scholarly journals Predicting Unconfined Compressive Strength Decrease of Carbonate Building Materials against Frost Attack Using Nondestructive Physical Tests

2020 ◽  
Vol 12 (4) ◽  
pp. 1379 ◽  
Author(s):  
Marzouk Mohamed Aly Abdelhamid ◽  
Dong Li ◽  
Gaofeng Ren
Keyword(s):  
Compressive Strength ◽  
Wave Velocity ◽  
Unconfined Compressive Strength ◽  
Building Materials ◽  
Construction Materials ◽  
Strong Relationship ◽  
Compressional Wave ◽  
Compressional Wave Velocity ◽  
Frost Weathering ◽  
Spatial Attenuation

Carbonate building materials and engineering constructions are exposed to severe seasonal environmental fluctuations and result in a full or partial disintegration, especially in cold regions, and employment of nondestructive methods for evaluating the durability of building materials subject to frost weathering is gaining great significance. This research aims to obtain reliable relationships between unconfined compressive strength decrease and nondestructive parameters variations of limestone types under frost conditions and provide useful information regarding their durability in order to ensure the long-term viability or sustainability of these materials used for constructions against frost conditions. In this study, five important types of Chinese limestone used as construction materials were subjected to 50 frost cycles. Unconfined compressive strength, compressional wave velocity and spatial attenuation, and porosity were obtained at the end of every 10 cycles. As a result of progression in frost cycles, the increase and decrease rates were determined at the end of every 10 cycles, and the relationships between them were obtained to predict the loss ratios of unconfined compressive strength (RDσc). Results indicated that at the end of 40th cycles, there was a high correlation between RDσc and spatial attenuation loss with an R2 of 0.8584. Furthermore, there was also a strong relationship between RDσc and compressional wave velocity decrease after the end of 20th and 50th cycles with an R2 of 0.9089 and 0.9025, respectively. Therefore, these relations are reliable to provide useful information for durability and viability of studied samples under frost conditions and support the use of the ultrasonic measurements. It can also be successfully used for pre-estimation of unconfined compressive strength loss of studied limestone types against frost weathering without any tests.

Investigation of Weak Sandstones

1986 ◽  
Vol 2 (1) ◽  
pp. 199-205
Author(s):  
L. Dobereiner ◽  
M. H. de Freitas
Keyword(s):  
Compressive Strength ◽  
Moisture Content ◽  
Uniaxial Compressive Strength ◽  
Wave Velocity ◽  
Compressional Wave ◽  
Weak Rock ◽  
Index Test ◽  
Compressional Wave Velocity ◽  
Compressional Waves ◽  
Weak Sandstone

AbstractIt is proposed that coverage of the class of material described in BS 5930 as weak rock, is in need of improvement.Results from research into the behaviour of weak sandstone (0.5-20 MPa uniaxial compressive strength) are presented to illustrate this need. The strength, deformability, and propagation of compressional waves are reported for weak sandstones and recommendations presented for describing these materials and for testing their strength and deformability. Problems associated with the measurement of compressional wave velocity are also considered.An index test for assessing the strength of weak sandstone (the index of vacuum saturated moisture content) is described and presented.

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

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