This paper presents an experimental investigation on the mechanical properties and microstructure of geopolymer repair materials mixed using fly ash (FA) and concrete substrates. An optimal combination of FA and concrete substrate was determined using the compressive test of geopolymer mortar mixed with various concrete substrate classes. It was found that the contribution of (C35/45) concrete substrates with the FA geopolymer mortar increases the 28-day bonding strength by 25.74 MPa. The microstructure analysis of the samples using scanning electron microscopy showed the denser structure owing to the availability of high calcium and iron elements distribution. These metal cations (Ca2+ and Fe3+) are available at OPC concrete substrate as a result from the hydration process reacted with alumina-silica sources of FA and formed calcium aluminate silicate hydrate (C-A-S-H) gels and Fe-bonding linkages.

In this study, the electrospray deposition (ESD) method was used to deposit carbon nanotubes (CNT) onto the surfaces of carbon fibers (CF) in order to produce hybrid carbon fiber-carbon nanotubes (CF-CNT) which is rarely reported in the past. Extreme high-resolution field emission scanning electron microscopy (XHR-FESEM), high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS) were used to analyse the hybrid carbon fiber-carbon nanotube (CF-CNT). The results demonstrated that CNT was successfully and homogenously distributed on the CF surface. Hybrid CF-CNT was then prepared and compared with CF without CNT deposition in terms of their tensile properties. Statistically, the tensile strength and the tensile modulus of the hybrid CF-CNT were increased by up to 3% and 25%, respectively, as compared to the CF without CNT deposition. The results indicated that the ESD method did not cause any reduction of tensile properties of hybrid CF-CNT. Based on this finding, it can be prominently identified some new and significant information of interest to researchers and industrialists working on CF based products.

Currently, the world of material requires intensive research to discover a new-class of materials those posses the properties like lower in weight, greater in strength and better in mechanical properties. This led to the study of light and strong alloys or composites. This study focuses to produce current novel aluminium composite with an appreciable density, good machinable characteristics, less corrosive, high strength, light weight and low manufacturing cost product. In this research, an aluminium metal matrix composites (AMMC) (Al-0.5Si-0.5Mg-2.5Cu-15SiC) was developed using the metallurgical powdered method and subjected to the investigation of erosion wear characteristics. Here the solid particle erosion test was conducted on AMMC samples. The article presents, the design of Taguchi experiments and statistical techniques of erosion wear characteristics and the behaviors of the composite. The rate of erosion wear found to decrease with increasing impact angle, regardless of the rate of impact. With higher impact velocity erosion rate increases but decreases with stand of distance.