Effects of Water-Borne Polyurethane on Calcium Silicate Hydrate and Toughness of Properties of Cementitious Composites

2012 ◽  
Vol 619 ◽  
pp. 545-552
Author(s):  
Bei Ding ◽  
Xia Zhang ◽  
Dong Liang Zhou ◽  
Chan Wen Miao
Keyword(s):  
Mechanical Performance ◽  
Concrete Strength ◽  
Harmful Effect ◽  
Impact Resistance ◽  
29Si Nmr ◽  
Size Change ◽  
Block Polymer ◽  
Chain Conformations ◽  
The Impact ◽  
Water Borne

A novel kind of block polymer with characteristics of rod-like chain conformations-water-borne polyurethane (PUA) was synthesized by incorporate polyacrylate (PA) into the PU chain to prepare an aqueous polyurethane-polyacrylate (PUA) hybrid emulsion with core-shell structure. The interactions between Water-borne PUA and C-S-H nanostructure, which include intercalation and the polymerization degree of C-S-H silicate chains, were studied by small angle X-ray diffraction spectra and 29Si NMR spectra, respectly. The influences of water-borne PUA on mechanical performance of C-S-H were investigated experimentally. The small XRD results show that no evidence is observed for any fundamental size change in the C-S-H particles that have been formed in the presence of polymer. The NMR results indicate that there is a significant increase in the Q2/Q1 ratio ranging from 0.5 for pure C-S-H to 2.2 for PUA-C-S-H, respectively. The degree of silicate polymerization increases from 3.0 for pure C-S-H to 6.4 for PUA-C-S-H by calculation. PUA had minimal harmful effect on the compressive strength whereas the flexural strength was increased by 23.2% with dosage of 0.5% and 23.3% with dosage of 1.0%, respectively.The fracture energy ratios of concrete with a dosage of PUA less than 1% are greatly improved more than double with the decreasing of concrete strength less than 10%. The water-borne PUA also enhances the impact resistance of concrete. The impact energy consumption of samples with PUA increase nearly three times more than reference samples, also better than samples with PP fiber.

Toughness Properties of Concrete Modified with Water-Borne Polyurethane

2012 ◽  
Vol 238 ◽  
pp. 109-117
Author(s):  
Bei Ding ◽  
Xia Zhang ◽  
Dong Ling Zhou ◽  
Chan Wen Miao
Keyword(s):  
Mechanical Performance ◽  
Concrete Strength ◽  
Harmful Effect ◽  
Impact Resistance ◽  
Block Polymer ◽  
Influence Of Water ◽  
Energy Ratios ◽  
Chain Conformations ◽  
The Impact ◽  
Water Borne

A novel kind of block polymer with characteristics of rod-like chain conformations, water-borne polyurethane (PUA), was synthesized by incorporate polyacrylate (PA) into the PU chain to prepare an aqueous polyurethane-polyacrylate (PUA) hybrid emulsion with core-shell structure. The influence of water-borne PUA on workability and mechanical performance of concrete were investigated experimentally. PUA had minimal harmful effect on the compressive strength whereas the flexural strength was increased by 23.2% with dosage of 0.5% and 23.3% with dosage of 1.0%, respectively. The fracture energy ratios of concrete with a dosage of PUA less than 1% are greatly improved more than double with the decreasing of concrete strength less than 10%. The water-borne PUA also enhances the early plastic cracking resistance and the impact resistance of concrete. The impact energy consumption of samples with PUA increase nearly three times more than reference samples, also better than samples with PP fiber. And PUA can refine the crack from 2-4mm to 0.2-0.5mm of the main distribution, decreasing total area of crack greatly.

scholarly journals Axial Impact Load of a Concrete-Filled Steel Tubular Member with Axial Compression Considering the Creep Effect

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3134 ◽  
Author(s):  
Tao Lan ◽  
Guangchong Qin ◽  
Jinzhao Zhuang ◽  
Youdi Wang ◽  
Qian Zheng ◽  
...  
Keyword(s):  
Impact Load ◽  
Slenderness Ratio ◽  
Concrete Strength ◽  
Pressure Ratio ◽  
Impact Resistance ◽  
Axial Pressure ◽  
Axial Impact ◽  
Creep Effect ◽  
The Impact ◽  
Peak Value

The dynamic loads acting on concrete-filled steel tubular members under axial impacts by rigid bodies were studied herein by FEM. The whole impact process was simulated and the time history of the impact load was obtained. The effects of eight factors on the axial impact load were studied; these factors were the impact speed, mass ratio, axial pressure ratio, steel ratio, slenderness ratio, concrete strength, impact position, and boundary conditions. Besides this, the effects of concrete creep on the impact load were also considered by changing the material parameters of the concrete. The results show that axial impact load changes with time as a triangle. The peak value of impact load increases and the impact resistance improves with the growth of the axial pressure ratio, steel ratio, slenderness ratio, and concrete strength after creep occurs. As the eccentricity of the axial impact acting on a concrete-filled steel tubular member increases, the peak value of the impact load decreases. The enhancement of constraints at both ends of the member can improve the impact resistance. The creep reduction coefficients for the peak axial impact load of a concrete-filled steel tubular member under axial compression and considering the creep effect over 6 months and 30 years are 0.60 and 0.55, respectively. A calculation formula for the peak value of impact load was suggested based on the existing formula, and its accuracy was proved by finite element calculation in this study.

scholarly journals Experimental Investigation on the Impact Resistance of Carbon Fibers Reinforced Coral Concrete

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4000 ◽  
Author(s):  
Bing Liu ◽  
Jingkai Zhou ◽  
Xiaoyan Wen ◽  
Jianhua Guo ◽  
Xuanyu Zhang ◽  
...  
Keyword(s):  
Weibull Distribution ◽  
Carbon Fibers ◽  
Impact Test ◽  
Concrete Strength ◽  
Impact Resistance ◽  
Initial Crack ◽  
Drop Weight ◽  
Weight Impact ◽  
The Impact ◽  
Two Parameter

In this study, the impact resistance of coral concrete with different carbon fiber (CF) dosages subjected to drop-weight impact test was investigated. For this purpose, three concrete strength grades (C20, C30, C40) and six CF dosages (0.0%, 0.3%, 0.6%, 1.0%, 1.5%, and 2.0% by weight of the binder) were considered, and a total of 18 groups of carbon fibers reinforced coral concrete (CFRCC) were cast. For each group, eight specimens were tested following the drop-weight impact test suggested by CECS 13. Then, the two-parameter Weibull distribution theory was adopted to statistically analyze the variations in experimental results. The results indicated that the addition of CFs could transform the failure pattern from obvious brittleness to relatively good ductility and improve the impact resistance of coral concrete. Moreover, the impact resistance of CFRCC increases with the CF dosage increasing. The statistical analysis showed that the probability distribution of the blow numbers at the initial crack and final failure of CFRCC approximately follows the two-parameter Weibull distribution.

Quasi-Static Impact Response of Single-Curved Foldcore Sandwich Shells

2014 ◽  
Author(s):  
Joseph M. Gattas ◽  
Zhong You
Keyword(s):  
Energy Absorption ◽  
Mechanical Performance ◽  
Numerical Models ◽  
Preliminary Investigation ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Future Research ◽  
Initial Strength ◽  
Sandwich Shells ◽  
The Impact

Honeycomb core sandwich shells are used for many applications, but available unit architectures and global curvatures are limited. Numerous origami-core sandwich shells, known as foldcores, have been proposed as alternatives, but studies into their mechanical performance are few. This paper conducts a preliminary investigation into the impact resistance and energy absorption of single-curved foldcore sandwich shells that utilise Miura-derivative patterns as their core geometry. A numerical analysis on three Miura-derivative core patterns, the Arc-Miura (AM), Non-Developable Miura (ND), and Non-Flat Foldable Miura (NF) patterns, shows that ND and AM-type shells have similar impact resistance to each other, and superior impact resistance to NF-type shells. Prototypes of aluminium ND and AM-type foldcores are constructed and used to validate numerical models. Numerical models were then used to draw comparisons with an over-expanded honeycomb (OX-core) sandwich shell. It was seen that the OX-core had a better energy absorption capacity than either of the foldcores. However the AM-type foldcore possessed superior initial strength, and the ND-type possessed superior response uniformity, attributes that might be exploitable with future research. A brief parametric study on ND-type shells suggested that in general, for a given design radius and density, a foldcore shell configuration with a lower unit cell area-to-height ratio will have a higher energy absorption capability.

scholarly journals Properties of core-half wrapped shell structure wood-polymer composites containing glass fiber-reinforced shells

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 9088-9102
Author(s):  
Runzhou Huang ◽  
Xian Zhang ◽  
Zhuangzhuang Teng ◽  
Fei Yao
Keyword(s):  
Thermal Expansion ◽  
Glass Fiber ◽  
Polymer Composites ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Shell Layer ◽  
Flame Resistance ◽  
Wood Polymer ◽  
Wood Polymer Composites ◽  
The Impact

Glass fiber (GF) is commonly applied as a filler in the preparation of polymer composites. Due to the presence of GF, composite mechanical performance, flame resistance, and thermal performance could be greatly improved. The influence of a GF-filled polymer shell layer was investigated relative to the morphology, mechanical, thermal, and fire flammability performance of the core-half wrapped shell structured wood high-density polyethylene (HDPE) composites prepared via co-extrusion. The use of the relatively less-stiff pure HDPE with high linear coefficients of thermal expansion (LCTEs) lowered the general thermal stability and modulus of the wood polymer composites (WPCs). Flexural and thermal expansion properties were improved for the GF-filled HDPE shells in comparison to the unmodified material, enabling a well-balanced performance of this novel core–shell material. Implementation of GF-modified HDPE or unmodified HDPE layers as a shell for WPC core remarkably improved the impact resistance of the co-extruded WPCs. In comparison with composites possessing unmodified HDPE shell, the flame resistance performance of the shell layer was slightly improved in case that the GF content was below 25 wt%. A slight decrease in composite general heat release and rate was discovered in case that the GF content was greater than 25 wt%.

Based on the Digital Design of the Pneumatic Pick Force Analysis and Research of Key Parts

2013 ◽  
Vol 753-755 ◽  
pp. 1347-1350
Author(s):  
Chen Shen ◽  
Hua Liang Gui ◽  
Ming Ming Wu
Keyword(s):  
Mechanical Performance ◽  
Raw Materials ◽  
Design Method ◽  
Impact Resistance ◽  
Digital Design ◽  
Working Process ◽  
Air Power ◽  
Power Machinery ◽  
Resistance Performance ◽  
The Impact

Pick is a hand-held machine of the air power machinery, using compressed air as power, hit a rundown coal and ore body or other objects. In the working process of the pneumatic pick, pick cylinder under different loading easily lead to early obsolescence. In order to improve the impact resistance performance to pick picks, prolong the service life of pneumatic pick, based on the digital design method for pneumatic pick pick cylinder is modeled, and based on the simulated stress analysis, for the process improvement, improve its mechanical performance, reduce the waste of raw materials.

Response of Dolos Concrete Armor Units to Impact Loads

1991 ◽  
Vol 113 (4) ◽  
pp. 286-291 ◽  
Author(s):  
J. W. Tedesco ◽  
P. B. McGill ◽  
W. G. McDougal
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Concrete Strength ◽  
Impact Resistance ◽  
Nonlinear Material ◽  
Impact Loads ◽  
Model Formulation ◽  
Element Analysis ◽  
The Impact

A finite element analysis is conducted to determine the critical impact velocities for concrete dolos. The model formulation includes deformations at the contact surface and nonlinear material properties. Two dolos orientations are considered: vertical fluke seaward and horizontal fluke seaward. In both cases, the larger units fail at lower angular impact velocities. It is also shown that doubling the concrete strength increases the impact resistance by approximately 40 percent.

Preparation and Test of Conventional Composite Abrasives Using Recycled Alumina Grains

2016 ◽  
Vol 874 ◽  
pp. 199-204 ◽  
Author(s):  
Alexandre Dutra Golanda ◽  
Sandro Galisteu Luiz ◽  
Katia C. Gandolpho Candioto ◽  
Carlos Yujiro Shigue
Keyword(s):  
Impact Strength ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Silica Content ◽  
Alumina Content ◽  
Test Results ◽  
Abrasive Tools ◽  
Penetration Tests ◽  
The Impact ◽  
Preparation And Evaluation

In this work we report the preparation and evaluation of the mechanical characteristics of resin-bond composite abrasives using virgin and recycled alumina grains. The composite abrasives were made with phenolic resin as binder and as-received virgin and recycled alumina grains. Three different recycled alumina grains were studied: i) alumina from wood firing resin-bond abrasive tools; ii) alumina from wood firing vitrified-matrix abrasive tools; and iii) ground alumina from vitrified-matrix abrasive tools. The virgin alumina grains were employed in order to compare the mechanical performance of the prepared composite abrasive. The composition of alumina grains, analyzed by X-ray fluorescence spectroscopy revealed the recycled alumina grains have lower alumina content and higher concentration of silica in vitrified-matrix abrasives samples. The sand blast penetration tests have shown lower penetration depth in the virgin and the ground vitrified-matrix grains composites. The impact strength test results revealed its dependence on the alumina and silica content: samples with higher alumina content present the higher impact resistance whereas samples with higher silica content present lower impact strength.

scholarly journals Study on Mechanical Characteristics of Energy-Absorbing and Anti-Scour Bolts

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhi Tang ◽  
Hao Wu ◽  
Jinguo Lv ◽  
Zhuangzhuang Xin ◽  
Wenbo Zuo
Keyword(s):  
Impact Energy ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Energy Criterion ◽  
Energy Balance Equation ◽  
Surrounding Rock ◽  
Support Design ◽  
The Stability ◽  
Energy Absorbing ◽  
The Impact

In order to improve the impact resistance and mechanical performance of anchor rods and satisfy the requirements for supporting rockburst roadways, the energy balance equation of the energy-absorbing support and roadway surrounding rock system is established. Moreover, to effectively prevent rockburst disasters, the energy criterion for roadway instability is derived. From the perspective of an energy-absorbing support, a yield-absorbing anti-shock anchor composed of a rod body, tray, constant resistance energy-absorbing device, and special-shaped nut is designed and developed; compared with ordinary anchor rods, this rod has stronger mechanical properties for resisting impact. Theoretical and numerical simulation studies show that the energy-absorbing device has a repeatable deformation failure mode and a constant yield force. The paper also presents the principle involved in the design of anti-shock bolt supports. The energy-absorbing support not only effectively guides and controls the release and conversion of impact energy but also consumes the impact energy in the buffering process of the anchor to ensure the stability of surrounding rock and support protection system. This study aims to provide reference for roadway support design and to improve rock bolts used in rockburst roadways.

The Influence of Polypropylene Fiber on the Performance of Concrete Pavement

2012 ◽  
Vol 178-181 ◽  
pp. 1099-1103 ◽  
Author(s):  
Hua Rong Shen ◽  
Yue Xin She ◽  
Pei Wei Gao
Keyword(s):  
Mechanical Performance ◽  
Impact Resistance ◽  
Polypropylene Fiber ◽  
Plain Concrete ◽  
Concrete Pavement ◽  
Cement Concrete Pavement ◽  
Average Crack ◽  
Tensile Splitting Strength ◽  
Resistance Performance ◽  
The Impact

This paper presents the influence of the appropriate polypropylene fibers on the performance of cement concrete pavement. The experimental results show that the fibers can obviously reduce cracks and improve the mechanical performance and durability of concrete. When the content of polypropylene fiber is 0.8 kg/m3, the time of the first crack appearance is 45min and 2h 17min later than that of the concrete samples with 0.4 kg/m3 polypropylene fiber and plain concrete. Comparing with the concrete samples with 0.4 kg/m3 polypropylene fiber and plain concrete, the indexes of average crack area, numbers of cracks per area, and total crack area per area of concrete with 0.8 kg/m3 polypropylene fiber reduce 16.2%, 33.0%, 44.3% and 26.9%, 48.1%, 62.2% respectively. Comparing with plain concrete, the 7d and 28d compressive strength of concrete with 0.4 kg/m3 and 0.8 kg/m3 polypropylene fiber enhances 3%, 4% and 4%, 2%, the 90d tensile splitting strength enhances 7% and 10%, and the impact resistance performance of concrete enhances 130% and 250% respectively.

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