Performance and compatibility of phosphonate-based superplasticizers for concrete

Abstract

The paper deals with the effectiveness of an innovative phosphonate-based superplasticizer (PNH) for ready mixed concrete. Concrete specimens were manufactured by considering a constant initial workability, equal to 220 mm slump at the end of the mixing procedure. Workability was measured at 0, 30, and 60 min to evaluate the workability retention performances of the innovative superplasticizer. Compressive tests at 1, 7, and 28 days were carried out to evaluate the influence of the phosphonate-based superplasticizer on concrete setting and hardening. The concrete mixes were designed by considering 13 different cements to assess the superplasticizer-cement compatibility. The PNH-based admixture showed a better performance in terms of water reduction and workability retention with respect to napthalenesulphonate based admixtures (NSF); however, a higher dosage of PNH with respect to polycarboxylate ethers (PCEs) was needed to get the same initial fluidity.