Improve the mechanical properties of lightweight foamed concrete by using nanomodified sand

The current study aims to solve the agglomeration problem of carbon nanotubes (CNTs). Many researchers have been solved this task by using dispersion by ultrasonic along with adding a dispersant to prevent carbon precipitation for as long as possible. However, some researchers have confirmed that the dispersed materials affect the mechanical properties of the concrete when added with carbon nanotubes. This problem was solved in this work via the growth of the carbon nanotubes on a sand surface using the chemical vapor deposition method (CVD). The modified sand by (CNTs) was incorporated into the main components of the lightweight concrete. A catalyst solution for the carbon nanotubes growth on the sand surface was prepared by a chemical vapor deposition method. Through this method, the direct use of carbon nanotubes could be achieved without using dispersion methods. Also, this method ensured the distribution of the nanomodified sand grains in the concrete body. In addition, two types of solutions were applied for controlling the density of the carbon nanotubes growing on the sand surface. The first method was without water dilution, while the second was with water dilution. The percentages of the modified sand were 0.1%, 0.2%, 0.5% and 1.0% of the sand weight, and the particle sizes were 0.63 mm, 0.315 mm and 0.16 mm. The results showed an increase of the compressive strength of the sample containing modified sand without diluted 11.0%, 19.0%, 29.0%, and 40.0%, diluted sand 11.0%, 20.0%, 26.0%, and 35.2%, for additives 0.1%, 0.2%, 0.5%, and 1.0% from the sand weight. The highest increase of the flexural strength of the sample containing modified without diluted sand was 22.0%, 28.0%, 36.0% and 45.0%, and for diluted sand 15.8%, 19.7%, 18.1%, and 20.3% for additives 0.1%, 0.2%, 0.5% and 1.0% from the sand weight.