Design of high strength cement based materials: Part 3 State of the art

1988 ◽  
Vol 4 (4) ◽  
pp. 291-300 ◽  
Author(s):  
H. M. Jennings
2020 ◽  
Vol 9 (1) ◽  
pp. 303-322 ◽  
Author(s):  
Zhifang Zhao ◽  
Tianqi Qi ◽  
Wei Zhou ◽  
David Hui ◽  
Cong Xiao ◽  
...  

AbstractThe behavior of cement-based materials is manipulated by chemical and physical processes at the nanolevel. Therefore, the application of nanomaterials in civil engineering to develop nano-modified cement-based materials is a promising research. In recent decades, a large number of researchers have tried to improve the properties of cement-based materials by employing various nanomaterials and to characterize the mechanism of nano-strengthening. In this study, the state of the art progress of nano-modified cement-based materials is systematically reviewed and summarized. First, this study reviews the basic properties and dispersion methods of nanomaterials commonly used in cement-based materials, including carbon nanotubes, carbon nanofibers, graphene, graphene oxide, nano-silica, nano-calcium carbonate, nano-calcium silicate hydrate, etc. Then the research progress on nano-engineered cementitious composites is reviewed from the view of accelerating cement hydration, reinforcing mechanical properties, and improving durability. In addition, the market and applications of nanomaterials for cement-based materials are briefly discussed, and the cost is creatively summarized through market survey. Finally, this study also summarizes the existing problems in current research and provides future perspectives accordingly.


2021 ◽  
Vol 65 (4) ◽  
pp. 643-651
Author(s):  
Th. Nitschke-Pagel ◽  
J. Hensel

AbstractThe consideration of residual stresses in fatigue-loaded welds is currently done only qualitatively without reliable knowledge about their real distribution, amount and prefix. Therefore, the tools which enable a more or less unsafe consideration in design concepts are mainly based on unsafe experiences and doubtful assumptions. Since the use of explicitly determined residual stresses outside the welding community is state of the art, the target of the presented paper is to show a practicable way for an enhanced consideration of residual stresses in the current design tools. This is not only limited on residual stresses induced by welding, but also on post-weld treatment processes like HFMI or shot peening. Results of extended experiments with longitudinal fillet welds and butt welds of low and high strength steels evidently show that an improved use of residual stresses in fatigue strength approximation enables a better evaluation of peening processes as well as of material adjusted welding procedures or post-weld stress relief treatments. The concept shows that it is generally possible to overcome the existing extremely conservative but although unsafe rules and regulations and may also enable the improved use of high strength steels.


2019 ◽  
Vol 276 ◽  
pp. 01016
Author(s):  
M. Jamil ◽  
A. B. M. A. Kaish ◽  
E. I. Sahari ◽  
N. L. Fong ◽  
L. Nahar

The challenge of repairing cracked or damaged concrete has been increasing worldwide. Several cement-based materials, such as ferrocement, fiber-reinforced cementitious mortar (FRCM), and textilereinforced mortar (TRM), have been developed and used to address the aforementioned challenge. Self-consolidating mortar is required to accelerate structural concrete repair using cementitious composites (e.g., ferrocement, FRCM, and TRM). In this study, a high-strength selfconsolidating mortar is developed using higher-volume (50% by weight of cement) blended pozzolans. Experimental results exhibit potential in terms of flowability and strength. Therefore, this type of cementitious selfconsolidating mortar can be used to expedite concrete repair or strengthening using cementitious composites.


2018 ◽  
Vol 35 (1) ◽  
pp. 65-98 ◽  
Author(s):  
Ayesha Kausar

This article presents a state-of-the-art overview on indispensable aspects of polymer/nanowire nanocomposites. Nanowires created from polymers, silver, zinc, copper, nickel, and aluminum have been used as reinforcing agents in conducting polymers and non-conducting thermoplastic/thermoset matrices such as polypyrrole, polyaniline, polythiophene, polyurethane, acrylic polymers, polystyrene, epoxy and rubbers. This review presents the combined influence of polymer matrix and nanowires on the nanocomposite characteristics. This review shows how the nanowire, the nanofiller content, the matrix type and processing conditions affect the final nanocomposite properties. The ensuing multifunctional polymer/nanowire nanocomposites have high strength, conductivity, thermal stability, and other useful photovoltaic, piezo, and sensing properties. The remarkable nanocomposite characteristics have been ascribed to the ordered nanowire structure and the development of a strong interface between the matrix/nanofiller. This review also refers to cutting edge application areas of polymer/nanowire nanocomposites such as solar cells, light emitting diodes, supercapacitors, sensors, batteries, electromagnetic shielding materials, biomaterials, and other highly technical fields. Modifying nanowires and incorporating them in a suitable polymer matrix can be adopted as a powerful future tool to create useful technical applications.


1984 ◽  
Vol 42 ◽  
Author(s):  
Sidney Mindess

AbstractThe mechanical properties of cement-based materials must be controlled by the microstructure, pore geometry and chemical composition of the cement, by the properties of the aggregate, and by the nature of the cement-aggregate bond. While the precise form of the strength vs. microstructure relationship is as yet only imperfectly understood, enough is known to permit us to predict what alterations in the microstructure are required for the production of materials with very high strengths. There are also techniques available for reducing the brittleness that is often a characteristic of high-strength materials. The present paper presents an overview of the strength vs. microstructure relationships that can be used to predict the properties of high strength cement-based materials, and a brief review of some of the methods for achieving high strengths.


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