DYNA® THERMOBOND 915 is a dry pre-blended hydraulic refractory mortar and is designed for setting masonry units in fireplaces, fire pits, and chimney applications. It provides high temperature resistance. It provides thermal shock and temperature resistance to 1400°C (2550°F).
It is suitable for both indoor and outdoor applications.


- Laying fire brick or clay masonry in high heat applications
- For use in outdoor fire pits and fireplaces exposed to high heat
- Setting of clay flue liners
- Parging or setting of a smoke chamber
- Use to construct fireplaces, barbecues and chimneys
- Use to tuck point fireplaces, barbeques and chimneys
- Excellent for exterior and interior applications
- Can be used for repair, preservation and restoration work
- Install with conventional masonry practices and conventional masonry joints


- ASTM C-199
- ASTM C-1283
- ASTM E-136
- ASTM C-198
- NFPA-211
- IRC (International Residential Codes)
- IBC (International Building Code)


- Resistant to heat to 1400°C (2550°F)
- Hydraulic setting and non-water soluble
- Used for indoor and outdoor applications. It is air entrained for freeze-thaw resistance
- Freeze / thaw resistant
- Great workability and long pot / board life
- Greater strength than type S Masonry Mortar. Can be used for above grade, below grade and load bearing applications
- Cures quicker than conventional masonry mortar >30 MPa in 24 hours
- Easy to use. Ready to use, just add water, mix and then use
- Can be colored if desired with conventional masonry mortar pigments


- Install only at temperatures between 0°C and 35°C (32°F and 95°F)
- Do not apply to frozen or frost filled surfaces
- Do not apply in direct sunlight on hot and windy days
- Do not apply in outdoor applications when the subject work will be exposed to rain within 24
hours after application
- Allow the mortar to cure for 48 hours before heat is applied

SECTIONS     -    042000



- All substrates should be structurally sound, stable, dry, clean and free of any substances thatmay reduce or prevent proper adhesion.
- Painted surfaces must be completely sanded, scrapped, or chipped to promote adhesion.  Surfaces may be cleaned with a DYNA brand of cleaner if thoroughly flushed and neutralized.
- Dry, dusty concrete slabs or masonry should be dampened and excess water swept off. Installation may be made on a damp surface.


Read the SDS for this product thoroughly and wear the appropriate safety gear.

1. Into a clean mixing vessel, pour about 3.25 to 3.75 L (3.5 to 4 U.S. qts.) of cool clean potable water.
2. Gradually add 50 lbs. (22,7 kg) of powder while slowly mixing.
3. Use a low-speed mixing drill (at about 300 rpm). Mix thoroughly until mixture becomes a smooth, homogenous, and lump-free consistency. Avoid prolonged mixing as this may entrain air.
4. Allow the mortar to stand (“slake”) for 3 minutes. Remix but do not add more water.
5. Wash your tools immediately after mixing.
6. The pot life of the mix is between 1 and 2 hours. If mixture becomes heavy or stiff, remix without adding more water or powder.

1. Pour the full bag into a mortar mixing tub.
2. Create a trough in the powder and pour about 3.25 to 3.75 L (3.5 to 4 U.S. qts.) of cool clean potable water in the trough.
3. Mix with a shovel or hoe to a smooth, homogeneous, and lump-free consistency.
4. Allow the mortar to stand (“slake”) for 3 minutes. Remix but do not add more water.
5. Wash your tools immediately after mixing.
6. The pot life of the mix is between 1 and 2 hours. If mixture becomes heavy or stiff, remix without adding more water or powder. The use of warm water or high ambient temperatures will shorten the pot life and accelerate the cure time.


1. Fire brick and clay brick typically use 3 mm (1/8”) to 9 mm (3/8”) joint thickness. For clay flue liners a 3 mm (1/8”) is most common.
2. It is recommended that you contact your brick manufacturer and obtain installation guidelines and their recommended joint thickness to use.


A 22.7 kg (50 lb.) bag of DYNA® THERMOBOND 915 will yield approximately 80 to 100 fire bricks at 3 mm (1/8”) thickness.


Refer to the Safety Data Sheet (SDS) for additional information on this product.


DYNA® THERMOBOND 915  is available in 22.7 kg (50 lbs) Bag.


Protect site-work from freezing and complete water immersion for at least 48 hours after the completion of the work performed. Protect walls from impact, heavy hammering and vibration on opposite and adjacent walls for at least 14 days after installation. When working in cold temperatures or high humidity protect the site-work for an extended period of time to permit the mortar to adequately cure.


Wash your tools immediately after mixing. Clean your hands and tools with water while the mortar is wet.


This product is corrosive as it contains Portland cement. Portland cement when mixed withwater results in a solution of calcium hydroxide and is therefore injurious to the eyes and can cause skin irritation. Therefore, avoid eye contact and prolonged contact with the skin. Protect eyes with goggles and skin with waterproof gloves. If splashed in eyes, flush thoroughly for at least 15 minutes and consult a physician immediately. If product is ingested, consult a physician immediately.


DYNA shall not be liable for incidental and consequential damages, indirectly or directly sustained, nor for any loss by application of these goods not in accordance with the printed instructions or for other than the intended use. Before using the user shall determine the suitability of the product for its intended use and the user will assume all risks and liabilities that may arise in connection therewith. DYNA’s liability is expressly limited to the replacement of defective goods. Any claim shall be deemed waived unless the claim is made in writing to DYNA within 15 days
from the date it was, or reasonably should have been,
discovered that the product was defective.


This premium quality product was designed to satisfy the user. If you are not satisfied after Surface Testing on a small area, please contact our technical service department immediately.
NO WARRANTIES expressed or implied are offered by DYNA. The Manufacturer’s liability is limited to the replacement of products proven defective.
The user assumes all risks and liabilities associated with the use of this product.

Product Performance

Test Procedure Conditions Test Results
Compressive Strength at 20°C (68°F) 24 hrs.
at 800°C (1472°F) 6 hrs.
at 1000°C (1832°F) 6 hrs.
at 20°C (68°F) 28 days
30 MPa (4351 psi)
12 MPa (1740 psi)
9 MPa (1305 psi)
38 MPa (5500 psi)
Flexural Strength at 20°C (68°F) 28 days 5 MPa (725 psi)
ASTM C-199 Pier Test at 1510°C (2750°F) No cracks or shrinkage
ASTM C-198 Bonding Strength at 1343°C (2450°F) 5.15 MPa (750 psi)

at 22°C (72°F) and 50% relative humidity
Shelf life 1 year
Pot life / Board Life 1 to 2 hours
Initial Cure 24 hours
Final Cure 7 days
VOCs (Rule #1168 of California's SCAQMD) 0 g/L.


Product Code Size And Color
915G50 22.7 kg (50 lbs.) Grey
915W50 22.7 kg (50 lbs.) White