The effects of sol-gel silicates on hydration kinetics and microstructure of Portland cement systems

Research output: Contribution to conferencePaper

Abstract

The effects of sol-gel silicates on Portland cement hydration were investigated. Silica sols were realized by tetraethylorthosilicate, triethoxymethylsilane, ethanol, water and nitric acid or ammonia. Solvent-free sols were also synthesised. The prepared sols were mixed with cement pastes at a w/c of 0.4 or 0.5 at varying doses of 0.5–10% by mass of dry cement. The solvent-free synthesised sol appeared to be a more suitable candidate. This is because observation of the hydration kinetics revealed a shortening of the dormant phase of cement hydration and exhibited a higher power output during this stage, representative of additional nucleation sites created in the system. However, the main peak power output that occurs at the end of acceleratory stage was decreased, further pronounced at higher sol dosages. This can be attributed to the ethoxy-based precursor, which produces ethanol as a by-product of hydrolysis reactions. It is therefore of great interest to investigate possible routes to optimise the sols to limit the alcohol content. SEM analyses on fractured surfaces of 28 day old pastes revealed a distinctive morphology, particularly at higher sol dosages. The development of C-S-H on portlandite was observed, which further suggests that the sol-gel silicates could be providing additional nucleation sites therefore acting as a seeding agent.

Conference

ConferenceThe 9th International Concrete Conference 2016
CountryUK United Kingdom
CityDundee and Angus
Period4/07/166/07/16
Internet address

Fingerprint

hydration
microstructure
cement
gel
silicate
kinetics
nucleation
ethanol
nitric acid
seeding
alcohol
hydrolysis
ammonia
silica
scanning electron microscopy
effect
water
dosage

Keywords

  • Silica, Sol-gel, Nanotechnology, Nucleation seeding, C-S-H polymerisation

Cite this

Shakil, M., Holley, J., Paine, K., & Ansell, M. (2016). The effects of sol-gel silicates on hydration kinetics and microstructure of Portland cement systems. Paper presented at The 9th International Concrete Conference 2016, Dundee and Angus, UK United Kingdom.

The effects of sol-gel silicates on hydration kinetics and microstructure of Portland cement systems. / Shakil, Muzzamil; Holley, Juliana; Paine, Kevin; Ansell, Martin.

2016. Paper presented at The 9th International Concrete Conference 2016, Dundee and Angus, UK United Kingdom.

Research output: Contribution to conferencePaper

Shakil, M, Holley, J, Paine, K & Ansell, M 2016, 'The effects of sol-gel silicates on hydration kinetics and microstructure of Portland cement systems' Paper presented at The 9th International Concrete Conference 2016, Dundee and Angus, UK United Kingdom, 4/07/16 - 6/07/16, .
Shakil M, Holley J, Paine K, Ansell M. The effects of sol-gel silicates on hydration kinetics and microstructure of Portland cement systems. 2016. Paper presented at The 9th International Concrete Conference 2016, Dundee and Angus, UK United Kingdom.
Shakil, Muzzamil ; Holley, Juliana ; Paine, Kevin ; Ansell, Martin. / The effects of sol-gel silicates on hydration kinetics and microstructure of Portland cement systems. Paper presented at The 9th International Concrete Conference 2016, Dundee and Angus, UK United Kingdom.
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AB - The effects of sol-gel silicates on Portland cement hydration were investigated. Silica sols were realized by tetraethylorthosilicate, triethoxymethylsilane, ethanol, water and nitric acid or ammonia. Solvent-free sols were also synthesised. The prepared sols were mixed with cement pastes at a w/c of 0.4 or 0.5 at varying doses of 0.5–10% by mass of dry cement. The solvent-free synthesised sol appeared to be a more suitable candidate. This is because observation of the hydration kinetics revealed a shortening of the dormant phase of cement hydration and exhibited a higher power output during this stage, representative of additional nucleation sites created in the system. However, the main peak power output that occurs at the end of acceleratory stage was decreased, further pronounced at higher sol dosages. This can be attributed to the ethoxy-based precursor, which produces ethanol as a by-product of hydrolysis reactions. It is therefore of great interest to investigate possible routes to optimise the sols to limit the alcohol content. SEM analyses on fractured surfaces of 28 day old pastes revealed a distinctive morphology, particularly at higher sol dosages. The development of C-S-H on portlandite was observed, which further suggests that the sol-gel silicates could be providing additional nucleation sites therefore acting as a seeding agent.

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