Important properties of an ultrafine cement — Part I

Sarkar, S.; Wheeler, J.

doi:10.1016/s0008-8846(00)00393-8

Cited by 29 publications

(18 citation statements)

References 1 publication

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“…The reason for this tendency was that inserting the resistance needle was difficult in the case of NS, which used very fine nano-silica. The flow results were consistent with those of a literature survey (Sarkar and Wheeler 2001), in that very fine binder (NS) caused the content of high-range water-reducing agents to increase, whereas nano fly ash (NFA) did not. Figure 11 shows the compressive strength of mortars with different binders on days 3, 7, 28, 56, and 180.…”

Section: Setting and Fluiditysupporting

confidence: 89%

Comparison of innovative nano fly ash with conventional fly ash and nano-silica

et al. 2014

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This report is an experimental study on the nano-powdering of fly ash and the improvement of cement performance by nano fly ash. Mortars with nano fly ash or nano-silica produced by a physical method are compared with mortar without a nano-binder. Mortar with nano-silica showed rapid setting. However, mortar with fly ash or nano fly ash exhibited delayed setting. The smaller the particle sizes, the higher is the compressive strength, demonstrating that mortar with nano fly ash shows superior performance with higher compressive strength from the beginning. Durability assessments revealed that chloride penetration resistance increased by 70% for mortar with nano fly ash or nano-silica. This shows that mortar with a smaller particle binder has excellent carbonation resistance. Nano-powdering effectively enhances the activation of a pozzolanic reaction and provides densely charged effects. These changes solve the problem of initial strength reduction -the greatest weakness of fly ash. Résumé :Ce rapport d'une étude expérimentale sur le nano-poudrage de cendres volantes et l'amélioration du rendement des ciments par des nano-cendres volantes. Les mortiers contenant des nano-cendres volantes ou de la nano-silice produites par une méthode physique sont comparés à un mortier sans nano-liant. Le mortier contenant de la nano-silice a démontré une prise rapide. Toutefois, le mortier contenant des cendres volantes ou des nano-cendres volantes présentait une prise retardée. Plus les particules sont de petites dimensions, plus la résistance en compression est forte, indiquant que le mortier contenant des nano-cendres volantes a un meilleur rendement et une résistance supérieure à la compression dès le départ. Les évaluations de la durabilité ont révélé que la résistance à la pénétration du chlorure a augmenté de 70 % pour le mortier contenant des nano-cendres volantes ou de la nano-silice. Cela montre que le mortier ayant un liant de particules de plus petites dimensions présente une excellente résistance à la carbonatation. Le nano-poudrage améliore efficacement l'activation de la réaction pouzzolanique et fournit des effets densément chargés. Ces changements résolvent le problème de réduction initiale de la résistance -le plus grand problème avec les cendres volantes. [Traduit par la Rédaction]

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Section: Setting and Fluiditysupporting

confidence: 89%

Comparison of innovative nano fly ash with conventional fly ash and nano-silica

et al. 2014

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“…Sarkar and Wheeler have stated that the heat evolution of ultrafine cement within the first 24 hours can be exceptionally high compared to that of an ASTM Type III cement 14 . This results in rapid consumption of the available water, which in turn leads to limited hydration at later ages.…”

Section: Introductionmentioning

confidence: 99%

Dry-grinded ultrafine cements hydration. physicochemical and microstructural characterization

et al. 2013

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The aim of the present research work was the evaluation of the physicochemical and microstructural properties of two ultrafine cements, produced by dry grinding of a commercial CEM I 42.5N cement. The effect of grinding on particle size distribution was determined by laser scattering analyzer. All cements were tested for initial and final setting times, consistency of standard paste, soundness, flow of normal mortar and compressive strengths after 1, 2, 7 and 28 days. The effect of the fineness on the heat of hydration was also investigated. The hydration products were determined by X-ray diffraction analysis and by Fourier transform infrared spectroscopy, at 1, 2, 7 and 28 days. The microstructure of the hardened cement pastes and their morphological characteristics were examined by scanning electron microscopy. Porosity and pore size distribution were evaluated by mercury intrusion porosimetry. The effects of greater fineness on compressive strengths were evident principally at early ages. After the first 24 hours of hydration, the compressive strength of the finest cements was about 3 times higher (over 48 MPa) than the corresponding of CEM I 42.5N (15.1 MPa).

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“…In contrast, China is a late comer to research on filling and plugging materials. Chinese workers still use materials like wood, loess, cement grouting [11], and fly ash grouting in coal mines. Recent years have witnessed the development and application of new filling materials, including gel materials, fly ash composite colloid [12,13], paste backfilling [14], thickened mortar [15], rigid polyurethane foam [16], Marithan, and Igloneige [17].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study and Application of Inorganic Solidified Foam Filling Material for Coal Mines

Wen¹,

Zhang²,

Yu³

et al. 2017

Advances in Materials Science and Engineering

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Spontaneous combustion of residual coal in a gob due to air leakage poses a major risk to mining safety. Building an airtight wall is an effective measure for controlling air leakage. A new type of inorganic solidified foam-filled material was developed and its physical and chemical properties were analyzed experimentally. The compressive strength of this material increased with the amount of sulphoaluminate cement. With an increasing water-cement ratio, the initial setting time was gradually extended while the final setting time firstly shortened and then extended. The change in compressive strength had the opposite tendency. Additionally, as the foam expansion ratio increased, the solidification time tended to decrease but the compressive strength remained approximately constant. With an increase in foam production, the solidification time increased and the compressive strength decreased exponentially. The results can be used to determine the optimal material ratios of inorganic solidified foamfilled material for coal mines, and filling technology for an airtight wall was designed. A field application of the new material demonstrated that it seals crossheadings tightly, leaves no fissures, suppresses air leakage to the gob, and narrows the width of the spontaneous combustion and heat accumulation zone.

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Important properties of an ultrafine cement — Part I

Cited by 29 publications

References 1 publication

Comparison of innovative nano fly ash with conventional fly ash and nano-silica

Comparison of innovative nano fly ash with conventional fly ash and nano-silica

Dry-grinded ultrafine cements hydration. physicochemical and microstructural characterization

Experimental Study and Application of Inorganic Solidified Foam Filling Material for Coal Mines

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