The maximum depth of pour is limited by exotherm.

What is exotherm?

Exotherm is the heat generated by the system, above the cure temperature, during the reaction. The amount of heat (exotherm) generated depends on the epoxy formulation and the (mass) amount of product being reacted at one time. The exotherm generated by resins and/or hardeners heated to reduce the viscosity will be greater than without the application of heat.

As a general rule, fast reacting epoxy systems generate higher exotherm during the reaction.

If the exothermic heat is excessive, components of the system may boil before cure. Additionally, the system might “gel” at an elevated temperature and shrinkage stresses will be incorporated as it cools.

What influences exotherm?

1. The reactivity of the system being used
2. The temperature of the system components themselves
3. The temperature & thermal mass of the surrounding structure
4. The ambient temperature conditions

Why is temperature so important?

Temperature influences the rate of all chemical reactions. Curing rates are accelerated at higher temperatures.  Assume a halving of cure time for every 15°C increase.

So what is the practical situation?

EpiMax 225 Construction Grade Epoxy Binder extended with EA2 / EA3 / EA37 (washed, dried pea gravel / quartz blend)

In most situations, with surrounding steel or concrete equipment (large heat sinks), at 20 – 23 deg C, EpiMax 225 combined with EpiMax EA2 at 1:2.5 pbv, with all components pre-conditioned at or below 25 deg C, will perform satisfactorily with single pours of up to 75 mm.

In most situations, with surrounding steel or concrete equipment (large heat sinks), at 20 – 23 deg C, EpiMax 225 combined with EpiMax EA3 at 1:2.5 pbv, with all components pre-conditioned at or below 25 deg C, will perform satisfactorily with single pours of up to 100 mm.

In most situations, with surrounding steel or concrete equipment (large heat sinks), at 20 – 23 deg C, EpiMax 225 combined with EpiMax EA37 (washed, dried pea gravel / quartz blend) at 1:2.75 pbv, with all components pre-conditioned at or below 25 deg C, will perform satisfactorily with single pours of up to 150 mm.

It is always recommended that, when approaching the limits, the possibility of two separate pours should be considered.

Note that EA37 is a well graded blend, combining 5 – 7 mm pea gravel, 16/30 quartz and 0.2 mm quartz. It is usually prepared on site using locally sourced washed, dried components.

Well graded blends contain less air and can provide higher strengths

EpiMax 480 Precision Epoxy Grout

In most situations, with surrounding steel or concrete equipment (large heat sinks), at 20 – 23 deg C, EpiMax 480, with pre-conditioned hardener and compound at or below 25 deg C, will perform satisfactorily with single pours of up to 45 mm.

However, since some exotherm might result in a small amount of liquid stage expansion, some stresses could result with particular applications at depths of 45 mm.

It is always recommended that, when approaching the 45 mm limit, the possibility of two separate pours should be considered.

EpiMax 480 UT Precision Extreme Life Epoxy Grout

In most situations, with surrounding steel or concrete equipment (large heat sinks), at 20 – 23 deg C, EpiMax 480 UT, with pre-conditioned hardener and compound at or below 25 deg C, will perform satisfactorily with single pours of up to 150 mm.

However, since some exotherm might result in a small amount of liquid stage expansion, some stresses could result with particular applications at depths of 150 mm.

It is always recommended that, when approaching the 150 mm limit, the possibility of two separate pours should be considered.

EpiMax 480 UT Precision Extreme Life Epoxy Grout extended with 16/30 Aggregate

In most situations, with surrounding steel or concrete equipment (large heat sinks), at 20 – 23 deg C, EpiMax 480 UT with 16/30 Aggregate at 1:3 pbv, with all components pre-conditioned at or below 25 deg C, will perform satisfactorily with single pours of up to 225 mm.

However, since some exotherm might result in a small amount of liquid stage expansion, some stresses could result with particular applications at depths of 225 mm.

It is always recommended that, when approaching the 225 mm limit, the possibility of two separate pours should be considered.