scholarly journals Degradation of Strength and Stiffness of Sandstones Caused by Wetting-Drying Cycles: The Role of Mineral Composition

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Lu Chen ◽  
Yichao Rui ◽  
Yihan Zhao
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Moisture Content ◽  
Mechanical Parameters ◽  
Test Results ◽  
Strength And Stiffness ◽  
Rock Mechanical Properties ◽  
Mineral Constituents ◽  
Compressive Tests

Rock mechanical parameters are of great importance for the construction and design of rock engineering. Rocks are usually subjected to the deteriorating effect of cyclic wetting-drying because of the change in moisture content. The main objective of this study is to reveal the degradation effects of wetting-drying cycles on strength and modulus on varying rocks. Three kinds of sandstones with different mineral constituents are selected for testing. Artificial treatments of cyclic wetting-drying are conducted on respective specimens of the three sandstones (0, 10, 20, 30, and 40 cycles) to simulate the damage of rocks exposed to natural weathering. Uniaxial compressive tests are carried out on sandstone specimens to obtain their strength and modulus. Test results show that, for the tested sandstones, both of the uniaxial compressive strength (UCS) and modulus are reduced as the cyclic number rises. In the first ten cycles, the losses of UCS and modulus are very significant. Subsequently the changes of UCS and modulus become much more placid against cyclic number. When the cyclic number is the same, the loss percentages of rock mechanical properties of the three sandstones are very different which mainly depends on the contents of expandable and soluble minerals.

scholarly journals Effect of Freeze-Thaw Cycles on the Mechanical Properties of Polyacrylamide- and Lignocellulose-Stabilized Clay in Tibet

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Haiping Shi ◽  
Zhongyao Li ◽  
Wenwei Li ◽  
Shaopeng Wang ◽  
Baotian Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Internal Friction ◽  
Unconfined Compressive Strength ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Test Results ◽  
Freeze Thaw ◽  
Original Strength ◽  
Compressive Tests

Laboratory freezing experiments were conducted to evaluate the effect of polyacrylamide (PAM) and lignocellulose on the mechanical properties and microstructural characteristics of Tibetan clay. Direct shear and unconfined compressive tests and field emission scanning electron microscopy analyses were performed on clay samples with different contents of stabilizers. The test results show that the addition of PAM can improve the unconfined compressive strength and cohesion of Tibetan clay, but an excessive amount of PAM reduces the internal friction angle. After several freeze-thaw cycles, the unconfined compressive strength and cohesion of samples stabilized by PAM decrease significantly, while the internal friction angle increases. Samples stabilized by PAM and lignocellulose have higher internal friction angles, cohesion, and unconfined compressive strength and can retain about 80% of the original strength after 10 freeze-thaw cycles. PAM fills the pores between soil particles and provides adhesion. The addition of lignocellulose can form a network, restrict the expansion of pores caused by freeze-thaw cycles, and improve the integrity of PAM colloids. It is postulated that the addition of a composite stabilizer with a PAM content of 0.4% and a lignocellulose content of 2% may be a technically feasible method to increase the strength of Tibetan clay.

Effect of white soil substitution on fly ash based mortar geopolymers with sodium hydroxide activator

2020 ◽  
Vol 26 (1) ◽  
pp. 9-16
Author(s):  
Yulita Arni Priastiwi ◽  
Arif Hidayat ◽  
Dwi Daryanto ◽  
Zidny Salamsyah Badru
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Moisture Content ◽  
Sodium Hydroxide ◽  
Modulus Of Elasticity ◽  
Physical And Mechanical Properties ◽  
Test Results ◽  
Alkaline Activator ◽  
Made In

The presence of white soil in a geopolymer mortar affects the physical and mechanical properties of the mortar itself, especially in compressive strength, density and modulus of elasticity produced. Geopolymer mortar composed of fly ash, sand, water, and NaOH which acts as an alkaline activator compared to mortar from the same material, but white soil from Kupang is added as a substitution of fly ash. Specimens are made in six variations. Geopolymer mortar composers using a ratio of 1 binder: 3 sand with w/b of 0.5. Binder composed of fly ash with white soil substitution of 0; 5; 10; 15; 20 and 30% by weight of fly ash. An activator NaOH 8M solution was added to the mixture. Both white soil and fly ash pass of sieve no. 200 with a moisture content of 0%. Mortar made measuring 5x5x5 cm. The mortar was treated by the oven of method at 60 oC for 24 hours until the mortar does not change in weight. The test results show geopolymer mortar with 15% substitution of white soil to fly ash has the highest compressive strength, density and modulus of elasticity among other variations. In all mortar variations, compressive strength at 14 days has reached 75% of strength at 28 days.

scholarly journals Effect of Moisture Content on Bursting Liability of Sandstone due to Freeze-Thaw Action

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Kesheng Li ◽  
Maotong Li ◽  
Deng Zhang ◽  
Chuanxiao Liu ◽  
Depeng Ma
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Elastic Strain Energy ◽  
Test Results ◽  
Energy Index ◽  
Cold Region ◽  
Freeze Thaw ◽  
Uniaxial Compressive Test ◽  
Rock Mechanical Properties ◽  
The Relationship

Moisture content (MC) and freeze-thaw (F-T) process have an important influence on the mechanical properties of rock and its rockburst tendency in the cold region. In addition, uniaxial compressive strength (UCS) of rock is of great importance in evaluating weathering durability, frost resistance, and bursting liability of rock. In this study, the UCS of rock and bursting liability index of rock including elastic energy index (WET), impact energy index (WCF), elastic strain energy index (ES), and modified values of brittleness index (BIM) were measured by laboratory tests. These tests were implemented in six different MC (0, 0.58, 1.06, 1.82, 2.43, and 2.80%) and 20 F-T cycles. The relationship between rock mechanical properties, bursting liability of rock, and MC after freeze-thaw damage was established, and the control mechanism of moisture content on mechanical properties and rockburst tendency of rocks in cold regions was revealed. Uniaxial compressive test results showed that the UCS of rock decreases significantly with the increase of MC. Under the action of F-T cycles, WET, WCF, and ES decrease with the increase of MC, and BIM of rock increases gradually. This indicates that the rockburst tendency of sandstone decreases with the increase of MC. To calculate WET, WCF, ES, and BIM of sandstone samples, new empirical equations were established and put forward under different MC after 20 F-T cycles.

scholarly journals Properties of High-Strength Flowable Mortar Reinforced with Palm Fibers

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Eethar Thanon Dawood ◽  
Mahyuddin Ramli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Test Results ◽  
Palm Fiber ◽  
Toughness Index ◽  
Strength And Toughness

This study was conducted to determine some physical and mechanical properties of high-strength flowable mortar reinforced with different percentages of palm fiber (0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6% as volumetric fractions). The density, compressive strength, flexural strength, and toughness index were tested to determine the mechanical properties of this mortar. Test results illustrate that the inclusion of this fiber reduces the density of mortar. The use of 0.6% of palm fiber increases the compressive strength and flexural strength by about 15.1%, and 16%, respectively; besides, the toughness index (I5) of the high-strength flowable mortar has been significantly enhanced by the use of 1% and more of palm fiber.

Size Effect on Mechanical Properties of LVL

2014 ◽  
Vol 887-888 ◽  
pp. 824-829
Author(s):  
Qing Fang Lv ◽  
Ji Hong Qin ◽  
Ran Zhu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Size Effect ◽  
Tensile Test ◽  
Compression Test ◽  
Test Results ◽  
Laminated Veneer Lumber ◽  
Object Of Study ◽  
The Relationship

Laminated veneer lumber is taken as an object of study, and use LVL specimens of different sizes for compression test and tensile test. The goal of the experiment is to investigate the size effect on compressive strength and tensile strength as well as the influence of the secondary glued laminated face, which appears in the secondary molding processes. The results show that both compressive strength and tensile strength have the size effect apparently and the existence of the secondary glued laminated face lower the compressive strength of LVL specimens. Afterwards, the relationship between compressive strength and volume along with tensile strength and area are obtained by the test results.

Deterioration of Mechanical Properties of High-Strength Pumpcrete after Exposure to High Temperatures

2010 ◽  
Vol 168-170 ◽  
pp. 564-569
Author(s):  
Guang Lin Yuan ◽  
Jing Wei Zhang ◽  
Jian Wen Chen ◽  
Dan Yu Zhu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Heating Rate ◽  
High Strength Concrete ◽  
Heating Temperature ◽  
High Strength ◽  
Air Cooling ◽  
Test Results ◽  
Strength Deterioration ◽  
Residual Compressive Strength

This paper makes an experimental study of mechanical properties of high-strength pumpcrete under fire, and the effects of heating rate, heating temperature and cooling mode on the residual compressive strength(RCS) of high-strength pumpcrete are investigated. The results show that under air cooling, the strength deterioration speed of high-strength concrete after high temperature increases with the increase of concrete strength grade. Also, the higher heating temperature is, the lower residual compressive strength value is. At the same heating rate (10°C/min), the residual compressive strength of C45 concrete after water cooling is a little higher than that after air cooling; but the test results are just the opposite for C55 and C65 concrete. The strength deterioration speed of high-strength concrete after high temperature increases with the increase of heating rate, but not in proportion. And when the heating temperature rises up between 200°C and 500°C, heating rate has the most remarkable effect on the residual compressive strength of concrete. These test results provide scientific proofs for further evaluation and analysis of mechanical properties of reinforced-concrete after exposure to high temperatures.

Effect of Surface Penetrating Sealer on the Microstructure Properties of Cement-Based Composites

2013 ◽  
Vol 651 ◽  
pp. 245-250
Author(s):  
Tasi Lung Weng ◽  
Wei Ting Lin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Concrete Durability ◽  
Test Results ◽  
Chloride Permeability ◽  
Durability Test ◽  
Chloride Resistance ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Effect Of Surface

The effect of penetrating sealer on the structure of surface pore, mechanical properties, and durability of cement-based composites was studied. Concrete specimens with various water/cement ratios (w/c=0.35, 0.45, 0.55) were cast and treated surfaced with various amounts of penetrating sealer at different ages. The effect of penetrating sealer on the mechanical properties of concrete was assessed by compressive strength. And, the rapid chloride permeability was also explored to test concrete durability. Test results indicate that the application of penetrating sealer significantly improves concrete compressive strength and chloride resistance. By using scanning electron microscopes observation, the penetrating depth of penetrating sealer can be determined and is about 2 cm. The penetrating sealer in this study may be categorized as deep penetrating sealer.

scholarly journals Mechanical Properties and Microstructural Features using Stone Dust as a Partial Replacement of Sand

2019 ◽  
Vol 8 (6) ◽  
pp. 5232-5237
Keyword(s):  
Mechanical Properties ◽  
Economic Growth ◽  
Sustainable Development ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Natural Resources ◽  
Strength Test ◽  
Partial Replacement ◽  
Test Results ◽  
Stone Dust

Today’s world is always leads to development in technology as well as the economic growth though sometime these will affect the environment badly. That’s why world environmental commission coined the termed called sustainable development where development takes place without hampering the others’ needs. Concrete industry is rapidly growing industry in India which consumes lots of natural resources during the production of concrete. Here Stone dust is used as a sustainable material in place of sand partially. M25 grade of concrete has been chosen for the experiments. Different mechanical properties of concrete like compressive strength, Split tensile, flexural strength etc. and Microstructural features like SEM, EDX have been included in this study. Compressive Strength and flexural strength test results shown the increase in the strength. Sulphate Resistance Properties have been tested by curing the cubes in the MgSO4 solution and increase in weight has been observed. Similarities are found in the SEM pictures

scholarly journals Characterization and Performance of Mechanical Properties of GGBS Based Geo Polymer Mortars

2019 ◽  
Vol 8 (4) ◽  
pp. 8336-8342
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Construction Industry ◽  
Research Paper ◽  
Setting Times ◽  
And Performance ◽  
Creep And Shrinkage

From decades it has been recognized that Geopolymer will considerably replace the role of cement in the construction industry. In general, Geopolymer exhibits the property of the peak compressive strength, minimal creep and shrinkage. In this current research paper, Geopolymer mortar is prepared by using GGBS and Fly ash. The mix proportions are of (100-60)%GGBS with Fly ash by 10% replacement. The alkali activators Na0H and Na2Sio3 are used in the study for two different molarities of 4&8. The ratio to Sodium silicates to sodium hydroxide is maintained from 1.5, 2, 2.5 & 3 were used. Mortars are prepared and studied the effect of molarities of alkali activators in their setting times and strengths

scholarly journals Research on the Dynamic Mechanical Properties and Energy Dissipation of Expansive Soil Stabilized by Fly Ash and Lime

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Sheng-quan Zhou ◽  
Da-wei Zhou ◽  
Yong-fei Zhang ◽  
Wei-jian Wang ◽  
Dongwei Li
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Expansive Soil ◽  
Dynamic Mechanical Properties ◽  
Test Results ◽  
Absorbed Energy ◽  
Dynamic Mechanical ◽  
Stabilized Soil ◽  
Dynamic Compressive Strength

To probe into the dynamic mechanical properties of expansive soil stabilized by fly ash and lime under impact load, the split-Hopkinson pressure bar (SHPB) test was carried out in this study. An analysis was made on the dynamic mechanical property and final fracture morphology of stabilized soil, and the failure mechanism was also explored from the perspective of energy dissipation. According to the test results, under the impact pressure of 0.2 MPa, plain soil and pure fly ash-stabilized soil exhibit strong plasticity. After the addition of lime, the stabilized soil shows obvious brittle failure. The dynamic compressive strength and absorbed energy of stabilized soil first increase and then decrease with the change of mix proportions. Both the dynamic compressive strength and the absorbed energy reach the peak value at the content of 20% fly ash and 5% lime (20% F + 5% L). In the process of the test, most of the incident energy is reflected back to the incident bar. The absorbed energy of stabilized soil increases linearly with the rise of dynamic compressive strength, while the absorbed energy is negatively correlated with the fractal dimension. The fractal dimension of pore morphology of the plain soil is lower than that of the fly ash-lime combined stabilized soil when it comes to the two different magnification ratios. The test results indicate that the modifier content of 20% F + 5% L can significantly improve the dynamic mechanical properties of the expansive soil.

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