scholarly journals Predicting the Uniaxial Compressive Strength of a Limestone Exposed to High Temperatures by Point Load and Leeb Rebound Hardness Testing

2021 ◽  
Author(s):  
María Elvira Garrido ◽  
Ferry B. Petnga ◽  
Víctor Martínez-Ibáñez ◽  
José B. Serón ◽  
Carlos Hidalgo-Signes ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
High Temperatures ◽  
Rock Strength ◽  
Point Load ◽  
Load Test ◽  
Historic Buildings ◽  
Indirect Determination ◽  
Non Destructive ◽  
Cooling Methods

AbstractThe effect of exposure to high temperature on rock strength is a topic of interest in many engineering fields. In general, rock strength is known to decrease as temperature increases. The most common test used to evaluate the rock strength is the uniaxial compressive strength test (UCS). It can only be carried out in laboratory and presents some limitations in terms of the number, type and preparation of the samples. Such constrains are more evident in case of rocks from historical monuments affected by a fire, where the availability of samples is limited. There are alternatives for an indirect determination of UCS, such as the point load test (PLT), or non-destructive tests such as the Schmidt’s hammer, that can also be performed in situ. The aims of this research are: (i) measuring the effect of high temperatures and cooling methods on the strength and hardness of a limestone named Pedra de Borriol widely used in several historic buildings on the E of Spain, and (ii) studying the possibility of indirectly obtaining UCS by means of PLT and Leeb hardness tests (LHT), using Equotip type D. Limestone samples were heated to 105 (standard conditions), 200, 300, 400, 500, 600, 700, 800 and 900 ºC and cooled slowly (in air) and quickly (immersed in water). After that, UCS, PLT and LHT tests were performed to evaluate the changes as temperature increases. Results show decreases over 90% in UCS, of between 50 and 70% in PLT index and smaller than 60% in LHT index. Insignificant differences between cooling methods were observed, although slowly cooled samples provide slightly higher values than quickly cooled ones. The results indicate that LHT can be used to indirectly estimate UCS, providing an acceptable prediction. Research on correlating strength parameters in rocks after thermally treated is still scarce. This research novelty provides correlations to predict UCS in historic buildings if affected by a fire, from PLT and non-destructive methods such as LHT whose determination is quicker and easier.

Study on the Relation between Uniaxial Compressive Strength and Point Load Strength

2014 ◽  
Vol 501-504 ◽  
pp. 282-285
Author(s):  
Rui Hong Wang ◽  
Yu Zhou Jiang ◽  
Jin Long Guo ◽  
Tian Cai Tang
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Point Load ◽  
Load Test ◽  
Key Factors ◽  
Point Load Strength ◽  
Result Show ◽  
Internal Relations ◽  
Rock Specimens ◽  
Test Result

In order to investigate the relation between uniaxial compressive strength and point load strength, several homogeneous rock specimens were tested, and the influence of the different rock type was investigated using regression analysis and the derived equations were statistically tested. The test result show that there are some correlations and trends between uniaxial compressive strength and point load strength, the shape size and lithology of rock specimens have important influence on the result of point load test, and the greain size, the mineral compositon and the structral compact are key factors. It is difficult to realize that using one or several function to describe all internal relations between uniaxial compressive strength and point load strength.

scholarly journals Aggregate suitability and Geo-chemical investigation of limestone for construction industries in Pakistan: An approach for economic development

2021 ◽  
Author(s):  
Asad Kamran ◽  
Liaqat Ali ◽  
Waqas Ahmed ◽  
Sobia Zoreen ◽  
Shah Jehan
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Point Load ◽  
Load Test ◽  
Raw Material ◽  
Schmidt Hammer ◽  
Point Load Test

Abstract This study investigated the aggregate suitability and geo-chemical characteristics of limestone (LS) for construction industries. The results of aggregate parameters for different applications revealed that specific gravity (SG = 2.6), water absorption (WA = 0.47%), bulk density (BD = 1.58 g/cm3), flakiness index (FI = 16.8%), elongation index (EI = 16.39%), soundness (S = 1.6%), aggregate impact value (AIV = 14%), Los Angles Abrasion value (LAAV = 23.51%), clay lumps (CL = 0.35%), uniaxial compressive strength (UCS = 86.7 MPa), point load test (PLT = 5.18 MPa), ultrasonic pulse velocity (UPV = 5290 m/s) and Schmidt hammer rebound test (SHRT = 49 N) are in accordance with ASTM, ISRM and BSI. Petrographically, the LS is dominantly composed of ooids, peloids, bioclasts and calcite (CaCO3) with trace concentration of the dolomite. Geochemical results (n = 18) indicated that the LS is dominantly made up of calcite (95.81%); while on average it is composed of 52.08 wt.% CaO, 1.13 wt. % SiO2, 0.66 wt. %, MgO, 0.80 wt. % Al2O3, 0.76 wt. % Fe2O3 and LOI were recorded as 42.13 wt. %. Whereas, P2O5, TiO2, MnO, K2O and Na2O are found in trace amount. Regression analysis demonstrates that the empirical correlation equation for estimating uniaxial compressive strength with ultrasonic pulse velocity is more reliable than Schmidt hammer rebound test and point load test. The findings of this study strongly suggest LS of the area has a great potential as a raw material in construction industries.

scholarly journals Studies on the Mechanical Properties of Dry, Saturated, and Frozen Marls Using Destructive and Non-destructive Laboratory Approaches

2021 ◽  
Author(s):  
Seyed Morteza Davarpanah ◽  
Mohammad Sharghi ◽  
Abolfazl Tarifard ◽  
Ákos Török ◽  
Balázs Vásárhelyi
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Point Load ◽  
Load Tests ◽  
Water Saturated ◽  
Brazilian Splitting ◽  
Dry Water ◽  
Non Destructive

AbstractThe mechanical properties of frozen rocks vary significantly from the properties of the same lithology under ambient temperature. The goal of this paper is to investigate these changes in the physical and mechanical properties of rocks due to saturation and freezing. Besides, the attention was paid on discovering new correlations between the mechanical characteristics. To fulfill these objectives, 36 uniaxial compressive strength tests, 36 Brazilian splitting tests, and 48 point load tests were carried out. The samples were tested in air dry, water saturated, and frozen (− 20 °C) conditions. The measured physical and mechanical parameters were analyzed by using regression analyses. It was found that the average uniaxial compressive strength of frozen samples (21.93 MPa) is 86.4% more than saturated ones (11.76 MPa) but 25.9% less than dry specimens (29.62 MPa). Additionally, high correlations were established between uniaxial compressive strength and IS(50) under air-dry, saturated, and frozen conditions for the investigated marl samples. Furthermore, it is of particular interest to observe a high correlation with the determination coefficient (R2 = 0.95) between the constants of previously published linear regressions of UCS- Is(50) under dry status.

Comparative experimental study on physical and mechanical properties of quartz sandstone after water-cooling and natural-cooling under high temperature

2021 ◽  
pp. qjegh2020-181
Author(s):  
Haopeng Jiang ◽  
Annan Jiang ◽  
Fengrui Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Heating Temperature ◽  
Physical And Mechanical Properties ◽  
P Wave ◽  
Water Cooling ◽  
Average Value ◽  
Cooling Methods

Experimental tests were conducted to study the influence of natural cooling and water cooling on the physical and mechanical properties of quartz sandstone. This study aims to understand the effect of different cooling methods on the physical and mechanical properties of quartz sandstone (such as mass, volume, density, P-wave velocity, elastic modulus, uniaxial compressive strength, etc.). The results show that the uniaxial compressive strength (UCS) and elastic modulus(E) of the specimens cooled by natural-cooling and water-cooling decrease with heating temperature. At 800℃, after natural cooling and water cooling, the average value of UCS decreased by 34.65% and 57.90%, and the average value of E decreased by 87.66% and 89.05%, respectively. Meanwhile, scanning electron microscope (SEM) images were used to capture the development of microcracks and pores within the specimens after natural-cooling and water-cooling, and it was found that at the same temperature, water cooling treatment was more likely to cause microcracks and pores, which can cause more serious damage to the quartz sandstone. These results confirm that different cooling methods have different effects on the physical and mechanical properties of quartz sandstone, and provide a basis for the stability prediction of rock mass engineering such as tunnel suffering from fire.

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