Improvement in pozzolanic reactivity of coarse fly ash by mechano-chemical method

Title: Improvement in pozzolanic reactivity of coarse fly ash by mechano-chemical method
Author(s): B.Singh, Simmi Tyagi, M.Gupta and S.K. Bhattacharyya
Paper category : conference
Book title: International RILEM Conference on Advances in Construction Materials Through Science and Engineering
Editor(s): Christopher Leung and K.T. WAN
ISBN: 978-2-35158-116-2
e-ISBN: 978-2-35158-117-9
Publisher: RILEM Publications SARL
Publication year: 2011
Pages: 78 - 85
Total Pages: 8
Nb references: 13
Language: English

Abstract: The coarse fly ash was ground to > 80% passing through a 45 μm sieve and activated with NaOH, NaNO3, Ca(OH)2 and their binary mixtures. The resulting ash was characterized for the specific surface area, particle size distribution, surface morphology and microanalysis. It is found that the activated fly ashes are finer, higher total pore volume and lower mean particle size than the non-activated coarse ash. FE-SEM shows irregular shape of the particles containing pre-zeolitic and C-S-H phases. EDAX mapping indicates that Si/Al ratio decreases and Al/Fe ratio increases in the activated ash when compared with the coarse ash. The coarse ash exhibited 0.5% lime removal capability whereas the activated ash removed 4-32% lime depending on the efficiency of single and binary mixture of activators as observed in lime solubility curve. The strength of lime mortars consisted of the various activated fly ash are in the range of 4.7-9 MPa as compared to 2.2 MPa of coarse ash containing mortar. The compressive strength of cement-activated ash mortar retained 82-95% of the plain cement mortar after 28 days age while the strength of cement-coarse ash mortar was 68.27% only. Based on these results, it is observed that the binary mixture of NaOH and NaNO3 gave best pozzolanic reactivity with the maximum lime removal efficiency at 1 N solution supportive of its suitability for use in cement concrete.

Online publication: 2011-10-31
Publication type : full_text
Public price (Euros): 0.00