Concrete Acceleration
Calcium chloride is the preferred additive for completing cement jobs as quickly and economically as possible. Accelerate cement hydration and reduce application set time by as much as two-thirds with calcium chloride.
Where To Use
Calcium chloride accelerates cement hydration and reduces set time for concrete applications by as much as two-thirds. This helps contractors produce concrete faster and complete jobs as quickly and economically as possible, particularly in colder weather. Calcium chloride can also improve mix workability, improve the strength of air-entrained concrete, and reduce bleeding by enabling earlier final finishing.
Research has shown that concrete produced with 2% calcium chloride exhibits equivalent cure strength at 50°F as plain concrete at 70°F. Set times below 50°F will be longer, but the accelerated cure rate will still be greater than that of plain concrete.
Recommended Products
Anhydrous Calcium Chloride 94-97% Mini-Pellets
DOWFLAKE® Xtra 83-87% Calcium Chloride Flakes
Concrete Acceleration FAQs
First, determine the amount of dry calcium chloride to mix with water using our helpful Making Solutions Calculator tool.
Always start with cool water and add the solid calcium chloride slowly to the water while continuously mixing. Significant heat is released when dissolving solid calcium chloride, and a temperature increase will occur. For example, when dissolving DOWFLAKE® Xtra 83-87% Calcium Chloride Flakes while making up a 30% solution, the temperature can be expected to increase almost 84°F.
If solids are allowed to sit motionless while in contact with water, a hard cake will form that will be slow to dissolve.
Please consult our Diluting Solutions Calculator, which covers three different options:
- Diluting with water
- Diluting with a lower concentration calcium chloride solution
- Diluting with both water and a lower concentration calcium chloride solution
The pH reading for an undiluted sample of 35% solution is approximately 9. OxyChem calcium chloride products are alkaline due to the presence of a slight calcium hydroxide impurity.
Accurate and consistent pH measurement in concentrated salt solutions can be challenging. Results vary depending on the pH probe used and the degree of sample dilution.
No, OxyChem does not have a calcium chloride dihydrate product. DOWFLAKE® Xtra is the closest to a dihydrate concentration.
Calcium chloride dihydrate has two water molecules for every one calcium chloride molecule, giving an overall calcium chloride concentration of 75.5%. OxyChem’s DOWFLAKE® Xtra product contains a minimum of 83% calcium chloride, making it more concentrated than the calcium chloride dihydrate flake on the market.
Store product in a dry area, and tightly reseal after each use. To maintain product quality while in storage, solid calcium chloride must be protected from moisture. If the product is on a pallet covered by an intact plastic shroud, it can be stored outdoors on a well-drained surface. If the shroud is torn, pierced, or removed, the palletized product should be stored indoors or under a waterproof covering.
For additional information, see our Calcium Chloride Handbook.
The preferred material of construction for large liquid storage tanks is carbon steel with an epoxy-based interior coating and a durable, high-quality coating on the exterior. Non-metallic materials, such as fiberglass or plastic, work well for smaller tanks storing product at ambient temperature; however, these materials are not as durable as carbon steel, and they lose strength at high temperature.
Common stainless steels are not recommended for liquid calcium chloride storage as they are subject to chloride stress corrosion cracking, even at temperatures as low as 100°F (38°C).
For additional information, see our Calcium Chloride Handbook.
When properly stored to protect from moisture contact, the expected shelf life for solid calcium chloride products is 36 months from the date of manufacture. Calcium chloride does not degrade or deteriorate; however, the shelf life is limited based on the potential for moisture intrusion into the product, which may cause product clumping. Solid calcium chloride absorbs moisture from the air (i.e., is hygroscopic), even to the point of converting to liquid brine (i.e., is deliquescent).
OxyChem calcium chloride products deliver reliable, effective deicing performance on concrete surfaces that are at least one year old and properly designed, constructed, and cured for winter conditions. When concrete meets these standards, it is better equipped to handle deicing applications. Surfaces that are more porous or not fully cured may be more vulnerable to natural freeze–thaw cycles, where absorbed moisture can refreeze and potentially lead to spalling or scaling.
For expert guidance, we recommend consulting the American Concrete Institute Committee 201.
The amount of calcium chloride used should not exceed 2% and application rates should vary with temperature.
Preferably, add calcium chloride solution to aggregates in the mixer drum or as a portion of the mixing water. Add calcium chloride at the ready-mix plant if the concrete will be discharged within one hour of the start of mixing. Otherwise, add it at the job site, mixing for at least three minutes or 30 revolutions of the mixer, whichever is longer.
If dry calcium chloride is used, it should be free of lumps and added to aggregates in the mixer drum before mixing, or to the mixed concrete just before discharge.
Please refer to the publication Calcium Chloride in Portland Cement Concrete for more complete information about the use of calcium chloride as an accelerating admixture.
Consult the most recent reports from the following American Concrete Institute (ACI) committees for information about the amounts of calcium chloride that are allowed in concrete under various exposure conditions, and conditions in which calcium chloride should not be used. Relevant reports include:
ACI 201 Durability of Concrete
ACI 212 Admixtures for Concrete
ACI 222 Corrosion of Metals in Concrete
ACI 306 Cold Weather Concreting
ACI 318 Standard Building Code for Reinforced Concrete
