Multifunctional structural supercapacitor based on cement/PVA-KOH composite and graphene

2020 ◽  
pp. 002199832096985
Author(s):  
Chang Xu ◽  
Dong Zhang
Keyword(s):  
Mechanical Properties ◽  
Specific Capacitance ◽  
Sandwich Structure ◽  
Crystalline State ◽  
Ionic Conduction ◽  
Amorphous State ◽  
Hardened Cement ◽  
Polymerization Degree ◽  
Hardened Cement Paste ◽  
Hydrolysis Degree

Multifunctional structural supercapacitor based on the structural electrolyte of cement/PVA-KOH composite and the structural electrode of highly electrically graphene was fabricated with sandwich structure. A bicontinuous microstructure composed of PVA and hardened cement paste is formed. Flexible PVA in cement/PVA-KOH composite increases ions’ accessibility with graphene at the interface between the structural electrode and the structural electrolyte. The addition of KOH changes the structure of PVA from crystalline state to amorphous state. So PVA can complex and discomplex with KOH to realize ionic conduction. The effects of PVA’s content, polymerization degree and hydrolysis degree on the electrochemical properties and mechanical properties were analyzed. The composite’s ionic conductivity increases with PVA’s content and hydrolysis degree, and it shows a tendency of decreasing after increasing with PVA’s polymerization degree. Similarly, the specific capacitance of the structural supercapacitor also increases with PVA’s content and hydrolysis degree, but decreases with PVA’s polymerization degree. Compared with the polymerization degree, the hydrolysis degree plays a more prominent part in affecting the specific capacitance of the structural supercapacitors. For mechanical properties of cement/PVA-KOH composite, the compressive strength is mostly improved by PVA at a content of 2%. It decreases with PVA’s polymerization degree and increases with PVA’s hydrolysis degree. The conflict between the power density and energy density in structural energy storage is eased remarkably and the electrical and mechanical properties can be improved simultaneously. The two chief obstacles are tackled in the PVA1799-based structural supercapacitor.

scholarly journals Effect of Ground Slag on Mechanical Properties of Concrete under Low Temperature

2021 ◽  
Vol 2109 (1) ◽  
pp. 012019
Author(s):  
Xuelian Yuan ◽  
Jie Hu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Compressive Strength ◽  
Low Temperature ◽  
Cement Paste ◽  
High Volume ◽  
Hardened Cement ◽  
Micro Structure ◽  
Hardened Cement Paste ◽  
Fracture Properties

Abstract Through using cube resisting compression test, fracture properties and micro-structure, the mechanical properties of high volume ground slag concrete under low temperature are studied in this paper. The results show that low temperature can improve the compressive strength of high volume ground slag concrete. And strength increased with the decreased of temperature. Low temperature can also improve the fracture energy and fracture toughness. Not only can ground slag reduce the content of calcium hydroxide in hardened cement paste, but ground slag can improve the compactness of hardened cement paste, reduce porosity and improve the strength of the interface.

The Influence of Pore-Strucrure on the Campressive Strength of Hardened Cement Paste

1984 ◽  
Vol 42 ◽  
Author(s):  
Huang Yiun-Yuan ◽  
Ding Wei ◽  
Lu Ping
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Structure ◽  
Cement Paste ◽  
Total Porosity ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
New Information ◽  
The Relationship ◽  
Empirical Constants

AbstractThe pore-structure strongly influences the carpressive strength of hardened cement paste (hcp) and other porous materials, as well as other mechanical properties. The simplest but most currently used expression representing the relationship between the pore-structure and compressive strength is fram Balshin: σ = σ0 (l-P)A, in which only the total porosity P is involved as a single parameter and σ0 and A are empirical constants. The influence of pore size distribution and pore shapes etc. are not considered.The authors introduce second parameter w - the factor of relative specific surface area of the pores other than the total porosity P into consideration and a new expression is proposed:σc=K11-p/1+2p(K2(1-p))K3w+K4 all the constants K1 - K4 can be determined experimentally. By using of this expression the new information relating the influence of pore-structure on the caopressive strength of hcp can be predicted.

Effects of Microstructure on Fracture Behavior of Hardened Cement Paste

1994 ◽  
Vol 370 ◽  
Author(s):  
Asif Ahmed ◽  
Leslie Struble
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Paste ◽  
Fracture Behavior ◽  
Curing Temperature ◽  
Hardened Cement ◽  
Curing Time ◽  
Hardened Cement Paste ◽  
Fracture Parameters ◽  
Initial Hypothesis

AbstractMechanical properties of any material, including hardened cement paste, are assumed to be controlled by its microstructure. An attempt has been made here to establish a link between bulk fracture parameters of hardened cement paste and its microstructure. Paste microstructure has been varied by changing the initial w/c ratio, curing time and curing temperature, and by addition of chemicals to change the calcium hydroxide morphology. It has been found that, like compressive strength, fracture parameters depend directly on porosity. Contrary to our initial hypothesis, CH morphology was found to have no effect on the fracture parameters.

Mechanical Properties of Alite-Calcium Barium Sulphoaluminate Cement Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 121-124
Author(s):  
Zong Hui Zhou ◽  
Ling Chao Lu ◽  
Xing Kai Gao ◽  
Xin Cheng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Early Age ◽  
Hardened Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Hardened Cement Paste ◽  
Sulphoaluminate Cement

In this paper, preparation and mechanical properties of Alite-calcium barium sulphoaluminate (Alite-C2.75B1.25A3 ) cement concrete were studied. The results showed the compressive strength of Alite-C2.75B1.25A3 cement concrete was much higher than that of Portland cement concrete, especially the early-age compressive strength. The 24-hour compressive strength of Alite-C2.75B1.25A3 cement concrete could reach 22.81Mpa for w/c=0.45, 17.29Mpa for w/c=0.50 and 17.04Mpa for w/c=0.55 respectively. They were about 50 to 65 percent higher than those of Portland cement concrete. The 7-day compressive strength could reach about 80 to 90 percent of 28-day strength for Alite-C2.75B1.25A3 cement concrete. The 28-day strength could reach 55.85Mpa for w/c=0.45, 48.01Mpa for w/c=0.50 and 44.21Mpa for w/c=0.55 respectively. The results of SEM showed the interfaces between the hardened cement paste and aggregates in Alite-C2.75B1.25A3 cement concrete were more compact than those in Portland cement concrete. Distribution of particulate bulk was more uniformity and a majority of clinker particles was wrapped by hydrated gel in Alite-C2.75B1.25A3 concrete. And, the structure of Alite-C2.75B1.25A3 cement concrete was much more compact than that of Portland cement concrete.

Effect of Variability of Recycled Aggregate on Properties of Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 1122-1132
Author(s):  
Chao Jun Wan ◽  
Xu Chen ◽  
Teng Li ◽  
Tai Zhong Huang ◽  
Tian Ming Deng
Keyword(s):  
Mechanical Properties ◽  
High Variability ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Hardened Cement ◽  
Essential Factor ◽  
Hardened Cement Paste ◽  
Aggregate Concrete ◽  
Natural Aggregate

Low, medium and high variability of aggregates of concrete were designed and prepared and the influence of variability of recycled aggregates on the mechanical properties and durability of concretes was investigated. The experimental results indicated that the kinds of strengths, static compressive elastic modulus and durability of recycled concrete were decreased at engineering-acceptable level compared with natural aggregate concrete; the most properties of recycled concrete with high variability of recycled aggregates are not very different from that of recycled concrete with medium variability of recycled aggregates even that of natural aggregate concretes; however, the variability of properties of recycled concrete with high variability of recycled aggregates are much different from that of medium variability of recycled aggregates and more different from that of natural aggregate concretes, which means if only one or limited properties of recycled concrete were tested, the existing high variability of properties of concrete may not be revealed to a full enough extent, and the possible neglect of this high variability may result in potential engineering risk in application of high variability of recycled aggregate; the content of hardened cement paste and mortar attached to the recycled aggregate is found to be the essential factor to influence the properties of recycled concrete.

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