CONCRETE

Pervious (No-Fines) Concrete

Concrete with little/no fine aggregate giving interconnected voids for drainage

Also calledpervious concreteporous concreteno fines concretepermeable concretedraining concrete
Related on InfraLens
CODES
IS 456
Definition

Pervious (no-fines / porous) concrete is made with gap-graded coarse aggregate, cement and water but little or no sand, producing a high-void (15-30%) structure of interconnected pores that lets water pass straight through at high infiltration rates. The cement paste coats the coarse particles and bonds them at contact points only, leaving the voids open.

Its main use is sustainable storm-water management — permeable pavements, parking lots, walkways, shoulders and recharge structures that reduce run-off and aid ground-water recharge (relevant to rain-water-harvesting and 'sponge city' goals). It also serves as a free-draining sub-base/backfill behind retaining walls and as lightweight no-fines walling. The trade-off is much lower strength (typically 5-15 MPa) and the need to protect the voids from clogging, so it is used in low-load drainage applications, designed per IS 456 with project-specific void/strength targets.

Where used
  • Permeable pavements + parking lots (storm-water)
  • Ground-water recharge + sponge-city drainage
  • Free-draining backfill behind retaining walls
  • Sub-surface drainage layers
  • Lightweight non-load no-fines walls
Acceptance / threshold
Designed per IS 456 with project-specific void content (15-30%), infiltration rate + strength (typically 5-15 MPa); limited to low-load drainage applications with anti-clogging maintenance.
Frequently asked
What is pervious concrete used for?
Mainly permeable pavements, parking areas and recharge structures that let storm water drain through to reduce run-off and recharge ground water; also as free-draining backfill behind retaining walls.
Why is pervious concrete weaker than normal concrete?
Removing the fine aggregate leaves 15-30% interconnected voids and only point-contact bonding of the coarse particles, so strength is much lower (≈5-15 MPa) — acceptable for its low-load drainage role.
Related terms
Laitance
Weak, porous layer of cement fines and water on concrete surface. Must be removed before next pour to ensure bond.
Honeycomb in Concrete
Voids in concrete from poor compaction or formwork leakage. Repair with grouting; severe cases require demolition.
Segregation of Concrete
Separation of coarse aggregate from cement paste due to over-vibration, drop height >1.5 m, or low cohesion.
High Strength Concrete (HSC)
Concrete with characteristic strength above M60. Requires silica fume, low w/c (<0.35), and quality aggregate.
Pumpable Concrete
Concrete designed for pumping — slump 100-150 mm, well-graded fines, no segregation. Up to 350 m vertical placement.
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
Self-Compacting Concrete (SCC)
Highly fluid concrete that flows under its own weight, fills formwork, and consolidates without vibration.
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.