CONCRETE

Construction Joint

Planned stoppage between concrete pours, located + treated for monolithic bond

Also calledcold jointday jointpour jointkicker joint
Related on InfraLens
CODES
IS 456IS 3370
Definition

A construction joint is a deliberate, pre-planned interface between two successive concrete pours where work has stopped and resumed. Unlike movement (expansion/contraction) joints it is intended to behave monolithically — full structural continuity must be restored across it. Its location is chosen at points of low shear and bending: typically at mid-span (or within the middle third) of beams and slabs, and at the underside of beams or floor level for columns/walls, never near maximum-moment or maximum-shear zones.

IS 456 Cl. 13.4 governs treatment: the hardened surface is roughened to expose aggregate, all laitance + loose material removed, cleaned, and wetted to a saturated-surface-dry condition; a cement slurry or bonding agent is applied immediately before the fresh pour, which is well compacted against the old face. For water-retaining structures, IS 3370 additionally requires water-stops across construction joints. A poorly made joint is a prime path for leakage, honeycombing and a structural weak plane.

Where used
  • Multi-lift columns + shear walls (joint at floor/beam soffit level)
  • Long slabs + rafts poured in panels
  • Water tanks + retaining walls (with water-stops, IS 3370)
  • Large foundations cast in sections
  • Sequencing big pours within concrete supply limits
Acceptance / threshold
Located in low shear/moment zones; surface roughened + laitance removed + bonding coat applied per IS 456 Cl. 13.4; water-stops provided for liquid-retaining structures (IS 3370). The joint must develop full design continuity.
Frequently asked
Where should a construction joint be located in a beam?
In a zone of low shear and moment — usually within the middle third of the span, and the joint should be vertical. Avoid locating it near supports (max shear) or at max-moment regions.
What is the difference between a construction joint and an expansion joint?
A construction joint is meant to be monolithic — full structural continuity is restored. An expansion/movement joint deliberately separates the structure to allow thermal + shrinkage movement and is never bonded across.
Related terms
Laitance
Weak, porous layer of cement fines and water on concrete surface. Must be removed before next pour to ensure bond.
Early Age Strength of Concrete
Strength gain at 1, 3, 7, 14 days — typically 16%, 40%, 65%, 90% of 28-day strength for OPC.
Alkali-Aggregate Reaction (AAR/ASR)
Expansive internal reaction between cement alkalis and reactive aggregate silica
Concrete Curing
Min 7 days for OPC, 10 days for PPC, 14 days for sulphate-resistant
Segregation of Concrete
Separation of coarse aggregate from cement paste due to over-vibration, drop height >1.5 m, or low cohesion.
Self-Compacting Concrete (SCC)
Highly fluid concrete that flows under its own weight, fills formwork, and consolidates without vibration.
High Strength Concrete (HSC)
Concrete with characteristic strength above M60. Requires silica fume, low w/c (<0.35), and quality aggregate.
Bleeding of Concrete
Upward migration of mix water to the concrete surface. Excessive bleeding causes weak top layer, dusting.
RCC (Reinforced Cement Concrete)
Concrete with steel reinforcement. Per IS 456:2000.
Honeycomb in Concrete
Voids in concrete from poor compaction or formwork leakage. Repair with grouting; severe cases require demolition.