• Computers and Concrete
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• v.27 no.3
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• pp.241-252
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• 2021

An experimental program was conducted to investigate the fresh properties, mechanical properties and durability characteristics of the self-compacting mortars (SCM) produced with pumice powder and Artificial Lightweight Fine Aggregate (aLWFA). aLWFA was produced by using fly ash. A total of 16 different mixtures were designed with a constant water-binder ratio of 0.37, in which natural sands were partially replaced with aLWFA and pumice powder at different volume fractions of 5%, 10% and 15%. The artificial lightweight aggregates used in this study were manufactured through cold bonding pelletisation of 90% of class-F fly ash and 10% of Portland cement in a tilted pan with an ambient temperature and moisture content. Flowability tests were conducted on the fresh mortar mixtures beforehand, to determine the self-compacting characteristics on the basis of EFNARC. To determine the conformity of the fresh mortar characteristics with the standards, mini-slump and mini-V-funnel tests were carried out. Hardened state tests were conducted after 7, 28 and 56 days to determine the flexural strength and axial compressive strength respectively. Durability, sorptivity, permeability and density tests were conducted at the end of 28 days of curing time. The test results showed that the pumice powder replacement improved both the fresh state and the hardened state characteristics of the mortar and the optimum mixture ratio was determined as 15%, considering other studies in the literature. In the aLWFA mixtures used, the mechanical and durability characteristics of the modified compositions were very close to the control mixture. It is concluded in this study that mixtures with pumice powder replacement eliminated the negative effects of the aLWFA in the mortars and made a positive contribution.

• Structural Engineering and Mechanics
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• v.88 no.2
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• pp.141-157
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• 2023

In the present paper, the effect of recycled aggregates on the rheological and mechanical properties of self-consolidating concrete is investigated experimentally and numerically. Hence, the specimen with two types of recycled aggregates, i.e., known and unknown resistance origins, are utilized for the studied specimens. The experiments in this study are designed using the Box-Behnken method, which is one of the response surface methods. Input variables in mixtures include silica fume in the range of 5-15% as a percentage substitute for cement weight and recycled coarse and fine aggregates in the range of 0-50% for both series of recycled materials as a substitute for natural materials. The studied responses are slump flow, V funnel, compressive strength, tensile strength, and durability. The results indicate that the increase in the amount of recycled aggregates reduces the rheological and mechanical properties of the mixtures, while silica fume effectively improves the mechanical properties. In addition, the results demonstrate that the fine recycled aggregates affect the total response of the concrete significantly. The results of tensile and compressive strengths indicate that the mixtures including 50% recycled materials with known resistance origin demonstrate better responses up to 8 and 10% compared to the materials with unknown resistance origins, respectively. Recycled materials with a specific resistance origin also show better results than recycled materials with an unknown resistance origin. Durability test results represent those concretes containing recycled coarse aggregates have lower strength compared to recycled fine aggregates. Also, a series of mathematical relationships for all the responses are presented using variance analysis to predict mixtures' rheological and mechanical properties.

• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.73-86
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• 2012

In this research, the possible applicability of mixture blended with natural, crushed, and recycled fine aggregate are discussed. The fresh and hardened properties of mortar using blended fine aggregates are monitored depending on various blending ratio of fine aggregates. Newly developed ternary diagram was also utilized for better interpretation of the data. It was found that air content increased and unit weight decreased as recycled fine aggregate content increased. With moisture type processing of recycled fine aggregate, the mortar flow was not negatively affected by increase in the recycled fine aggregate content. The ternary diagram is found to be an effective graphical presentation tool that can be used for the quality evaluation of mortar using blended fine aggregate.

• Journal of the Korean Ceramic Society
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• v.31 no.3
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• pp.337-345
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• 1994

The reaction-sintered alumina and zirconia-alumina ceramics having low firing shrinkage were prepared from the Al/Al2O3 or Al/ZrO2(Ca-PSZ) powder mixtures via the attrition milling. And in this milling process the effect of the characteristics of used powders was investigated. Attrition milling was much more effective in reducing the particle size of ceramic/metal mixed powders than ball milling. Powder mixtures of flake-type Al with coarse alumina was much more effectively comminuted by the attrition milling than the mixtures of globular-type Al with coarse alumina powders. And coarse alumina than fine alumina was much more beneficial in cutting and reducing the ductile Al particles. In the contrary to Al/Al2O3 powder mixtures, Al/ZrO2 powder mixtures was not effectively comminutd. But whether using the alumina ball media or attrition milled with Al2O3 powder rather than Al, the milling efficiency was much more increased.

• Journal of Dairy Science and Biotechnology
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• v.40 no.3
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• pp.134-142
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• 2022

Protein-enriched dairy powder is widely consumed to promote muscle synthesis. Recently, in Korea, elderly people have also begun consuming protein powder products to prevent muscle loss. However, these protein-enriched powders have poor flowability and hydration properties because of the fine particles of spray-dried milk protein powder. Therefore, in this study, the fluidized bed agglomeration process was used to solve these problems. The rheological and physical properties of milk protein isolate (MPI)/skim milk powder (SMP) mixtures were effectively improved via fluidized bed agglomeration. The particle size of the MPI/SMP mixtures significantly increased from 35.7-58 ㎛ to 118-136 ㎛, the flowability level improved from fair (21.4-26.3) to good (15.7-16.3), and the cohesiveness level changed from intermediate (1.27-1.36) to low (1.18-1.19) after fluidized bed agglomeration. In addition, the wetting time of the agglomerated MPI/SMP mixtures was effectively reduced to 4.67-58.3 s by fluidized bed agglomeration. These findings may be useful for manufacturing protein-enriched dairy powders with good instant properties.

• Advances in concrete construction
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• v.10 no.2
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• pp.127-140
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• 2020

This study explores the feasibility of granite waste aggregate (GWA) as a partial replacement of natural fine aggregate (NFA) in binary blend self-compacting concrete (SCC) prepared with fly ash. Total of nine SCC mixtures were prepared wherein one was Ordinary Portland cement (OPC) based control SCC mixture and remaining were fly ash based binary blend SCC mixtures which included the various percentages of GWA. Fresh properties tests such as slump flow, T₅₀₀, V-funnel, J-ring, L-box, U-box, segregation resistance, bleeding, fresh density, and loss of slump flow (with time) were conducted. Compressive strength and percentage of permeable voids were evaluated in the hardened state. All the SCC mixtures exhibited sufficient flowability, passing ability, and resistance to segregation. Besides, all the binary blend SCC mixtures exhibited lower fresh density and bleeding, and better residual slump (up to 50% of GWA) compared to the OPC based control SCC mixture. Binary blend SCC mixture incorporating up to 40% GWA provided higher compressive strength than binary blend control SCC mixture. The findings of this study encourage the utilization of GWA in the development of binary blend SCC mixtures with satisfactory workability characteristics as a replacement of NFA.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.135-147
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• 2007

Segregation in asphalt pavements occurs as a result of the non-uniform distribution of coarse and fine aggregates and causes premature distresses, such as cracking, raveling, and stripping. The effect of segregation on rutting, however, has not been clearly identified. Experimental and analytical work performed in this study indicates that rutting performance is affected by segregation of mixtures. However, the aggregate structure of mixtures appears to be a more critical factor that determines the rutting performance, rather than the level of segregation. Based on the field mixtures evaluated, an increase of coarse aggregate volume in an asphalt mixture is an important factor that results in good rutting performance. This effect holds true for mixtures with lower levels of air voids, but for mixtures with higher levels of air voids, the air voids effect becomes dominant, resulting in a reduction in rutting performance. An air void content of 10% appears to be a threshold that determines the rutting performance of Superpave mixtures. Once the air void content exceeds 10%, the rutting performance of Superpave mixtures decreases significantly, despite the coarse aggregate volume.

• Journal of Powder Materials
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• v.9 no.5
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• pp.329-335
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• 2002

Recently, the fabrication process of the W-Cu nanocomposite powders has been studied to improve the sinterability through the mechanical alloying and reduction of W and Cu oxide mixtures. In this study. the W-Cu composites were produced by mechanochemical process (MCP) using $WO_3-CuO$ mixtures with two different milling types of low and high energy, respectively. These ball-milled mixtures were reduced in $H_2$ atmosphere. The ball-milled and reduced powders were analyzed through XRD, SEM and TEM. The fine W-Cu powder could be obtained by the high energy ball-milling (HM) compared with the large Cu-cored structure powder by the low energy ball-milling (LM). After the HM for 20h, the W grain size of the reduced W-Cu powder was about 20-30 nm.

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.4
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• pp.4799-4804
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• 1978

In order to investigate the effect of delayed compaction on the strength of the lime soil mixtures, labroatory test with two kind of soils was performed at four levels of lime content, at five levels of water content, and at six love's of delayed times. The results are summarized as follows; 1. Maximum dry density and optimum moisture content decreased with increase of the delayed times. The decreasing rate of those values at the earlier delayed time were large, and those values showed almost constant after about four hours of delayed time. 2. According to the increase of the delayed time, the decreasing rate of maximum dry density and optimum moisture content was large ia S-2 sampl, but was a little in S-1 sample. 3. Unconfined compressive strength of lime soil mixtures decreased with the increase of the delayed time, and the decreasing rate of its strength increased with the increase of the lime content. 4. Water content corresponding to the maximum strength was a little higher than the optimum moisture content along the increase of lime content and delayed time but its value was large in fine soil.

• Computers and Concrete
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• v.25 no.1
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• pp.59-65
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• 2020

The premise for the study reflected in this article is the need to dispose of industrial waste, which is increasingly being used in the construction materials industry. Also, dynamically developing building industry demands attention of scientists and a direction of their works on improvement of the technology of carrying out construction works. Thus, the article is devoted to studying the influence of various chemical additives and fine fillers (industrial wastes) available in Kazakhstan on self-compacting concrete (SCC) mixtures and its rheological, physical, and technical properties. According to the studies, revealed the most efficient type of fine-dispersed filler and the most optimal type of chemical additive to enable obtaining a high-quality SCC mixture based on local raw materials. As a result, the use of microsilica in comparison with other industrial wastes resulted in a conglomerate with high compressive strength of SCC at early terms of curing. In terms of economic efficiency and quality improvement, the results of study are of practical value for the manufacturers of ready-mixed concrete operating in Kazakhstan.