Experimental Study of the Effect of Nano-silica on the Mechanical Properties of Concrete/PET Composites

Effect of nanosilica on the mechanical and microstructural properties of a normal strength concrete produced in Nigeria

“…There was 85% increase in compressive strength of nano-concrete mix between 3 and 28 days of curing, whereas 10.81% compressive strength gain was recorded between 28 and 90 days of curing. This shows that the most significant increase in compressive strength of the nano-concrete mix was between 3 and 28 days of curing, which is in line with the conclusions of [12], [14] and [17] whose study considered a curing period of 3 to 28 days. This pattern of strength development in the optimal nano-concrete mix could be attributed to accelerated hydration of the mix leading to early consumption of portlandite and lime in the presence of nS.…”

“…This shows that nanoconcrete has higher tensile strength than an equivalent conventional concrete. Moreover, the improvement in splitting tensile strength of the nano-concrete mix was more pronounced at 7 days of curing than at the other curing ages as concluded by [14]. The early age splitting tensile strength gain of the nano-concrete mix might be due to accelerated hydration reaction on addition of optimal dosage of nS.…”

“…[13] investigated the behavior of binary concrete containing nS and nanoferric (nF) oxide and observed that the addition of optimal dosage of nS determined to be 1.5% by weight of cement improved the strength and durability characteristics of the concrete. In another study conducted and reported in [14] for Polyethylene Terephthalate (PET) bottle waste nano-concrete, it was found that the addition of optimal nS dosage determined to be 3% by weight of cement improved the compressive, tensile and flexural strengths of the PET-nS concrete, the study also showed an improvement in microstructural properties of the PET-nS concrete caused by pore reduction in the interfacial transition zone between PET and cement in the concrete, resulting in dense microstructure. The improvement in mechanical and microstructural properties of the nano-concrete obtained in the studies presented was determined on a short-term curing period of 28days, whereas, a better understanding of the strength development characteristic and microstructural properties improvement of the nano-concrete could be achieved when a medium or long term concrete curing period is considered.…”

A Review on Bubble Stability in Fresh Concrete: Mechanisms and Main Factors

“…Surface tension is one of the essential factors affecting the stability of bubbles [75,78,79]. Surface tension exerts its effect in the thin interfacial region between air and liquid [80], and the surface tension of liquid originates from the unbalanced forces on the molecules of liquid surface layer [81]. The forces on the molecules inside liquid can offset each other, so the molecules inside the liquid are at a state of force equilibrium; however, the attractive force from bulk molecules is much bigger than that of gas-phase molecules, because the density of the gas phase is lower, so that the molecules of the liquid surface layer are exposed to unbalanced forces which tends to pull the molecules of surface layer deep into the liquid, and the resultant force points to the liquid lower surface, as demonstrated in Figure 5 ( 'A' represents a molecule deep into the liquid, and the resultant force 'F A ' is equal to 'zero' which means a balanced force, while 'B' represents a molecule on the surface of the liquid and the resultant force 'F B ' is more than 'zero' which indicates an unbalanced force).…”

“…Nano-particles can promote interfacial interactions [157] and increase bubble stability [158]. Besides, the use of nano-particles could accelerate cement hydration, improve the mechanical properties of concrete [81], as well as enhance the resistance to water penetration [159]. The application of nano-particles in cement-based material is a current trend [158,160,161].…”