scholarly journals Mechanical Characteristics and Failure Prediction of Cement Mortar with a Sandwich Structure

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 143 ◽  
Author(s):  
Xuesheng Liu ◽  
Qingheng Gu ◽  
Yunliang Tan ◽  
Jianguo Ning ◽  
Zhichuang Jia
Keyword(s):  
Sandwich Structure ◽  
Inflection Point ◽  
Turning Point ◽  
Mechanical Characteristics ◽  
Cement Mortar ◽  
Fracture Propagation ◽  
Failure Prediction ◽  
B Value ◽  
Sandwich Materials ◽  
Ae Counts

It is necessary to master the mechanical properties and failure prediction of the composite of mortar and rock block in a mined-out area. In this study, uniaxial compression and acoustic emission (AE) synchronous tests of mortar specimens with different sandwich materials and cement–sand ratios were carried out. The results showed that the compressive strength and elastic modulus of mortar specimens increased with an increase in the cement–sand ratio and the stiffness of the sandwich material. The AE counts and energy of mortar specimens with a high-stiffness sandwich material were maximum when they were destroyed. The b value, a number that reflects the extent of fracture propagation, decreased first and then increased with the increase in strain. The inflection point of the b value can be taken as the indication of the imminent failure of the mortar. A method for determining the b value at the turning point was proposed and verified.

scholarly journals Modification and in-place mechanical characteristics research on cement mortar with fly ash and lime compound admixture in high chlorine environment

2019 ◽  
Vol 8 (1) ◽  
pp. 1451-1460 ◽  
Author(s):  
Bingqian Yan ◽  
Kouame Joseph Arthur Kouame ◽  
Wensheng Lv ◽  
Peng Yang ◽  
Meifeng Cai
Keyword(s):  
Fly Ash ◽  
Mechanical Characteristics ◽  
Cement Mortar

scholarly journals Study of the Spatio-Temporal Differentiation of Factors Influencing Carbon Emission of the Planting Industry in Arid and Vulnerable Areas in Northwest China

2019 ◽  
Vol 17 (1) ◽  
pp. 187
Author(s):  
Yujie Huang ◽  
Yang Su ◽  
Ruiliang Li ◽  
Haiqing He ◽  
Haiyan Liu ◽  
...  
Keyword(s):  
Carbon Emissions ◽  
Carbon Emission ◽  
Agricultural Development ◽  
Inflection Point ◽  
Turning Point ◽  
Northwest China ◽  
Kuznets Curve ◽  
Similar Time ◽  
Average Value ◽  
Spatio Temporal

Due to the importance of understanding the relationship between agricultural growth and environmental quality, we analyzed how high-quality agricultural development can affect carbon emissions in Northwest China. Based on the concept of the environmental Kuznets curve, this study uses provincial panel data from 1993 to 2017 to make empirical analyses inflection point changes and spatio-temporal differences in agricultural carbon emissions. The highlights of our findings are as follows: (1) In Northwest China, there is an inverse N-shape curve, and the critical values are 3578 yuan/hm2 and 45,738 yuan/hm2, respectively. (2) For 2017, the agricultural economic intensity was 50,670 yuan/hm2, exceeding the critical value (high inflection point) of 45,738 yuan/hm2. (3) Ningxia, Gansu, and Qinghai have not reached the turning point. Having comparable climate, natural conditions, and overall environmental factors, these three provinces would reach the turning point at similar time periods. (4) The average value in agricultural carbon emission intensity in the region is 767.79 kg/hm2, and the order based on intensity is Xinjiang > Shaanxi > Ningxia > Gansu > Qinghai.

Preliminary Approach to Mechanical Characteristics of Cement Mixed Superfine Iron Tailings

2011 ◽  
Vol 299-300 ◽  
pp. 718-721
Author(s):  
Bao Kuan Ning ◽  
Jin Meng ◽  
Yi Nan Ren ◽  
Tong Jiang ◽  
Xiao Lei Cui
Keyword(s):  
Mechanical Properties ◽  
Frost Resistance ◽  
Mechanical Characteristics ◽  
Cement Mortar ◽  
Deformation Curve ◽  
Experiment Data ◽  
Freeze Thaw ◽  
Different Ages ◽  
Series Of Experiments

A large number of specimens with different contents of cement mixed superfine tailings, which took superfine iron tailings as aggregate, were produced to carry out a series of experiments on the mechanical properties of different ages and freeze-thaw cycling tests. The strength, load -deformation curve, frost resistance and other performances of cement mixed superfine tailings were obtained. The experiment data were compared with cement mortar and cement-mixed soil ones under the same conditions. The results are listed as follows: on even ground, the strength of cement-superfine tailings can be 4-6 times higher than that of cement-mixed soil, and about 10% lower than that of cement mortar; the relation of load-deformation and the characteristics of freeze-thaw cycles are basically the same as cement mortar under the same conditions.

Damage Evaluation of Concrete Based on Acoustic Emission b-Value

2013 ◽  
Vol 395-396 ◽  
pp. 515-519
Author(s):  
Zheng Zheng Xu ◽  
Yan Wang ◽  
Sheng Xing Wu ◽  
Yao Wang
Keyword(s):  
Acoustic Emission ◽  
Continuous Monitoring ◽  
Cement Mortar ◽  
B Value ◽  
Damage Evaluation ◽  
Technical Problems ◽  
Final Fracture ◽  
Concrete Damage ◽  
Damage Process ◽  
Important Position

Acoustic emission (AE) is capable of real time continuous monitoring and it's not sensitive to the geometry of components,so it's widely used in nondestructive testing of concrete. The AE b-value occupies an important position in the study of concrete damage evaluation as a parameter of AE technology. The basic theory of AE b-value and the related technical problems of AE b-value calculation was discussed. Then the research of AE b-value on concrete was reviewed. At last, the AE b-value in the damage process of cement mortar (CM) and polypropylene diber reinforced mortar (PFRM) under compression was studied and concluded that the trend of AE b-value of CM and PFRM was obviously different.The AE b-value is closely related to the formation and propagation of cracks in the damage process of concrete and it declines rapidly before final fracture occurs.

The Fundamental Mechanical Characteristics Evaluation for Bolted Pipe Flange Connections With RTJ Gaskets Under Internal Pressure

2019 ◽  
Author(s):  
Kenshiro Nakade ◽  
Koji Sato ◽  
Toshiyuki Sawa
Keyword(s):  
Plastic Deformation ◽  
Contact Stress ◽  
Inflection Point ◽  
Mechanical Characteristics ◽  
Design Method ◽  
Leak Rate ◽  
Bolt Preload ◽  
Higher Temperature ◽  
Sealing Mechanism ◽  
Better Than

Abstract Bolted pipe flange connections with metallic flat gaskets or ring type joint (RTJ) gaskets are used under higher pressure and higher temperature. However, a sealing mechanism is not known and a design method is not established how to determine bolt preload for preventing leakage from the connection with metallic gaskets. In addition, the characteristics of the connection are not known when oval and octagonal gaskets are used. In previous paper, when the contact stress of metallic flat gasket reaches the stress at plastic deformation inflection point, the leak rate is decreased rapidly. However, the leak rate could be measured up to 1.0 × 10−5 Pa · m3/s level. The objectives of the paper are to measure the leak rate of the metallic flat gasket of which the contact stress is over the stress at plastic deformation inflection point, and to measure the leak rate of 1.0 × 10−9∼10 Pa · m3/s level in the flat metallic gasket in the platen tests and the connection with RTJ gaskets. In addition, the characteristics of the connection are examined when oval and octagonal gaskets are used. As a result, it is found that the leak rate for the metallic flat gasket can be measured around 1.0 × 10−9∼10 Pa · m3/s in the platen tests when the contact stress of aluminum gasket reaches the stress at plastic deformation inflection point and more while the leak rate of SUS 304 flat gasket is around 1.0 × 10−7∼8 Pa · m3/s even if the contact stress is over 1.3 times of the stress at plastic deformation inflection point. In addition, the sealing characteristics of the connection with oval gasket are shown to be better than that with octagonal gasket. From a laser microscope observation, it is found that the contact area of oval gasket in the connection is smaller than that of octagonal gasket in the connection.

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