scholarly journals Predicting pore volume, compressive strength, pore connectivity, and formation factor in cementitious pastes containing fly ash

Author(s):  
Keshav Bharadwaj ◽  
Rita Maria Ghantous ◽  
Feyza Sahan ◽  
O. Burkan Isgor ◽  
W. Jason Weiss
2010 ◽  
Vol 146-147 ◽  
pp. 1690-1697 ◽  
Author(s):  
An Shun Cheng ◽  
Chung Ho Huang ◽  
Tsong Yen ◽  
Yong Lin Luo

This research aims to investigate the pore structures and the interfacial transition zone (ITZ) of concrete containing both slag and fly ash. Test variables include three water-to-binder ratios (0.35, 0.50, 0.70) and four substitute ratios of cement with pozzolanic materials (20%, 30%, 50% and 60%). The specimens were tested to determine compressive strength, MIP porosity measurement and ITZ microhardness. Test results show that concrete containing slag and fly ash produce evident filling effect and the pozzolanic reaction after 28 days. At the age of 91 days the pozzolanic materials has provided prominent contribution to the strength, the porosity and the ITZ of concrete, making the pore volume smaller and ITZ property of pozzolanic concrete better than that of normal concrete. The concrete that adds suitable amount of pozzolanic materials (ex. 10% slag + 10% fly ash) has the optimum microstructure and mechanical property. Too much pozzolanic materials (ex. 40% slag + 20% fly ash) may be disadvantage to the concrete, and the suggested substitute ratio is under 50%. It is found that the compressive strength has the closest relationship with the total pore volume, so we use the total pore volume to predict the compressive strength of pozzolanic concrete and establish a prediction model as follow: S= -662.68Vt+87.29, R2=0.946.


2018 ◽  
Vol 17 (9) ◽  
pp. 2023-2030
Author(s):  
Arnon Chaipanich ◽  
Chalermphan Narattha ◽  
Watcharapong Wongkeo ◽  
Pailyn Thongsanitgarn

2018 ◽  
Vol 17 (8) ◽  
pp. 1855-1861
Author(s):  
Nicolae Taranu ◽  
Monther Abdelhadi ◽  
Ancuta Rotaru ◽  
Maria Gavrilescu

Author(s):  
A. Z. Mohd Ali ◽  
◽  
N. A. Jalaluddin ◽  
N. Zulkiflee ◽  
◽  
...  

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.


Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2694 ◽  
Author(s):  
Shansuo Zheng ◽  
Lihua Niu ◽  
Pei Pei ◽  
Jinqi Dong

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.


2013 ◽  
Vol 864-867 ◽  
pp. 1923-1928
Author(s):  
Yue Xu ◽  
Jian Xi Li ◽  
Li Li Kan

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.


Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1003
Author(s):  
Pantharee Kongsat ◽  
Sakprayut Sinthupinyo ◽  
Edgar A. O’Rear ◽  
Thirawudh Pongprayoon

Several types of hematite nanoparticles (α-Fe2O3) have been investigated for their effects on the structure and properties of fly ash (FA) blended cement. All synthesized nanoparticles were found to be of spherical shape, but of different particle sizes ranging from 10 to 195 nm depending on the surfactant used in their preparation. The cement hydration with time showed 1.0% α-Fe2O3 nanoparticles are effective accelerators for FA blended cement. Moreover, adding α-Fe2O3 nanoparticles in FA blended cement enhanced the compressive strength and workability of cement. Nanoparticle size and size distribution were important for optimal filling of various size of pores within the cement structure.


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