ENHANCING THE COMPATIBILITY OF SUPERPLASTICIZERS WITH CEMENTS

Extreme performances of concrete are required nowadays. Very low water cement ratio to meet the requirements of strength and exposure conditions but, at the same time, long workability retention to meet the requirement of transportation and delivery of high quality concrete are needed. Superplasticizers are the key components that can greatly modify the properties of the fresh and hardened concrete, but, only recently, reaching simultaneously high water reduction and long workability retention, which are conflicting properties, has been possible through the development of new admixtures. The development of these new admixtures and the optimisation of their polymeric structure has been the result of a preliminary comprehension of their interaction with cement in relation with the workability retention. Several studies were carried out with different cements to determine the mode of action of the new superplasticizers. It has been identified that the most important feature related to workability retention is the adsorption rate of the various types of superplasticizers, which is strongly affected by the chemical composition of the cement. The correlation found between the chemical composition of cement, the type of admixtures and their interaction with the new superplasticizers is presented.

• INTRODUCTION

• EXPERIMENTAL DETAILS

• RESULTS AND DISCUSSION

• CONCLUDING REMARKS

• AKNOWLEDGMENTS

• REFERENCES