Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment.
The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na(2)SO(4)+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al(2)O(3) content of the fly ash. The diffusion of SO(4)(2-), Na+ and Cl- ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition.
Lorenzo
Ma P
MP
Institute of Construction Science Eduardo Torroja C/Serrano Galvache s/n 28033 Madrid, Spain.
Goñi
S
S
Guerrero
A
A
D003031:Coal; D003252:Construction Materials; D017745:Incineration; D008422:Materials Testing; D008628:Mercury / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D012037:Refuse Disposal; D012623:Seawater / Q000737:chemistry; D014873:Water Pollutants / Q000032:analysis*; D014961:X-Ray Diffraction
D003031:Coal; D014873:Water Pollutants; D008628:Mercury