The effect of lime rich sludge in presence and absence of rice husk ash on hydration characteristics of granulated blast-furnace slag.
Dear Dr. Saleh,
Free lime is one of the causes that led to expantion due to hydration of CaO, So it considered assistant to deleterious concrete.
Best wishes
Dear Hasanen
Anyway , But I thought there is a difference chemical behavior of free lime and chemically compound lime (Ca(OH)2 calcium hydroxide ).
Thank you for the informations and thank you for sharing it with us.
Please tell me more about this reactions ( effect lime on pozzolanic materials) , or if possible send me some references.
presently, I just have the attached artical.
Thanks in advance.
I completely agree with that, GGBFS requires longer time to exhibit its Pozzolanic reaction and to activate its lime. So in the presence of free lime which is associated with high Ph value, GGBFS becoms activated and we can get a higher early strength. However, in the presence of RHA the effect of free lime could be decreased as it is being utilised in the pozolanic reaction with the glassy phase of the silica provided by RHA. In case of Portland slag cement , GBFS has latent hydraulic activity and is accelerated in the presence of hydrated calcium phases such as C-S-H, or even C-H. Thus if used in controlled, lime rich sludge may accelerate the hydration reaction. In case of alkali activated cement, it will give rise to N-A-S-H and N-C-S-H hydration product. Rice husk ash will give the Pozzolanic reactivity.
Dear Dr. Hassnen Mosa Jafer , Thank you so much for your interesting and valuable comments.
As the amount of LRS increases, the combined water and free lime increase also. The compressive strength values of GBFS-LRS mixes increase with LRS content up to 20 wt., %, and then decrease at 30 wt., % LRS. In order to enhance the compressive strength of the mixture containing 30 wt., % of LRS, different amounts of rice husk ash (RHA) were added. The compressive strength increases with RHA content. The results of chemical and mechanical properties of GBFS-LRS blends in presences and absence of RHA are in a good harmony with those of XRD, FTIR and TG/DTG analyses.
Dear Dr. Hassnen , I am so much thankful to you and very happy with your friendship. I am also pleased to communicate and collaborate with you. I do appreciate your admirable scientific contributions very much.
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Sincerely Yours,
Prof. Dr. Saleh Abd El-Aleem Mohammed
(Applied and Engineering Inorganic Chemistry)
Vice-Dean of Faculty of Science, Fayoum University, Fayoum, Egypt
The higher the amount of RHA, the lower the combined water at one day of curing. Meanwhile, at later hydration ages, the combined water contents increase with RHA percentage. In contrast, the free lime contents decrease with the increase of RHA, % at all ages of curing. The combined water and free lime contents as well as compressive strength values of GBFS/LRS mix containing 10% RHA are nearly the same and closed to the corresponding values of GBFS/LRS mix containing 7.5% RHA, indicating that, the addition of 7.5% RHA to GBFS-LRS is the optimum addition level.
The RHA has a good pozzolanic activity as confirmed by the decrease in free lime content and the decrease in the intensity of CH characteristic peaks in XRD, FTIR and DSC techniques as well as the increase of the compressive strength values with RHA content. The GBFS-LRS-RHA composite, which contains 30% LRS and 7.5% RHA can be beneficially used to prepare low cost temporary structure. It can be used in preparation of non-structural elements in the low range compressive strength (F Compression) where strength is not required. Also, this composite may be used in masonry mortar to improve the long-term strength.
I am deeply impressed by your kind appreciation. I am an admirer of your work, and I am glad that we had the chance to share our knowledge. Thank you I wish you all my best. Please, send me your E-mail
Sincerely Yours,
Saleh
(S. Abd El-Aleem)
The combined water and free lime contents as well as compressive strength values of GBFS/LRS mix containing 10% RHA are nearly the same and closed to the corresponding values of GBFS/LRS mix containing 7.5% RHA
GGBFS requires longer time to exhibit its Pozzolanic reaction and to activate its lime. So in the presence of free lime which is associated with high Ph value, GGBFS becoms activated and we can get a higher early strength. However, in the presence of RHA the effect of free lime could be decreased as it is being utilised in the pozolanic reaction with the glassy phase of the silica provided by RHA. In case of Portland slag cement , GBFS has latent hydraulic activity and is accelerated in the presence of hydrated calcium phases such as C-S-H, or even C-H. Thus if used in controlled, lime rich sludge may accelerate the hydration reaction.
Dear Dr. Doha, Thank you so much for your interesting and valuable comments.
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