Xi Chen^1,2, Ying Li^1,2,*, Hualei Bai^1,2, Liyuan Ma^1,2

Journal of Renewable Materials, Vol.9, No.12, pp. 2189-2208, 2021, DOI:10.32604/jrm.2021.015394 - 22 June 2021

Abstract Recycled concrete powder (RCP) is used more and more in cement-based materials, but its influence on the hydration process is still unclear. Therefore, this paper studied the influence of recycled concrete powder (RCP) on the hydration process of cement and provides a theoretical basis for the hydration mechanism of cement composite materials. The hydration heat method was used to systematically analyze the thermal evolution process of cement paste with or without RCP. Hydration products were identified using X-ray diffraction (XRD) and thermal analysis (TG–DSC). The pore structure change of cement pastes was analyzed by mercury… More > Graphic Abstract

Jianbing Zhang¹, Rongjin Liu^1,2,3,*, Siyuan Fu¹, Tianyu Gao¹, Zhongfei Zhang¹

Journal of Renewable Materials, Vol.9, No.11, pp. 2001-2013, 2021, DOI:10.32604/jrm.2021.015812 - 04 June 2021

Abstract Based on aluminum sulfate, a fluorine-free and alkali-free liquid accelerator (FF-AF-A) was prepared in this study. The setting time and compressive strength of three cement types with different FF-AF-A dosages were fully investigated. The compatibility of the FF-AF-A with the superplasticizers were also investigated, and the early hydration behavior and morphology of the hydration products of reference cement paste with the FF-AF-A were explored by hydration heat, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). Test results indicated that adding the FF-AF-A at 8 wt% of the cement weight resulted in 2 min 35 s… More >

Yongdong Xu, Tingshu He^*

Journal of Renewable Materials, Vol.9, No.11, pp. 1991-1999, 2021, DOI:10.32604/jrm.2021.015931 - 04 June 2021

Abstract This work aims to utilize waste glass powder (WGP) as a plementary material to mitigate the strength shrinkage caused by the alkaline accelerator. Waste glass power was used to replace cement by 0%, 10%, and 20% to evaluate waste glass powder on the alkaline accelerator’s strength retrogradation. The results show that the strength improvement effect of unitary glass powder is inconspicuous. Innovative methods have been proposed to use sodium sulfate and waste glass powder synergism, using the activity of amorphous silica in glass powder. Compared with the reference group, the compressive strength of 28d mortar More >

Mario Bonagura, Lucio Nobile^*

Structural Durability & Health Monitoring, Vol.15, No.2, pp. 125-137, 2021, DOI:10.32604/sdhm.2021.015644 - 03 June 2021

Abstract The compressive strength of concrete is one of most important mechanical parameters in the performance assessment of existing reinforced concrete structures. According to various international codes, core samples are drilled and tested to obtain the concrete compressive strengths. Non-destructive testing is an important alternative when destructive testing is not feasible without damaging the structure. The commonly used non-destructive testing (NDT) methods to estimate the in-situ values include the Rebound hammer test and the Ultrasonic Pulse Velocity test. The poor reliability of these tests due to different aspects could be partially contrasted by using both methods together,… More >

Weijun Yu^1,2, Jiangang Sun³, Ying Wu^1,*, Si-Tong Chen⁴

International Journal of Mental Health Promotion, Vol.23, No.2, pp. 277-288, 2021, DOI:10.32604/IJMHP.2021.016153 - 30 April 2021

Abstract Purpose: Physical activity is a well-recognized protective factor against depression in adolescents. As a component of physical activity, muscle strengthening exercise (MSE) is also viewed as a correlate associated with lower risks of depression in adults. However, little is known about the association in adolescents. This study aimed to explore the association between MSE and depression in a sample of Chinese adolescents. Method: A self-reported questionnaire was used for data collection including variables of MSE, depression (assessed by Children’s Depression Inventory) and selected sociodemographic factors (e.g., sex, grade, height and weight [for body mass index]). Generalized… More >

Boqing Li, Xiaolong Bai, Yongli Zhu^*

Molecular & Cellular Biomechanics, Vol.18, No.2, pp. 99-105, 2021, DOI:10.32604/mcb.2021.014748 - 09 April 2021

Abstract In the process of swimming, the shoulder joint will be damaged when the arm is stroking. To reduce the injury of shoulder joints and improve the speed of stroke, it is necessary to train the flexibility of shoulder joints. This paper briefly introduced the concept of shoulder joint and flexibility and then explained the traditional stretching training method and proprioceptive neuromuscular facilitation (PNF) stretching method. Then, taking 20 college team swimmers of Yunnan University as the subjects, the comparative experiment of the traditional and PNF stretching methods was carried out. The results showed that the More >

Zhiyu Weng¹, Lina Wang^1,2,*, Qiang Liu², Xuemin Pan¹, Yonghao Xu³, Jing Li¹

Journal of Renewable Materials, Vol.9, No.8, pp. 1503-1517, 2021, DOI:10.32604/jrm.2021.015003 - 08 April 2021

Abstract To explore an environmentally friendly improvement measure for red clay, the function and mechanism of xanthan gum biopolymer and polypropylene fibers on the strength properties of red clay were investigated by unconfined compressive strength and scanning electron microscopy tests. The test results demonstrated that the contents and curing ages of xanthan gum had significant influences on the unconfined compressive strength of red clay. Compared with untreated soil, 1.5% xanthan gum content was the optimal ratio in which the strength increment was between 41.52 kPa and 64.73 kPa. On the other hand, the strength of xanthan… More >

Lei Liu^*, Chuanhui Huang, Xinghua Lu, Ping Yu, Longhai Li, Huafeng Guo

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.2, pp. 501-509, 2021, DOI:10.32604/fdmp.2021.015161 - 02 April 2021

Abstract In order to study the effect of Al₂O₃ nanoparticles in the cavitation-based strengthening process of magnesium alloys, the impact of a micro-jet generated by bubble collapse has been considered. The strengthening mechanism is based on the transfer of the energy of cavitation due to bubble collapse to Al₂O₃ particles, which then undergo collision with the surface of the sample. The hardness, surface morphology, element content and chemical state of the strengthened samples have been analyzed by microhardness tests, SEM (scanning electron microscopy) and XPS (X-ray photoelectron spectroscopy) techniques. The results show that: after 5 min of More >

Yun Teng¹, Zhendong Sha^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.23, No.1, pp. 18-18, 2021, DOI:10.32604/icces.2021.08471

Abstract For all engineering materials, the flaws are introduced inevitably from fabrication, mechanical damage, and corrosion. These stress raisers always induce catastrophic failures and it is therefore of great importance to understand the effect of flaws on the mechanical properties of engineering materials. The effect of flaws on metallic glasses (MGs) is a debatable topic because many relevant works have reported notch strengthening, notch weakening and notch insensitivity for brittle MGs. The significant notch strengthening of MGs was attributed to the transition of failure mechanism, from catastrophic shear banding to ductile fracture. Here we investigate systematically… More >

Ei Yamamoto^1,*, Yuki Tanifuji², Masaya Nishimoto², Yuki Kawamura²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.23, No.1, pp. 17-17, 2021, DOI:10.32604/icces.2021.08434

Abstract Bone tissue is a viscoelastic material which shows time-dependent mechanical manner. Moreover, it is known that bone microdamage is generated by physiological normal mechanical loading in vivo [1-3]. In order to know basic insight into the adverse effects of creep loading on bone strength, in the present study, we focused on the mechanical behavior of cortical bone after nondestructive creep loading at high stress magnitude. Cylindrical specimens were obtained from cortical bone in the longitudinal and tangential direction of bovine femur. We statically applied a compressive stress to the specimens (creep group) for 24 hours. More >