scholarly journals An Experimental Study on the Microstructures of Cemented Paste Backfill during Its Developing Process

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Bo Zhang ◽  
Jie Xin ◽  
Lang Liu ◽  
Lijie Guo ◽  
Ki-Il Song
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Physical And Mechanical Properties ◽  
Pore Distribution ◽  
Early Age ◽  
Pore Shape ◽  
Cemented Paste Backfill ◽  
Sem Images ◽  
Paste Backfill ◽  
Analysis System

The aim of this study was to examine the microstructure of cemented paste backfill (CPB) during its development and relate the characteristics of the microstructure to the physical and mechanical properties of CPB. The geometry and morphology of the microstructures of CPB were observed by the scanning electron microscopy (SEM). The characteristics including pore size, pore shape, and orientation of the microstructures of CPB at different curing times were analyzed based on the SEM images. The porosity, fractal dimension, and probability entropy were characterized using the Particles and Pore Recognition and Analysis System (PPRAS). It was found that the pore size, pore shape, and orientation of the microstructure of CPB significantly change as the curing time increases, resulting in the increase of UCS. Meanwhile, the arrangement of the pores affects the mechanical properties of CPB. At the early age of CPB development, the probability entropy is above 0.96, indicating a chaotic pore distribution and no obvious orientation. At the late age of CPB development, the probability entropy becomes smaller and the order and orientation of the pore distribution are enhanced, leading to an increase in USC. The UCS of CPB is also greatly affected by the characteristics of the pore morphology. During the development of CPB, the pore shape becomes smoother. The UCS of CPB approximately linearly improves with an increase in the average roundness of pores.

scholarly journals Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 523-540
Author(s):  
Imed Beghoura ◽  
Joao Castro-Gomes
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Size ◽  
Physical And Mechanical Properties ◽  
Critical Parameters ◽  
Porous Structures ◽  
Foaming Agent ◽  
Al Powder ◽  
Highly Porous ◽  
Alkali Activated

This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components.

scholarly journals Experimental Investigation on Mechanical Properties of In Situ Cemented Paste Backfill Containing Coal Gangue and Fly Ash

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xinguo Zhang ◽  
Shichuan Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fly Ash ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Friction Angle ◽  
Coal Gangue ◽  
Cemented Paste Backfill ◽  
Paste Backfill

Cemented paste backfill containing coal gangue and fly ash (CGFACPB) is an emerging backfill technique for coal mines that allows environmentally hazardous coal gangue and fly ash to be reused in the underground goaf. Meanwhile, CGFACPB can provide an efficient ground support and reduce the surface subsidence. Due to the difference of consolidation environment between the laboratory and the field, the mechanical properties of the cemented paste backfill vary significantly. In this paper, the core specimens were collected from an underground coal mine where the CGFACPB was used for coal mining, and the mechanical properties of the collected specimens were investigated. The cores were obtained from the underground coal mine, and then the standard cylinders or discs were prepared in laboratory. The uniaxial compressive strength (UCS), Young’s modulus, and Poisson’s ratio were determined by the compression tests, and the tensile strength was achieved by the Brazilian test. Then the internal friction angle and cohesion were calculated using the improved Mohr–Coulomb strength criterion. The results showed the development of UCS can be divided into four stages, and the final long-term stable value was about 5.1 MPa. The development of Young’s modulus had similar trend. Young’s modulus had a range from 550 MPa to 750 MPa and the mean value of 675 MPa. Poisson’s ratio gradually increased with the underground curing duration and eventually approached the stable value of 0.18. The failure type of compression samples was mainly single-sided shear failure. The development of tensile strength can be divided into two stages, and the stable value of the tensile strength was about 1.05 MPa. The development of cohesion can be divided into four stages, and the stable value was about 1.75 MPa. The stable value of the internal friction angle was about 25°. This study can provide significant references for not only the long-term stability evaluation of CGFACPB in the field but also the design of optimal recipe of the cemented paste backfill (CPB).

Relevance of SEM to Long-Term Mechanical Properties of Cemented Paste Backfill

2018 ◽  
Vol 36 (4) ◽  
pp. 2171-2187 ◽  
Author(s):  
Naguleswaran Niroshan ◽  
Ling Yin ◽  
Nagaratnam Sivakugan ◽  
Ryan Llewellyn Veenstra
Keyword(s):  
Mechanical Properties ◽  
Cemented Paste Backfill ◽  
Paste Backfill

scholarly journals Experimental Investigation on Mechanical Properties of Cemented Paste Backfill under Different Gradations of Aggregate Particles and Types and Contents of Cementing Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Jiangyu Wu ◽  
Meimei Feng ◽  
Guansheng Han ◽  
Xiaoyan Ni ◽  
Zhanqing Chen
Keyword(s):  
Mechanical Properties ◽  
Cemented Paste Backfill ◽  
Compression Tests ◽  
Deformation Properties ◽  
Paste Backfill ◽  
Strength And Deformation ◽  
Cementing Material ◽  
Optimal Strength ◽  
Ae Signals ◽  
Aggregate Particles

Obtaining the optimal gradation of aggregate particles is beneficial for improving the strength of cemented paste backfill (CPB). Consequently, the uniaxial compression tests with acoustic emission (AE) monitoring were performed on CPB, for which the aggregate particles satisfied the Talbot grading theory. The effects of the Talbot indices of aggregate particles and types and contents of cementing materials on the mechanical properties of CPB were analyzed. The AE characteristics and stress-strain behaviors of CPB were discussed. The results show that the specific Talbot index reflected the optimal strength and deformation properties of CPB is 0.45, and the maximum UCS is 7.6 MPa. The mechanical properties of CPB also can be optimized by changing the type of cementing material and increasing the content of cementing material. The effects of the Talbot indices of aggregate particles and types and contents of cementing materials on the crack damages reflected by the AE signals of CPB are mainly observed in the oa stage and ab stage during the loading process.

Direct measurement of matric suction in triaxial tests on early-age cemented paste backfill

2009 ◽  
Vol 46 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Paul Simms ◽  
Murray Grabinsky
Keyword(s):  
Testing Procedure ◽  
Matric Suction ◽  
Water Retention Curve ◽  
Triaxial Tests ◽  
Early Age ◽  
Cemented Paste Backfill ◽  
Triaxial Cell ◽  
Paste Backfill ◽  
Observed Behaviour ◽  
Stope Design

Hydration occurring in cemented paste backfill (CPB) is shown to generate matric suction through self-desiccation. This complicates determination of the water-retention curve and mechanical properties during curing, which are important in stope design, and renders problematic the use of axis-translation testing procedure to control suctions in strength testing. An alternative is to monitor suction directly during testing. To this end, a miniature tensiometer is inserted into the base of a triaxial cell. A series of unconfined and confined tests are performed on early-age (less than two weeks old) CPB. The observed behaviour is similar to that observed in weakly cemented soils, showing a distinct tendency to dilate during shearing.

scholarly journals The effect of changing injection temperature on some mechanical and morphological properties for polypropylene material (PP)

2019 ◽  
Vol 24 (24) ◽  
pp. 20-24
Author(s):  
Ali Al-Zubiedy ◽  
Ruaa M. Muneer
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Injection Molding ◽  
Physical And Mechanical Properties ◽  
Surface Damage ◽  
Morphological Properties ◽  
Sem Images ◽  
Molding Temperature ◽  
Operation Temperature ◽  
Injection Temperature

Abstract This is a study of a medical injection factory-Babylon carried out in order to achieve proper mechanical and morphological properties, PP has been injection molded by using cold runner injection molding machine with temperature variation (198, 200, 203……220°C) for ten samples. The physical and mechanical properties of PP product were examined. It has been found that the Shore hardness decreases linearly with injection molding temperature increasing. The tensile strength has a similar behavior to the hardness. However, it has been found that the MIF (Melt Index Flow) rates increases with the increase of injection molding temperature. The density of PP has been found for both virgin PP and the samples, it has been found that the density decreases with increasing operation temperature. FTIR (Fourier Transmission Infrared) spectra were taken for both samples with high and low operation temperature. Besides the SEM (Scanning Electronic Microscopy) test shows the difference in the morphology of the product surface and the PP product at high and low operation temperature. Moreover, for all these properties, the PP product exhibits good mechanical properties (hardness, tensile strength, density) for the samples produced at temperature lower than 207°C. While the physical properties such as MIF improved with injection temperature increasing, additionally, the SEM images show that the sample produced in low temperature have surface damage.

Sign in / Sign up

Export Citation Format

Share Document