scholarly journals A STUDY ON THE INFLUENCE OF CURING TEMPERATURE ON HYDRATION REACTION AND PORE STRUCTURE OF CEMENT PASTE WITH MODIFIED FLY ASH

2020 ◽  
Vol 73 (1) ◽  
pp. 118-125
Author(s):  
Kento ONOMOTO ◽  
Koji TAKASU ◽  
Hidehiro KOYAMADA ◽  
Hiroki SUYAMA
2011 ◽  
Vol 343-344 ◽  
pp. 246-249 ◽  
Author(s):  
Ting Yu Zhu ◽  
Jun Yan Kuang ◽  
Wen Qing Xu ◽  
Meng Ye ◽  
Yang Yang Guo ◽  
...  

The fly ash was modified by Cl, Fe, Cu salts to investigate the mercury adsorption performance and analyze the impacts on it. Experiment results indicate that significant improvement of removal efficiencies with FeCl3、CuCl2 and CuBr2 impregnation onto fly ash. The modification adjusted the pore structure of fly ash and formed more pores to absorb Hg, also it was found that new active sites were generated after the treatment, which can oxidize Hg0 and improve chemical adsorption.


2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Ki-Bong Park ◽  
Takafumi Noguchi

The aim of this work is to know clearly the effects of temperature in response to curing condition, hydration heat, and outside weather conditions on the strength development of high-performance concrete. The concrete walls were designed using three different sizes and three different types of concrete. The experiments were conducted under typical summer and winter weather conditions. Temperature histories at different locations in the walls were recorded and the strength developments of concrete at those locations were measured. The main factors investigated that influence the strength developments of the obtained samples were the bound water contents, the hydration products, and the pore structure. Testing results indicated that the elevated summer temperatures did not affect the early-age strength gain of concrete made using ordinary Portland cement. Strength development was significantly increased at early ages in concrete made using belite-rich Portland cement or with the addition of fly ash. The elevated temperatures resulted in a long-term strength loss in both belite-rich and fly ash containing concrete. The long-term strength loss was caused by a reduction in the degree of hydration and an increase in the total porosity and amount of smaller pores in the material.


Author(s):  
Hirotaka Matsuo ◽  
Koji Takasu ◽  
Hidehiro Koyamada ◽  
Hiroki Suyama

Using fly ash as an admixture for concrete can contribute to environmental load reduction and concrete quality improvement. However, as the quality of fly ash fluctuates depending on the ash source, quality stabilization is required. It was proved that concrete with fly ash of Japanese Industrial Standardized class II has different strength properties depending on curing temperature, but it is not obvious whether concrete with modified fly ash by flotation method has similar properties. In this study, the influence was examined on the mechanical properties when changing the curing temperature of mortar using fly ash modified by the flotation technique. The sealing curing was set to 5°C, 20°C, 40°C and 60°C. Also, after 7 days, 5°C, 40°C and 60°C, is changed to 20°C and compression strength and static elasticity coefficient were measured. The value of compressive strength and static elastic modulus showed that mortar using modified fly ash had the same characteristics as mortar with ordinary fly ash. Because it was represented by one strength compressive estimation curve regardless of the curing temperature, it became clear that compressive strength can be evaluated by roughly using accumulated temperature as an indicator.


2010 ◽  
Vol 97-101 ◽  
pp. 552-555 ◽  
Author(s):  
Le Hua Yu ◽  
Hui Ou ◽  
S.X. Zhou

The parameters on pore structure of Portland cement pastes blended respectively with 0, 10, 20, 30 and 40% perlite admixture at 3,28,60 curing day were determined by Mercury Intrusion Porosimetre and presented in the paper to investigate affection on performance of cement-based material due to mix the admixture. The research results indicated that since the second hydration reaction had gone on with curing time, perlite admixture could diminish porosity, decrease pore diameter and reduce pore surface area in cement paste. Pores were gradually evolved from original small pores to later smaller pores, moreover fully filled with hydration products and disappeared during hydration reaction. So that the total pore volume in the paste was descended, and the proportion of harmless pores (gel pores and micropores) to whole pores was increased but that of harmful pores (macropores) subtracted. It is concluded that perlite admixture should help to increase the mechanical strength and durability of cement-based materials.


2014 ◽  
Vol 507 ◽  
pp. 295-299 ◽  
Author(s):  
Bo Zhang ◽  
Jin Hu ◽  
Meng Yuan Li

The non-evaporable water content, compressive strength, and pore distribution of steel slag paste cured under different curing temperature conditions were investigated in this paper. The non-evaporable water content of steel slag paste at early ages is obviously larger at higher curing temperature. At the age of 28 days, the non-evaporable water content of steel slag paste at normal curing temperature is close to that at high curing temperature, but the compressive strength of steel slag paste at normal curing temperature is much lower than that at high curing temperature. The pore structure of steel slag paste is much coarser than that of cement paste under the same conditions.


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