Effect of Nanosilica and Carbon Nanotubes Addition on Mortar Mechanical and Durability Properties

Nowadays, nanomaterials are being extensively used in civil engineering works for improving their quality. Improved compressive strength, flexural strength, modulus of elasticity, and good durability performance of nanocomposites attracted the researcher's interest in understanding these nanomaterials’ behavior in cementitious composites. In the present paper, mechanical and durability properties of 1.0 wt% nanosilica (NS) and four different types of 0.3 wt% carbon nanotubes (CNTs) admixed cement mortar was assessed at 28, 56, 90 and 120 days under sulphate water curing. The outside diameters of CNTs are 10-20 nm and 30-50 nm, each type are un-treated and treated with COOH group, respectively. Results showed that flexural and compressive strength was improved for mortar sample admixed with nanomaterials than normal one. Also, nanomaterials came up as a good solution against abrasion and sulphate attacks. The durability is also enhanced for such mortar samples as the density increases, reducing the porosity and water absorption capacity. Resistivity results indicated negligible to low risk of corrosion, thus increasing the durability of these mortar samples. Overall, the sample formed with treated CNTs and 30nm – 50nm outside diameter gave better results than control specimen and other admixed mortar. Scanning Electron Microscopic  images were in strong correlation with the experimental results.