Type 1 and Type 2 aggregate are different classifications of construction aggregate. Type 1 aggregate, also known as "DTp1" or "DTp Type 1," is a granular material that is typically made from crushed rock, such as limestone, granite, or gritstone. It is typically used in road construction and other transport infrastructure, also serving as a sturdy sub-base layer for building foundations. Type 2 aggregate is a material that is typically made from crushed rock, but is of a lower quality than Type 1. Type 1 aggregate is considered to be of higher quality, and is used for more critical applications, while Type 2 aggregate is finer and has a higher dust content.