scholarly journals Behaviour of high-performance concrete at high temperatures: some highlights

2017 ◽  
Vol 2 ◽  
pp. 45-52 ◽  
Author(s):  
Pierre Pimienta ◽  
Maria Cruz Alonso ◽  
Robert Jansson McNamee ◽  
Jean-Christophe Mindeguia
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Performance ◽  
High Performance Concrete ◽  
State Of The Art ◽  
Technical Committee ◽  
Rilem Technical Committee ◽  
Civil Structures ◽  
Physicochemical Changes ◽  
Materials Used

High-performance concrete (HPC) is one of the most recent types of concrete among the materials used routinely in building and civil structures. Their development in structures applications and the growing need for the justification of their fire resistance has led several laboratories to carry out research on their properties at high temperature. This letter presents some main aspects related to their physicochemical changes, thermal properties and mechanical properties at high temperature. It introduces a State of The Art prepared by the RILEM Technical Committee 227-HPB (Physical properties and behaviour of High-Performance Concrete at high temperature) and untitled “Behaviour of High-Performance Concrete at high temperatures”. This State of the Art will be publish in a next future.

scholarly journals Effects of Combined Usage of Supplementary Cementitious Materials on the Thermal Properties and Microstructure of High-Performance Concrete at High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1833 ◽  
Author(s):  
Dong Lu ◽  
Zhuo Tang ◽  
Liang Zhang ◽  
Jianwei Zhou ◽  
Yue Gong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Amorphous Phases ◽  
Micro Cracks

Concrete has low porosity and compact microstructure, and thus can be vulnerable to high temperature, and the increasing application of various types of supplementary cementitious materials (SCMs) in concrete makes its high-temperature resistant behavior more complex. In this study, we investigate the effects of four formulations with typical SCMs combinations of fly ash (FA), ultra-fine fly ash (UFFA) and metakaolin (MK), and study the effects of SCMs combinations on the thermal performance, microstructure, and the crystalline and amorphous phases evolution of concrete subjected to high temperatures. The experimental results showed that at 400 °C, with the addition of 20% FA (wt %), the thermal conductivity of the sample slightly increased to 1.5 W/(m·K). Replacing FA with UFFA can further increase the thermal conductivity to 1.7 W/(m·K). Thermal conductivity of concrete slightly increased at 400 °C and significantly reduced at 800 °C. Further, combined usage of SCMs delayed and reduced micro-cracks of concrete subjected to high temperatures. This study demonstrates the potential of combining the usage of SCMs to promote the high-temperature performance of concrete and explains the micro-mechanism of concrete containing SCMs at high temperatures.

Temperature Control in High Performance Concrete

2015 ◽  
Vol 1100 ◽  
pp. 162-165
Author(s):  
Martin Sedlmajer ◽  
Jiri Zach ◽  
Jitka Peterková ◽  
Lenka Bodnárová
Keyword(s):  
High Temperature ◽  
Temperature Distribution ◽  
Heat Source ◽  
High Temperatures ◽  
Temperature Control ◽  
High Performance ◽  
High Performance Concrete ◽  
Cement Composites ◽  
Fire Temperature ◽  
Temperature Observation

The paper addresses the methodology of temperature observation of cement composites, such as concrete. It is mainly the monitoring of the course of hydration temperature and the possibilities of its regulation. Subsequently, the observation of temperature within samples which are exposed to high temperatures. Attention is paid to a variety of temperatures of a concrete segment which is being acted upon by a high-temperature source, e.g. fire. Temperature distribution at a varied distance from the heat source is observed.

scholarly journals Insight into the Mechanical Performance of the UHPC Repaired Cementitious Composite System after Exposure to High Temperatures

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4095
Author(s):  
Qing Chen ◽  
Zhiyuan Zhu ◽  
Rui Ma ◽  
Zhengwu Jiang ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
High Temperatures ◽  
Bonding Strength ◽  
Composite System ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Interfacial Structure ◽  
Cementitious Composite ◽  
Average Percentage

In this paper, the mechanical performance of an ultra-high-performance concrete (UHPC) repaired cementitious composite system, including the old matrix and the new reinforcement (UHPC), under various high temperature levels (20 °C, 100 °C, 300 °C, and 500 °C) was studied. In this system, UHPC reinforced with different contents of steel fibers and polypropylene (PP) fibers was utilized. Moreover, the physical, compressive, bonding, and flexural behaviors of the UHPC repaired system after being exposed to different high temperatures were investigated. Meanwhile, X-ray diffraction (XRD), baseline evaluation test (BET), and scanning electron microscope (SEM) tests were conducted to analyze the effect of high temperature on the microstructural changes in a UHPC repaired cementitious composite system. Results indicate that the appearance of the bonded system changed, and its mass decreased slightly. The average percentage of residual mass of the system was 99.5%, 96%, and 94–95% at 100 °C, 300 °C, and 500 °C, respectively. The residual compressive strength, bonding strength, and flexural performance improved first and then deteriorated with the increase of temperature. When the temperature reached 500 °C, the compressive strength, bonding strength, and flexural strength decreased by about 20%, 30%, and 15% for the UHPC bonded system, respectively. Under high temperature, the original components of UHPC decreased and the pore structure deteriorated. The cumulative pore volume at 500 °C could reach more than three times that at room temperature (about 20 °C). The bonding showed obvious deterioration, and the interfacial structure became looser after exposure to high temperature.

State of the Art for Fabricating and Emplacing Concrete Containers Into Large Horizontal Disposal Caverns in the French Geological Repository

2011 ◽  
Author(s):  
Jean-Michel Bosgiraud ◽  
Maurice Guariso ◽  
Franc¸ois Pineau
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
State Of The Art ◽  
Gantry Crane ◽  
Deep Geological Repository ◽  
Initial Development ◽  
The Public ◽  
Building Process ◽  
License Application ◽  
Geological Repository

The research and development work presented in this paper was initialized by Andra in 2007. The work necessary for manufacturing and testing a full scale demonstrator is presently implemented. The case story is twofold. The first part is related to the initial development of a high performance concrete formulation used for fabricating concrete storage containers (containing Intermediate Level and Long Lived Waste primary canisters) to be stacked and emplaced into 400-m long concrete lined horizontal disposal vaults (also called cavern), excavated in the Callovo-Oxfordian clay host formation at a 550 to 600-m depth, with an inside diameter of approximately 8-m. The fabrication of the concrete boxes is illustrated. The second part presents the outcome at the end of the detailed design phase, for a system which is now being manufactured (for further test and assembly), for the emplacement of the concrete containers inside the vault. The application was engineered for remote emplacing a pile of 2 concrete containers (the containers are preliminarily stacked in a pile of 2, inside a hot cell, thanks to a ground travelling gantry crane). The emplacement process is justified and the related emplacement synoptic is illustrated. The test campaign is scheduled in 2011–2012. The successful completion of the technical trials is mandatory to confirm the mechanical feasibility of remotely emplacing concrete containers into large horizontal disposal caverns over long distances. The later display of the machinery at work in Andra’s showroom will be instrumental for the confidence building process involving the various stakeholders concerned by the public enquiry period (mid-2013) preceding the deep geological repository license application (2014–2015).

Material Properties of Ultra - High Performance Concrete in Extreme Conditions

2016 ◽  
Vol 711 ◽  
pp. 157-162 ◽  
Author(s):  
David Citek ◽  
Milan Rydval ◽  
Stanislav Rehacek ◽  
Jiří Kolísko
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Material Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Accurate Information ◽  
Extreme Conditions ◽  
Ultra High Performance Concrete ◽  
Freeze Thaw

The Ultra High Performance Concrete (UHPC) is a very promising material suitable for application in special structures. However, the knowledge of performance of this relatively new material is rather limited. The exceptional mechanical properties of UHPC allow for a modification of the design rules, which are applicable in ordinary or high strength concrete. This paper deals in more detail with impact of thermal stress on bond properties between prestressing strands and UHPC and an influence of high temperature to final material properties of different UHPC mixtures. Specimens in the first experimental part were subjected to the cycling freeze-thaw testing. The relationship between bond behavior of both type of material (UHPC and ordinary concrete) and effect of cycling freeze-thaw tests was investigated. The second part of experimental work was focused on mechanical properties of UHPC exposure to the high temperature (Tmax = 200°C to Tmax = 1000°C). Tested mechanical properties were compressive and flexural strengths, the fracture properties will be presented in the next paper. The obtained experimental data serve as a basis for further systematic experimental verification and more accurate information about the significantly higher material properties of UHP(FR)C and its behavior in extreme conditions.

Contribution of Reinforcing Fiber Types on the Mechanical Properties of High Performance Concrete Subjected to High Temperature

2013 ◽  
Vol 368-370 ◽  
pp. 1052-1055
Author(s):  
Seung Jo Lee ◽  
Jung Min Park
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperature ◽  
Weight Reduction ◽  
High Performance ◽  
High Performance Concrete ◽  
Reduction Ratio ◽  
Fiber Types ◽  
Residual Compressive Strength ◽  
Reinforcing Fiber

The aim of the study is to improve the understanding of the influence of reinforcing fiber types on the mechanical properties of high performance concretes (HPC) subjected to high temperature. The mechanical properties measured include residual compressive strength, weight reduction ratio, outward appearance property, and failure mode. Nylon, polypropylene, and steel fiber were added to enhance mechanical property of the concretes. After exposure to high temperatures ranged from 100 to 800°C, mechanical properties of fiber-toughened HPC were investigated. For HPC, although residual compressive strength was decreased by exposure to high temperature over 500°C, weight reduction ratio was significantly higher than that before heating temperature.

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