Engineering and Technology Journal

This research study examines the practicability of using micro and nano size silica to improve the asphalt characteristics. Asphalt cement penetration grade of (60 /70) was prepared using (0%, 2%, 4% and 6%) of silica filler by weight of asphalt and investigated in terms of the softening point, penetration, and penetration index, viscosity, and ductility values. To modify the asphalt binder, the silica powder was mixed by a mechanical blender set at (2000) rpm at a mixing temperature of 140°C. However, the main challenge is an agglomeration of nano-silica powder which can reduce the ductility of nano silica modified binder. Therefore, this paper studies the efficiency of mixing period to obtain a homogeneous composite binder while alleviating the agglomeration issue. To do so, the effect of periods of mixing ranged between (30 to 60) minutes were examined on characteristics of modified asphalt binders. Overall, the addition of silica filler has an encouraging impact on the asphalt binder rheological properties. Also, the ductility value decreases with the addition of nano-silica content, attributed to the huge surface area and degree of agglomeration. Furthermore, results exhibited that 6% of micro silica powder and 4 % of nano silica powder were reasonable to develop the rheological properties.

This paper aims to give a recommendation about the suitable nano silica proportion and curing method for testing its strength pozzolonic activity, in addition to suggest a mixing or batching procedure of this material with other concrete ingredients. Theinfluence of nanoand micro silicaon concrete compressive strength is also studied. Three proportions of nano silica (0.5, 5, &10%) , two curing methods (accelerated in oven and normal in water) and two tested agesare used in pozzolonic activity test of nano silica. For compressive strength test, eleven mixes are considered:without-adding (two mixes), three micro silica (M) mixes with replacement ratios of 5, 10 & 15%, four nano silica (N) mixeswith replacement ratiosof 0.5,1.5, 3 & 5%, and three micro plus nano silica mixes (0.5N+9.5M,1.5N+8.5M and 3N+7M%) are adopted.Results of pozzolanic activity test denoted that nano silica has remarkable pozzolanic activity for all tested replacements.However, it is suggest using 5% nano silica for performing this testby usingeither accelerated or water curing. Additionally, it was found that nano silica had more impact on compressive strength of concrete than micro silica for all tested ages.Where, maximum enhancement ratios of compressive strength were about 33% and 27% for 3% nano silica mix at 7 and 90 days age respectively, and 22% for 5% nano silica mix at 28 days age. For micro silica mixes, higher improvement ratios were found in 15% micro silica mix: 2%,5%&7% at 7,28 &90 days age respectively.

Nano-SiO2 with different weight percentage (1,2 ,3, 4 and 5) % wt. , and 3% MWCNT were usedto fabricate nano-SiO2/MWNT/epoxy composite samples by hand layup method. Ultrasonic mixing processwas used to disperse the nano additives into the resin system. scanning electron microscopy (SEM)where usedto carry out the characteristic of fracture surface. By both the high aspect ratio and the very high modulus ofnano fillers. The mechanical properties of the composite with different weight percentages of nano-SiO2 havebeen investigated and After examine, the Scanning Electron Microscopy (SEM) explains well dispersednanotubes and SiO2 nano particles in the matrix. No evidence of agglomeration of the nanotubes can be foundin this micrographs. By adding SiO2 nano particles to epoxy/MWCNT composite, this would dramaticallyimprove the bending properties and The Young’s modulus has been doubled and quadrupled for compositeswith respectively 2 and 4 wt.% nano SiO2, compared to the pure resin matrix samples (3.36 ,4.06 ,and 1.59 )GPa respectively .While flexural strength has been increased in random manner with maximum value for 2 wt%(111 MPa). The hardness of nano composite increased with increase of SiO2 filler loading, it can be seen thatthe SiO2 filler greatly increased the hardness, which can be attributed to the higher hardness and moreuniform dispersion of SiO2 filler. The higher hardness is exhibited by the 5 wt% SiO2 filled compared to othernanocomposites. The results show that at 5wt% nano SiO2 content there is 11% increase in hardness