Effect of Dry-Wet Cycling on the Mechanical Properties of Rocks: A Laboratory-Scale Experimental Study

Yang, Xiao‐Jun; Wang, Jiamin; Hou, Dinggui; Zhu, Chun; He, Manchao

doi:10.3390/pr6100199

Cited by 39 publications

(19 citation statements)

References 38 publications

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“…Cyclic wetting‐drying is a well‐known yet poorly understood weathering process. Many studies have been conducted on the effect of wetting‐drying cycles on the physical and mechanical properties of rocks, concerning water adsorption, acoustic wave velocity, elastic modulus, tensile strength, and static uniaxial or triaxial compressive strength . The deterioration process of rock mechanical properties under cyclic wetting‐drying could also be induced by original defects …”

Section: Introductionmentioning

confidence: 99%

Influence of cyclic wetting‐drying on the mechanical strength characteristics of coal samples: A laboratory‐scale study

Chen

Jiang

Wang³

et al. 2019

Energy Science & Engineering

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Water‐coal interactions have gained much recent attention, although few studies focus on the strength of coal under wetting‐drying cycles. This study investigates changes in the microstructure and mechanical strength of coal that are induced by water‐coal interactions, at the macroscale and microscale. Fourteen specimens after continuous wetting and fourteen specimens after wetting‐drying cycles were tested, indicating that peak stress and elastic modulus decrease with increasing continuous wetting time and number of wetting‐drying cycles, while peak strain increases. We analyzed changes in the coal microstructure using a scanning electron microscope (SEM) and the Image Pro Plus 6.0 (IPP 6.0) software. The regression model for cyclic wetting‐drying reveals that porosity and pore circularity are the main correlation indicators associated with uniaxial compressive strength. Therefore, different numbers of wetting‐drying cycles could induce different degrees of damage to coal, which increases progressively through gradual changes to its microstructure. These findings indicate that wetting‐drying cycles have a more significant impact on the stability of coal mass than continuous wetting. Our results are of use in determining the size of coal pillars, and expanding the knowledge base related to the mechanical properties of coal mass, water bursting, water recharge channels, and the stress‐crack‐permeability evolution law in mines.

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Section: Introductionmentioning

confidence: 99%

Influence of cyclic wetting‐drying on the mechanical strength characteristics of coal samples: A laboratory‐scale study

Chen

Jiang

Wang³

et al. 2019

Energy Science & Engineering

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“…The mechanical strength or the stability of the CPDT samples was usually evaluated using UCS [12,32] in accordance with TYE-300D (Wuxi Jianyi Instrument Machinery Co., Ltd., Wuxi, China), as illustrated in Figure 1. UCS tests were carried out on the CPDT samples with different amount of NCM and OPC and curing 3, 7 and 28 days.…”

Section: The Ucs Experimentsmentioning

confidence: 99%

Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge

et al. 2019

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Blast furnace slag (BFS) is often used as a cement-based raw material for underground filling and surface cemented paste discharge of tailings during mining processes. This paper studied a new cement-based material (NCM) with BFS to replace ordinary Portland cement (OPC). A uniaxial compressive strength (UCS) experiment was used to test the mechanical strength of samples; X-ray diffraction and thermal gravity experiments were used to test the crystalline phases and amount of hydration products by samples; a scanning electron microscope experiment was used to observe the influence of the hydration products morphology by samples; mercury intrusion porosimetry experiment was used to analyze the pore size distribution of samples. The samples with NCM had an optimum UCS; the crystalline phases of the hydration products were similar in OPC and NCM. However, the amount of product formed in OPC was less than that in NCM at the same curing time; more ettringite and calcium silicate hydrate were produced in samples with NCM, which filled the pores and enhanced the UCS of the samples. The final mercury intrusion volume of the samples with NCM were lower than the samples with OPC at the same curing time, which showed that samples with NCM had lower porosities. For the samples with NCM and OPC cured from 7 days to 28 days, the mercury intrusion volume was reduced by 18% and 13%, and the most common pore size of the samples reduced by 53% and 29%, respectively. This showed after 21 days curing time, the pores of all the samples getting smaller; however, the samples with NCM were more compact. The main ingredients of the NCM were clinker, lime, gypsum and BFS, and its ratio was 14:6:10:70. The content of additives to NCM was 0.4%, and the ratio of sodium sulfate: alum: sodium fluorosilicate was 2:1:1.Processes 2019, 7, 47 2 of 17 combined both methods and proposed the technology of cemented paste discharge of tailings (CPDT) [10,11]. The method involved adding some cement to the tailings and discharging them to valleys or subsidence areas; the tailings need to be transported by pipes or belts. This method guarantees the stability of the tailings for the cemented piles. In addition, mines no longer need to build tailings pond and can also achieve safe pile-up. Because the cemented tailings pile can be built up to a high height, the limited footprint can pile up more tailings than tailings ponds. Presently, this technology has been applied and developed in some metal mines [11].During the cemented paste backfill, the amount of cement was 2% to 7% of the total weight of the tailing slurry, and it may be up to 10% to remain independent across pillar extraction process [12]. Cement costs account for more than 60-80% of the filling costs, as discussed by Li et al. [13]. The idea of CPDT was derived from cemented paste backfill, thus, the process of CPDT was similar to this, and the cost of cement also occupied a large proportion of CPDT costs. Therefore, the search for cheap, cementitious industrial by-products to replace cement and ...

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“…e mechanical strength or the stability of the CTB samples was usually evaluated using UCS [20,23,24]. UCS tests were carried out on the different CTB samples in accordance with TYE-300D (Wuxi Jianyi Instrument Machinery Co., Ltd., Wuxi, China).…”

Section: E Ucs Experimentmentioning

confidence: 99%

Study on Relationship between UCS of Cemented Tailings Backfill and Weight Losses of Hydration Products

Wang

Gao

Xiong

et al. 2019

Advances in Civil Engineering

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The weight losses of cement-based material samples were often used to characterize the content of their hydration products and explain the strength changes of cement-based materials. However, the quantitative relationship has not been studied between the weight loss of hydration products and strength of cement-based materials. This paper studied the relationship between the strengths of cemented tailings backfills (CTBs) and the weight losses of its hydration products. The CTB samples have been done, especially on different binders, cement-tailing ratios, mass concentrations, and different curing ages. The uniaxial compressive strength (UCS) experiments were used to test the mechanical strength of samples; X-ray diffraction (XRD) experiments were used to test the crystalline phases of hydration products by samples; thermal analyses (thermogravimetric and differential thermogravimetric (TG/DTG)) experiments were used to test the weight losses of hydration products. By means of regression analysis, the relationship model was established between the UCS of CTB and the weight losses of hydration products at different concentrations. The results show that there is a strong linear correlation between the UCS and the weight loss of the hydration product calcium silicate hydrate (C-S-H) for the CTB made of glue powder, while the UCS is related to the weight losses of C-S-H and Ca(OH)2 for the CTB made of ordinary Portland cement. The results acquired by this paper provide a scientific basis for studying hydration products by thermal analyses and explaining the strength changes of cement-based materials.

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Effect of Dry-Wet Cycling on the Mechanical Properties of Rocks: A Laboratory-Scale Experimental Study

Cited by 39 publications

References 38 publications

Influence of cyclic wetting‐drying on the mechanical strength characteristics of coal samples: A laboratory‐scale study

Influence of cyclic wetting‐drying on the mechanical strength characteristics of coal samples: A laboratory‐scale study

Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge

Study on Relationship between UCS of Cemented Tailings Backfill and Weight Losses of Hydration Products

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