Slurry Preparation Effects on the Cemented Phosphogypsum Backfill through an Orthogonal Experiment

The cemented phosphogypsum (PG) backfill technique provides a new method for massive consumption of PG, and therefore alleviating the environmental pollution of PG. This study considered the effects of slurry preparation on the performance of cemented PG backfill. A L16(44) orthogonal experiment was designed to analyze four factors, namely the solid content, phosphogypsum-to-binder ratio (PG/B ratio), stirring time and stirring speed, with each factor having four levels. According to the range analysis, the solid content played the dominant role in controlling the bleeding rate, while the setting times strongly depended on the PG/B ratio. In terms of strength development of the backfill, the PG/B ratio was shown to be the most significant factor determining the unconfined compressive strength (UCS), followed by the solid content, stirring time and stirring speed. Furthermore, the results showed that the slurry preparation affected the environmental behavior of impurities that originated in PG. By analyzing the concentrations of impurities in the bleeding water of the slurry as well as the leachates of the tank leaching test, the results showed that the release of F− and SO42− was aggravated clearly with the increase in the PG/B ratio, while the release of PO43− always remained at relatively low levels.

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Structural Optimization Design on the Sunflower Shaped Arch Bridge

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.427-429.90 ◽

2013 ◽

Vol 427-429 ◽

pp. 90-93 ◽

Cited By ~ 1

Author(s):

Wen Qing Wang

Keyword(s):

Optimization Design ◽

Mechanical Response ◽

Mechanical Performance ◽

Orthogonal Experiment ◽

Design Parameters ◽

Analysis Model ◽

Range Analysis ◽

Element Analysis ◽

Arch Bridge ◽

Four Levels

Based on the principle of orthogonal test, the optimization model of sunflower shaped arch bridge scheme was set up. The five key design parameters were selected as the main factors. The four computation index, which reflect mechanical performance, were selected as analytical objects. The 16 orthogonal experiment schemes were arranged with four levels orthogonal table . The curves of the factors to the index were obtained from the mechanical response under dead load and live load through the finite element analysis model. By the range analysis method, the influential levels of the factors to the index were obtained from the result of the test , and the factor optimizatuion level of the factors was determined to further optimize the layout scheme of the sunfloawer shaped arch bridge.

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Workability and Compressive Strength Behavior of a Cemented High-Porosity Backfill Material

Advances in Civil Engineering ◽

10.1155/2021/7526616 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

W. H. Cao ◽

X. F. Wang ◽

D. S. Zhang ◽

X. J. Ji ◽

X. Z. Chen ◽

...

Keyword(s):

Compressive Strength ◽

Silica Fume ◽

Interparticle Distance ◽

Solid Content ◽

Western China ◽

Strength Development ◽

Optimal Dosage ◽

High Porosity ◽

Strength Behavior ◽

Binder Ratio

A full understanding of the workability and unconfined compressive strength (UCS) of the cemented high-porosity (CHPB) material, made of surface sand, widely distributed in the western mining area, foam, and cementing materials, is important for applying in ecologically fragile mining areas of western China. In this article, the influence of solid content, density grade, sand/binder ratio, and silica fume dosage in binder on workability and strength development of CHPB samples in different curing ages is studied. Test results show that the fresh CHPB mix has good workability, due to the existence of a large number of bubbles. With the increase of density grade, the UCS of the CHPB sample increases exponentially. Workability of fresh CHPB samples significantly decreases with increasing solid content due to the reduction of interparticle distance. For a given mix proportion, the optimal solid content of CHPB samples is 83.7%. The variation of the sand/binder ratio from 3 to 4.5 results in a slight increase of workability and a significant increase of the UCS. Silica fume demonstrates improvement on workability and strength behavior, and the optimal dosage in the binder should not exceed 10%.

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Optimization of Preparation of Foamed Concrete Based on Orthogonal Experiment and Range Analysis

Frontiers in Materials ◽

10.3389/fmats.2021.778173 ◽

2021 ◽

Vol 8 ◽

Author(s):

Menglong Cong ◽

Shanshan Zhang ◽

Dandan Sun ◽

Kunpeng Zhou

Keyword(s):

Thermal Conductivity ◽

Water Glass ◽

Orthogonal Experiment ◽

Glass Content ◽

Range Analysis ◽

Geopolymer Matrix ◽

Binder Ratio ◽

Concrete Blocks ◽

Foamed Concrete ◽

Water Binder Ratio

For the purpose of reducing the energy consumption and construction cost of buildings, the preparation process of geopolymer based foamed concrete, which is a novel material of the wall and roof of building, had been studied in detail. Water glass and sodium hydroxide were used as the alkali activator to excite the mixture consists of slag, fly ash and Kaolin to form the geopolymer matrix, and finally the foams generated using the physical foaming method were filled into the geopolymer matrix to produce geopolymer-based foamed concrete blocks. In the preparation process, firstly one of the four parameters of foam content, water-binder ratio, water glass content, and water glass modulus had been changed separately to study the influence of a single factor on the compressive strength, dry density, thermal conductivity and specific strength of foamed concrete blocks. The experimental results show that the above four factors have different degrees of influence on the concerned performances. Next, some representative combinations of these factors were constructed by orthogonal experiment method, and the influence degree of each combination on the concerned performances was determined by means of range analysis. According to the results of analysis, the most important influencing factor in terms of thermal conductivity was the water-binder ratio, followed by foam content, water glass modulus and water glass content. When the foam content is 1.58%, the water-binder ratio is 0.45, the water glass content is 30%, and the water glass modulus is 1.2, the thermal conductivity of the prepared geopolymer foam concrete reaches 0.044 W/(m·K), which satisfies the expected requirements for heating in severe cold areas.

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Multi-Objective Optimization Design and Test of Compound Diatomite and Basalt Fiber Asphalt Mixture

Materials ◽

10.3390/ma12091461 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1461 ◽

Cited By ~ 10

Author(s):

Yongchun Cheng ◽

Liding Li ◽

Peilei Zhou ◽

Yuwei Zhang ◽

Hanbing Liu

Keyword(s):

Optimization Design ◽

Orthogonal Experiment ◽

Asphalt Mixture ◽

Basalt Fiber ◽

Asphalt Mixtures ◽

Orthogonal Experimental Design ◽

Basalt Fibers ◽

Contributing Factors ◽

Range Analysis ◽

Four Levels

This study focuses on improving the performance of asphalt mixture at low- and high- temperature and analyzing the effect of diatomite and basalt fiber on the performance of the asphalt mixture. Based on the L16(45) orthogonal experimental design (OED), the content of diatomite (D) and basalt fiber (B) and the asphalt-aggregate (A) ratio were selected as contributing factors, and each contributing factor corresponded to four levels. Bulk volume density (γf), volume of air voids (VV), voids filled with asphalt (VFA), Marshall stability (MS) and splitting strength at −10 °C (Sb) were taken as the evaluation indexes. According to the results of the orthogonal experiment, the range analysis and variance analysis were used to study the effect of the diatomite content, basalt fiber content and asphalt-aggregate ratio on the performance of the asphalt mixture, and the grey correlation grade analysis (GCGA) was used to obtain the optimal mixing scheme. Furthermore, the performance tests were conducted to evaluate the performance improvement of asphalt mixtures with diatomite and basalt fibers, and the scanning electron microscopy (SEM) tests were carried out to analyze the mechanism of diatomite and basalt fibers in asphalt mixtures. The results revealed that the addition of diatomite and basalt fiber can significantly increase the VV of asphalt mixture, and reduce γf and VFA; the optimal performance of the asphalt mixture at high- and low-temperature are achieved with 14% diatomite, 0.32% basalt fibers and 5.45% asphalt-aggregate ratio. Moreover, the porous structure of diatomite and the overlapping network of basalt fibers are the main reasons for improving the performance of asphalt mixture.

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Long-Term Strength Evolution in Ambient-Cured Solid-Activator Geopolymer Compositions

Minerals ◽

10.3390/min11020143 ◽

2021 ◽

Vol 11 (2) ◽

pp. 143

Author(s):

Vincent Wong ◽

William Jervis ◽

Benjamin Fishburn ◽

Takafumi Numata ◽

William Joe ◽

...

Keyword(s):

Early Stage ◽

Sodium Metasilicate ◽

High Energy ◽

Strength Development ◽

Gel Formation ◽

Factors Affecting ◽

Setting Times ◽

Binder Ratio ◽

Alkaline Activator ◽

Aluminium Silicate

The major downsides of cement manufacturing are the high CO2 emissions and high energy usage. Geopolymers, which are fabricated by activation of blends of fly ash (FA) and ground granulated blast furnace slag (GGBFS) using an alkaline activator, offer a promising solution to this issue. However, to enhance the replacement of cement in construction applications, geopolymer compositions have to be designed such that they can be activated on site by just adding water, similar to how cements are used. Therefore, the present work uses solid sodium metasilicate (MS, Na2SiO3) as the alkaline activator in order to design an add-water-style FA/GGBFS-based geopolymer composition. These compositions were designed by optimising the binder (FA/GGBFS) ratio, Na2SiO3/binder ratio, and water/binder ratio individually to assess the effects of these parameters on the setting times and mechanical (flexural and compressive) strengths over extended curing times (three months). The major factors affecting the strength development and setting times (initial and final) were the amounts of GGBFS and Na2SiO3, with the former demonstrating the more dominant effect. The consistent strength development with curing time was attributed to calcium aluminium silicate hydrate (CASH) gel formation in the early curing times which was affected by the slag addition levels, and sodium aluminium silicate hydrate (NASH) gel formation at later curing times which was influenced by the metasilicate addition levels. The metasilicate amounts were observed to impact on CASH gel formation in early stage curing. Geopolymer compositions with FA/GGBFS ratio of 35/65 and MS/water ratios of 0.2 showed high compressive strengths of ~70 MPa at 28 days, which are superior to values seen in conventional ordinary Portland cement (OPC) mixes for the same curing times.

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Screening and Optimization of Demulsifiers and Flocculants Based on ASP Flooding-Produced Water

Processes ◽

10.3390/pr7040239 ◽

2019 ◽

Vol 7 (4) ◽

pp. 239 ◽

Cited By ~ 4

Author(s):

Bin Huang ◽

Jie Wang ◽

Wei Zhang ◽

Cheng Fu ◽

Ying Wang ◽

...

Keyword(s):

Produced Water ◽

Orthogonal Experiment ◽

Low Cost ◽

Optimization Method ◽

Range Analysis ◽

Asp Flooding ◽

Treatment Conditions ◽

Five Factors ◽

Stirring Time ◽

Oil Concentration

The water produced by alkaline–surfactant–polymer (ASP) flooding is difficult to treat due to the presence of residual chemicals. Therefore, research and development of efficient and low-cost methods for the treatment of ASP flooding produced water is necessary. Chemical destabilization is the most common and effective way to treat the produced water. This paper describes an optimization method for demulsification and flocculation. Some demulsifiers and flocculants commonly used in oilfields were screened, compounded, and optimized. Since the effect of treatment using only demulsifier or flocculant to treat the produced water is often not enough to meet the reinjection standard, an orthogonal experiment was carried out to study the demulsification–flocculation method to treat produced water. Five main influencing factors of the oil concentration were investigated. Based on the results of the range analysis and the relationship between the five factors and oil concentration, the order of significant factors was found to be demulsifier dosage > flocculant dosage > settling time > stirring time > stirring intensity, and the optimal demulsification–flocculation treatment conditions were successfully optimized.

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Control of the setting reaction and strength development of slag-blended volcanic ash-based phosphate geopolymer with the addition of boric acid

Journal of the Australian Ceramic Society ◽

10.1007/s41779-021-00610-4 ◽

2021 ◽

Author(s):

Jean Noël Yankwa Djobo ◽

Dietmar Stephan

Keyword(s):

Blast Furnace ◽

Boric Acid ◽

Blast Furnace Slag ◽

Volcanic Ash ◽

Strength Development ◽

Main Process ◽

Reaction Products ◽

Setting Times ◽

Granulated Blast Furnace Slag ◽

Furnace Slag

AbstractThis work aimed to evaluate the role of the addition of blast furnace slag for the formation of reaction products and the strength development of volcanic ash-based phosphate geopolymer. Volcanic ash was replaced by 4 and 6 wt% of ground granulated blast furnace slag to accelerate the reaction kinetics. Then, the influence of boric acid for controlling the setting and kinetics reactions was also evaluated. The results demonstrated that the competition between the dissolution of boric acid and volcanic ash-slag particles is the main process controlling the setting and kinetics reaction. The addition of slag has significantly accelerated the initial and final setting times, whereas the addition of boric acid was beneficial for delaying the setting times. Consequently, it also enhanced the flowability of the paste. The compressive strength increased significantly with the addition of slag, and the optimum replaced rate was 4 wt% which resulted in 28 d strength of 27 MPa. Beyond that percentage, the strength was reduced because of the flash setting of the binder which does not allow a subsequent dissolution of the particles and their precipitation. The binders formed with the addition of slag and/or boric acid are beneficial for the improvement of the water stability of the volcanic ash-based phosphate geopolymer.

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Fabrication of highly stable and durable furfurylated wood materials. Part I: process optimization

Holzforschung ◽

10.1515/hf-2019-0286 ◽

2020 ◽

Vol 74 (12) ◽

pp. 1135-1146

Author(s):

Wanju Li ◽

Minghui Liu ◽

Hankun Wang ◽

Yan Yu

Keyword(s):

Orthogonal Experiment ◽

Weight Percent Gain ◽

Weight Percent ◽

Chinese Fir ◽

Curing Temperature ◽

Modulus Of Rupture ◽

Scale Production ◽

Range Analysis ◽

Decay Fungi ◽

Mold Resistance

AbstractIn order to improve dimensional stability and durability of wood, furfurylation of poplar and Chinese fir wood using newly developed furfuryl alcohol (FA) formulation combined with a common vacuum and pressure impregnation process was studied. An orthogonal experiment was designed to optimize the furfurylation process for the two wood species. The weight percent gain (WPG), equilibrium moisture content (EMC), anti-swelling efficiency (ASE), modulus of rupture (MOR), modulus of elasticity (MOE), as well as resistance to mold, decay fungi, and termites were evaluated. The results showed that nearly all the properties of the furfurylated wood could be improved to various extents. The average ASE of the furfurylated Chinese fir and poplar could reach as high as 80, 71, 92% and 79, 90, 75% in tangential and radial directions, and by volume, respectively, higher than most previously reported wood modification processes. Furthermore, the modified wood had excellent biological durability, with nearly 100% mold resistance, strong decay and termite resistance. Finally, processing parameters with 50% FA, 105–115 °C curing temperature, and 5–8 h curing time were therefore recommended for pilot-scale production of furfurylated poplar and Chinese fir wood based on range analysis.

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Laboratory Investigation of Compaction Characteristics of Plant Recycled Hot-Mix Asphalt Mixture

Sustainability ◽

10.3390/su13063005 ◽

2021 ◽

Vol 13 (6) ◽

pp. 3005

Author(s):

Jiangang Yang ◽

Chen Sun ◽

Wenjie Tao ◽

Jie Gao ◽

Bocheng Huang ◽

...

Keyword(s):

Regression Model ◽

Hot Mix Asphalt ◽

Orthogonal Experiment ◽

Asphalt Mixture ◽

Material Design ◽

Void Content ◽

Range Analysis ◽

Aggregate Gradation ◽

Compaction Characteristics ◽

Compaction Energy

In this study, the compaction characteristics of recycled hot-mix asphalt (RHMA) were evaluated using the void content (VV), compaction energy index (CEI), slope of accumulated compaction energy (K), and lock point (LP). Then, the effects of the compaction parameters, including the gradation of the RHMA, reclaimed asphalt pavement (RAP) content, temperature of gyrations, and number of gyrations, on the compaction characteristics of RHMA were investigated. An orthogonal experiment was designed and the data collected were analyzed via range analysis; then, a regression model was generated relying on a quadratic polynomial. Furthermore, the regression model was used for the comparison and prediction of the mixture’s compactability during the material design. Finally, the compaction mechanism of RHMA was discussed from the perspective of the void content of RAP particles. The results showed that a finer aggregate gradation, a higher gyration temperature, a greater number of gyrations, and a higher RAP content were effective for increasing the compactability of RHMA. The range analysis results suggest that the gradation of RHMA has the greatest influence on compactability, followed by the RAP content. The RAP aggregate cannot diffuse to a new mixture completely, so the remained RAP particle reduces the void content of RHMA. Therefore, a higher RAP content up to 50% can help RHMA to achieve the designed void content with higher efficiency.

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Performance Characteristics of Concrete Produced with Fluidized Bed Combustion Ash Residue

MRS Proceedings ◽

10.1557/proc-136-23 ◽

1988 ◽

Vol 136 ◽

Cited By ~ 3

Author(s):

A. E. Bland ◽

C. E. Jones ◽

J. G. Rose ◽

J. L. Harness

Keyword(s):

Fluidized Bed ◽

Performance Characteristics ◽

Strength Development ◽

Fluidized Bed Combustion ◽

Portland Cement Concrete ◽

Conventional Concrete ◽

Setting Times ◽

Pulverized Fuel ◽

Tennessee Valley ◽

Pulverized Fuel Ash

ABSTRACTOver the last five years, the Kentucky Energy Cabinet (KEC) and the Tennessee Valley Authority (TVA) have developed and demonstrated the production of concrete from atmospheric fluidized bed combustion (AFBC) spent bed (SB) ash, and pulverized fuel ash (PFA). This AFBC concrete contains no cement and relies on the reaction of residual lime in the SB ash to react with the pozzolan PFA to form cementitious products. The SB ash is prehydrated in order to reduce exothermic lime hydration reactions and minimize molar volume expansion. Laboratory tests were conducted to establish the performance characteristics of AFBC concretes relative to conventional concrete. AFBC concretes exhibit slower strength gain characteristics, but long term (60 day), unconfined compressive strengths of 5,000 psi have been documented. This slow strength development is typical of pozzolanic concretes. AFBC concrete is more flexible and less brittle than conventional Portland cement concrete, as evidenced by its much lower modulus of elasticity. Setting times for AFBC concretes are extended, requiring the use of accelerators under certain applications. Field demonstrations of the AFBC concretes in ready mix concrete, masonry units, and road base applications have indicated excellent workability and finishing characteristics and confirm the laboratory performance characteristics.The paper describes the results of the testing program with emphasis on the ash chemistry/conditioning, the performance characteristics and field demonstrations.

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