scholarly journals Mechanical Properties, Curing Mechanism, and Microscopic Experimental Study of Polypropylene Fiber Coordinated Fly Ash Modified Cement–Silty Soil

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5441
Author(s):  
Linfang Lu ◽  
Qiang Ma ◽  
Jing Hu ◽  
Qingfu Li
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Strain Curve ◽  
Soil Mass ◽  
Foundation Engineering ◽  
Soil Particles ◽  
Silty Soil ◽  
Curing Mechanism ◽  
Dry Soil ◽  
Modified Soil

Silty soil has the characteristics of low natural moisture content and poor viscosity, and the strength and deformation required for foundation engineering can be satisfied by reinforcing and improving the silt. In order to study the reinforcement and improvement effects of polypropylene (PP) fiber and fly ash (FA) on cement–silty soil, an unconfined compressive strength (UCS) test, scanning electron microscope (SEM) test, and X-ray diffraction (XRD) analysis test were carried out. Cement (mixed amounts are 4%, 8%, 12%, and 16% of dry soil mass) was used as the basic modifier, and PP fiber (mixed amounts are 0%, 0.15%, 0.3%, and 0.45% of dry soil mass) compounded with FA (adding amounts of 0%, 5%, 10%, and 15% of dry soil mass) were used as an external admixture of cement–silty soil to study the mechanical properties, curing mechanism, and microstructure of the modified soil in different ages of 7 d, 14 d, 28 d, and 60 d. The test results show that with the increase in cement and curing age, the UCS of the modified soil increases, and with the increase in the PP fiber and FA, the UCS of the modified soil first increases and then decreases; there is an optimal content of FA and PP fiber, which are 10 and 0.15%, respectively. A large amount of C-S-H and AFt substances are produced inside the modified soil to cover the surface of soil particles or fill in the pores between soil particles, forming a tight spatial network structure and improving the mechanical properties of the cement–soil. The intensity of the diffraction peaks of the mineral components within the modified soils is more influenced by the cement and age, and the effect of FA is weaker. The stress–strain curve of the modified soil is divided into elastic stage, plastic deformation stage, and strain-softening stage, and the specimens in each stage have corresponding deformation characteristics. By analyzing the behavioral characteristics and curing improvement mechanism of modified soil from the duo perspective of macro-mechanical properties and microstructural composition, it can provide some basis for the engineering application of silty soil.

scholarly journals Research on Static Triaxial Mechanical Properties of New CementSoil Reinforced with Polypropylene Fiber

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Qiang Wang ◽  
Rui Tang ◽  
Qun Cheng ◽  
Xiankun Wang ◽  
Fang-ling Liu
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Polypropylene Fiber ◽  
Strain Curve ◽  
Friction Angle ◽  
Confining Pressure ◽  
Gypsum Content ◽  
Amplitude Increase ◽  
Dry Soil ◽  
Soil Weight

Through the laboratory test, the mechanical properties of cementsoil with adding desulfurization gypsum, fly ash, and polypropylene fiber were studied. Three different percentages (0%, 0.5%, and 1.0%) of polypropylene fiber were mixed into new cementsoil for which the cement content is 15% of the dry soil weight, the desulfurization gypsum content is 2% of the dry soil weight, and the fly ash content is 1.0% of the dry soil weight. The new cementsoil strength reinforced with polypropylene fiber was studied by triaxial test under different polypropylene fiber mixing ratio, different age, and different confining pressure. The experimental results show that, compared with ordinary soil, the deviatoric stress and the peak shear strength reinforced with polypropylene fiber have different amplitude increase. At the same time, the internal friction angle of new cementsoil with polypropylene fiber increases slightly with the growth of the age. The stress-strain curve of the polypropylene fiber cementsoil has the typical work hardening characteristic and has the characteristics of bulge fracture.

The Research of Test on Stress-Strain Constitutive Relations of Straw Concrete

2014 ◽  
Vol 584-586 ◽  
pp. 987-992
Author(s):  
Wei Liu ◽  
Wei Xi ◽  
Yi Lu Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Constitutive Relations ◽  
Strain Curve ◽  
Green Building ◽  
Corn Straw ◽  
Stress Strain Curve ◽  
Stress Strain

As a new green building material, straw concrete are introduced about its mechanical properties and characteristics. Mechanical properties test such as prism compressive strength, elastic modulus and Poisson's ratios use standard prismatic blocks. Under different rate of corn straw, cement, sand and fly ash, test gets the full stress-strain curve. Results show that with increase of volume of corn straw, the prism compressive strength reduces significantly. Comparing with natural concrete, elastic modulus of straw concrete can reduces greatly. Poisson’s ratio reduces with increase of volume of corn straw. Fly ash could improve property of the material and replace cement, but excessive replacement will reduce the strength of material.

scholarly journals Mechanical Properties, Failure Mode, and Microstructure of Soil-Cement Modified with Fly Ash and Polypropylene Fiber

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Xue-lei Duan ◽  
Jing-shuang Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fly Ash ◽  
Failure Mode ◽  
Unconfined Compressive Strength ◽  
Polypropylene Fiber ◽  
Peak Strain ◽  
Soil Cement ◽  
Dry Soil ◽  
Rise Phase

In order to investigate the effects of fly ash and polypropylene fiber on mechanical properties, failure mode, and microstructure of soil-cement, the unconfined compression test, splitting tension test, and scanning electron microscopy (SEM) test of soil-cement with different polypropylene fiber contents (0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% by weight of dry soil) and fly ash contents (0%, 4%, 8%, and 12% by weight of dry soil) were carried out. The compressive and tensile strengths, deformation characteristics, failure mode, and microstructure of soil-cement modified with fly ash and polypropylene fiber were analyzed. The results show that the unconfined compressive strength and splitting tensile strength of soil-cement show a trend of increasing first and then decreasing with the increase of polypropylene fiber and fly ash content. Under the condition of 0.4% polypropylene fiber and 8% fly ash, the unconfined compressive strength and the splitting tensile strength are 4.90 MPa and 0.91 MPa, respectively, which increased by 32.79% and 51.67% as compared with the plain soil-cement, respectively. When 8% fly ash was used in the experiment, the unconfined compressive peak strain and the splitting tensile peak strain of the inclusion of 0.4% polypropylene fiber were 0.0410 and 0.0196, respectively. The corresponding peak strains were increased by 20.94% and 68.97% as compared with non-fiber-stabilized soil-cement, respectively. The stress-strain curve of fly ash soil-cement modified with polypropylene fiber can be divided into compaction phase, linear rise phase, nonlinear rise phase, and failure phase. Polypropylene fiber constrains the lateral deformation of fly ash soil-cement, which improves the peak strain and the failure mode of soil-cement.

scholarly journals Experimental Study on Mechanical Properties of Fly Ash Stabilized with Cement

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Shengquan Zhou ◽  
Yongfei Zhang ◽  
Dawei Zhou ◽  
Weijian Wang ◽  
Dongwei Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Early Stage ◽  
Strain Curve ◽  
Pozzolanic Reaction ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Compressive Test ◽  
Plastic Properties

Cement-fly ash mixture has been commonly used for the foundation treatment projects in the fly ash stratum, as it is effective in improving foundation bearing capacity and reducing settlement of stratum. In order to figure out the effect of dynamic and static load on the mechanical properties exhibited by the cement-fly ash and the reaction mechanism of cement-fly ash, a combination of the unconfined compressive test, impact test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) method was adopted in this study to investigate the cement-fly ash test samples. As demonstrated by the results, the observed growth rate of 0–60 days (d) is higher than that in the later stages and the typical stress-strain curve can be divided into six sections under the unconfined compressive test. At the gas pressure of 0.2 MPa, the cement-fly ash samples exhibited obvious plastic properties in early curing time (0–60 d), and brittle failure was observed in the final stage (90 d). It is obvious that the value of dynamic compressive strength (DCS) is higher than that of unconfined compressive strength (UCS). The analysis of XRD has revealed that the hydration products are primarily derived from the hydration reaction of cement in the early stage and the pozzolanic reaction in the late stage. The pores of cement-fly ash are found to be filled with the hydration products, despite the presence of a mass of pores in the interior.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Mechanical Properties of Alkali Activated Fly Ash Geopolymer Stabilized Expansive Clay

2019 ◽  
Vol 23 (9) ◽  
pp. 3875-3888 ◽  
Author(s):  
Anant Lal Murmu ◽  
Anamika Jain ◽  
Anjan Patel
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Expansive Clay ◽  
Alkali Activated

scholarly journals Mechanical Behavior of Brick Masonry in an Acidic Atmospheric Environment

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2694 ◽  
Author(s):  
Shansuo Zheng ◽  
Lihua Niu ◽  
Pei Pei ◽  
Jinqi Dong
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Acid Rain ◽  
Cement Mortar ◽  
Brick Masonry ◽  
Atmospheric Environment ◽  
Peak Strain ◽  
Lime Mortar ◽  
Attenuation Model

In order to evaluate the deterioration regularity for the mechanical properties of brick masonry due to acid rain corrosion, a series of mechanical property tests for mortars, bricks, shear prisms, and compressive prisms after acid rain corrosion were conducted. The apparent morphology and the compressive strength of the masonry materials (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), the shear behavior of the masonry, and the compression behavior of the masonry were analyzed. The resistance of acid rain corrosion for the cement-lime mortar prisms was the worst, and the incorporation of fly ash into the cement mortar did not improve the acid rain corrosion resistance. The effect of the acid rain corrosion damage on the mechanical properties for the brick was significant. With an increasing number of acid rain corrosion cycles, the compressive strength of the mortar prisms, and the shear and compressive strengths of the brick masonry first increased and then decreased. The peak stress first increased and then decreased whereas the peak strain gradually increased. The slope of the stress-strain curve for the compression prisms gradually decreased. Furthermore, a mathematical degradation model for the compressive strength of the masonry material (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), as well as the shear strength attenuation model and the compressive strength attenuation model of brick masonry after acid rain corrosion were proposed.

scholarly journals Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Strain Curve ◽  
Confining Pressure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Model ◽  
Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

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