TECHNISCHE UNIVERSITÄT BERLIN

Accelerating cement hydration
with C-S-H seeds

All authors
All authors
1 Scheme of the mechanochemical synthesis of calcium silicate hydrate
1 Scheme of the mechanochemical synthesis of calcium silicate hydrate
2 Particle size distribution of C-S-H prepared mechanochemically (MC) or bypozzolanic reaction at room temperature (RT) with different reaction times ranging from 24 h up to 6 months. The mean particle size is given in brackets
2 Particle size distribution of C-S-H prepared mechanochemically (MC) or by
pozzolanic reaction at room temperature (RT) with different reaction times ranging from 24 h up to 6 months. The mean particle size is given in brackets
3 SEM images of C-S-H prepared by sol-gel synthesis a) and by pozzolanic reaction b)
3 SEM images of C-S-H prepared by sol-gel synthesis a) and by pozzolanic reaction b)
4 SEM images of crystalline C-S-H: A – killalaite (Ca6.4 [H0.6Si2O7]2 (OH)2), B – gyrolite (Ca1Si24O60 (OH)8(14+x) H2O) in a tobermorite matrix, C – hillebrandite (Ca2SiO3 (OH)2), D – xonotlite (Ca6 [Si6O17] (OH)2). Product formation is dependent on Ca/Si, treatment temperature and duration
4 SEM images of crystalline C-S-H: A – killalaite (Ca6.4 [H0.6Si2O7]2 (OH)2), B – gyrolite (Ca1Si24O60 (OH)8(14+x) H2O) in a tobermorite matrix, C – hillebrandite (Ca2SiO3 (OH)2), D – xonotlite (Ca6 [Si6O17] (OH)2). Product formation is dependent on Ca/Si, treatment temperature and duration
5 Acceleration of cement hydration with rising levels of C-S-H added (left). Acceleration of cement hydration in dependence on the calcium to silicon ratio of the added 1 wt.-% C-S-H (right)
5 Acceleration of cement hydration with rising levels of C-S-H added (left). Acceleration of cement hydration in dependence on the calcium to silicon ratio of the added 1 wt.-% C-S-H (right)
6 Compressive strength development during the first hours of cement hydration and over 28 days with 0.5 wt.-% C-S-H before and after optimization of the synthesis [19]
6 Compressive strength development during the first hours of cement hydration and over 28 days with 0.5 wt.-% C-S-H before and after optimization of the synthesis [19]
7 Ultrasonic sound speed measurement of cement pastes with 0.5 wt.-% C-S-H before and after optimization of the synthesis [19]. The setting time could be accelerated by approximately 1.5 hours through non-optimized C-S-H and by further 2 hours through optimization
7 Ultrasonic sound speed measurement of cement pastes with 0.5 wt.-% C-S-H before and after optimization of the synthesis [19]. The setting time could be accelerated by approximately 1.5 hours through non-optimized C-S-H and by further 2 hours through optimization
8 Scheme of the impact of C-S-H crystal seeding in comparison to normal hydration
8 Scheme of the impact of C-S-H crystal seeding in comparison to normal hydration

The acceleration of cement hydration through synthetic C-S-H shows great potential in increasing the early strength of cementitious systems. The selection of a suitable calcium-to-silicon ratio and optimized synthesis conditions results in a significant strength gain compared to non-optimized systems. Polymers may contribute during synthesis to stabilizing the C-S-H aggregates, thus enhancing the storage stability of the suspensions.

1 Introduction

According to the European climate and energy policy, the emission of greenhouse gases is to be reduced by 40 % by 2030 compared to 1990 [1]. The German cement industry contributes essentially to the issue with annual emissions of 17450 million t CO2 (2015). Nevertheless, their 1995 self-imposed climate goal of a 28 % reduction of energy conditioned CO2 emissions was achieved in 2012 [2]. The application of alternative fuels, together with more effective kilns and improved clinker mineralogy contributed to the achievement of climate goals just as well as the development of...

Find out more in

ZKG 4/2019

Find out more in

ZKG 4/2019

Ressort:  Materials
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TEXT M.Sc. Elisabeth John, Prof. Dr. Dietmar Stephan, Dr. Christian Lehmann, Institute of Civil Engineering, Group of Building Materials and Constructional Chemistry, Technische Universität Berlin, Berlin/Germany

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