scholarly journals Test Study on Strength and Permeability Properties of Lime-Fly Ash Loess under Freeze-Thaw Cycles

2014 ◽  
Vol 8 (1) ◽  
pp. 172-176
Author(s):  
Zhiquan Zhang ◽  
Yufen Zhang
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Fly Ash ◽  
Water Stability ◽  
Direct Shear ◽  
Compressive Test ◽  
Freeze Thaw ◽  
Coefficient Of Permeability ◽  
Test Study ◽  
Uniaxial Compressive Test

In order to study the application of lime-fly ash loess in permafrost subgrade engineering, uniaxial compressive test, fast direct shearing test and permeability tests were carried out on lime-fly ash loess under different curing ages and freeze-thaw cycles. Uniaxial compressive strength of lime-fly ash loess increases slowly with the curing ages, and can reach 3.5 Mpa after the curing ages of 90 days (This strength is called 90d strength). 14d strength of lime-fly ash loess has already reached 50% of 90d strength; later strength including 28d strength and 90d strength is basically stable under different freeze-thaw cycles, so lime-fly ash loess has good water stability and freeze-thaw stability. Fast direct shear strength decreases with the number of freeze-thaw cycles without consideration of moisture content; the coefficient of permeability increases with the number of freeze-thaw cycles．All test data show that lime-fly ash loess with good behaviors can be applied in permafrost subgrade engineering.

scholarly journals Strength Time–Varying and Freeze–Thaw Durability of Sustainable Pervious Concrete Pavement Material Containing Waste Fly Ash

2018 ◽  
Vol 11 (1) ◽  
pp. 176 ◽  
Author(s):  
Hanbing Liu ◽  
Guobao Luo ◽  
Longhui Wang ◽  
Yafeng Gong
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Pervious Concrete ◽  
Early Age ◽  
Pavement Materials ◽  
Freeze Thaw ◽  
Replacement Method ◽  
Porosity And Permeability ◽  
Volume Method

Pervious concretes, as sustainable pavement materials, have great advantages in addressing a number of environmental issues. Fly ash, as the industrial by-product waste, is the most commonly used as cement substitute in concrete. The objective of this paper is to study the effects of waste fly ash on properties of pervious concrete. Fly ash was used to replace cement with equivalent volume method at different levels (3%, 6%, 9%, and 12%). The control pervious concrete and fly ash modified pervious concrete were prepared in the laboratory. The porosity, permeability, compressive strength, flexural strength, and freeze–thaw resistance of all mixtures were tested. The results indicated that the addition of fly ash decreased the early-age (28 d) compressive strength and flexural strength, but the long-term (150 d) compressive strength and flexural strength of fly ash modified pervious concrete were higher than that of the early-age. The adverse effect of fly ash on freeze–thaw resistance of pervious concrete was observed when the fly ash was added. The porosity and permeability of all pervious concrete mixtures changed little with the content of fly ash due to the use of equal volume replacement method. Although fly ash is not positive to the properties of pervious concrete, it is still feasible to apply fly ash as a substitute for cement in pervious concrete.

scholarly journals Strength Tests and Numerical Simulations of Loess Modified by Desulfurization Ash and Fly Ash

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 512
Author(s):  
Zhi Cheng ◽  
Xinrong Cheng ◽  
Yuchao Xie ◽  
Zhe Ma ◽  
Yuhao Liu
Keyword(s):  
Shear Strength ◽  
Fly Ash ◽  
Power Plants ◽  
Utilization Rate ◽  
Direct Shear ◽  
Test Results ◽  
Mass Ratio ◽  
Direct Shear Tests ◽  
Strength Tests ◽  
Actual Test

Desulfurization ash and fly ash are solid wastes discharged from boilers of power plants. Their utilization rate is low, especially desulfurization ash, most of which is stored. In order to realize their resource utilization, they are used to modify loess in this paper. Nine group compaction tests and 32 group direct shear tests are done in order to explore the influence law of desulfurization ash and fly ash on the strength of the loess. Meanwhile, FLAC3D software is used to numerically simulate the direct shear test, and the simulation results and the test results are compared and analyzed. The results show that, with the increase of desulfurization ash’s amount, the shear strength of the modified loess increases first and then decreases. The loess modified by the fly ash has the same law with that of the desulfurization ash. The best mass ratio of modified loess is 80:20. When the mass ratio is 80:20, the shear strength of loess modified by the desulfurization ash is 12.74% higher than that of the pure loess on average and the shear strength of loess modified by fly ash is 3.59% higher than that of the pure loess on average. The effect of the desulfurization ash on modifying the loess is better than that of the fly ash. When the mass ratio is 80:20, the shear strength of loess modified by the desulfurization ash is 9.15% higher than that of the fly ash on average. Comparing the results of the simulation calculation with the actual test results, the increase rate of the shear stress of the FLAC3D simulation is larger than that of the actual test, and the simulated shear strength is about 8.21% higher than the test shear strength.

scholarly journals Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1251
Author(s):  
Tao Luo ◽  
Chi Zhang ◽  
Xiangtian Xu ◽  
Yanjun Shen ◽  
Hailiang Jia ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Concrete Structures ◽  
Freezing Temperature ◽  
Frost Damage ◽  
Freezing And Thawing ◽  
Shear Properties ◽  
Freeze Thaw ◽  
Steel Bar ◽  
Concrete Interface

Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze–thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze–thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze–thaw cycles.

Study on the antiseepage mechanism of the PBFC slurry for landfill site

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744087 ◽  
Author(s):  
Guozhong Dai ◽  
Weicheng Shi ◽  
Xiaoshu Jiang ◽  
Guicai Shi ◽  
Yaxing Zhang
Keyword(s):  
Heavy Metal ◽  
Compressive Strength ◽  
Fly Ash ◽  
Polyvinyl Alcohol ◽  
Metal Ions ◽  
Sodium Carbonate ◽  
Heavy Metal Ions ◽  
Landfill Site ◽  
Low Permeability ◽  
Coefficient Of Permeability

In order to develop a kind of slurry with low permeability which has some adsorption and retardation to the pollutants in leachate to be used in antiseepage engineering of leachate for landfill site, experiments based on orthogonal method were performed. The optimal PBFC slurry was selected: bentonite 18–26%, cement 16–24%, fly ash 18–20%, TOJ800-10 water reducing agent 0.01–0.03%, polyvinyl alcohol 0.2–0.8%, sodium carbonate 0.8–1.5% and water 680–780/1000 mL seriflus. The material has good groutability and a concretion stone ratio which is greater than 99.6%. The coefficient of permeability of 28-day concretion body is 0.53 × 10[Formula: see text]–1.86 × 10[Formula: see text] cm/s and the compressive strength is 0.64–1.04 MPa. The slurry has good adsorption and retardation properties. The block rate of NH4-N and phosphorus reached 98.28%, and the block rate of CODCr and BOD5 reached 85.67%. The block rate of Hg, Pb and other heavy metal ions reached 99.8%. The PBFC slurry improved the retardation capability of the pollutants of the leachate at the landfill site by its infiltration sedimentation and adsorption fixation.

scholarly journals Recycling of Oily Sludge as a Roadbed Material Utilizing Phosphogypsum-Based Cementitious Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Wei Xiao ◽  
Xiao Yao ◽  
Fuyang Zhang
Keyword(s):  
Heavy Metals ◽  
Compressive Strength ◽  
Pore Structure ◽  
Cementitious Materials ◽  
Solid Particles ◽  
Oily Sludge ◽  
Water Stability ◽  
Volume Stability ◽  
Freeze Thaw ◽  
Stability Performance

Oily sludge is a hazardous waste containing emulsified petroleum hydrocarbons, water, heavy metals, and solid particles. The objective of this work is to employ solidification/stabilization (S/S) techniques to utilize oily sludge as a roadbed material with ordinary Portland cement (OPC), fly ash (FA), and silica fume (SF) as binders and phosphogypsum (PG) as a stabilizer. The efficacy of the S/S process is assessed mainly through an unconfined compressive strength (UCS) test and a toxicity leaching test. Road performance, including water stability, freeze-thaw resistance, and volume stability, is also tested on the solidified samples. The mineralogical compositions, microstructures, and pore structure are characterized through X-ray diffractometry (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results show that the addition of 20% binders (OPC : FA : SF = 1 : 0.7 : 0.8) in combination with phosphogypsum to the oily sludge not only increases the 28-day compressive strength of the solidified samples and remarkably decreases the release of heavy metals but also refines the pore structure and compacts the microstructure. The solidified body had sufficient strength and good water stability performance, freeze-thaw resistance, and volumetric stability. This solidification/stabilization (S/S) process, which combines oily sludge treatment and phosphogypsum resource utilization, significantly enhances environmental protection and renders the solidified product economically profitable.

The effects of marble dust and fly ash on clay soil

2014 ◽  
Vol 21 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Ismail Zorluer ◽  
Suleyman Gucek
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Soil Stabilization ◽  
Clay Soil ◽  
Waste Materials ◽  
Curing Time ◽  
Freeze Thaw ◽  
Marble Dust ◽  
Increased Strength

AbstractThe use of waste materials as an additive in soil stabilization has been widespread. This is important in terms of recycling of waste materials and reducing environmental pollution. The objective of this study is to investigate the beneficial reuse of marble dust and fly ash in soil stabilization. Tests were performed on clay soil mixtures amended with marble dust and fly ash. Marble dust was used as an activator due to fly ash being inadequate for self-cementing. Unconfined compressive strength (qu), freeze-thaw, swelling, and California bearing ratio (CBR) tests were conducted to investigate the effect of marble dust and fly ash, curing time, and molding water content on geotechnical parameters. Addition of marble dust and fly ash increased unconfined compressive strength, CBR, and freeze-thaw strength, but these additives decreased swelling potential and grain loss after freeze-thaw. Increasing the curing time results in increased strength of mixtures and decreased grain loss. As a result, this study shows that the geotechnical properties of clay soil are improved with the addition of marble dust and fly ash. This is an economical and environmentally friendly solution.

scholarly journals Physical and Mechanical Characteristics of Shallow Expansive Soil due to Freeze-Thaw Effect with Water Supplement

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yanlong Li ◽  
Zili Wang ◽  
Yang Luo
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Expansive Soil ◽  
Freezing Temperature ◽  
Strength Reduction ◽  
Dry Density ◽  
Direct Shear ◽  
Soil Columns ◽  
Freeze Thaw ◽  
Shear Strength Reduction

Shear strength of shallow expansive soil varies along with the depth under the freeze-thaw effect. This work investigates shear strength characteristics of shallow expansive soil by simulating the actual freeze boundary conditions of seasonal frozen areas with water supplement. An integrated approach incorporating the freeze-thaw test and direct shear test was adopted. Firstly, unidirectional freezing tests for expansive soil columns under three different freezing temperature gradients were carried out. Secondly, direct shear tests under low vertical stress were performed on the standard samples, which were prepared by using cutting rings cut the thawed expansive soil columns into nine segments along with the depth. Temperature, water content, and dry density at different depths were also investigated after the freeze-thaw process. The test results showed that, after the freeze-thaw process, the shear strength of expansive soil columns showed significant differences along with the depth and highly correlated with water content, specifically the higher water content and the lower shear strength. The minimum shear strength in the expansive soil columns occurred at the soil layer below the frozen and unfrozen zones interface. The expansive soil column’s shear strength changed most under the moderate freezing temperature gradient corresponding to the most considerable shear strength reduction. Moreover, the significant decrease in cohesion was the main reason for the shear strength reduction of expansive soil after the freeze-thaw process. These results indicate significant depth variability in shear strength of expansive soil under the freeze-thaw effect.

scholarly journals The Synergy between Bio-Aggregates and Industrial Waste in a Sustainable Cement Based Composite

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6158
Author(s):  
Cătălina Mihaela Grădinaru ◽  
Adrian Alexandru Șerbănoiu ◽  
Radu Muntean ◽  
Bogdan Vasile Șerbănoiu
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Splitting Tensile Strength ◽  
Partial Replacement ◽  
Cement Matrix ◽  
Freeze Thaw ◽  
Corn Cobs ◽  
Study Results ◽  
Sunflower Stalks

The effects of the fly ash and of the sunflower stalks and corn cobs within a cement-matrix composite were studied under the aspects of density, compressive strength, splitting tensile strength, elasticity modulus, and resistance to repeated freeze-thaw cycles. In the research were developed 20 recipes of cement-based composite, including the reference composite. Fly ash was used as partial cement replacement (10, 20 and 30% by volume), and the vegetal aggregates made by corn cobs and sunflower stalks as partial replacement of the mineral aggregates (25 and 50% by volume). The study results revealed that a lightweight composite can be obtained with 50% of vegetal aggregates, and the fly ash, no matter its percentage, enhanced the compressive strength and splitting tensile strength of the compositions with 50% of sunflower aggregates and the freeze-thaw resistance of all compositions with sunflower stalks.

Quantitative Analysis of Several Influencing Factors on TBM Advance Speed

2012 ◽  
Vol 594-597 ◽  
pp. 1318-1323
Author(s):  
Chao Li ◽  
Joachim Tiedemann ◽  
Hong Wei Zhou
Keyword(s):  
Compressive Strength ◽  
Quantitative Analysis ◽  
Rock Strength ◽  
Thrust Force ◽  
Compressive Test ◽  
Experiment System ◽  
Uniaxial Compressive Test ◽  
Csm Model ◽  
The Relationship ◽  
Advance Speed

Aiming at the problem of a difference between the TBM advance speed estimated by the NTNU and CSM model, and the actual advance speed, a quantitative analysis is carried out in the paper. Combining the experimental results of the uniaxial compressive test with the rock mechanics experiment system TAW-2000 and MTS815, the paper quantitatively characterizes the main parameters including the rock compressive strength, elastic modulus, abrasiveness, and the thrust force of cutterhead, corresponding to TBM advance speed by using the method of quantitative analysis of multi-factors. Moreover, the relationship between the TBM advance speed and the parameters was established. It is indicated that higher rock strength, abrasion and a smaller thrust force of cutterhead are reasons resulting in a lower TBM advance speed.

Sign in / Sign up

Export Citation Format

Share Document