Planetary boundary layer. The planetary boundary layer (PBL) is also known as the atmospheric boundary layer (ABL). It is the lowest part of the atmosphere and its behavior is directly influenced by its contact with the ground. It responds to surface forcings in a timescale of an hour or less.
Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout. It was developed from other types of hydraulic lime in England in the mid 19th century and usually originates from limestone.
A Portland cement containing calcium aluminate to give rapid hardeningand setting properties: â¢ for repair and maintenance where rapid hardening is required, eg, fence posts, setting manholes, repairs to paths and steps. â¢ suitable for concrete, mortar, rendering and floor screeds.roperties â¢ Portland cement based. â¢ Contains calcium aluminate togiverapid setting and rapid hardeningproperties. â¢ Sets soon after placing and gainsstrength rapidly to allow normalservices to be brought back intooperation in a working day. â¢ Similar final strength to Blue CircleMastercrete Original.