SS250 vs ST-AF information below:

Shotcrete SS250 Liquid Accelerator

SS250 is our workhorse and is used all over the world since the 1980’s.

A modified silicate-based accelerator, Shot-Set 250 Liquid Accelerator provides better adhesion, increasing thickness on the first pass.

Shot-Set 250 is easier to work with than other accelerators because its' higher viscosity allows the injected accelerator to blend more completely with the shotcrete mix, creating a more predictable, homogeneous result at lower dosages (two to six percent). With its unique chemical composition, Shot-Set 250 doesn't generate heat to accelerate like other products. So, there's negligible strength loss.

Shot-Set 250 is non-toxic containing no chlorides, nitrates or aluminates, and increases safety underground. Plus, it's compatible with all cement types, and meets or exceeds all ASTM, ACI and other requirements for "in-situ" shotcrete testing. At a dosage rate of two to four percent by weight of the cement, petrographic, tests show no deterioration of "in-place" shotcrete after several years.

Basic Shot-Set 250 Specifications:

• Available in 275 gallon totes and in bulk

• Shelf life of two years plus when properly stored

Shot-Set 250 is compatible with all types of cement, but certain Polycarboxylate add mixtures may affect the compatibility. A Naphthalin based w/r always work well.

Please note: The suggested mix design and requirements below are for example only. Mix designs and requirements will vary according to application and desired results.

This liquid, non caustic accelerator has a proven track record. With dosages of two to five percent by weight of cement, SS250 Liquid Accelerator lowers rebound to 10 percent or less - even overhead; it allows the nozzle person to place thick layers.

ST-ALKALI FREE Accelerator

ST-AF has a low viscosity, does not coagulate so no need to remix every day.

When your shotcreting project requires super adhesion and high first-pass thickness (5 to 6 inches), your choice is ST-ALKALI FREE.

This liquid accelerator blends easily and completely and can be injected directly at the shotcrete nozzle, permitting low dosages (2% to 6% by weight of cement). Within seconds it generates low heat that lasts for approximately 15 minutes outlasting the initial set stage to enable another pass without fallout and without compromising final strength.

ST-ALKALI FREE provides extreme workability and meets or exceeds ASTM, ACI, and all other "in-situ" shotcrete requirements for initial and final strength. It is ideal for use in mines, tunnels, piers, soil stabilization, bridge repair and any other shotcrete applications.

This accelerator is a stable modified alum in an aqueous solution. It is designed for wet or dry process shotcreteing applications. Because it is alkali free, non-caustic, non-toxic, and free of chlorides or nitrates, ST-ALKALI FREE is extremely safe for all applications, even underground or in other confined areas. ST-ALKALI FREE is the most environmentally safe accelerator available.

ST-ALKALI FREE is a cost saver, too. In addition to lower dosages, you get better adhesion, which means that more material stays in place. There is minimum rebound and cleanup is easy.

Properties:
Low Dosages (2% to 6% by weight of cement)
Only compatible with type 1 cement
Meets or Exceeds ASTM and ACI Requirements

Applications:
Mines
Tunnels
Piers
Soil Stabilization
Bridge Repair

St-AF is only compatible with type 1 cement. Various Polycarboxylate add mixtures may affect the compatibility, and if you need more than 8% by weight of cement there can be problems so an in-situation testing should be done. A naphthalin based admixture always work well

Provides extreme workability. When your shotcrete project calls for super adhesion and high “first-pass” thickness, ST-ALKALI FREE is the one. This homogenous liquid accelerator blends easily and completely. It requires low dosage rates and is also compatible with virtually all cement types.