Rapid Hardening GFRC Mix Design

Below is a mix design for rapid hardening GFRC applications using Calcium Sulfoaluminate Cements (CSA).   Mix will set based upon ambient & mix temperatures along with amount of retarder use.  By increasing the amount of CSA cement you can have a mix that can reach final set in as little as 10 minutes.  The mix design below produces approximately 1/3 cu. ft.and will reach final set in about one hour in 75 degree temperature.

CSA GFRC

Portland (Type 1)

15.5 lbs

CSA cement (20% cement replacement)

4.5

Alto-Pozz

3 lbs

CSA Retarder

10-42 grams

Silica Sand (#40-50 sieve)

23 lbs

Water (use ice as part to slow initial set)

6.5-7 lbs

KongKrete™ Liquid Acrylic Polymer

2.3lbs

PVA 8mm fibers  (optional/ Not needed in backer)

85 grams

Optimum 380 superplasticize

23-42 mL

C-64 Defoaming & Densifying admixture

5-10 mL

For Backer Coat Only

½” or ¾” AR glass fibers (Add last after mixed)

2.6 lbs

Set times for different additions of CSA

The following table provides useful information regarding the average strength of CSA Cement mixes using different percentages with Greencastle Type I cement (except for 100% CSA test w/c=0.35). All data was obtained per ASTM C-109 for w/c=0.50.

CSA

Set Time

3 Hrs. (psi)

24 Hrs. (psi)

28 Days (psi)

20%

70 min.

N/A

1610

N/A

30%

40 min.

1060

2490

N/A

40%

30 min.

1770

2730

N/A

50%

20 min.

2840

4290

N/A

60%

17 min.

3560

4800

N/A

100%

11 min.

3720

4940

8700