyethylene foam (compatible with hot-pour sealants), and polyurethane foam (open-cell, moisture-absorbing, used with hot-pour sealants). For longitudinal joints, a 1.0-2.0 mm thick debonding tape suffices (Clause 2.0). Backer rods must conform to ASTM C 5249-95 or ASTM D 3575.

Key specifications from Clause 13.8 include:

Installation requires groove cleaning and preferably machine installation (Clause 6.4).

Sources: Clause 6.4, Clause 6.3, Clause 2.0, Clause 13.8

The Movement Accommodation Factor (MAF) defines a sealant's ability to expand or contract without volume change and revert to its original shape. It is calculated as:

[ \text{MAF} = \frac{\text{Compressed Width} - \text{Original Width}}{\text{Original Width}} \times 100 = \frac{\text{Expanded Width} - \text{Original Width}}{\text{Original Width}} \times 100 ]

As per Clause 6.10, typical MAF values are:

• Polysulphide sealants: ±25% or more
• Silicone sealants: -50% to +100% (can compress to 50% and stretch to 100% of original length)

Sealants must be applied with a recessed surface 2–4 mm below pavement surface, avoiding air bubbles, and tooling to a parabolic shape. Polysulphide sealants conform to BS 5212-Part II; silicone sealants conform to ASTM D 5893-96.

Additionally, Table 2 in Clause 7 lists ASTM D 2628 requirements for preformed seals, including tensile strength, elongation, hardness, aging, and recovery properties.

Example thermal expansion calculation for a 4.5 m slab with coefficient 10×10⁻⁶/°C and 21°C temperature difference yields 0.945 mm expansion, with MAF considered as 25%.

Sources: Clause 6.10, Table 2, Clause 7

Cold poured sealants used in cement concrete pavements per IRC 57 Clause 6.9 include Polysulphide (IS 11433/BS 5212), Silicone (ASTM 5893, ASTM C 793, BS/EN 14187-5), and Polyurethane (BS 5212-Part II). These sealants are applied at ambient temperature and cure chemically, allowing larger joint movement accommodation (up to ±30%) compared to hot-poured sealants (±20%) as per Clause 6.9. The Movement Accommodation Factor (MAF) is defined in Clause 6.10 as:

MAF (%) = [(Compressed Width - Original Width) / Original Width] × 100 = [(Expanded Width - Original Width) / Original Width] × 100

Typical MAF values:

• Polysulphide: ±25%
• Silicone: -50% to +100%

Cold poured sealants require careful surface preparation (drying, cleaning, priming) and tooling to a recessed parabolic shape 2-4 mm below pavement surface (Clause 6.10). They are applied by hand or machine following manufacturer instructions. Sealants must be fresh (not older than 6 months) and free of air bubbles. Polysulphide sealants are two-component mixed before use; silicone sealants are single-component curing by moisture absorption.

Key properties from Table 1 include:

These sealants provide longer life and better movement accommodation but are costlier than hot-poured types (Clause 6.9).

Sources: Clause 6.7, Clause 6.9, Clause 6.10, Table 1

For resealing old joints as per IRC 57, the key steps and specifications are:

• Remove cracked or detached old sealant using a raker (see Fig. 9) and clean the joint surface by brushing, special tools, or sawing a new groove to a depth of 20-25 mm.
• Insert temporary jute rope seal to prevent dirt ingress before resealing.
• Repair any spalled edges with epoxy or polymer-based fine concrete.
• Apply primer on cleaned surfaces before sealant application.
• Groove width and depth depend on manufacturer specifications; installation preferably by machine after cleaning (Clause 8).

Sealant types include hot-poured (rubberized bitumen, polymeric, elastomeric) and cold-poured (silicone, polysulphide, polyurethane) with properties and standards listed in Table 1 (Clause 6.7).

Preformed seals must meet ASTM D 2628 requirements as per Table 2, including tensile strength ≥13.8 MPa, elongation at break ≥250%, hardness 55±5 durometer, and other durability criteria.

Movement Accommodation Factor (MAF) defines sealant elasticity; polysulphide sealants have ±25% MAF, silicone sealants range from -50% to +100% (Clause 6.10).

Sample calculation for joint width uses thermal expansion coefficient α = 10×10⁻⁶/°C and max temperature differential 21°C (IRC:58-2015).

Table 2: ASTM D 2628 Requirements for Preformed Seals

This ensures durable, elastic, and weather-resistant resealing of joints in concrete pavements.

Sources: Clause 8, Clause 6.7, Clause 6.10, Clause 7, Table 2

Key quality control and inspection specifications from IRC 57 include:

• Movement Accommodation Factor (MAF) defines sealant elasticity as per Clause 6.10: [ \text{MAF} = \frac{\text{Compressed or Expanded Width} - \text{Original Width}}{\text{Original Width}} \times 100 % ] Silicone sealants have MAF from -50% to +100%, polysulphide sealants > ±25%.

• Sealant Application: Surface recessed 2-4 mm below pavement; avoid air bubbles; sealant age ≤ 6 months; tooling to parabolic shape (Clause 6.10).

• Preformed Seals Requirements (Table 2, Clause 7):

• Groove dimensions must be within ±1 mm of specified size (Clause 5.6).

• Resealing old joints requires removal of old sealant, cleaning, possible groove sawing, priming, and resealing (Clause 8).

These ensure sealant performance and durability in pavement joints.

Sources: Clause 6.10, Table 2, Clause 5.6, Clause 8

The sample calculation for the width of a contraction joint in IRC 57 uses the formula based on thermal expansion: ( W = a \times L \times \Delta T ), where ( a = 10 \times 10^{-6} / ^\circ C ) (coefficient of thermal expansion as per IRC:58-2015), ( \Delta T = 21 ^\circ C ) (maximum temperature differential as per IRC:58-2015), and ( L ) is the length of the concrete slab. The groove dimensions (width and depth) must conform to manufacturer specifications and should not deviate by more than +1 mm (Clause 5.6). Installation is preferably machine done after cleaning the groove (Clause 6). For resealing old joints, grooves should be cleaned to a depth of 20-25 mm and repaired if spalled (Clause 8). Preformed seals have specified hardness, elongation, and recovery properties detailed in Table 7 (Clause 13.8).

Sources: Clause 5.6, Clause 6, Clause 8, Clause 13.8, Annexure - I