Concrete Basics

What is Concrete Made of

Pouring Concrete

Concrete Mix Designs

Aggregates in Ready-Mix Concrete

Building Concrete Slabs

Concrete Testing

Seasonal Pouring Tips

Repairing Concrete

Concrete Repair

Fixing Decorative Concrete

Applications

Staining Concrete

Stamped Concrete

Concrete Countertops

Concrete Patios

Concrete Floors

Commercial Concrete

Important Aggregate Dos and Don'ts

DO use aggregate that's in compliance with ASTM C 33, "Standard Specifications for Concrete Aggregates." Aggregates must be sound, clean, hard, durable, and free of excessive fines or contaminates that can affect cement hydration or disrupt the paste-aggregate bond.

DON'T exceed limits for deleterious material content in fine and coarse aggregates. These limits are presented in ASTM C 33 Tables 1 and 3, respectively. Some specifications may require more stringent limitations.

DO monitor moisture contents of coarse and fine aggregates on a regular basis to promote batch-to-batch consistency and uniformity. Moisture probes in aggregate bins should be calibrated according to manufacturers' recommendations. Moisture probes should also be checked periodically with standard burn-off moisture determinations (ASTM C 566).

DO make sure stockpiles are properly managed. They should be built in horizontal or gently sloping layers to reduce segregation and be adequately spaced to allow working the piles properly. In areas where yard space is limited and stockpiles are difficult to keep separate, barriers should be used to avoid intermingling and cross-contamination of different-sized materials.

For additional information about aggregates and concrete mix design, read:

Design and Control of Concrete Mixtures, Portland Cement Association (see Chapter 5, Aggregates for Concrete).

American Concrete Institute (ACI) Committee Report 221R-96, Guide for Use of Normal Weight and Heavyweight Aggregates in Concrete, Section 4.5.

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