NEW GENERATION OF POLYCARBOXYLATE SUPERPLASTICIZER TO ELIMINATE STEAM CURING OF CONCRETE

Superplasticizers are key components for enhancing the performance of precast concrete. Without heat curing, the very early strength, especially in winter, are not high enough for a quick and safe removal of formwork. Steam curing is therefore used to accelerate the hydration of cement and in this way higher initial strengths are obtained. In contrast, lower long term strengths, higher permeability, shrinkage and creep are often observed with steam cured concrete, especially because of increased porosity and cracking due to the negative effects of steam on the hydration process. This paper presents a new generation of polycarboxylate ether superplasticizer, which shows high early compressive strength even at very low temperature and maintains good long-term performance. Extensive laboratory and field tests are presented focusing the attention on early age strength (10–18 hours). Several studies were carried out to determine the mode of action of the new superplasticizer. Great attention was paid to the hydration rate and to the microstructure of the cement paste investigated by thermogravimetric analysis and mercury porosimetry. Results of those studies are presented and correlated with the performance of the superplasticized concrete cured in different conditions in comparison with the standard polycarboxylates ether superplasticizers.

• INTRODUCTION

• MECHANISM OF ACTION OF THE NEW GENERATION POLYCARBOXYLATE ETHER SUPERPLASTICIZERS

• EXPERIMENTAL

• RESULTS AND DISCUSSION

• CONCLUDING REMARKS

• REFERENCES