Topic
Silica fume
About: Silica fume is a(n) research topic. Over the lifetime, 10177 publication(s) have been published within this topic receiving 173857 citation(s).
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TL;DR: In this paper, the influence of nano-SiO 2 (NS) addition on properties of hardened cement paste (hcp) as compared with silica fume (SF) has been studied through measurement of compressive and bond strengths of hcp, and by XRD and SEM analysis.
Abstract: The influence of nano-SiO 2 (NS) addition on properties of hardened cement paste (hcp) as compared with silica fume (SF) has been studied through measurement of compressive and bond strengths of hcp, and by XRD and SEM analysis. Results indicated that the influence of NS and SF on consistency and setting time of fresh cement paste showed different. NS made cement paste thicker and NS accelerated the cement hydration process. Compressive strengths of hcp and bond strengths of paste–aggregate interface incorporating NS were obviously higher than those incorporating SF, especially at early ages. And with increasing the NS content, the rate of bond strength increase was more than that of their compressive strength increase. With 3% NS added, NS digested calcium hydroxide (CH) crystals, decreased the orientation of CH crystals, reduced the crystal size of CH gathered at the interface and improved the interface more effectively than SF. The results suggest that with a small amount of added NS, the CH crystals at the interface between hcp and aggregate at early ages may be effectively absorbed in high performance concrete (HPC).
887 citations
TL;DR: In this paper, the properties of cement mortars with nano-SiO 2 were experimentally studied, and the results showed that the compressive strength of mortars containing nano SiO 2 particles was significantly higher than those of those containing silica fume at 7 and 28 days.
Abstract: The properties of cement mortars with nano-SiO 2 were experimentally studied. The amorphous or glassy silica, which is the major component of a pozzolan, reacts with calcium hydroxide formed from calcium silicate hydration. The rate of the pozzolanic reaction is proportional to the amount of surface area available for reaction. Therefore, it is plausible to add nano-SiO 2 particles in order to make high-performance concrete. The experimental results show that the compressive strengths of mortars with nano-SiO 2 particles were all higher than those of mortars containing silica fume at 7 and 28 days. It is demonstrated that the nano-particles are more valuable in enhancing strength than silica fume. In addition, the continuous hydration progress was monitored by scanning electron micrograph (SEM) observation, by examining the residual quantity of Ca(OH) 2 and the rate of heat evolution. The results of these examinations indicate that nano-scale SiO 2 behaves not only as a filler to improve microstructure, but also as an activator to promote pozzolanic reaction.
755 citations
TL;DR: In this article, a method for reducing autogenous shrinkage in a material based on a hydraulic mineral binder, e.g. cement, by preparing a mixture comprising the binder and water and a water-entraining agent selected from the group consisting of hydrogels and microencapsulated water, casting the mixture in a desired configuration, and allowing the mixture to cure.
Abstract: The invention relates to a method for reducing autogenous shrinkage in a material based on a hydraulic mineral binder, e.g. cement, by preparing a mixture comprising the binder, water and a water-entraining agent selected from the group consisting of hydrogels and microencapsulated water, casting the mixture in a desired configuration, and allowing the mixture to cure. The method is in particular directed to high performance cement-based materials with a low water/cement ratio and optionally comprising ultrafine particles such as silica fume. The water-entraining agent is in particular a hydrogel. Also disclosed are dry compositions comprising fine particles such as cement, ultrafine particles such as silica fume, optionally a dispersing agent such as a concrete superplasticizer, and a water-entraining agent such as a hydrogel.
677 citations
Book•
29 Dec 2001
TL;DR: The use of Synchroton sources in the study of Cement Materials as discussed by the authors has been shown to be useful in the analysis of Cements and their applications in many applications.
Abstract: 1. Cement Manufacture 2. Composition of Cement Phases 3. The Hydration of Portland Cement 4. Calcium Aluminate Cements 5. Properties of Concrete with Mineral and Chemical Admixtures 6. Special Cements 7. Developments with Oilwell Cements 8. Gypsum in Cements 9. Alkali-Silica Reaction in Concrete 10. Delayed Ettringite Formation 11. Chloride-Corrosion in Cementitious Systems 12. Blastfurnace Cements 13. Properties and Applications of Natural Pozzolanas 14. Pulverised Fuel Ash as a Cement Extender 15. Metakaolin as a Pollolanic Addition to Concrete 16. Condensed Silica Fume as a Cement Extender 17. Cement-Based Composite Micro-Structures 18. X-Ray Powder Diffraction Analysis of Cements 19. Electron Microscopy of Cements 20. Electrical Monitoring Methods in Cement Science 21. Nuclear Magnetic Resonance Spectroscopy and Magnetic Resonance Imaging Studies of Cements and Cement-Based Materials 22. The Use of Synchroton Sources in the Study of Cement Materials
612 citations
TL;DR: In this article, a water permeability resistant behavior and microstructure of concrete with nano-SiO2 were experimentally studied and it was shown that the micro-structured concrete with SiO2 is more uniform and compact than that of normal concrete.
Abstract: Water permeability resistant behavior and microstructure of concrete with nano-SiO2 were experimentally studied. A water permeability test shows that, for concretes of similar 28-day strength, the incorporation of nano-SiO2 can improve the resistance of water penetration of concrete. An ESEM test reveals that the microstructure of concrete with nano-SiO2 is more uniform and compact than that of normal concrete. Mechanism about the effect of nano-SiO2 on concrete is described.
557 citations