The acceleration of cement hydration by seeding: influence of the cement mineralogy

1 Examples of heat flow evolutions during the hydration of cement with and without an addition of x% of C-S-H seeds. The two large vertical arrows point out the hydration peak characterizing the sulfate depletion.

2 Hydration of cements D, E, F and alite 1 in presence of different quantities of C-S-H seeds. The square in dashed line points out the dormant period.

3 Evolutions of the relative acceleration A and parameter X according to the dosage in C-S-H seeds, for three cements and the alite 1

4 Evolutions of the relative acceleration A for all cements and both alites

5 Evolution of the minimum amount of C-S-H to have an acceleration compared to the reference and evolution of the parameter X_ref in function of (1) on the right-hand side the sulfate concentration and (2) on the left-hand side the alkali concentration. Both are measured 5 minutes after the mixing with water.

6 Evolution of the dosage of C-S-H necessary to reach the acceleration plateau, and amount of C-S-H necessary to observe a second acceleration, in function of the gypsum content

7 Evolution of the acceleration performances and Acc._ref against the surface of C₃S in cements

Hydrated C₃S paste with 3% XSEED after 8 h (W/Z=0,5). In blue non-hydrated grains, in yellow CSH phases that grow around the seeds

A new seeding technology, successfully applied in the concrete sector, is allowing concrete producers to accelerate their production or to replace cement by more cementitious materials.

1 Introduction

The development of the mechanical properties in ordinary Portland cement is closely linked to the hydration of tricalcium and dicalcium silicates. Accelerating the hydration of these phases, and therefore the setting and hardening of concrete, is highly desired in many applications, mainly for speeding up the production or to reduce the cement portion in the concrete mix design. The addition of seeds, namely the “seeding”, is a common practice to accelerate and control the crystallization and in this case to accelerate the cement hydration. Despite the fact that this idea is not...