توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Bond Improvement in Cementitious Mortars Reinforced with Continuous Carbon Filaments
نویسنده(ها): ، ،
اطلاعات انتشار: نخستین کنفرانس بین المللی تکنولوژی بتن، سال
تعداد صفحات: ۱۰
Among various parameters that influence the properties of the composite, the bond between the cementitious matrix and the fibres is the most important one. This paper investigates the influence of admixtures – silica fume, superplasticizer and air entraining agent – on the improvement of the bond between bundled carbon filaments and cementitious mortars. An overall microstructural analysis has shown that the addition of silica fume strengthen the interfacial transition zone by both the reduction of its porosity and the consumption of CH crystals. The addition of a superplasticizer increased the workability of fresh mortars, but the bond improvement was insignificant. The application of the air entraining agent caused the formation of air bubbles inside the mortar matrix. Air bubbles formed in the vicinity of the multifilament yarn were found to provide mechanical anchoring for fibres leading to a significant increase in interface friction. Fibre–bundle pullout tests were carried out to confirm the effectiveness of the admixtures to improve the interface bonding. Based on the resulting load–displacement curves, air entraining agent was found to be most effective in enhancing the bonding characteristics of the cementitious composite.<\div>

۲Hardening of concrete with a planned delayed ettringite formation
نویسنده(ها): ، ،
اطلاعات انتشار: نخستین کنفرانس بین المللی تکنولوژی بتن، سال
تعداد صفحات: ۸
Delayed ettringite formation (DEF) in cementitious materials is widely considered as a harmful chemical reaction that causes extensive damages in hardened concrete. However, preventative measures and possible improvements in general are not extensively studied and require further attention. In this study was presented an investigation into a type of controlled DEF in places of finely dispersed crystallisation nuclei and provide evidence that the process may improve compressive strength of cementitious materials. The Alkali–Silica Reaction (ASR) in hydrated concrete was achieved with the addition of fly ash and was further accelerated with the Duggan’s test. Achieved strengths and monitoring of microstructure development conducted with electronic microscopy revealed that growth of ettringite crystals in the nuclei led to harmless internal compressive stresses, expansion of hydrated concrete and overall strengthening of the concrete matrix.<\div>
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