SCC and UHPC — Effect of Mixing Technology on Fresh Concrete Properties

Schießl, P; Mazanec, Oliver; Lowke, Dirk

doi:10.1007/978-3-540-72448-3_52

Cited by 21 publications

(21 citation statements)

References 2 publications

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“…It also has to be taken in account that PCE can have different base and depending on the binder components one or other should be chosen. Methacrylate based PCE adsorbs preferentially on cement particles and allyl ether PCE on silica fume [210].…”

Section: Superplasticizermentioning

confidence: 95%

“…The admixture addition is recommended in two parts [206] [225] [210], first one just after the water and the second after agglomerates are already formed, in order not to entrap all the PCE inside in them. This method provides higher workability than one single PCE addition [225].…”

Section: Mixing Processmentioning

confidence: 99%

“…This is a second reason for the delayed admixture addition: The rapid formation during the mixing of the first ettringite crystals, between 300 and 500 nm [210]. The PCE molecules, with sizes 20 or 30 times smaller, are overgrown by these crystals or are chemically incorporated to these new formed hydration products, taking part of their structure and losing their efficiency [247].…”

Section: Mixing Processmentioning

confidence: 99%

“…Many authors have used it with different mixing processes [144] [56] [42] [154] [211]. The power of the agitator is 11 kW, and adding the pan and discharge system is 13.9 kW.…”

Section: Liter Intensive Mixermentioning

confidence: 99%

“…In the UHPFRC made with FC3R the primary ettringite formation may increase due to its high Al2O3 content. In an alkaline medium the change to Al 2 − takes place, and forms ettringite crystals of sizes between 300 and 500 nm [210]. These are the first molecules of the rapid forming ettringite.…”

Section: Figure 421: Slump Flow For the Different Mixing Times Of Domentioning

confidence: 99%

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Dosage optimization and bolted connections for UHPFRC ties

Camacho¹,

Efraím²

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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...

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Section: Superplasticizermentioning

confidence: 95%

Section: Mixing Processmentioning

confidence: 99%

Section: Mixing Processmentioning

confidence: 99%

“…Many authors have used it with different mixing processes [144] [56] [42] [154] [211]. The power of the agitator is 11 kW, and adding the pan and discharge system is 13.9 kW.…”

Section: Liter Intensive Mixermentioning

confidence: 99%

Section: Figure 421: Slump Flow For the Different Mixing Times Of Domentioning

confidence: 99%

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Dosage optimization and bolted connections for UHPFRC ties

Camacho¹,

Efraím²

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Mixing Optimization of an Alumina based LC‐Castable by Applying Variable Power Inputs

Kasper

Krause

2014

Proceedings of the Unified International Technical Conference on Refractories (UNITECR 2013)

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Effect of type of mixer on rheological and mechanical behavior of ultra high‐performance concrete

Christ

Pacheco

Ehrenbring

et al. 2023

Structural Concrete

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Ultrahigh‐performance concrete (UHPC) is becoming increasingly frequent in several civil construction projects such as industries, buildings, and even infrastructure. The rheological and mechanical behaviors, coupled with durability, are the driving motives for this increase in use over the last few decades. However, the type of mixer used in UHPC production considerably affects the final composites performance due to variations in mixing velocity and the need to disperse particles with low granulometry. This study evaluated the effect of type of mixer in the properties of UHPC in the fresh and hardened states. This study evaluates three types of mixers: planetary vertical axis, horizontal axis, and drum. Results showed that the drum mixer was the least efficient in homogenizing the composite. It showed an average mixing time about 126% longer than planetary vertical or horizontal‐axis mixers to reach the same level of flowability. The composite from the drum mixer also had the most entrained air and void index. The planetary vertical‐axis mixer was the most efficient, with the resulting composite having a potential compression strength of 169.1 MPa, 19.3% higher than the composite from the horizontal‐axis mixer.

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SCC and UHPC — Effect of Mixing Technology on Fresh Concrete Properties

Cited by 21 publications

References 2 publications

Dosage optimization and bolted connections for UHPFRC ties

Dosage optimization and bolted connections for UHPFRC ties

Mixing Optimization of an Alumina based LC‐Castable by Applying Variable Power Inputs

Effect of type of mixer on rheological and mechanical behavior of ultra high‐performance concrete

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