CORRECTION OF THE CONSISTENCY OF SCC BY REDOSING SUPERPLASTICISER

The question, whether SCC can become an alternative to concrete or needs to be vibrated, depends essentially on the ability of the industry to produce and deliver a concrete type as dependable as ordinary concrete. For the production of SCC the use of superplasticisers are indispensable. Unfortunately, the time the superplasticiser can maintain the liquefaction of the concrete is limited. For this reason, a time delay can cause the loss of its self-compacting ability during the time it has to be placed into the formwork. The maintenance of the liquefaction of five PCE-based superplasticizers under different temperature-conditions and the required dosage to regain the SCC-consistency were investigated. Once proofed, laboratory-test results can be transferred to production in a concrete plant. Findings indicate that the maintenance of the liquefaction is strongly dependant on the compatibility between the powder and the superplasticiser. Temperature also has a major effect. Conclusions drawn from laboratory-tests can be qualitatively transferred to site, with full consideration of environmental circumstances, to determine how long concrete is processable and the dosage of superplasticiser required.

• INTRODUCTION

• BASIC ELEMENTS OF PCE-BASED SUPERPLASTICIZERS

• EXPERIMENTAL INVESTIGATIONS

• RESULTS

• CONCLUSIONS

• REFERENCES