1.0 Scope

This methodology shall be applicable for construction of dowel jointed or plain cement concrete of M40 grade pavement in accordance with the lines, grades, camber and thickness as shown in the drawings using fixed forms.

2.0 Materials

(All clauses preserved verbatim from your input — arranged for readability.)

2.1 Cement

These shall consist of Ordinary Portland Cement of approved source. The minimum cement content shall be 350 Kg/m³ and maximum 425 Kg/m³.

2.2 Admixtures

The admixtures shall conform to IS 6925 and IS 9103 and shall improve the workability of concrete or extension of time and they will not have any effect on the properties of concrete. The performance of these admixtures will be proved both on laboratory trials and in trial paving works. Admixtures containing calcium chloride shall not be used.

2.3 Aggregates

The aggregates shall be of crushed stone or naturally available conforming to IS 383. The coarse aggregate shall be clean, hard, strong, dense and durable. The fine aggregate shall be clean natural sand or crushed stone sand or combination of both. These shall be free from clay, shale, loam, mica and other organic matter.

2.4 Water

Water used for mixing and curing of concrete shall be free from oil, salt, acid and other substances which are harmful to concrete.

2.5 Mild steel bars for dowel and tie bars

These shall conform to the requirements of IS: 432, IS: 1139 and IS: 1786 as relevant. The dowel bars shall conform to Grade S 240 and tie bars to Grade S 415 of I.S.

2.6 Pre-Molded joint filler

To be used for expansion joints abutting structures like bridges, culverts and at end of the day's work. Thickness 20–25 mm or as shown in drawings, complying to IS 1838. It shall be 25 mm less in depth than the thickness of slab and provided in suitable lengths not less than lane width. Holes shall be made to accommodate dowel bars.

2.7 Joint sealing compound

Hot poured elastomeric type as per AASHTO M282 or cold poured polysulphide type as per BS 5212-part2, having flexibility, resistance to age hardening and durability.

2.8 Separation membrane

A separation membrane of impermeable plastic sheeting 125 microns thick shall be laid between the concrete slab and sub-base by nailing with concrete nails to the lower layer. Where overlap is necessary the same shall be at least 300 mm.

2.9 Concrete Strength

The concrete mix design in the laboratory, correlation between flexural and compressive strengths shall be established on the basis of at least thirty tests on samples. Quality control in the field shall be exercised on the basis of flexural strength. Materials and mix proportions shall remain substantially unaltered during daily production. Maximum free water cement ratio: 0.50.

The ratio between the 7 and 28 day strengths shall be established in advance by testing pairs of beams and cubes on at least six batches of trial mix. The average 7-day strength divided by average 28-day strength yields ratio R (to three decimals).

If any four consecutive 7-day test results fall below the required 7-day strength (derived from R), the cement content shall be increased by 5% by weight (or as agreed by the Engineer) without extra payment. Maintain the increased cement content until four corresponding 28-day strengths have been assessed. Adjust mix to maintain required workability.

2.10 Workability

Workability requirements at batching plant and site shall be established by slump tests during trial length. Typical slump values: Slip form — 30 ± 15 mm; Fixed form — 50 ± 15 mm.

3.0 Construction Procedure

3.1 Mixing

Materials shall be mixed in a mechanized batching plant with air-conditioned centralized control cabin, minimum 4 bins, weigh hoppers and automatic weighing devices using calibrated load cells. Mixer shall be capable of producing a homogeneous mix without segregation. Mix timing per manufacturer's recommendations; automatic alarm/timing device recommended.

3.2 Joints

The location and type of joints shall be as shown in the drawings.

3.2.1 Transverse Joints

Transverse joints shall be contraction and expansion joints constructed at the spacing described in the Drawings. They shall be straight within tolerances except at junctions/roundabouts where drawings govern.

3.2.2 Contraction Joints

Contraction joints shall be mechanical saw cut; can start as early as 6–8 hours after paving (initial hardening). Groove width 3–5 mm, depth 1/4 to 1/3 slab depth. Expansion joints shall have joint filler board and prefabricated assemblies. Dowel bars: mild steel as indicated in drawings, positioned at mid-depth within ±20 mm tolerance. Sheathing requirements: contraction joints — sheath at least 2/3 length from one end; expansion joints — sheath 1/2 length + 50 mm with 100 mm cap at sheath end. Use compressible sponge to block cement slurry entry.

Dowel support: cradles/chairs in prefabricated assemblies or mechanically inserted ensuring correct placement and full re-compaction around dowels.

3.2.3 Expansion Joint

Expansion joints shall consist of a joint filler board complying with MoRT&H Clause 602.2.7 and dowel bars complying with Clause 602.6.5 as detailed in drawings. Adjacent slabs shall be completely separated and space around dowels packed with compressible material to block slurry.

3.2.4 Longitudinal Joints

Longitudinal joints shall be saw cut as shown. Groove depth 1/3 slab depth. Tie bars shall be deformed steel (IS 1786), painted with bituminous paint for 75 mm at both ends and positioned within middle third of slab depth. Tie bar assemblies must be rigid and supported.

3.2.5 Construction Joints

Transverse construction joints shall be placed whenever concreting is completed for the day's work or suspended for more than 30 minutes. Provide at regular contraction joint locations using dowel bars. Seal transverse and longitudinal joints using sealants not before 14 days after construction, and prior to opening to traffic.

3.3 Separation membrane

Separation membrane: impermeable plastic sheeting 125 microns thick. Lay by nailing to lower layer. Overlap at least 300 mm. Prior to placing, clean sub-base using high pressure water jetting or compressed air.

3.4 Dowel bars

Dowel bars shall be mild steel rounds in accordance with MoRT&H Clause 602.2.6, free from oil, dirt and scale. Straight, without irregularities or burrs. Support on cradles/dowel chairs or mechanically insert with vibration to ensure correct placement and full re-compaction. Sheath thickness not more than 1.25 mm; sheath lengths per clause 3.2.2.

3.5 Tie bars

Tie bars projecting across longitudinal joints shall be protected from corrosion for 75 mm on each side with bituminous paint. Coating shall be dry when used. Tie bars assemblies must remain firmly in position. Alternatively, tie bars may be mechanically or manually inserted into plastic concrete by vibration ensuring correct placement.

3.6 Construction by fixed form

Fixed forms: straight steel side forms minimum 5 mm thick, minimum 3000 mm length, depth equal to slab thickness. Forms must be rigid and interlocking to prevent springing. Vibrators: surface pan type or internal type (immersed tube or multiple spuds). Surface vibrator frequency >= 3500 impulses/min; internal vibrator >5000 impulses/min.

4.0 Trial length

A trial length of 60 m shall be constructed full width and rolled, involving at least one transverse construction joint between hardened and fresh concrete. After side form removal, correct slab edges using fine concrete (1:3 cement : fine chips/aggregate).

After final regulation and before curing membrane application, brush-texture surface at right angles to longitudinal axis using a 32-gauge wire brush grouped in tufts at 10 mm centers and width not less than 450 mm.

Total time from addition of water to completion of surface finishing and texturing: not to exceed 120 minutes when concrete temperature < 25°C and 90 minutes when concrete temperature is between 25–30°C.

Immediately after texturing, cure surface and sides by application of a curing compound (mechanical sprayer) with water retention efficiency of 90%. After 3 hours, cover pavement with moist Hessian cloth or pond with water for at least 14 days.

Sand Patch Test (Texture Depth)

Surface must be dried and cleaned. Use sand passing 300 µm sieve and retained on 150 µm. Cylinder volume 25 ml. Spread sand into a circular patch using flat wooden disc (64 mm diameter, 1.5 mm thick). Measure diameter to nearest 5 mm. Texture depth (mm) = 31000 / D² where D is mean diameter of patch.

Take five tests along diagonal across lane width at least 2 m apart, between 50 m points. No measurement within 300 mm of longitudinal edges of slab constructed in one pass.

Requirements (MoRT&H table 600-2):

Safety requirements

1. All concrete transit mixers shall be provided with reverse horns.
2. Flagman shall be provided at all exit points of the trucks / tippers.
3. The speed of vehicles plying in the work area shall be restricted to 40 km/h maximum.
4. If night work is carried out the area shall be provided with sufficient lighting.
5. Check working condition of safety valves of air compressors if compressed air is used for cleaning.
6. The 1000 mm work area on both sides of the paving area shall be kept clear of unauthorized persons / workmen.
7. All exposed moving parts of joint saw cutters shall be provided with guards.
8. Hand gloves shall be used while application of joint sealants.