What is Mortar?

Perhaps you’re considering putting together an assembly of glass block to build a fashionable window. It’s possible you’re thinking about building a glass brick wall for your yard. Maybe you want a basement for your dream home that you’re building. To do these tasks requires mortar. But you might find yourself wondering, what is mortar?

Mortar is the dried material in between brick gaps that holds together the glass brick wall structure you are building.  While it fills the gaps between the brick layout, it also prevents air and water from coming through.

The mortar mixture is routinely made up of sand, a binder, and water. Our GBS mixture is made up of a special blend of cement, sands, polymers, and fiber.

Mortar has been used for thousands of years. The first mixture used was simple mud and clay. For a very long time the most popular was lime mortar. The perks of lime were the soft and porous characteristics of the material. It was very useful for the stones and bricks used historically as it could handle movement well without cracking. Lime is still to this day called for when renovating old historical buildings.

The most common source of mortar used today is usually called Portland cement. This was invented in 1756, and became the most popular mortar by the 1930s. This made the drying process quicker, and was easier for the everyday builder. The ASTM C150 classifies it as a cement that hardens with water while also forming the useful water-resistant mortar we use today.

Mortar dries in four to twelve hours, and will achieve maximum strength in seven days. Approximately 25 Glass Block units measuring 8”x8”x3-7/8” with a 1/4” wide joint will require one 50-pound bag.

What Else Do You Need for a Glass Block Installation?

We use two mortar building systems for our Seves Glass Block. Along with free instructions, we sell the supply of glass block and material conveniently here at GBS.

A step-by-step tutorial on how to install glass block windows. What method you choose to use depends on your assignment:

(Link and download for instructions attached HERE)

The Mortar I System utilizes glass block perimeter channels on all four sides.

The Mortar II System uses expansion strips, panel reinforcing wires, and anchors.

Both projects use mortar mix and spacers.

The supplies needed for these assignments:

  1. Seves Glass Block 3-in or 4-in Series Glass Block
  2. Universal Spacers
  3. Perimeter Channels – 4-in (4″) or 3in (3″)
  4. Expansion Strips
  5. #12 x 1″ zinc-plated pan head screws
  6. Glass Block white premixed mortar
  7. Glass Block Sealant
  8. Latex paint, Weldbond® adhesive, or asphalt emulsion depending upon application
  9. White touch up paint (I System)
  10. #6 x 1” flat-headed screws (I System)
  11. Panel reinforcing (II System)
  12. Panel anchors (II System)

Contact GBS: The Glass Block Supply Co.

The Glass Block Supply Company has been a glass block supplier for over 30 years. As one of the largest providers of premium glass block products and accessories for homeowners, wholesalers, dealers, and contractors, we continue to expand our services to meet customers’ needs.

Our knowledgeable staff will help you with all project details, from pre-planning and design validation, to selecting all the correct materials. As one of the largest proud suppliers of SEVES Glass Block products, we are positioned to deliver our customers the best product, the best service, and the best value.

For more information, contact us at Contact Form

Contractors, Wholesale Supply Yards, and Architects call 877-427-8775


History of lime in mortar. (2019, May 14). Retrieved July 31, 2019, from   https://www.graymont.com/en/markets/building-construction/mortar/history-lime-mortar
What Is Mortar - Introduction To Mortar. (n.d.). Retrieved July 31, 2019, from https://www.theitcell.com/2018/07/what-is-mortar-introduction-to-mortar.html
"ASTM C 270-51T". ASTM
International. Retrieved July 31, 2019.