scholarly journals Application of the C-S-H Phase Nucleating Agents to Improve the Performance of Sustainable Concrete Composites Containing Fly Ash for Use in the Precast Concrete Industry

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6514
Author(s):  
Grzegorz Ludwik Golewski ◽  
Bartosz Szostak
Keyword(s):  
Fly Ash ◽  
Industrial Waste ◽  
Precast Concrete ◽  
High Strength ◽  
Nucleating Agents ◽  
Negative Effects ◽  
Sustainable Concrete ◽  
Wide Range ◽  
Time Periods ◽  
Positive Effect

Siliceous fly ash (FA) is the main additive to currently produced concretes. The utilization of this industrial waste carries an evident pro-ecological factor. In addition, such actions have a positive effect on the structure and mechanical parameters of mature concrete. Unfortunately, the problem of using FA as a Portland cement replacement is that it significantly reduces the performance of concretes in the early stages of their curing. This limits the possibility of using this type of concrete, e.g., in prefabrication, where it is required to obtain high-strength composites after short periods of curing. In order to minimize these negative effects, this research was undertaken to increase the early strength of concretes with FA through the application of a specifically formulated chemical nano-admixture (NA) in the form of seeds of the C-S-H phase. The NA was used to accelerate the strength growth in concretes. Therefore, this paper presents results of tests of modified concretes both with the addition of FA and with innovative NA. The analyses were carried out based on the results of the macroscopic and microstructural tests in five time periods, i.e., after 4, 8, 12, 24 and 72 h. The results of tests carried out with the use of NA clearly indicate the possibility of using FA in a wide range of management areas in sustainable concrete prefabrication.

scholarly journals PEMAKAIAN FLY-ASH SEBAGAI CEMENTITIOUS PADA BETON MUTU TINGGI DENGAN STEAM CURING (THE USE OF FLY-ASH AS CEMENTITIOUS ON HIGH-STRENGTH CONCRETE WITH STEAM CURING)

2014 ◽  
Vol 10 (2) ◽  
Author(s):  
Erwin Rommel ◽  
Yunan Rusdianto
Keyword(s):  
Fly Ash ◽  
Precast Concrete ◽  
Chemical Properties ◽  
High Strength ◽  
Steam Curing ◽  
Initial Strength ◽  
Speed Up ◽  
Physical And Chemical ◽  
And Chemical Properties

Erwin Rommel1 & Yunan Rusdianto2Jurusan Teknik Sipil Fakultas Teknik Universitas Muhammadiyah MalangAlamat Korespondensi :Jalan Raya Tlogomas 246 Malang 65144email : [email protected] HP 08123314432ABSTRACTThe use of fly-ash as cementitious will be made to utilize physical and chemical properties offly-ash that has a dominan of silica and good of modulus fines. The use of steam curing will be donein this study which can speed up the cycle of making concrete. This is advantageous in the productionof precast concrete and velocity field construction.The research was conducted by making concrete cube 15x15x15 cm for 80 pieces and thentested the compressive strength and absorption of concrete. Achieve the quality of concrete madewith the provision of K600 with giving the fly-ash respectively 7.5%, 15% and 30% by weight ofcement.The results of the research obtained by the use of fly-ash as much as 7.5% as a cementitiousthat was given to the steam curing will provide the initial strength of concrete reached 47% ofcompressive strength at 28 days. While the effect of giving fly-ash in concrete has not seen absorptionsignificantly when compared to concrete without fly-ash.Key word : concrete, fly-ash, steam curing

Geopolymer Sourced with Fly Ash and Industrial Aluminum Waste for Sustainable Materials

2020 ◽  
pp. 676-696
Author(s):  
Sujitra Onutai ◽  
Sirithan Jiemsirilers ◽  
Takaomi Kobayashi
Keyword(s):  
Fly Ash ◽  
Industrial Waste ◽  
Raw Materials ◽  
Acid Resistance ◽  
High Strength ◽  
Microwave Oven ◽  
Silicate Material ◽  
High Acid ◽  
Alumino Silicate ◽  
Geopolymer Cement

Geopolymer is alumino-silicate material which can apply for many applications due to that geopolymers have several attractive properties of high strength, low permeability, high acid resistance, hazardous materials, and immobilization of toxic materials. This chapter presents synthesis of the dense and the porous structures of geopolymer by using fly ash and industrial waste as the raw materials. Aluminum hydroxide waste (Al-waste) and fly ash (FA) were used to synthesis the dense geopolymers for cement materials. The Al-waste based geopolymer influenced the geopolymer strength, when sodium hydroxide (NaOH) concentration was changed at different curing temperatures. As preliminary microwave oven was exposed in the lower NaOH paste of geopolymer, the successful synthesis of geopolymer cement was obtained. In addition, porous fly ash geopolymers was achieved using a household microwave oven. The geopolymer paste was cured within 1 min by using a microwave oven at different output power. Porous geopolymers were formed immediately as ued at 850 W power of the microwave oven.

scholarly journals Strength Calculation Features and Tests Results on Bearing Capacity and Operational Serviceability of Hollow-Core Floor Slabs of Formwork-Free Shaping in Seismic Areas

2020 ◽  
Vol 9 (1) ◽  
pp. 2219-2225
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Construction Industry ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforced Concrete Structures ◽  
Hollow Core ◽  
Wide Range

The technology of manufacturing reinforced concrete structures of long-line systems of formwork-free shaping is widely used lately in construction industry in many countries. Using this technology, industrial construction can be carried out in accordance with the requirements of modern regulatory documents that allow projects to be developed individually, and production can be reoriented in a very short time in accordance with emerging needs. This means that on the same production line it is possible to produce various structural elements of buildings and structures. Also, this technology allows the production of structures according to a wide range of products that meet operational requirements, and increases the possibility of their use in design of buildings and structures with various architectural, planning and structural decisions. Prestressed hollow-core slabs of formwork-free shaping reinforced with high-strength wire reinforcement are widely used due to the simplicity of construction and their relatively low cost, as well as their high bearing capacity, large spans and better quality. The problem of their introduction into construction industry of Uzbekistan is that the issues of designing, manufacturing and using them in construction have not been studied. Besides, the production technology of such slabs is mostly associated with the construction in non-seismic areas, and the country does not have an appropriate regulatory framework for the possibility of slab designing and production. The aim of the study is to assess the strength and serviceability of hollow-core slabs of formwork-free shaping, designed on the basis of the proposed structural solution of the slab cross section and intended for construction in seismic areas. Therefor the issues of optimizing the main reinforcement consumption (prestressed high-strength wire reinforcement) at class B30 concrete strength without using the non-stressed reinforcement (reinforcing products) for the product range under consideration were addressed. Theoretical and constructive solutions of the slabs were developed in accordance with the standard requirements of Uzbekistan KMK 2.03.01-96 “Concrete and reinforced concrete structures”, KMK 2.01.03 “Construction in seismic areas” and considering the Euronorm EN 1168-2005 requirements “Precast concrete. Hollow-core slabs”.

Geopolymer Sourced with Fly Ash and Industrial Aluminum Waste for Sustainable Materials

2017 ◽  
pp. 165-185
Author(s):  
Sujitra Onutai ◽  
Sirithan Jiemsirilers ◽  
Takaomi Kobayashi
Keyword(s):  
Fly Ash ◽  
Industrial Waste ◽  
Raw Materials ◽  
Acid Resistance ◽  
High Strength ◽  
Microwave Oven ◽  
Silicate Material ◽  
High Acid ◽  
Alumino Silicate ◽  
Geopolymer Cement

Geopolymer is alumino-silicate material which can apply for many applications due to that geopolymers have several attractive properties of high strength, low permeability, high acid resistance, hazardous materials, and immobilization of toxic materials. This chapter presents synthesis of the dense and the porous structures of geopolymer by using fly ash and industrial waste as the raw materials. Aluminum hydroxide waste (Al-waste) and fly ash (FA) were used to synthesis the dense geopolymers for cement materials. The Al-waste based geopolymer influenced the geopolymer strength, when sodium hydroxide (NaOH) concentration was changed at different curing temperatures. As preliminary microwave oven was exposed in the lower NaOH paste of geopolymer, the successful synthesis of geopolymer cement was obtained. In addition, porous fly ash geopolymers was achieved using a household microwave oven. The geopolymer paste was cured within 1 min by using a microwave oven at different output power. Porous geopolymers were formed immediately as ued at 850 W power of the microwave oven.

scholarly journals Effects of Exogenous Application of Indole-3-Butyric Acid on Maize Plants Under Cadmium Stress

2021 ◽  
Author(s):  
Kristína Šípošová ◽  
Eva Labancová ◽  
Danica Kučerová ◽  
Karin Kollárová ◽  
Zuzana Vivodová
Keyword(s):  
Butyric Acid ◽  
Toxic Metal ◽  
Cadmium Stress ◽  
Cd Stress ◽  
Negative Effects ◽  
Positive Effects ◽  
Cadmium Treatment ◽  
Wide Range ◽  
Maize Plants ◽  
Positive Effect

Abstract Exogenously-applied auxins can alleviate the toxicity of various metals and improve a plant’s tolerance to stress. Cadmium (Cd) is a toxic metal that has a wide range of negative effects on plants. The mechanisms that result in the positive effects of auxins on stressed plants are still not fully understood. In the present study, we found that the application of indole-3-butyric acid (IBA) in concentration 10− 9 M had positive effect on the plants cultivated in the presence of Cd. IBA caused changes in the growth and morphology of the maize also under non-stress conditions; hence, we were able to select three concentrations of IBA (10− 7 M as inhibitory, 10− 8 M as non-effective, and 10− 11 M as stimulatory). Cadmium treatment increased the concentration of H2O2 and the activity of the antioxidant enzymes: superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT), while IBA (10− 9 M) ameliorated its negative effects. IBA affected the content of macronutrients and micronutrients in roots in relation to the concentration of applied IBA and the presence of Cd in the solution. The heatmap visualises the differences between the Cd and Cd + IBA effects on all parameters studied, and indicates the positive effects of IBA (10− 9 M) during Cd stress.

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

Brief history and ways of further development of the department of hydraulic engineering and hydraulics FSBI «VNIIGiM named after A.N. Kostyakov»

2020 ◽  
pp. 18-23
Author(s):  
Alexey Shcherbakov ◽  
Valentin Zhezmer
Keyword(s):  
Land Reclamation ◽  
Water Source ◽  
Water Sources ◽  
Hydraulic Engineering ◽  
Negative Effects ◽  
Extensive Experience ◽  
Safety Level ◽  
Theoretical Substantiation ◽  
Wide Range ◽  
Construction Operation

Department of hydraulic engineering and hydraulics FGBNU «VNIIGiM them. A.N. Kostyakova «has a long history. For many years, the department’s staff has been such scientists and water engineers with extensive experience as M.A. Volynov, V.S. Verbitsky, S.S. Medvedev, N.V. Lebedev, B.C. Panfilov, T.G. Voynich-Syanozhentsky, V.A. Golubkova, G.V. Lyapin and others. The department solved a wide range of tasks, the main areas of research were the following: – theoretical and applied hydrodynamics and hydraulics, with reference to the open channel flows that affect the state and level of safety of the hydraulic structures; – integrated use and protection of water bodies – water sources and water sources of water resources used in land reclamation; – development of measures and technical solutions for the protection of objects from the negative effects of water; – theoretical substantiation of works to improve the safety level of the GTS (declaration); – development and implementation of digitalization methods for solving design, construction, operation and control of landreclamation facilities. Currently, promising areas of research is the development of a decision-making algorithm in the designation of measures to rationalize the provision of resources to water amelioration. The algorithm is developed on the basis of a detailed study, systematization and processing of data both on safety and on the efficiency of systems and structures, ensuring the delivery of irrigation water of the required quality and in sufficient quantity from a water source to the field.

Study on Strength Development of High Strength Concrete Containing Alccofine and Fly-Ash

2012 ◽  
Vol 2 (3) ◽  
pp. 102-104 ◽  
Author(s):  
Suthar Sunil B ◽  
◽  
Dr. (Smt.) B. K. Shah Dr. (Smt.) B. K. Shah
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Strength Development ◽  
Strength Concrete

Utilization of Industrial Waste Copper Slag and Fly Ash in Concrete

2014 ◽  
Vol 3 (3) ◽  
pp. 25-33
Author(s):  
Jagmeet Singh ◽  
◽  
Jaspal Singh ◽  
Manpreet Kaur ◽  
◽  
...  
Keyword(s):  
Fly Ash ◽  
Industrial Waste ◽  
Copper Slag

MORPHOLOGICAL AND BIOCHEMICAL RESPOSES OF COW PEA (CV. PUSA BARSATI) GROWN ON FLY ASH AMENDED SOIL IN PRESENCE AND ABSENCE OF MELOIDOGYNE JAVANICA AND RHIZOBIUM LEGUMINOSARUM

1970 ◽  
Vol 17 ◽  
pp. 17-22 ◽  
Author(s):  
Kamal Singh ◽  
A. A. Khan ◽  
Iram Khan ◽  
Rose Rizvi ◽  
M. Saquib
Keyword(s):  
Fly Ash ◽  
Plant Growth ◽  
Rhizobium Leguminosarum ◽  
Growth Yield ◽  
Maximum Growth ◽  
Meloidogyne Javanica ◽  
Growth And Yield ◽  
Negative Effects ◽  
Positive Effects ◽  
Insignificant Difference

Plant growth, yield, pigment and protein content of cow-pea were increased significantly at lower levels (20 and 40%) of fly ash but reverse was true at higher levels (80 and 100%). Soil amended by 60% fly ash could cause suppression in growth and yield in respect to 40% fly ash treated cow-pea plants but former was found at par with control (fly ash untreated plants). Maximum growth occurred in plants grown in soil amended with 40% fly ash. Nitrogen content of cow-pea was suppressed progressively in increasing levels of fly ash. Moreover,  Rhizobium leguminosarum  influenced the growth and yield positively but Meloidogyne javanica caused opposite effects particularly at 20 and 40% fly ash levels. The positive effects of R. leguminosarum were marked by M. javanica at initial levels. However, at 80 and 100% fly ash levels, the positive and negative effects of R. leguminosarum and/or M. javanica did not appear as insignificant difference persist among such treatments.Key words:  Meloidogyne javanica; Rhizobium leguminosarum; Fly ash; Growth; YieldDOI: 10.3126/eco.v17i0.4098Ecoprint An International Journal of Ecology Vol. 17, 2010 Page: 17-22 Uploaded date: 28 December, 2010  

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