الفهرس 
INTRODUCTION AND OBJECT OF INVESTIGATION
Object of investigationOnly 14 pages are availabe for public view
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Abstract
This study aimed to utilize some laboratory prepared nano oxides
namely; nano silica (NS), nano alumina (NA), nano hematite (NF) and
nano zinc oxide (NZ) as active additions for improving the
microstructure, mechanical properties and thermal resistance of
hardened ordinary Portland cement (OPC) pastes. Nano silica was
synthesized from rice husk ash via extraction method, while, nano
alumina, nano hematite, and nano zinc oxide were synthesized from
AlCl3, FeCl3.6H2O and zinc acetate; respectively via the sol-gel
method in presence of CTAB as a cationic surfactant. The average
particle sizes of synthesized NS, NA, NF and NZ were 30, 40, 20 and
70 nm; respectively. NS, NA, and NF were added to OPC with ratios
of 0.5, 1, 2 and 3 by mass% of OPC. While, NZ was added to OPC
with ratios of 0.05, 0.1 and 0.2 by mass% of OPC. The
physicochemical and mechanical characteristics of the hardened pastes
were investigated after 1, 3, 7, 14, 28 and 90 days of curing under tap
water hydration. For thermal resistance test, the specimens were
hydrated for 28 days under tap water and fired at 300, 600 and 800oC
for 3 h. The compressive strength test was performed for all fired
specimens at each firing temperature. The results indicated that the
optimum addition of NS, NA, NF, and NZ was 1, 0.5, 2 and 0.05%;
respectively. XRD, TG/DTG, and SEM results indicated that illcrystalline
and nearly amorphous nature of the formed hydrates in
these hardened composites.
Keywords
Nano silica, Nano alumina, Nano hematite, Nano ZnO, Thermal
resistance, Compressive strength, Pozzolanic activity.