Impact of initial CA dissolution on the hydration mechanism of CAC

Hueller, F.; Naber, C.; Neubauer, J.; Goetz-Neunhoeffer, F.

doi:10.1016/j.cemconres.2018.06.004

Cited by 28 publications

(11 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If at all, only poor AH 3 (mic.) formation was detected during the first 18 hours indicating that most of the dissolved aluminium must have precipitated as X‐ray‐amorphous AH x gel as recently proposed for the CA hydration . Upon heating after 18 hours a renewed dissolution of CA takes place which stops after 22 hours at a minimum CA value of around 2.3 wt% which corresponds to a reaction turnover of 77.5%.…”

Section: Resultssupporting

confidence: 58%

“…At a w/s ratio of 0.36 a sufficient H 2 O amount for a complete CA 2 hydration and a good workability are simultaneously ensured. In previous studies on pure CA 2 the just described paste composition proved to be a suitable formula for different analytical procedures . Within the chosen compositions, the w/c ratio was thus kept constant at 0.9 for both mixes (CA/CA 2 and pure CA 2 ).…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

“…(microcrystalline AH 3 ) . In this temperature range the H 2 O content of the C 2 AH 8 phase varies between 7.5 and 8.2 moles during the hydration of calcium aluminates . Scheller and Kuzel determined space groups and lattice parameters for the 8‐, 7.5‐, and 5‐hydrates.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Hydration of calcium aluminates at 60°C – Development paths of C₂AH_x in dependence on the content of free water

et al. 2019

Self Cite

View full text Add to dashboard Cite

The influence of water loss during the hydration of calcium aluminates on the phase development is investigated at 60°C. This is relevant for applications in which calcium aluminate cement (CAC) based formulations are exposed to quick drying during hydration. The presented results provide new insights into the well‐known conversion processes occurring in CAC pastes. Using in situ XRD two different routes of the development of initially formed C2AH8 are determined: (a) transformation to C3AH6 + AH3 in the presence of sufficient free water and (b) dehydration to C2AH5 at a lack of free water. Moreover, the influence of precuring of the pastes at 23°C before heating to 60°C is investigated. The increasing loss of free water with increasing precuring time resulting from both, precipitation of hydrate phases and evaporation, causes incomplete hydration of CA or CA2 as well as dehydration of C2AH8 instead of conversion into C3AH6. Comparative investigations of sealed samples always revealed complete hydration of CA and CA2 as well as complete conversion of C2AH8.

show abstract

Section: Resultssupporting

confidence: 58%

Section: Materials and Experimental Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Hydration of calcium aluminates at 60°C – Development paths of C₂AH_x in dependence on the content of free water

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The mixtures with ≥5 wt‐% CA addition show an induction period which is typical for sulfate free mixtures with CA (see Figure C) . Low amounts of initially fast dissolved CA create a regime in the pore solution known from the neat CAC hydration with Ca/Al ~0.6 in the investigated mixture C 3 S/CA 85/15 (cf.…”

Section: Discussionmentioning

confidence: 89%

“…The reason for the observed induction period is still under discussion. According to Hueller et al formation of amorphous AH x might initiate the start of the CA dissolution by thereby increasing the Ca/Al ratio in pore solution.…”

Section: Discussionmentioning

confidence: 99%

Hydration of C₃S in presence of CA: Mineral‐pore solution interaction

et al. 2018

View full text Add to dashboard Cite

C3S and CA are the main phases of OPC and Fe‐rich CAC, respectively. The objective of this research was to investigate the influence of CA on C3S hydration, representing an under sulfated OPC‐rich binder, and to shed light on the underlying hydration mechanisms. To this end, C3S was blended with 1‐30 wt‐% CA and the pastes (w/c 0.5) were investigated by heat flow calorimetry, in situ X‐ray diffraction and analysis of the pore solution chemistry. CA additions ≥5 wt‐% reveal a separation into three distinct heat flow maxima, whereas additions ≤3 wt‐% just retard the start of the main reaction. The silicate reaction (dissolution of C3S and precipitation of C–S–H with or without CH) can be retarded for 4 to ≥22 hours in comparison to pure C3S depending on the admixed CA content. The start of the silicate reaction seems to be related to a decrease in Al‐ and increase in Ca‐concentration in the pore solution. However, it can be shown in this study that C3S is able to dissolve even at high Al concentrations in the pore solution.

show abstract

Evolution of kinetics and pore water composition during hydration of a CAC‐Calcite system by addition of Na₅P₃O₁₀

Rost,

Schramm,

Goetz‐Neunhoeffer

2023

ce papers

View full text Add to dashboard Cite

It was analysed how a low Na5P3O10 (STPP) concentration influences the hydration of a calcium aluminate cement. It is known that the hydration of a CAC‐Calcite system precipitates C2AHX as a precursor phase at 23°C during hydration before the formation of hemi‐ or monocarbonate and the additional formation of CAH10 and AH3. In our study the addition of 0.2 and 1.0 wt.% STPP (bwoc) to a CAC‐Calcite system at 23 °C and with a w/b of 0.33 was investigated and is compared with mixes without STPP addition. Heat flow calorimetry data showed that STPP accelerates the main reaction. Moreover, an additional heat flow event within the first 30 minutes was detected by STPP addition. However, from the results of QXRD analysis, crystalline hydrate phases are formed only during the main reaction. These are CAH10, C2AHX, AH3, hemicarbonate and monocarbonate. STPP shows an influence on the amount of crystalline C2AHX, otherwise, no difference in the qualitative phase content is observed. Gillmore‐Needle‐Testing (IMETER device) could observe an accelerated hardness development during the early heat flow event despite initially reduced viscosity. Pore water studies and thermodynamic modelling (PhreeqC) indicate the formation of an amorphous C‐P‐H phase during this early heat flow event.

show abstract

Impact of initial CA dissolution on the hydration mechanism of CAC

Cited by 28 publications

References 28 publications

Hydration of calcium aluminates at 60°C – Development paths of C₂AH_x in dependence on the content of free water

Hydration of calcium aluminates at 60°C – Development paths of C₂AH_x in dependence on the content of free water

Hydration of C₃S in presence of CA: Mineral‐pore solution interaction

Evolution of kinetics and pore water composition during hydration of a CAC‐Calcite system by addition of Na₅P₃O₁₀

Contact Info

Product

Resources

About

Impact of initial CA dissolution on the hydration mechanism of CAC

Cited by 28 publications

References 28 publications

Hydration of calcium aluminates at 60°C – Development paths of C2AHx in dependence on the content of free water

Hydration of calcium aluminates at 60°C – Development paths of C2AHx in dependence on the content of free water

Hydration of C3S in presence of CA: Mineral‐pore solution interaction

Evolution of kinetics and pore water composition during hydration of a CAC‐Calcite system by addition of Na5P3O10

Contact Info

Product

Resources

About

Hydration of calcium aluminates at 60°C – Development paths of C₂AH_x in dependence on the content of free water

Hydration of calcium aluminates at 60°C – Development paths of C₂AH_x in dependence on the content of free water

Hydration of C₃S in presence of CA: Mineral‐pore solution interaction

Evolution of kinetics and pore water composition during hydration of a CAC‐Calcite system by addition of Na₅P₃O₁₀