Recent Advances in C-S-H Nucleation Seeding for Improving Cement Performances

Abstract

Reducing cement CO2 footprint is a societal need. This is being achieved mainly by replacing an increasing amount of Portland clinker by supplementary cementitious materials. However, this comes at a price: lower mechanical strengths at early ages due to slow pozzolanic reaction(s). This is being addressed by using accelerator admixtures. In this context, calcium silicate hydrate nucleation seeding seems to have a promising future, as it can accelerate cement and pozzolanic reactions at early ages, optimising their microstructures, without compromising late strength and durability performances. In fact, these features could even be improved. Moreover, other uses are low temperature concreting, precasting, shotconcrete, etc. Here, we focus on reviewing recent reports on calcium silicate hydrate seeding using commercially available admixtures. Current knowledge on the consequences of nucleation seeding on hydration reactions and on early and late mechanical strengths is discussed. It is noted that other features, in addition to the classic alite hydration acceleration, are covered here including the enhanced ettringite precipitation and the very efficient porosity refinement, which take place in the seeded binders. Finally, because the seeded binders seem to be denser, durability properties could also be enhanced although this remains to be properly established.

Activation of LC3 binders by C‐S‐H nucleation seeding with a new tailored admixture for low‐carbon cements

“…The corresponding losses for PC-525-STE53 are 18.7%, 21.8% and 22.8% at the same ages, respectively. This shows that the effect of the STE53 additive is stronger at early ages, as widely reported [10]. For the LC 3 pastes, the activation is more similar at all the hydration times.…”

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There are different possibilities to accelerate early age hydration reactions of LC 3 binders, one of them is the addition of chemical admixtures [9]. For instance, the addition of C-S-H seeding [10,11] or alkanolamines [12,13]. Furthermore, a synergistic effect between C-S-H seeding in combination with alkanolamines [14-16] is being very recently reported.

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Crevice Corrosion Behavior of 201 Stainless Steel in NaCl Solutions with Different pH Values by In Situ Monitoring

“…It is challenging to build an in situ corrosion monitoring system and obtain real-time radial composition data in a crevice, because the large electrode size is insufficient for high-resolution monitoring of the ion dynamics in the micro-zone inside the fissure. Thus, it is quite challenging to assess the effect of the pH value of the bulk solution on the regional corrosion behaviors in the metal crevice; hence, the development of in situ micro-region detection methods has become quite important [ 29 , 30 , 31 , 32 ].…”

Examination of water absorption of low volume fly ash concrete (LVFAC) under water immersion conditions

“…It should also be noted that concretes made with the participation of SCMs allow not only to reduce CO 2 emissions generated during the burning of the Portland clinker [44,45], but also significantly reduce the amount of energy necessary to carry out this technological process [46]. The broad group of SCMs includes both traditional mineral additives such as: fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBFS) , metakaolin (MK) [47][48][49][50][51][52][53], volcanic pumice powder [54], or eggshells [55] as well as nanoadditives, which have been used to a large extent for several years [56][57][58][59][60][61][62][63][64][65]. Moreover, municipal sewage sludge are also used [66,67].…”