Girish C Dubey, President, STAR, INC.
The spring season of the year ushers in many transformations in nature and fills everyone with new vitality and enthusiasm. The spring is especially exciting for us in the sealcoating industry, who can barely wait for the start of the new season, after the idle months of winter. As sealcoating professionals, you must put the best foot forward to set the right tone for the rest of the season. Do not let errors or oversight turn into “spring allergies” that may become perennial; bad reputation is hard to shake off. For an effective commencement for the season, the sealcoating projects have to be planned meticulously and executed precisely in a cost effective manner, the stages of which are delineated in the following paragraphs.
Planning, Pricing & Thorough Preparation
a. Job inspection and Costing-New Jobs. In the spring you will have shorter workdays and will have to contend with low temperatures in early mornings and evenings when sealer shall not be applied. In other words, a normal 1 day job may take 2 days, which means more travel time, overheads, payroll, and other expenses that shall be factored in bid proposals and should be charged at a different rate than a job estimated for mid summer.
b. Carry over work from the last season- In many cases, the spring work may entail the jobs left over from the previous year that were not completed due to early winter setting or just time constraints. You should personally evaluate the property before showing up to perform the work. It is likely that asphalt may have deteriorated over the winter and needs more crack repairs/patching or replacement work before sealcoating can be performed. Hopefully, you have allowed for such contingencies in your bid proposal to recover your costs. If not, then it is a lesson for the future.
c. New Projects-Inspection prior to bidding. The inspection shall include the;
· Assessment of the over all condition and integrity of the asphalt pavement. i.e. the age, surface deterioration, any base or sub-base issues, and the drainage of the asphalt pavement.
· New asphalt installations, done in late fall of the previous year or early spring of the current year shall be checked for their suitability for sealcoatings. For the optimum performance of the sealcoating, it is essential that the asphalt pavement be allowed to age sufficiently to rid of its surface oils. Perform the “water-break-free-test” by casting a gallon of clean water out over he surface. If the water sheets out without crawling or showing oil rings, the surface is ready for sealcoating. If the asphalt fails this test, it shall be allowed additional time for cure and re-tested.
· Surface Profile of New Asphalt Installations. Observe the surface profile of the new asphalt closely to make sure that the asphalt was properly laid and compacted. Overly open, rough or “boney” surface appearance may be indicative of either cooling of the hot mix asphalt or inadequate compaction during paving. Report any abnormalities to the property owner and have him seek response from the paving contractor.
d. Equipment Check:
Make sure that your equipment is in good working condition before you venture out to sealcoat. It is preferred that you start the season with a clean tank; check the agitation, pump, gauges, compressors, hoses, spray tips, meaning the whole nine yards.
More rigorous checks are warranted if you have material left over in your tank from last year. In our experience, many contractors do only cursory checks; start their rig, open the spray for a quick minute or two and think they are ready to go. What they do not see in that amount of time are the floating chunks, caked sealer on the walls of the tank, settled sealer in the bottom and debris. All or any of these can cause equipment failure or the poor or the failed sealer performance, costing time, money and future jobs. Just test running the agitation and compressor is not enough. Start the agitation and circulate the material in the tank for a minimum of 15 minutes. Make sure that it is free from chunks and debris. Put the spray wand through the top of the tank and allow running in open mode for a minimum of 15 minutes, to check for any clogs in the lines. The material in the tank shall be uniform, hoses clear and machine ready to spray.
e. Materials Checks.
· Sealcoating in your holding tanks and application rigs- Make absolutely sure that the martials that your stored over the winter months are still in good condition, meaning that they meet all the original quality standards, as supplied by your manufacturer. Would it be a safe assumption that you kept the material agitated in the holding tanks on a regular basis? Still, just prior to starting in the spring, agitate the material in holding tank or the rig and submit samples to your supplier to make sure that they are still within the quality control (Q.C.) parameters. You may be advised to add some water, to adjust the solids or a pinch of biocide to take care of the foul odor, if any. Let the manufacturer instruct and you comply.
· Additives, Traffic Marking Paints, Cold Pour Crack Fillers, and other water-based products are still in good condition i.e. in their original consistency and fluidity. Any hardening, settling, watery separation or cottage cheese chunkiness may indicate freezing damage.
Sealcoating Application- The finer Points.
In this section, we will confine our discussions only to the finer points in application, which are tailored with consideration to ambient conditions in early spring months and the ravages of the past winter.
a. Pavement preparation-
· In addition to the standard cleaning and preparation methods, we recommend that you thoroughly wash (preferably power wash) the pavement with water to remove embedded salt, silt and de-icing chemicals. Furthermore, heavy rains in the spring can also require extra work as mulch and topsoil get washed out of the flowerbeds or parking lot islands onto asphalt surfaces. Such contaminants, if not thoroughly removed, are likely to cause sealer peeling and or pre-mature wear.
· Pay special attention to minor cracks that may hold a lot of moisture. You may need an effective compressed air source to dry out such cracks.
Weather Considerations and Limitations.
Some insight into sealcoating cure and the roles of ambient conditions.
Sealcoatings are water based coatings and like most water-borne coatings, start releasing water into the ambient atmosphere, as soon as applied. The surrounding air acts as a blotting paper to soak up the released water; its capacity depending upon the relative humidity (% R.H.) of the atmosphere. As the water leaves, the volume of the wet film shrinks, in direct proportion to its water content (by volume), in the mix. For example, if the mix design has 70% water by volume, the wet film will shrink by 70%, i.e. 30% of its original volume.
The evaporation of water from the wet film produces a steady turbulence in the film and forces the suspended particles into a closer proximity. The film becomes progressively denser, thus forcing the binder particles to touch each other and fuse into a continuous film, encapsulating the filler particles in the process. Simultaneously, the excess binder in the matrix allows the film to effectively bond to the pavement surface.
For understanding the drying and cure process, visualize the wet film not as one solid entity, but a composite of numerous layers of molecularly thin films (imagine a sheet of plywood). Like most water-based coatings, sealcoating dries, in successive layers, from top to bottom. As each layer dries, it shrinks in volume, becomes tight and relatively impervious, therefore, impeding the evaporation of water from the bottom layers. It has been established that the cumulative water loss happens rapidly in the early stages of film drying i.e. the first 80-90% of the film dries relatively fast, but the release of the last 15-20% of water takes much longer, requiring the right set of ambient and pavement conditions. For optimum performance, all water must leave the film: 80-90% is not good enough. The uncured bottom layers of the sealcoating will be torn or dislodged if traffic is allowed on it too soon. The percentages noted above are strictly to explain the phenomenon of the cure stages. The final cure will depend on many factors; mix design, coverage rate and the ambient conditions of temperature, humidity and the wind velocity.
The drying and final cure of sealcoatings is dependent upon temperature and Relative Humidity (R.H.). Higher temperatures and lower R.H. are favorable cure conditions where the converse is true for lower temperatures and high humidity.
Sealcoating Application During Early Spring.
· Sealcoatings should never be applied unless pavement temperatures are at least 50° F and the air temperature is 50° F and rising. When the sealcoating is applied below 50° F, the binder particles (refined tar or asphalt) do not soften and fuse to from a continuous sealer film. It is more like Swiss cheese i.e. full of holes and totally ineffective as a protective coating.
· In addition, the sealcoating cured under such conditions usually turns out gray and blotchy in appearance and never attains its characteristic slate/black color.
· Taking a notch down; during the curing stages, sealcoating shall never be subjected to ambient conditions where temperatures may fall below 32° F i.e. below the freezing point of water. The sealer film will simply dis-bond and or shatter.
· Plan sealcoating application as early in the day as possible. Avoid application in late afternoon because it may not have sufficient daylight for proper drying out as well as the danger of temperature dipping into the freezing zone in late evening/night.
· Always allow extra drying time in between coats for the previous coat to release as much water and volatiles as possible, for example if you allow say one hour in the summer months you may have to allow 2-3 hrs.
· In addition, you may have to keep the area blocked off longer. This ties up to the point made earlier about staging your work over 2-3 days and bidding accordingly.
· You may want to consider including a disclaimer in the bid if you are compelled to do the sealcoating job beyond the Best Sealcoating Practices that the seal coating may prematurely wear off in the event of a later snow event and salting.
Mix Design Recommendations
The recommendations made in the following section are based on scientific principles and are general in nature. We recommend that you have your manufacturer’s confirmation and acceptance before making any amendment to their recommendations.
· Suggest reducing water by 5% by volume in the mix design. Reduction in the amount will allow curing a bit faster because there will be less total water to be released by the wet film. Thus the wet film having a shorter life span is likely not to allow enough time for the finer filler particles to float up to the surface and interfere with the fully cured color of the film.
· Consider using a fast drying polymer-based additive that also contains carbon black, which, in turn, may be quite helpful in achieving the desired slate/black color, faster.
· Do not consider adding any kind of chemical that will slow down the drying (example glycols) to counteract overnight freezing of the wet sealer film. Such additives are slow evaporating and have a tendency to stay in cured film for a long time, thus keeping it a bit soft.
As a sealcoating professional you strive to do the very best in delivering the very best to your customers in materials and performance. As a sealcoating manufacturer, we want to provide you all the support based on our experience in the industry and the knowledge base. In this endeavor we have shared some fine points that may be overlooked, inadvertently. Have a great 2021 sealcoating season.
December 7, 2020