ST-Alkali Free Accelerator
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)Compatible with Most Cement TypesMeets or Exceeds ASTM and ACI Requirements
Applications:MinesTunnelsPiersSoil StabilizationBridge Repair
Basic ST-ALKALI FREE specifications:Furnished in 275-gallon (1,000 liters) plastic totes or bulk.Net weight: 3,060 pounds (1,400 kilograms) per plastic tote.Specific gravity: 1.35 Shelf life of 2 plus years. Not temperature sensitive.Corrosive to metal in pure solution.In permanent solution, no agitation is necessary, giving full flow control during application.
Note: The suggested mix design and requirements below are for example only. Mix designs and requirements will vary according to the application.
High Performance ST-ALKALI FREE Requirements:
Compressive Strength - Minimum*
Material Proportions
| kg/m3* | lb./cu.yd. | |
| Cement Type | 400 kg/m3 | 675 lb./cu.yd. |
| Silica Fume (optional) | 40 kg/m3 | 67 lb./cu.yd |
| 10mm Coarse Aggregate 3/8 | 420 kg/m3 | 710 lb./cu.yd. |
| Concrete Sand Well Graded F.M.-2.7 | 1130 kg/m3 | 1900 lb./cu.yd. |
| Water Reducing Admixture | 1 liter | 25 fl. oz. |
| Superplasticizer | 4 liter | 100 fl. oz. |
| Air Entraining Mixture | *as required | |
| Steel Fiber (if required) | 60 kg/m3 | 100 lb./cu.yd. |
| Shot-Set 250 3% | 11 liter | .26 lbs. |
| Water | 190 kg/m3 | 320 lb./cu.yd. |
| Total | 2255 | 3800 |
High Performance ST-ALKALI FREE Sample Mix Design
Material
Proportions
| Cement Type | 400 kg/m3 | 675 lb./cu.yd. |
| Pozzolan (optional) | 40 kg/m3 | 67 lb./cu.yd |
| 10mm Coarse Aggregate 3/8 | 420 kg/m3 | 710 lb./cu.yd. |
| Concrete Sand Well Graded F.M.-2.7 | 1130 kg/m3 | 1900 lb./cu.yd. |
| Water Reducing Admixture | 1 liter | 25 fl. oz. |
| Superplasticizer | 4 liter | 100 fl. oz. |
| Air Entraining Mixture | as required | as required |
| Synthetic Fiber (if required) | 4.53 kg/m3 | 10 lb./cu.yd. |
| ST-ALKALI FREE | 11 liter | .26 lbs. |
| Water | 190 kg/m3 | 320 lb./cu.yd. |
Material Safety Data Sheets
Click here to view MSDS data sheets for ST-Alkali Free.
Click here for a printable ST-Alkali Free product sheet