rigid non-metallic pipes and pipe fittings, namely, concrete pipes, concrete cylinder pipes, reinforced concrete pipes and fittings for such pipes for use in water systems, sewage systems, cooling water outfalls and tunnel liners, [acid-proof cement for building purposes; polymerizable and hardenable resin compositions for use as toppings for concrete and masonry flooring; coating materials in the nature of grout for coating steel structures; chemical-resistant cements, mortars, grouts and concretes for industrial, municipal and commercial use]