Dosage optimization and bolted connections for UHPFRC ties

Abstract

No part of this volume may be produced, stored in retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publishers. Los límites son físicos. Las limitaciones, mentales. Summary Dosage optimization and bolted connections for UHPFRC tiesConcrete technology has been in changeful evolution since the Roman Empire time. It is remarkable that the technological progress became of higher magnitude from the second part of the XX Century. Advances in the development of new cements, the appearance of the fibers as a reinforcement for structural applications, and specially the grand progress in the field of the water reducing admixtures enabled the emergence of several types of special concretes. One of the lasts is the Ultra High Performance Fiber Reinforced Concrete (UHPFRC), which incorporates advances of the Self-Compacting Concrete (SCC), Fiber-Reinforced Concrete (FRC) and Ultra High Strength Concrete (UHSC) technology. This exclusive material requires a detailed analysis of the components compatibility and a high control of the materials and processes. Mainly patented products have been used for the few structural elements carried out so far today, but the costs makes doubtful the development of many other potential applications.In accordance with the previously explained, a simplification of the UHPFRC components and processes is needed. This becomes the first main goal of this Ph.D. thesis, which emphasizes in the use of local available components and simpler mixing processes. Moreover, the singular properties of this material, between ordinary concrete and steel, allow not only the realization of slenderer structures, but also the viability of new concepts unthinkable with ordinary concrete. In this field is focused the second part of the Ph.D. thesis, which develops a bolted connection system between UHPFRC elements. This research summarizes, first of all, the subfamilies belonging to the HPC-UHPC materials. Afterwards, it is provided a detailed comparison between the dosage and properties of more than a hundred of mixtures proposed by several authors in the last ten years of technology. This becomes a useful tool to recognize correlations between dosages and properties and validate or no preconceived ideas about this material.Based on this state of art analysis was performed the later development of mixtures, on Chapter 4, which analized the effect of use of simpler components and processes on the UHPFRC. The main idea was use local components available in the Spanish market, identifying the combinations that provide the best rheological and mechanical properties. Steam curing use was avoided since a process simplification is intended. Diferent dosages were developed to be adapted to various levels of performance, and always trying to be as economical as possible. The concretes designed were selfcompacting and mainly combined two fiber types (hybrid), as the flexural performance was of greater relevanc...

Pull-Out Behaviour of Hooked End Steel Fibres Embedded in Ultra-high Performance Mortar with Various W/B Ratios

“…Research concerned with incorporating various types of steel fibres in UHPC has raised significantly interests due to its ability to achieve ductile behaviour under tension (Lim and Hong 2016;Abdallah et al 2016;Kang et al 2016;Wille et al 2014;Lee et al 2010). Yet, for the same ingredients of UHPC a significant difference in compressive strength can be found due to different W/B ratio (Torregrosa 2014). The great effect of W/B ratio on concrete performance may arise as a result of controlling the capillary pores which lead to increased concrete strength (Torregrosa 2014).…”

“…Yet, for the same ingredients of UHPC a significant difference in compressive strength can be found due to different W/B ratio (Torregrosa 2014). The great effect of W/B ratio on concrete performance may arise as a result of controlling the capillary pores which lead to increased concrete strength (Torregrosa 2014).…”

Effect of FC3R on the properties of ultra-high-performance concrete with recycled glass

“…Recycled glass powder, fluid catalytic cracking catalyst residue and limestone powder are some of the supplementary cementitious materials (SCM) that can be used as a partial substitution of Portland cement in UHPC [12,[19][20][21]. There are several UHPC mixture proportions from the literature using glass powder or limestone powder as a component of UHPC's binder.…”

“…On the other hand, little research has been conducted on the development of UHPC mixtures using FC3R, even though its use as a supplementary in pastes, mortars, and normal concrete has been widely studied [26][27][28][29]. The only reference in UHPC showed a strong decrease of workability when incorporating FC3R into an UHPC mixture [19].…”

“…Particles have a high degree of roughness with irregular shapes due to the previous process of grinding. Its special geometry implies a decrease in the workability of the mixtures if it substitutes Ordinary Portland Cement [19].…”