Determination of optimal microwave curing cycle for fly ash mortars

2008 ◽  
Vol 35 (4) ◽  
pp. 349-357 ◽  
Author(s):  
İlker Bekir Topçu ◽  
Mehmet Uğur Toprak ◽  
Devrim Akdağ
Keyword(s):  
Fly Ash ◽  
Processing Parameters ◽  
Microwave Energy ◽  
Strength Prediction ◽  
Strength Development ◽  
Microwave Curing ◽  
Optimal Processing ◽  
Cement Mortars ◽  
Curing Cycle

Microwave energy can accelerate the hydration of cement, which results in the rapid strength development of concrete. In this paper, prediction of later age compressive strength of fly ash cement mortars, based on the accelerated strength of mortars cured with microwave energy, was investigated. To accelerate curing properly, optimal processing parameters of microwave curing (MC) on Portland cement mortars (CM) and fly ash cement mortars (FA) were first determined and then were applied to mortars. The possible early ages for the strength prediction were found to be at 6 and 8 h for CM and FA, respectively. The error percentages for prediction of CM were ±2.22% and 2.91% for 7 and 28 d, respectively. Error percentages for FA, on the other hand, were ±4.36% and 5.20% for 7 and 28 d, respectively.

scholarly journals Determination of Processing Windows for the Hot Stamping of AA7075

2016 ◽  
Vol 716 ◽  
pp. 402-412 ◽  
Author(s):  
Qun Li Zhang ◽  
Kang Ji ◽  
Omer El Fakir ◽  
Xiao Chuan Liu ◽  
Li Liang Wang
Keyword(s):  
Ageing Time ◽  
Hot Stamping ◽  
Processing Parameters ◽  
Air Cooling ◽  
Artificial Ageing ◽  
Forming Process ◽  
Optimal Processing ◽  
Multi Stage ◽  
Force Transfer

Hot stamping of aluminium alloys is a tailored forming process, with the assigned processing windows determining the quality of each hot stamped component in terms of its post-form strength. In this work, a processing window calculator, ‘Tailor’, was developed in order to define the optimal processing parameters that should be used in a production line to successfully produce a component with the desired post-form strength using hot stamping. ‘Tailor’ was developed using the results of forming tests, air-cooling tests and multi-stage artificial ageing tests, which provided guidance on the values for the die closing force, transfer time and artificial ageing time to be used in the hot stamping process. The effectiveness of ‘Tailor’ was demonstrated in two case studies.

Effect of Microwave Curing to the Compressive Strength of Fly Ash Based Geopolymer Mortar

2016 ◽  
Vol 841 ◽  
pp. 193-199 ◽  
Author(s):  
Mohd Mustafa Al Bakri Abdullah ◽  
Muhammad Faheem Mohd Tahir ◽  
Kamarudin Hussin ◽  
Mohammed Binhussain ◽  
Januarti Jaya Ekaputri
Keyword(s):  
Global Warming ◽  
Fly Ash ◽  
Precast Concrete ◽  
Construction Materials ◽  
Cost Savings ◽  
Curing Temperature ◽  
Conventional Heating ◽  
Strength Development ◽  
Microwave Curing ◽  
Heat Curing

With the advancement of technology and the economic crisis in Malaysia, has been promoting the development of infrastructure in the use of new structural materials but overall is unsatisfactory in terms of cost savings. One of the alternatives that can be used is to use fly ash as a cement replacement in manufacturing mortar. Replacement of cement with geopolymerization mortar can reduce manufacturing costs and could reduce global warming arising from the production of cement for the production of Portland cement for the release of CO2 into the atmosphere, where CO2 gas gives the largest contribution to global warming . The study will be focused on the effect of microwave curing with various durations and temperature to the mechanical and physical properties of fly ash based geopolymer mortar. For the conventional heating technique, heat is distributed in the specimen from the exterior to the interior leading to the non-uniform and long heating period to attain the required temperature. Application of microwave to the fresh concrete results in removal of water, collapse of capillary pore and densification of sample. Heat curing has been applied to construction materials especially for the precast concrete to improve the strength development process. This concrete attains sufficient strength in short curing time, so the molds can be reused, and the final products can be rapidly delivered to the site. The effect of curing temperature together with their aging days of the cured product will also be investigated. Mechanical properties of the product will be tested using compressive test, and density of the samples.

Microwave curing process and mechanical properties study of epoxy mortars for repairing concrete pavement rapidly

2016 ◽  
Vol 36 (6) ◽  
pp. 443-451 ◽  
Author(s):  
Xu Zhang ◽  
Xiaoqun Wang ◽  
Xuehong Xu ◽  
Yueqing Zhao
Keyword(s):  
Fly Ash ◽  
Electric Field ◽  
Electromagnetic Fields ◽  
Electric Field Distribution ◽  
Microwave Energy ◽  
Concrete Pavement ◽  
Optimum Process ◽  
Curing Process ◽  
Microwave Curing ◽  
Mechanical Strengths

Polymer mortars are used frequently to repair pavement owing to their excellent properties (mix flexural strength ≥5.75 MPa, compressive strength ≥25 MPa). To repair concrete pavement with polymer mortars rapidly, uniform microwave energy can be used to reduce hardening time of polymer mortars. In this study, the distribution of electromagnetic fields in an industrial microwave facility was optimized, and an area AG with uniform and intensive electric field was obtained. Then microwave curing process of epoxy mortars containing fly ash in the area AG was optimized, and mechanical strengths of the epoxy mortars cured in the optimum process were tested. The results show that, although the distribution of electromagnetic fields in the microwave facility is non-uniform overall, there still are some brush-fire areas, where electric field distribution is relatively uniform. Epoxy mortars added with 10 wt% fly ash can be cured rapidly (approximately 20 min) in the area AG and exhibit outstanding mechanical strengths, which can be used to repair concrete pavement rapidly.

Fly Ash-Calcined Phosphogypsum Cementitous Materials with Different Thermally Treated Phosphogypsum

2011 ◽  
Vol 261-263 ◽  
pp. 816-819 ◽  
Author(s):  
Min Yang ◽  
Qing Chen Sun
Keyword(s):  
Electron Microscopy ◽  
Fly Ash ◽  
Strength Development ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Curing Conditions ◽  
X Ray ◽  
Scanning Electron ◽  
Thermally Treated

Experiments were performed to investigate the properties of fly ash-calcined phosphogypsum (PG) cementitous materials with PG different thermally treated, including being calcined at 135°C, 430°C and 800°C separately. Durability of the cementitous materials was investigated by determination of mass loss of binders immersed in water for different durations and strength development subjected to various curing conditions. X-ray diffraction analysis was used to study the differences in hydration products among binders with different thermally treated PG. Morphology and microstructure of the hardened binders were investigated by scanning electron microscopy. Results suggest that the binder with PG sintered at 430°C obtains the best performance, indicating both impurities in PG and the form of gypsum influence its utilization greatly. Considering this, it can be concluded that choice of a proper thermal treatment is important.

Quantitative determination of fly ash in fresh cement mortars and concretes

2013 ◽  
Vol 2 (1) ◽  
pp. 58-66 ◽  
Author(s):  
Caijun Shi ◽  
Shuyan Liu ◽  
Zhang Cao ◽  
Xiaopeng An ◽  
Fuqiang He
Keyword(s):  
Fly Ash ◽  
Quantitative Determination ◽  
Cement Mortars

Durability of Fly Ash Geopolymer Mortars in Corrosive Environments, Compared to that of Cement Mortars

2014 ◽  
Vol 92 ◽  
pp. 84-89 ◽  
Author(s):  
A. Asprogerakas ◽  
Aristea Koutelia ◽  
Glykeria Kakali ◽  
Sotirios Tsivilis
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Building Materials ◽  
Acid Resistance ◽  
Chloride Diffusion ◽  
Strength Development ◽  
Acid Attack ◽  
Calcareous Sand ◽  
Cement Mortars ◽  
Improved Performance

In the present paper the durability of fly ash geopolymer mortars compared to that of cement mortars is investigated. Geopolymers can improve the ecological image of building materials, especially when their production is based on industrial by-products such as fly ash. Three series of fly ash based geopolymer mortars were prepared using calcareous sand to fly ash ratio (S/FA) varying from 0.5 to 2. In addition, cement mortar specimens were prepared using cement CEM I 42.5 N and CEM II 32.5 N. Durability of geopolymer and cement mortars was evaluated by means of compressive strength development, acid resistance, chloride diffusion and sulfate resistance. It was found that fly ash can be effectively used to produce geopolymer mortars with calcareous sand. Geopolymers exhibit competitive compressive strength compared to that of cement mortars. Geopolymer mortars develop their maximum compressive strength a few days after their casting. Geopolymer and cement mortars exhibit satisfactory resistance to sulphate attack. Cement mortars, generally, show better behaviour (compared to geopolymers) in chloride diffusion. Finally, geopolymers indicate improved performance against acid attack, compared to that of cement mortars.

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

The Influence of the Ash Addition from Thermal Power Plant on the Mechanical, Thermal and Dielectric Characteristics of Mortars

2018 ◽  
Vol 69 (8) ◽  
pp. 2040-2044
Author(s):  
Georgeta Velciu ◽  
Virgil Marinescu ◽  
Adriana Moanta ◽  
Ladislau Radermacher ◽  
Adriana Mariana Bors
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Power Plant ◽  
Cement Mortar ◽  
Thermal Power ◽  
Total Content ◽  
Ash Content ◽  
Dielectric Losses ◽  
Dielectric Characteristics ◽  
Cement Mortars

The influence of fly ash adittion (90 % fraction [ 100 mm) on the cement mortar characteristics was studied. The XRD, XRF, SEM and FTIR determinations indicated that fly ash used has a hollow microstructure of microsphere and cenosphere whose total content in SiO2, Al2O3 and Fe2O3 is 88.63 % and that of CaO and MgO of 8.55 %. The mechanical, thermal and dielectric determinations made on mortar samples with content of fly ash in the 0-40 % range have highlighted fact that the mechanical strength of cement mortars is maximal at 20 %, the increase in fly ash content leads to a decrease in relative density and thermal conductivity as well as and to increased dielectric losses tgd.

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