Rheology of belite-cement – Effect of w/c and high-range water-reducer type

• The behavior of belite-cement in presence of PNS and PC types is highlighted.
• Flow curves of 2 cements, 2 HRWR, and various w/c are determined and analyzed.
• Factors affecting rheology of high-performance cement paste are discussed.
• Factors affecting cement–HRWR compatibility are identified and discussed.

The rheological properties of concrete determine its flow performance and thus they are of great importance in placement and consolidation. A full understanding of the behavior of fresh concrete can be achieved through a good understanding of the rheology of paste. Cement pastes exhibit complex rheological behavior affected by several physical and chemical factors, including water-to-cement ratio (w/c), type and dosage of high-range water-reducer (HRWR), and cement characteristics. An experimental investigation was carried out to investigate the rheological properties of belite cement (BC) mixtures made with various w/c ranging between 0.30 and 0.36 and two different types of HRWR. A polynaphthalene sulfonate (PNS) and a polycarboxylate-(PC) based HRWR were evaluated. Test results indicated that the use of BC in low w/c mixtures resulted in shear-thickening behavior when PC is employed and shear-thinning response for higher w/c. Compared to ordinary Portland cement (OC), the use of BC resulted in lower shear-thickening response, regardless of the w/c and HRWR type. The use of PC HRWR promoted the shear-thickening responses of mixtures for both types of cement. On the other hand, the use of PNS in combination with BC resulted in high yield stress values.