Concrete curing is affected by both temperature and water and it is essential to provide the conditions for its optimization. Traditional external curing has been effectively utilized for conventional concrete in order to defer the drying of concrete, which causes shrinkage and possibly cracking, and to promote the continued hydration of the cementitious binder. However, for certain concrete, external curing might not be enough.
Concrete curing technology has been challenged by the advent of modern concrete mixes. This includes high performance concrete (HPC), decorative concrete, and pervious concrete among others. Also, in order to improve durability, many concrete mixtures incorporate supplementary cementitious materials (SCM) and/or utilize a much lower w/cm ratio. Both low w/cm and SCM present new challenges to conventional curing. Low w/cm decreases cement particle spacing leading to increased autogenous shrinkage while SCM generally requires moist curing for longer periods to hydrate.
HydroMax® Internal Curing Admixture provides an internal source of water necessary to replace that consumed by chemical shrinkage during hydration. As the cement hydrates, this water is drawn from the pores in the admixture’s water reservoirs and absorbed into the pores of the cement paste. This process can minimize the development of autogenous shrinkage, help in avoiding early-age cracking, and improve strength.
For the most effective way to cure pervious concrete, we strongly advise our customers to include HydroMax® Internal Curing Admixture into a well balanced pervious concrete mix design followed by the application of PerviousShield™ to the finished product.
There are several products on the market now that claim to offer internal curing but by definition, internal curing is “the process by which the hydration of cement occurs because of the availability of additional internal water that is not part of the mixing water.” No other product can make such a claim.
How this works is that if you have a well balanced mix design that calls for 18 gallons of water per yard, then you would add an additional 3 gallons per yard that gets bound up by the HydroMax®. When the cement in the mix has used up all of the available batch water, then the cements pulls additional water from the HydroMax® and hydration continues offering higher strengths and a better product.