This is an updated answer. For a layman like me rounded sands occur in two forms. Beach sand and desert sand. Beach sand (sold as play sand) has a superior outcome in concrete surface restoration based upon my experience and experimentation in Missouri, US.
At the beginning of the 20th century, the U.S. production of construction sand and gravel was relatively small and its uses limited. Today, annual sand and gravel production tonnage ranks second in the non-fuel minerals industry after crushed stone.
Many naturally occurring substances, such as clay, sand, wood and rocks, even twigs and leaves have been used to construct buildings. Apart from naturally occurring materials, many man-made products are in use, some more and some less synthetic.
Why Manufactured Sand is Used? Manufactured sand is an alternative for river sand. Due to fast growing construction industry, the demand for sand has increased tremendously, causing deficiency of suitable river sand in most part of the word.
Following table shows unit weight of materials used at construction site. Please note this is for reference purpose only and may vary from place and type of material. Please note this is for reference purpose only and may vary from place and type of material.