Estimation the Initial Cement Dosage of Concrete from Mechanical Behavior and Chemical Analysis

The objective of this work is to determine a reliable experimental procedure and calculation method from simple laboratory tests to identify the initial cement dosage of the concrete in the hardened state and how to apply in quality inspection of a construction work. To reach the objective of the project, a combination of two methods was used: Inert method and Soluble silica method. The proposed approach is based on two series of experiments (mechanical and physical tests and chemical analysis tests), a comprehensive analysis that incorporates chemical analysis of the binder phase and lost on loss of ignition (LOI), porosity (void volume) and density of the mortar or concrete. The results of the physical and mechanical tests (the compressive strength, the porosity accessible to water, the density) present an overall picture on the properties of hardened concrete. These data then make it possible to calculate the cement dosage. The validation of this method will be carried out on different concretes with the same type and dosage of cement (350 kg/m3), the values of W/C varying from 0.5 to 0.8 and two value of superplasticizer (a new generation modified polycarboxylate). The results show a very good concordance between the two methods and the calculated cement dosage (the average value of both methods) corresponds perfectly to the actual dosage.