# Reactive Aggregate Distress

Pattern or map cracking (crazing) on the PCC slab surface caused by reactive aggregates. Reactive aggregates are those that either expand or develop expansive by products when introduced to certain chemical compounds.

- Canonical URL: https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/reactive-aggregate-distress/
- Last updated: 2018-09-19
- Review: reviewed by licensed professional engineers on the previous Pavement Interactive site, where reviewers were not recorded by name

## Description

Pattern or map cracking (crazing) on the PCC slab surface caused by reactive aggregates. Reactive aggregates are those that either expand or develop expansive by products when introduced to certain chemical compounds.

![Severe crazing (alkali-silica reaction).](https://pavementinteractive.org/wp-content/uploads/2006/10/Alkali-silica.jpg)

*Figure 1.* Severe crazing (alkali-silica reaction).

## Problem

[Roughness](https://pavementinteractive.org/reference-desk/pavement-management/pavement-evaluation/roughness/), an indication of poor aggregate - will eventually lead to PCC slab disintegration.

## Possible Causes

This type of distress is indicative of poor aggregate qualities. Most commonly, it is a result of an [alkali-aggregate reaction](https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/alkali-aggregate-reaction/).

## Repair

[Partial depth](https://pavementinteractive.org/reference-desk/materials/portland-cement/portland-cement-strength/pcc-patching/) patch for small areas of scaling or slab replacement for large areas of scaling.