Rapid Testing of Fresh Concrete

Quite a few methods have been recommended in the technical literature for the determination of the cement and water contents as well as the water cement ratio of a fresh concrete. This paper discusses several of the published methods for determination of cement content, including the well-known Dunagan method and some of its variants, another mechanical method based on consistency measurements by two different techniques, and two physiocochemical methods. Although drying is simplest method for determining water content it is not accurate enough. Other methods of estimating the water content include calculating the weight of the solids in the concrete, using chemical means measuring the electrical resistance or capacitance, or the thermal conductivity or the microwave absorption and performing repeated consistency tests. The methods suggested for determination of the watercement ratio are measuring essentially the water content.