Chapter 4 - Mixing and Placing Concrete

Abstract

Concrete is required to be proportioned to provide an average compressive strength. This strength requirement is determined by your local code enforcement office. To test strength, it is common for core samples to be taken and tested. Splitting tensile strength tests must not be used as a basis for field acceptance of concrete. All concrete proportions must be in compliance with the governing code used to establish minimum standards. The proportioning of concrete based on field experience and trial mixtures can be allowed if there is adequate, approved testing information available. If records from field test results are not available, there are other options available to establish compliance with acceptable standards. When mixing concrete, the goal is to achieve a mixture that offers a uniform distribution consistency. These materials must be used entirely before a mixer can be used to mix another batch of concrete. Particulate matter, consisting primarily of cement and pozzolan dust but including some aggregate and sand dust emissions, is the primary pollutant of concern. In addition, there are emissions of metals that are associated with this particulate matter. All but one of the emission points is fugitive in nature.