# Block Cracking

Interconnected cracks that divide the pavement up into rectangular pieces. Blocks range in size from approximately 0.1 m² (1 ft²) to 9 m² (100 ft²). Larger blocks are generally classified as longitudinal and transverse cracking.

- Canonical URL: https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/block-cracking/
- Last updated: 2026-11-01
- Review: reviewed by licensed professional engineers on the previous Pavement Interactive site, where reviewers were not recorded by name

## Description

Interconnected cracks that divide the pavement up into rectangular pieces. Blocks range in size from approximately 0.1 m² (1 ft²) to 9 m² (100 ft²). Larger blocks are generally classified as [longitudinal](https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/longitudinal-cracking/) and [transverse](https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/transverse-cracking/) cracking. Block cracking normally occurs over a large portion of pavement area but sometimes will occur only in non-traffic areas.

![Block cracking on a low volume pavement](https://pavementinteractive.org/wp-content/uploads/2009/06/Block_cracking.jpg)

![Block cracking in a residential driveway](https://pavementinteractive.org/wp-content/uploads/2009/06/Block_cracking2.jpg)

![Block cracking in a curbside parking area.](https://pavementinteractive.org/wp-content/uploads/2009/06/Block_cracking3.jpg)

*Figures 1–3.* Block cracking on a low volume pavement Block cracking in a residential driveway Block cracking in a curbside parking area.

## Problem

Allows moisture infiltration, [roughness](https://pavementinteractive.org/reference-desk/pavement-management/pavement-evaluation/roughness/)

## Possible Causes

HMA shrinkage and daily temperature cycling. Typically caused by an inability of [asphalt binder](https://pavementinteractive.org/glossary/asphalt-binder/) to expand and contract with temperature cycles because of:

- [Asphalt binder aging](https://pavementinteractive.org/reference-desk/materials/asphalt/durability/)
- Poor choice of asphalt binder in the mix design

## Repair

Strategies depend upon the severity and extent of the block cracking:

- **Low severity cracks (< 1/2 inch wide)**. [Crack seal](https://pavementinteractive.org/reference-desk/maintenance-and-rehabilitation/maintenance/crack-seals/) to prevent (1) entry of moisture into the subgrade through the cracks and (2) further raveling of the crack edges. HMA can provide years of satisfactory service after developing small cracks if they are kept sealed (Roberts et. al., 1996[^1]).
- **High severity cracks (> 1/2 inch wide and cracks with raveled edges)**. Remove and replace the cracked pavement layer with an [overlay](https://pavementinteractive.org/reference-desk/maintenance-and-rehabilitation/rehabilitation/overlay/).

## Sources

[^1]: Roberts et al. (1996). Hot Mix Asphalt Materials, Mixture Design, and Construction. National Asphalt Paving Association Education Foundation. Lanham, MD.