The effect of high temperatures on the mechanical performance of concrete blocks made with gneiss aggregates

2020 ◽  
pp. 571-576
Author(s):  
W.A. Medeiros ◽  
G.A. Parsekian ◽  
A.L. Moreno Jr
Keyword(s):  
High Temperatures ◽  
Mechanical Performance ◽  
Concrete Blocks

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.

scholarly journals State-of-the-Art Review on Experimental Investigations of Textile-Reinforced Concrete Exposed to High Temperatures

2021 ◽  
Vol 5 (11) ◽  
pp. 290
Author(s):  
Panagiotis Kapsalis ◽  
Tine Tysmans ◽  
Danny Van Hemelrijck ◽  
Thanasis Triantafillou
Keyword(s):  
Reinforced Concrete ◽  
High Temperatures ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Experimental Investigations ◽  
Textile Reinforced Concrete ◽  
Structural Applications ◽  
Promising Solution ◽  
Good Heat Resistance

Textile-reinforced concrete (TRC) is a promising composite material with enormous potential in structural applications because it offers the possibility to construct slender, lightweight, and robust elements. However, despite the good heat resistance of the inorganic matrices and the well-established knowledge on the high-temperature performance of the commonly used fibrous reinforcements, their application in TRC elements with very small thicknesses makes their effectiveness against thermal loads questionable. This paper presents a state-of-the-art review on the thermomechanical behavior of TRC, focusing on its mechanical performance both during and after exposure to high temperatures. The available knowledge from experimental investigations where TRC has been tested in thermomechanical conditions as a standalone material is compiled, and the results are compared. This comparative study identifies the key parameters that determine the mechanical response of TRC to increased temperatures, being the surface treatment of the textiles and the combination of thermal and mechanical loads. It is concluded that the uncoated carbon fibers are the most promising solution for a fire-safe TRC application. However, the knowledge gaps are still large, mainly due to the inconsistency of the testing methods and the stochastic behavior of phenomena related to heat treatment (such as spalling).

scholarly journals Mechanical Performance of Asphalt Mortar Containing Hydrated Lime and EAFSS at Low and High Temperatures

Materials ◽  
2017 ◽  
Vol 10 (7) ◽  
pp. 743 ◽  
Author(s):  
Ki Hoon Moon ◽  
Augusto Cannone Falchetto ◽  
Di Wang ◽  
Chiara Riccardi ◽  
Michael P. Wistuba
Keyword(s):  
High Temperatures ◽  
Mechanical Performance ◽  
Hydrated Lime ◽  
Asphalt Mortar

Mechanical Performance of RAC under True-Triaxial Compression after High Temperatures

2020 ◽  
Vol 32 (8) ◽  
pp. 04020194 ◽  
Author(s):  
Zhiheng Deng ◽  
Huaqiu Huang ◽  
Bailong Ye ◽  
Ping Xiang ◽  
Changqing Li
Keyword(s):  
High Temperatures ◽  
Mechanical Performance ◽  
Triaxial Compression ◽  
True Triaxial ◽  
True Triaxial Compression

scholarly journals Effect of Nano-SiO2 on the Microstructure and Mechanical Properties of Concrete under High Temperature Conditions

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 166
Author(s):  
Piotr Brzozowski ◽  
Jarosław Strzałkowski ◽  
Piotr Rychtowski ◽  
Rafał Wróbel ◽  
Beata Tryba ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Coarse Aggregate ◽  
Mechanical Performance ◽  
Mercury Porosimetry ◽  
Thermal Characteristics ◽  
Total Porosity ◽  
Cement Matrix ◽  
Cement Concrete ◽  
Structural Tests

The aim of the research was to determine how the admixture of nanosilica affects the structure and mechanical performance of cement concrete exposed to high temperatures (200, 400, 600, and 800 °C). The structural tests were carried out on the cement paste and concrete using the methods of thermogravimetric analysis, mercury porosimetry, and scanning electron microscopy. The results show that despite the growth of the cement matrix’s total porosity with an increasing amount of nanosilica, the resistance to high temperature improves. Such behavior is the result of not only the thermal characteristics of nanosilica itself but also of the porosity structure in the cement matrix and using the effective method of dispersing the nanostructures in concrete. The nanosilica densifies the structure of the concrete, limiting the number of the pores with diameters from 0.3 to 300 μm, which leads to limitation of the microcracks, particularly in the coarse aggregate-cement matrix contact zone. This phenomenon, in turn, diminishes the cracking of the specimens containing nanosilica at high temperatures and improves the mechanical strength.

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