Nanotechnology is being applied in construction materials to improve their properties. Concrete can be made stronger and more durable using nano-silica particles. Glass can be made self-cleaning using titanium dioxide nanoparticles. Carbon nanotubes increase the strength and stiffness of concrete when added in small amounts. Nanoparticles are also used to strengthen steel and improve its resistance to fatigue and high temperatures. Nanotechnology offers advantages over conventional materials but high costs currently limit its widespread use in construction.