scholarly journals Investigation on mechanical properties and water stability of porous polyurethane concrete

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Jie Yang ◽  
Hui Li ◽  
John Harvey ◽  
Bing Yang ◽  
Saifullah Mahmud ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Damage Mechanism ◽  
Water Stability ◽  
Cement Concrete ◽  
Porous Asphalt ◽  
Carbon Dioxide Gas ◽  
Polyurethane Film ◽  
Novel Material ◽  
Water Damage ◽  
Marshall Stability

Abstract Porous polyurethane concrete (PPUC) is a novel material for permeable pavements and is considered as an alternative to porous asphalt or porous cement concrete. However, studies of the mechanical properties of PPUC are still insufficient. In this study, the comprehensive mechanical properties and water stability of PPUC with different gradations and polyurethane dosages were investigated, and its water damage mechanism was preliminarily explored. The results show that the flexural strength and Marshall stability of PPUC can more easily reach the index in the standards of porous cement concrete or porous asphalt, while the compressive strength and abrasion resistance are the weak points of its mechanical properties and need to be further optimized. The mechanical properties and water stability of PPUC were effectively improved by increasing the polyurethane dosage and using continuously graded aggregates. PPUC is more susceptible to water damage because water reacts with the residual isocyanate groups within the polyurethane film to generate carbon dioxide gas, which reduces the cohesion and adhesion performance of polyurethane film. This study provides a comprehensive understanding of the mechanical properties of PPUC and an initial insight into the mechanism of water damage.

scholarly journals Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huren Rong ◽  
Jingyu Gu ◽  
Miren Rong ◽  
Hong Liu ◽  
Jiayao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Power Function ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

scholarly journals Comparison of Mechanical Properties of Normal and Fibre Reinforced Concrete (Grade M15)

2019 ◽  
Vol 5 ◽  
pp. 153-164
Author(s):  
Sagar Bista ◽  
Sagar Airee ◽  
Shikshya Dhital ◽  
Srijan Poudel ◽  
Sujan Neupane
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Steel Fibre ◽  
Residential Buildings ◽  
Fibre Reinforced Concrete ◽  
Cement Concrete ◽  
Normal Concrete ◽  
Steel Fibre Reinforced Concrete ◽  
Cracking Control ◽  
Different Types

Concrete is weak in tension, hence some measures must be adopted to overcome this deficiency as well as to enhance physical and other mechanical properties but in more convenient and economical method. Through many research from the past, it has been observed that addition of different types of fibres has been more effective for this purpose. This report presents the work undertaken to study the effect of steel and hay fibre on normal cement concrete of M-15 Grade on the basis of its mechanical properties which include compressive and tensile strength test and slump test as well. Although hay fibres are abundantly available in Nepal, no research have been popularly conducted here regarding the use of hay fibres in concrete and the changes brought by it on concrete’s mechanical properties. Experiments were conducted on concrete cubes and cylinders of standard sizes with addition of various percentages of steel and hay fibres i.e. 0.5%, 1% and 1.5% by weight of cement and results were compared with those of normal cement concrete of M-15 Grade. For each percentage of steel and hay fibre added in concrete, six cubes and six cylinders were tested for their respective mechanical properties at curing periods of 14 and 28 days. The results obtained show us that the optimum content of fibre to be added to M-15 grade of concrete is 0.5% steel fibre for compression and 0.5% hay fibre content for tension by weight of cement. Also, addition of steel and hay fibres enhanced the binding properties, micro cracking control and imparted ductility. In addition to this, two residential buildings were modeled in SAP software, one with normal concrete and other with concrete containing 0.5% steel fibre. Difference in reinforcement requirements in each building was computed from SAP analysis and it was found that 489.736 Kg of reinforcement could be substituted by 158.036 kg of steel fibres and decrease in materials cost of building with 0.5% steel fibre reinforced concrete was found to be Rs. 32,100.

scholarly journals Experimental and FEM Research on Airport Cement Concrete Direct-Thickening Double-Deck Pavement Slabs under Aircraft Single-Wheel Dynamic Loads

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Qingkun Yu ◽  
Liangcai Cai ◽  
Jianwu Wang
Keyword(s):  
Mechanical Properties ◽  
Structural Parameters ◽  
Element Model ◽  
Tension Stress ◽  
Cement Concrete ◽  
Wheel Load ◽  
Critical Position ◽  
Ansys Simulation ◽  
Longitudinal Edge ◽  
Airport Runway

The wide-use airport cement concrete direct-thickening double-deck pavement slabs (ACCDDPS) were selected as the research object to study their mechanical properties. The airport runway simulation test station (ARSTS) was used to conduct indoor tests to demonstrate the distribution of tension stress at the bottom of slabs and slabs deflection. Furthermore, ANSYS software was applied to establish finite element model (FEM) of ACCDDPS and analyze the mechanical laws under different loads. The indoor tests results are in good agreement with the ANSYS simulation results, and some consistent conclusions can be obtained that the maximum tension stress increases with wheel load, and the slab middle of the longitudinal edge is a critical position. In addition, we studied the influence of covered layer thickness, elastic modulus, and slab size on pavement slab mechanical properties by ANSYS, and we concluded that although the structural parameters are different, the critical position of ACCDDPS is still in the middle of the longitudinal edge. However, for the covered layer and the original surface layer, the law that the tension stress values vary with the structural parameters is different, but the maximum deflection value is about 0.1.

Mechanical Properties on Thermosetting Epoxy Asphalt Waterproof Bond Material for Cement Concrete Pavement Based on Composite Structures

2011 ◽  
Vol 99-100 ◽  
pp. 948-954
Author(s):  
Zhen Dong Qian ◽  
Ya Qi Wang ◽  
Xin Song
Keyword(s):  
Mechanical Properties ◽  
Composite Structures ◽  
Concrete Pavement ◽  
Cement Concrete ◽  
Epoxy Asphalt ◽  
Fatigue Durability ◽  
Bond Layer ◽  
Bending Fatigue Test ◽  
Cement Concrete Pavement ◽  
Thermosetting Epoxy

One of the important methods to ensure the durability of cement concrete pavement is utilizing excellent waterproof bond layer. Firstly, based on the mechanism of strength of the thermosetting epoxy asphalt waterproof bond material (EAWBM), the construction temperature which is strictly controlled above 130°C, is insured. Then the amount, the curing time and temperature of the thermosetting epoxy asphalt, are studied as the influencing factors of mechanical properties based on the composite structures of the concrete cement pavement. Finally, through the three-point bending fatigue test of composite structures, the fatigue durability of different waterproof bond material is compared. The results show that: the optimal amount of the thermosetting epoxy asphalt is 0.60~0.80L/m2; the asphalt concrete paving must be carried out within 24~32h after the EAWBM is constructed; the mechanical properties of the material decreases as the increasing test temperature; the waterproof bond materials have greater impact on the fatigue durability for the composite structures of the concrete cement pavement compared with the paving material, and the fatigue durability of the EAWBM is the optimal selection for cement concrete pavement.

Laboratory Investigation of the Adhesion and Self-Healing Properties of High-Viscosity Modified Asphalt Binders

2020 ◽  
Vol 2674 (1) ◽  
pp. 307-318 ◽  
Author(s):  
Mingjun Hu ◽  
Daquan Sun ◽  
Tong Lu ◽  
Jianmin Ma ◽  
Fan Yu
Keyword(s):  
Water Immersion ◽  
Gel Permeation Chromatography ◽  
High Viscosity ◽  
Healing Time ◽  
Adhesion Property ◽  
Asphalt Binders ◽  
Self Healing ◽  
Porous Asphalt ◽  
Modified Asphalt ◽  
Water Damage

Water damage often occurs on porous asphalt pavement during service life because of the well-developed pore structure. Determining the adhesion and adhesion healing properties of high-viscosity modified asphalt (HVMA) under water condition is beneficial to understand the water damage process of porous asphalt. In this study, the modified binder bond strength test was first conducted to investigate the adhesion property and self-healing behavior of HVMA at different conditions. Then, the surface energy test was carried out to further characterize the differences in adhesion property of HVMA. Moreover, the gel permeation chromatography test and fluorescence microscopic test were used to investigate the influence of chemical composition and polymer morphology on the adhesion property of HVMA. Results show that the presence of water reduces the adhesion property of HVMA. The addition of polymers leads to an increasing adhesion strength and a decreasing self-healing ability of HVMA. The self-healing ability of HVMA improves with the increase of temperature, but also shows a decreased trend when the healing time is long at high-temperature water immersion. The effect of polymers on the adhesion property of asphalt has two aspects. First, the swelling of polymers leads to an increasing content of polar heavy components in HVMA, thus enhancing polarity adsorption between asphalt and aggregate. Moreover, a polymer-centered interfacial diffusion layer can be formed during the adsorption of light components, which increases the overlapping area of structural asphalt between adjacent aggregates. This can also improve the adhesion property at the asphalt–aggregate interface.

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