Influence of thermal damage on the physical and mechanical properties of carbonate rocks

2013 ◽  
Vol 7 (12) ◽  
pp. 5543-5551 ◽  
Author(s):  
N. Sengun
2021 ◽  
pp. 1-10
Author(s):  
Menglin Du ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
Shanjie Su ◽  
Zekai Wang

Abstract Exploring the damage differences between different coal rank coal reservoirs subjected to liquid nitrogen (LN2) cooling is of great significance to the rational development and efficient utilization of coalbed methane. For this purpose, the mechanical properties, acoustic emission (AE) characteristics and energy evolution law of lignite and bituminous coal subjected to LN2 cooling were investigated based on the Brazilian splitting tests. Then, pore structure changes were analyzed to reveal the difference in the microscopic damage between lignite and bituminous coal after LN2 cooling. The results showed that compared with bituminous coal, the pore structure of lignite coal changed more obviously, which was manifested as follows: significant increases in porosity, pore diameters, and pore area; a larger transformation from micropores and transition pores to mesopores and macropores. After LN2 cooling, the thermal damage inside lignite and bituminous coal was 0.412 and 0.069, respectively. The thermal damage reduced the cohesive force between mineral particles, leading to the deterioration of the macroscopic physical and mechanical properties. Simultaneously, denser AE ringing counts and larger accumulated ringing counts were observed after LN2 cooling. Moreover, the random distribution of thermal damage enhanced the randomness of the macrocrack propagation direction, resulting in an increase in the crack path tortuosity. With more initial defects inside coal, a more obvious thermal damage degree and wider damage distribution will be induced by LN2 cooling, leading to more complicated crack formation paths and a higher fragmentation degree, such as that of lignite coal.


The use of carbonate rocks as aggregates for cement concretes and mortars is limited due to their insufficient strength and the threat of corrosion. The use of quarry dust from crushing carbonate rocks are technically and economically feasible in building compositions based on air-hardening lime. The results of the study of the effect of replacing a part of quartz sand in lime mortar by limestone and dolomite fine aggregates on the basic physical and mechanical properties of lime mortars for restoration are presented in the paper. The matrix of planning experiments, which allows increasing the informativity of the research results in order to reduce the number of experiments in the search for optimal values, is proposed. The efficiency of replacement of the quartz sand with quarry dust of carbonate rocks in the production of dry mixes for restoration is shown.


2020 ◽  
Vol 248 ◽  
pp. 118697
Author(s):  
Antonela Di Salvo Barsi ◽  
Guillermina Marchetti ◽  
Mónica A. Trezza ◽  
Edgardo F. Irassar

Author(s):  
Salih Muhammad Awadh , Linaz Anis Fadhil

The current study aimed to assess the Carbonate rocks as dimension stones for building. Carbonate rocks collected from the Mauddud Formation (Albian- Cenomanian), within the Western Desert of Iraq are studied petrographically, mineralogically and geochemically. Physical and mechanical properties of selected samples are found to assess their suitability as building stones. Field work is carried out and evaluated sampling of three sites of carbonate rocks. Petrography and mineralogy of these rocks are studied using polarized microscope and XRD technique.Three microfacies (peloidal wackstone-packstone, peloidal packstone and crystalline carbonate) are distinguished. Dolomitization, cementation and recrystallization are themain diagenetic processaffecting the physical and chemical properties of them. Dolomite is the predominant mineral in the 1M and 2M sites, whereas calcite is the most predominant mineral in the 3M site, so it is classified as limestone. Chemically samples are analyzedfor SiO2, Al2O3, CaO, MgO, Fe2O3, Na2O, K2O, TiO2, MnO and LOI. CaO and MgO are the most predominant oxides confirming the abundance of calcite and dolomiteso it is classified as a calcitic dolomite for 1M and 2M sites while classified as limestone for 3M site. The results of analysis physical and mechanical properties (bulk density, water absorption, compressive strength, modulus of rupture and abrasion resistance) are indicate that selected rocks are suitable as dimension stones for building according to American Standard for Testing Materials (ASTM) specification.


2019 ◽  
Vol 38 (2019) ◽  
pp. 849-855
Author(s):  
Chenchen Xu ◽  
Qiang Sun ◽  
Xiaohua Pan ◽  
Weiqiang Zhang ◽  
Yanbing Wang

AbstractTemperature significantly affects the physical and mechanical properties of granite. To have a comprehensive understanding of the thermal cycle effect on uniaxial compressive strength (UCS) and thermal damage rate, a series of thermal cycle experiments on granite specimens were carried out with five types of designed temperatures and five types of cycle number of thermal treatments. The experimental results indicate that UCS decreases and thermal damage rate increases as temperature and thermal cycle increase. UCS of specimens cooled in water condition after thermal damage treatment are lower than those cooled in air condition. In addition, two new phenomena related to thermal damage rate were observed. Firstly, previous studies have shown that a rapid value reduction of UCS of specimens with one thermal cycle treatment under air cooling condition can be observed at 400∘C. While the temperature threshold for the specimens treated with more than one thermal cycle under water cooling condition increases to 550∘C. Secondly, a thoroughly antipodal evolution law of the thermal damage rate for the specimens with multiple thermal cycle treatments is also observed as compared to those treated by only one thermal cycle. These differences might be induced by the different microcrack initial time and their development speed. The new findings are important to understand the failure mechanism and variation process of physical and mechanical properties of granite specimens subjected to thermal cycles.


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