In conjunction with the 25th Anniversary of its Dry-Block System, Grace Construction Products, is recognizing those companies that have achieved the greatest longevity in its Qualified Dry-Block Producer Program. Twelve companies, from Maine to Arizona, that have participated in the program for 20 years or more will be presented with a plaque honoring this milestone.

Crumb Colton Block of Rockford, Ill., which became a Dry-Block producer in 1983, holds the honors for the longest uninterrupted participation. Founded in 1914, the company has been in the block production business since 1937.

In addition, 11 companies became Qualified Dry-Block producers in 1984, and are celebrating their 20th anniversary this year. They are:

• Superlite Block of Phoenix, Ariz., part of the nationwide network of Oldcastle manufacturing facilities, produces architectural masonry and concrete aggregate products including concrete block as well as the traditional and antiqued paver and wall series.
  
  
• Elks Concrete Products of Lafayette, La., which is a manufacturer and supplier of concrete masonry products for the Baton Rouge area.
  
  
• Genest Concrete Works Inc. of Sanford, Maine, is one of New England's largest manufacturers and distributors of concrete pavers, retaining wall and architectural masonry products for the building trade.
  
  
• 4-D of Midland, Mich. is part of the nationwide network of Oldcastle manufacturing facilities, and has been supplying the Midwest with block, brick and related products since 1952.
  
  
• Arthur Whitcomb of Keene, N.H., also part of the nationwide network of Oldcastle manufacturing facilities, has been manufacturing and distributing wall and patio components, concrete block and precast, bricks, stone, pipe, culvert and masonry products to New England industries for more than 75 years.
  
  
• Barnes & Cone Inc. of Syracuse, N.Y., a long-standing, independent producer that has been manufacturing concrete masonry since 1926, specializes in manufacturing concrete masonry units (CMUs) from a variety of aggregates in creative shapes.
  
  
• Domine Builders Supply of Rochester, N.Y., which manufactures concrete blocks in hundreds of different shapes and sizes using specialized raw materials, mix designs and alternative curing methods, has served the needs of upstate and western New York since 1910.
  
  
• Tri County Block & Brick of Swanton, Ohio, which is family-owned and operated, is focused on producing CMUs and providing expert service.
  
  
• A. Duchini Inc. of Erie, Penn., one of the tri-state area's largest manufacturers of block and related masonry products, has been supplying building materials to the construction industry since 1932.
  
  
• Griswold and Company of Williston, Vt.., founded as a small ready mixed concrete producer in 1957, is now a diversified concrete company offering construction-related products and services, including U.L. fire-rated block, masonry supplies, high-tech wastewater treatment systems, precast (including architectural), and ready mixed concrete.
  
  
• Michigan Certified Concrete Products Inc., of Grand Rapids, Mich., has been a manufacturer of standard, scored, striated, split face and fluted masonry units since 1946.