scholarly journals Research on Preparation and Performance of Clay-Based Shield Tunnel Nonsintered Bricks

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Sibin Chen ◽  
Hao Jiang ◽  
Huitang Xing ◽  
Jing Wang ◽  
Yongliang Huang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Polyvinyl Alcohol ◽  
Mass Loss Rate ◽  
Rapid Development ◽  
Research Direction ◽  
Shield Tunnel ◽  
Doping Amount ◽  
Underground Engineering ◽  
Engineering Construction

With the rapid development of rail transit in China, the number and scale of underground engineering construction have increased significantly, and a large amount of shield muck has been generated, which has brought great challenges to the urban environment. The reuse of shield muck has become an important research direction in underground engineering construction. In this paper, a nonsintered brick is prepared with shield muck soil as the matrix. The influence of different doping amounts of lime, fly ash, cement, and polyvinyl alcohol on porosity, density, water absorption, saturation coefficient, compressive strength, and other properties was explored to realize the resource utilization of shield dregs and at the same time obtain excellent performance nonsintered bricks. Through research, it is found that when the lime doping amount is 10% and the cement doping amount is 5%, with the increase of the fly ash doping amount, the overall compressive strength increases significantly, and the maximum compressive strength can reach 13.69 MPa. Although the doping of trace amounts of polyvinyl alcohol reduces the compressive strength, it can significantly reduce the compressive strength and mass loss rate after 15 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 Technical Development and Safety Risk Analysis of Urban Underground Engineering

2018 ◽  
Vol 1 (4) ◽  
pp. 108
Author(s):  
Zhiqiang Ye
Keyword(s):  
Rapid Development ◽  
Rapid Expansion ◽  
Underground Engineering ◽  
Engineering Construction ◽  
Construction Methods ◽  
Safety Risks ◽  
Construction Techniques ◽  
Development And Utilization ◽  
Deep Underground ◽  
Effective Development

With the rapid development of China's urban construction, the acceleration of urbanization and the rapid expansion of population, the effective development and utilization of urban underground space have attracted great attention. Therefore, it is inevitable to study the comprehensive technology of deep underground engineering, and the research results will play an important guiding role in the design and construction of middle and shallow space of underground engineering in the future. This paper analyzes several common construction techniques and methods in the current construction process of urban underground engineering, summarizes the main construction methods of underground engineering, forecasts the development of urban underground engineering construction, and analyzes the safety risks of urban underground engineering construction.

scholarly journals A study based upon the effect of polyvinyl alcohol fiber, iron slag and fly ash over the strength aspects of geo-polymer concrete

2021 ◽  
Vol 889 (1) ◽  
pp. 012051
Author(s):  
farhan Maqbool ◽  
Jagdish Chand
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Polyvinyl Alcohol ◽  
Room Temperature ◽  
Research Work ◽  
Polymer Concrete ◽  
Result Section ◽  
Polyvinyl Alcohol Fiber ◽  
Iron Slag

Abstract In this research work fly ash, iron slag and polyvinyl alcohol fiber was utilized to enhance the strength parameters of the concrete. Fly ash and iron slag were used as replacement of the cement and polyvinyl alcohol fiber was used as an additive at 0 %, 2 %, 3 % and 4 %. After this several samples were casted and then verified for numerous test. Compressive strength test was executed and it finds out that concrete containing Polyvinyl Alcohol fibers (with different curing methods) was showing increasing strength as compared to concrete deprived of Fiber. Specimens of oven cured samples shown a large increase in strength as compared to room temperature curing as shown in the result section. Compressive strength increases up to three percent of adding Polyvinyl Alcohol fiber after that strength decreasing. Flexure strength was carried on the Geo-Polymer concrete with different curing techniques and result show’s an impressive increase in flexural strength, but room temperature cured specimens show lesser growth as compared oven cured specimens. But not lower than concrete which didn’t have Polyvinyl Alcohol fiber in it. Flexural strength increases up to three percent of adding Polyvinyl Alcohol fiber in both the curing techniques and decreases at four percent as shown in the result section. Split tensile test was also carried out for both the curing techniques oven curing and room temperature curing. The samples which were cured in oven curing show impressive growth in strength. Maximum split tensile strength attained at three percent of adding Polyvinyl Alcohol fiber. With the help of UPV, it was found that the concrete that makes with the help of a Polyvinyl Alcohol Fiber is of good quality as shown in results.

scholarly journals Experimental Investigation of Mechanical Behavior of Sandstone with Different Moisture Contents Using the Acoustic Emission Technique

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chuanming Li ◽  
Nan Liu ◽  
Wanrong Liu
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Moisture Content ◽  
Physicomechanical Properties ◽  
Underground Engineering ◽  
Softening Effect ◽  
Engineering Construction ◽  
Rock Samples ◽  
Saturated Rock ◽  
Water Saturated

The moisture content is a critical factor tightly related to rock deformation and its failure process since it leads to a significant change in the physicomechanical properties of rock during the underground engineering construction. As a result, engineering construction accidents take place frequently. To figure out the influence of the moisture content on the physicomechanical properties of water-bearing rock and then effectively avoid engineering accidents, multiple tests including the uniaxial compression test, Brazilian splitting test, and the acoustic emission (AE) test were carried out in this study. The experimental results showed that the water absorption rate of the sandstone gradually stabilizes after 5 h, and its uniaxial compressive strength, tensile strength, and elastic modulus all decline with the increase of the moisture content. Compared to the dry state of the sample, the reduction amplitudes of the elastic modulus, compressive strength, and tensile strength of water-saturated rock samples can reach up to 27.3%, 35.2%, and 38.1%, respectively. It indicates that the tensile strength is more sensitive to the softening effect of the moisture. Through the AE test, it can be found that the internal state of water-saturated rock samples is greatly changed; the compressive strength of rock samples drops, so the rock can be damaged after absorbing less energy. Thus, moisture shows a certain softening effect on rock. The research results are expected to provide a basis for underground engineering construction and rock fracture and failure.

COMPRESSIVE STRENGTH AND THERMAL CONDUCTIVITY OF WATER AND AIR CURED PORTLAND CEMENT-FLY ASH-SILICA FUME MORTARS

2018 ◽  
Vol 17 (9) ◽  
pp. 2023-2030
Author(s):  
Arnon Chaipanich ◽  
Chalermphan Narattha ◽  
Watcharapong Wongkeo ◽  
Pailyn Thongsanitgarn
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Silica Fume

COMPRESSIVE STRENGTH ANALYSIS ON PROBLEMATIC SOILS STABILIZED WITH FLY ASH IN JORDAN

2018 ◽  
Vol 17 (8) ◽  
pp. 1855-1861
Author(s):  
Nicolae Taranu ◽  
Monther Abdelhadi ◽  
Ancuta Rotaru ◽  
Maria Gavrilescu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Strength Analysis ◽  
Problematic Soils

The Effect of Dry Mix Sodium Hydroxide onto Workability and Compressive Strength of Geopolymer Paste

2020 ◽  
Vol 12 (9) ◽  
Author(s):  
A. Z. Mohd Ali ◽  
◽  
N. A. Jalaluddin ◽  
N. Zulkiflee ◽  
◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
High Emission ◽  
New Material ◽  
Curing Regime ◽  
Solid Form ◽  
Geopolymer Paste

The production of ordinary Portland cement (OPC) consumes considerable amount of natural resources, energy and at the same time contribute in high emission of CO2 to the atmosphere. A new material replacing cement as binder called geopolymer is alkali-activated concrete which are made from fly ash, sodium silicate and sodium hydroxide (NaOH). The alkaline solution mixed with fly ash producing alternative binder to OPC binder in concrete named geopolymer paste. In the process, NaOH was fully dissolved in water and cooled to room temperature. This study aims to eliminate this process by using NaOH in solid form together with fly ash before sodium silicate liquid and water poured into the mixture. The amount of NaOH solids were based on 10M concentration. The workability test is in accordance to ASTM C230. Fifty cubic mm of the geopolymer paste were prepared which consists of fly ash to alkaline solution ratio of 1: 0.5 and the curing regime of 80℃ for 24 hours with 100% humidity were implemented. From laboratory test, the workability of dry method geopolymer paste were decreased. The compressive strength of the dry mix of NaOH showed 55% and the workability has dropped to 58.4%, it showed strength reduction compared to the wet mix method.

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.

Investigation on a New Hydraulic Cementitious Binder Made from Phosphogypsum

2013 ◽  
Vol 864-867 ◽  
pp. 1923-1928
Author(s):  
Yue Xu ◽  
Jian Xi Li ◽  
Li Li Kan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Active Carbon ◽  
High Strength ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Cementitious Material ◽  
Saturation Ratio ◽  
Tricalcium Aluminate ◽  
Cementitious Binder

A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

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