scholarly journals Mechanical Properties Improvement Mechanism of Silica Fume-Modified Ultrafine Cement Used to Repair Pavement Microcracks

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Xiaofei Wang ◽  
Jiangbei Yao ◽  
Xinwei Li ◽  
Yinchuan Guo ◽  
Aiqin Shen ◽  
...  
Keyword(s):  
Silica Fume ◽  
Bonding Strength ◽  
Bending Strength ◽  
Pozzolanic Reaction ◽  
Concrete Pavement ◽  
Interfacial Bonding ◽  
Cement Concrete ◽  
Interfacial Bonding Strength ◽  
Cement Concrete Pavement ◽  
Ultrafine Cement

With heavy modern traffic and natural factors, cement concrete pavement cracks have become increasingly serious. However, most existing inorganic repair materials for cement concrete pavement cracks have low interfacial bonding strength. Ultrafine cement, silica fume (SF), and other admixtures, which are superfine and used to repair fine early cracks, are prepared as the mending material in our research. Compression strength, bending strength, and interfacial bonding strength are studied, and modification mechanisms are discovered by using a powder X-ray diffraction test, thermal analysis, and micromorphology observation. The result shows that mechanical strength of the stable period is improved with the right amount of mixing of SF, which leads to secondary pozzolanic reaction and makes the microstructure of the paste denser. Meanwhile, a large amount of Ca(OH)2 and water in the interface area are consumed by the secondary pozzolanic reaction, which brings out good interfacial effects with no water film between the new paste and existing concrete. Our experiments show that the pastes with 3–5% SF have better bending strength (15%∼17% improvement) and compressive strength (7%∼9% improvement). Interfacial bonding strength is also increased with a certain amount of SF. Tensile shear bonding strength has been improved more than 4 times when SF dosage is more than 3%. Thus, we recommend a paste with 5% SF as the best mixture to be used to repair cracks.

Repair and cryogenic mechanical properties with resin film infused (RFI) GFRP in out-of-autoclave processing

2020 ◽  
Vol 34 (07n09) ◽  
pp. 2040014
Author(s):  
Yun-Hae Kim ◽  
Kyo-Moon Lee ◽  
Seong-Jae Park ◽  
Kyung-In Jo ◽  
Soo-Jeong Park
Keyword(s):  
Mechanical Properties ◽  
Bonding Strength ◽  
Bending Strength ◽  
High Strength ◽  
Parent Material ◽  
Interfacial Bonding ◽  
Interfacial Bonding Strength ◽  
Resin Film ◽  
Air Pockets ◽  
Cryogenic Mechanical Properties

Prepreg technology generates air pockets at the interface of laminates under heating and pressurization. The air pockets cause defects in the through-thickness direction. This includes poor adhesion between layers, which degrades material properties. Therefore, in this study, cryogenic mechanical properties were compared to obtain uniform properties by using prepreg laminated and resin film infused glass fiber reinforced plastic (GFRP) composites (“PP-only” and “RF-only”, respectively) while maintaining the constituent contents of the fiber and polymer. Moreover, stepped repair was applied to extend the life of composites. The results demonstrated that the stiffness of the composites improved, and the brittleness increased in cryogenic environments. In the case of PP-only, numerous voids were observed inside the polymer, which showed higher bending strength than RF-only; however, it exhibited significantly lower interfacial bonding strength. When applied to secondary bonding of stepped repair, RF-only as repair layers showed high strength recovery rate in homogeneous materials, and not in heterogeneous materials. In contrast, the high strength PP-only as a parent material and RF-only as repair layers showed relatively good interfacial bonding strength due to primary damage in the PP of a parent material. Hence, the RF-only can be considered useful as a repair material.

Strengthening and Toughening Efficiency of Calcium Carbonate Whisker-Reinforced Portland Cement with or without Silica Fume

2012 ◽  
Vol 479-481 ◽  
pp. 536-540
Author(s):  
Ming Li Cao ◽  
Cong Zhang
Keyword(s):  
Calcium Carbonate ◽  
Portland Cement ◽  
Silica Fume ◽  
Bonding Strength ◽  
Cement Composite ◽  
Crack Deflection ◽  
Interfacial Bonding ◽  
Split Tensile Strength ◽  
Interfacial Bonding Strength ◽  
Calcium Carbonate Whisker

Strengthening and toughening efficiency contributed by calcium carbonate whisker was questioned in this study when the interfacial bonding strength between whisker and Portland cement was increased by adding silica fume. A simple proving experiment was employed and the basic mechanical properties were measured. The results showed that the compressive strength of the composites with silica fume was more sensitive to whisker loading. The flexural strength, split tensile strength and work of fracture were increased no matter with or without silica fume. However, the strengthening and toughening efficiency caused by whiskers in the composites with silica fume was lower than that without silica fume. The scanning electron microscopy images illustrated six mechanisms which can account for the strengthening and toughening effects. It is concluded that crack deflection was the efficient mechanism to toughen cement composite materials. And the interfacial bonding strength should be weak enough to introduce more crack deflection mechanism.

scholarly journals Research on Application Effect of Mixconverter in Cement Concrete Pavement

2021 ◽  
Vol 261 ◽  
pp. 02075
Author(s):  
Tao Wang ◽  
Tao Liu ◽  
Xiayi Liang ◽  
Hanxin Wei ◽  
Zhigang Zheng ◽  
...  
Keyword(s):  
Bending Strength ◽  
Concrete Strength ◽  
Chloride Ion ◽  
Concrete Pavement ◽  
Hydration Reaction ◽  
Cement Concrete ◽  
Road Pavement ◽  
Cement Concrete Pavement ◽  
Improvement Effect ◽  
Research On Application

In order to improve the strength of cement concrete pavement and reduce pavement cracking, the application effect of the hydration reaction enhancer Mixconverter in cement concrete pavement was studied by testing the compressive strength, bending strength, crack resistance and chloride ion permeability of concrete indoors. The test results show that the addition of Mixconverter to concrete can significantly improve the compressive and flexural strength of concrete, effectively prevent the expansion of plastic shrinkage and cracking of concrete, and significantly reduce the chloride ion diffusion coefficient. Finally, the test road pavement further proves the improvement effect of Mixconverter on concrete strength and cracking.

Stress Analysis of Cement Concrete Pavement under Overweight Loads

2012 ◽  
Vol 446-449 ◽  
pp. 949-953
Author(s):  
Ya Ni Lu ◽  
Tao Li Xiao
Keyword(s):  
Finite Element ◽  
Regression Analysis ◽  
Finite Element Model ◽  
Element Model ◽  
Concrete Pavement ◽  
The Other ◽  
Tension Stress ◽  
Statistical Regression ◽  
Cement Concrete ◽  
Cement Concrete Pavement

Special load has produced serious damage to the concrete pavement because of the great gross weight and heavy axle load, but the present specification has not mentioned this kind of load. On this occasion, Several conditions of critical load are identified through ANSYS finite element model analysis and the formula through statistical regression analysis to the bottom maximum tension stress is drawn up. Which can not only guide the concrete pavement design under the special load but also the result may be referred by the other kinds of engineering.

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