With a larger acceptability of crystalline technology by government and private contractors, there are many international and Indian players who have entered the arena in crystalline waterproofing technology. There has been a mushrooming of new products, both locally developed and imported that want a share of their pie. But not all products are effective. Pricing of crystalline products can vary drastically and so can the final results. What should one consider while choosing an effective and economical crystalline solution? What are the parameters that set one crystalline technology apart from the other? Let’s answer a few of these.
One of the most respected concrete bodies ACI has clearly defined standards of PRAH and PRAN. It explains in great details the difference between being hydrophobic and hydrophilic. According to ACI 212.10 chapter 15, an effective crystalline product reduces the permeability. An effective solution, it works under high hydrostatic pressure and still keeps the structure waterproof. In the same chapter, there is a detailed selection and evaluation process which expresses – “The distinction should be made based on the admixture’s demonstrated the ability to reduce water penetration under the expected service conditions. It should be emphasized that a PRAN should not be used in the presence of hydrostatic pressure if the penetration of water is expected to damage the structure or compromise interior spaces.”
An effective crystalline solution is a solution that waterproofs the structure for the entirety of its life cycle. For this, there is an essential requirement for the product to be designed chemically to do so. Where a majority of crystalline products available in the market currently react with free lime for waterproofing, an effective and durable crystalline solution reacts with unhydrated cement and moisture. The difference can be seen over a long period of time. When an admixture works with free lime (cement by product), its effectiveness is much shorter in terms of years as free lime reacts with other pozzolana and additives. On the other hand, unhydrated cement remains longer in the concrete.
Another chemical parameter to check before choosing the right crystalline solution is the presence of sterates. There are certain systems that have Stearates, Silicon ,Wax or bitumen emulsion either as a whole or as compounds in the waterproofing system. These systems are normally hydrophobic and act as a coating to the capillary surfaces and block some pores. And while these might be a preferred solution by many, sterates have a negative impact on the structure and do not work under the high hydrostatic head. These compounds produce the compressive strength typically 10 to 15 % of the plain concrete and reduce the effectiveness under high hydrostatics head. Sterates do not block the entrance of water into the concrete, in fact, they affect the life of the concrete as they eat into the molecular structure of the concrete and leave behind a void that needs to be filled by admixtures and other additives.
Recently a battle on the quantity of material (dosage) to be added to the structure has become a point of the contest, however, while choosing an effective and durable crystalline solution in large projects, does not make a huge difference given the complete life cycle and repair needs of the structure. Giving the right dosage, is the most essential part of effective waterproofing and that depends on depending on the quality of concrete, the laying practices and the specific needs of site. Trials and sampling are the ways to go forward as every site has its unique requirements.
And during these of trials and tests, it can sometimes be extremely confusing for a decision maker to compare test results of various products as the variation may be very high. But it is essential to ask a few questions before comparing 2 test results.
Is the lab certified?
Did the lab make the samples, or did the lab get the made samples?
Have the reports mentioned complete details about the sample and the testing (for e.g. do they identify and describe the mix design of the sample, the process and code of testing etc.)
Has the test been done for the correct amount of time?
Getting the right answers to these questions can lead you to the right crystalline waterproofing solution.
Also, never forget that most Crystalline products suppliers/applicators extend Warranty up to TEN years. But, the warranty only covers repairs and an ineffective crystalline solution, the damage to structure takes place internally through water seepage. By the time the signs show on the surface, the durability of the structure has already been compromised, so it is essential to identify the right crystalline waterproofing structure that stands out from the competition in chemical, physical and performance qualities.