Tag Archives: Waterproofing

Durable Waterproofing for Concrete Masonry Walls: Field Testing Methods of Water Repellency

by Robert M. Chamra, EIT and Beth Anne Feero, EIT

There are two main field testing methods used for water repellency of concrete masonry units (CMUs), for quality assurance before being placed in a wall: droplet and RILEM tube testing. Completed assemblies can also be tested with RILEM tubes or other standard water spray tests such as ASTM E514, Standard Test Method for Water Penetration and Leakage Through Masonry.

Droplet testing
The droplet test is a quick and simple test to observe the water mitigation capabilities of a CMU. This test requires the unit to be placed horizontally on a level surface with the face shell oriented upward. Droplets are placed at different locations around the unit from a height of 50 mm (2 in.) or less.

The specimens are to be placed in ambient temperature (22.9 ± 5.6 C [75 ± 10

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F]) and moderate relative humidity (50 ± 15 percent) and are monitored for evaporation facilitated by sunlight or wind; they are recorded at one-, five-, and 10-minute intervals. At the conclusion of the test, the droplets are classified as standing, partially absorbed, totally absorbed, or dry. Additional testing methods should be implemented to further evaluate failed droplet tests.*

Commencement of a droplet test on a concrete masonry unit (CMU) containing integral water repellent.

Commencement of a droplet test on a concrete masonry unit (CMU) containing integral water repellent.

After fi ve minutes, the originally beaded droplet has been partially absorbed into the CMU containing integral water repellent.

After five minutes, the originally beaded droplet has been partially absorbed into the CMU containing integral water repellent.

RILEM tube testing
The standard RILEM tube can hold 5 ml (0.17 oz.) of water, which correlates with the static pressure of a 158-kph (98-mph) wind-driven rain. The short RILEM tube was developed for porous materials that are unable to pass a standard RILEM test. A short RILEM tube (approximately 2 ml [0.06 oz.] of water) correlates with a 97-kph (60-mph) wind-driven rain.

Both RILEM tubes are plastic cylinders that are securely placed against the unit for testing using an impermeable putty. Once the RILEM tube is attached to the CMU, water is placed into the tube up to the 0 ml (0 oz) mark (top of tube). The RILEM tube is monitored at five-, 10-, 20-, 30-, and 60-minute intervals for any noticeable changes in the water column. Previous testing has shown specimens that hold water for 20 minutes will also typically hold for 60; this allows for shorter experiments. If 20 percent of the water is lost within a 20-minute interval, the CMU is considered to have failed the test—if such losses are not observed, then the CMU has passed.**

A standard RILEM tube is shown at the left CMU cell, while a short RILEM tube is shown at the right CMU cell.

A standard RILEM tube is shown at the left CMU cell, while a short RILEM tube is shown at the right CMU cell.

A standard RILEM tube test has failed on this CMU with integral water repellent.

A standard RILEM tube test has failed on this CMU with integral water repellent.

 

 

* See NCMA’s, Standard Test Methods for Water Stream and Water Droplet Tests of Concrete Masonry Units from 2009.
** See the article, “Testing the Test: Water Absorption with RILEM Tubes,” by Adrian Gerard Saldanha and Doris E. Eichburg in the August 2013 issue of The Construction Specifier. Visit www.constructionspecifier.com and select “Archives.”

To read the full article, click here.

Durable Waterproofing for Concrete Masonry Walls: Redundancy Required

All images courtesy Building Diagnostics Inc.

All images courtesy Building Diagnostics Inc.

by Robert M. Chamra, EIT and Beth Anne Feero, EIT

Single-wythe concrete masonry walls are popular because they are inexpensive to construct, and combine structural support and cladding in one system. However, they can be associated with leakage when the waterproofing design is simplistic. A single-wythe wall can, and should, have multiple waterproofing components.1

Concrete masonry units (CMUs) are characteristically porous building materials. When manufactured in accordance with the industry standard, ASTM C90, Standard Specification for Load-bearing Concrete Masonry Units, commonly used lightweight CMUs absorb up to 17 percent of their weight in water.

CS_July_2014.inddThis porosity is due in part to their composition. The mix for the units contains the usual concrete components of water, cement, and aggregates, but that third component will be a smaller coarse aggregate (i.e. gravel) than cast-in-place concrete. The smaller aggregate decreases the workability of the mix if all other variables are held constant. In some cases, this decrease in workability is compensated by the addition of water to the mix. Similar to cast-in-place concrete, the higher the water-to-cement (w/c) ratio in the CMU mix, the higher the permeability of the units. However, even a good-quality mix will remain permeable (Figure 1).

Furthermore, the geographical location where the CMUs are manufactured affects permeability. The types of aggregate available in different regions varies, which results in mixes with identical proportions of components, but with much different absorption. For this reason, a prescriptive approach for waterproofing CMUs cannot be applied globally. The guidelines for methods of waterproofing remain the same, but the proportions of water repellents must be tailored for the available materials.

An additional factor affecting the porosity of CMUs is the unit-forming process. After the components have been combined, the mix is compacted and vibrated in molds. If properly compacted, a large volume of the interconnected pores within the unit is eliminated. If poorly compacted, the resulting interconnected pores can provide a path for water to migrate through the unit. Even if the overall unit is compacted, extremely porous localized pockets can remain, as demonstrated in the testing described in this article.

Similarly, a CMU containing cracks will be prone to moisture migration. The curing process CMUs undergo after forming will limit shrinkage cracking within the units, but it does not prevent all subsequent shrinkage—especially when CMUs are installed immediately after manufacturing (21 days of curing is recommended). In addition to drying shrinkage, creep (i.e. time-dependent deformation) can occur in concrete masonry walls after sustained loading.2 The resulting hairline cracks from these phenomena will provide routes for water through the unit.

CS_July_2014.inddIn addition to the units themselves, the mortar joints can provide water sources into a concrete masonry wall assembly. If the mortar loses the water it needs to complete curing—due to wind, sun, or suction from the CMUs—shrinkage cracks and separations between units and mortar will develop. Similar to the CMUs, the mortar will also undergo creep after sustained loading—up to five times as much as the CMUs—since the mortar is less stiff than the concrete.3

For waterproofing, cracks within the mortar are worse than cracks within the units, since it is common to have mortar only at the inside and outside faces of the masonry (i.e. face shell bedding). Then, water only has to travel the thickness of the unit wall, approximately 32 mm (1 1/4 in.) to penetrate the assembly (Figure 2).

Recommendations
National Concrete Masonry Association (NCMA) publishes technical articles to provide recommendations for the design and construction of concrete masonry. TEK 19-2B, Design for Dry Single-wythe Concrete Masonry Walls, outlines waterproofing strategies for single-wythe concrete masonry walls at the surface, within the CMU, and at the drainage path. NCMA recommends redundancy to protect concrete masonry from water penetration, including surface repellents or coatings, integral repellents (admixtures), and adequate drainage systems.4

Surface repellents for concrete masonry—typically silicones, silanes, and siloxanes—provide waterproofing at the exterior of the wall assembly. They are applied by a roller or spray equipment after the mortar has had an opportunity to cure. The product is absorbed into the units and mortar and coats the pores. While some products can penetrate deeper, most surface repellents remain within 12.7 mm (1/2 in.) of the CMU surface. In addition to their ability to repel water, surface repellents provide other benefits, such as reducing dirt and staining on the wall’s surface.

Split-face units, shown here being tested with a RILEM tube, are even more challenging to waterproof than smooth CMUs because of the fractured surface.

Split-face units, shown here being tested with a RILEM tube, are even more challenging to waterproof than smooth CMUs because of the fractured surface.

Surface repellents typically allow water vapor to be transferred in and out of the wall, and drying when water does penetrate the assembly through cracks or other penetrations.5 These products have varying ultraviolet (UV) resistance, but most need to be reapplied at intervals recommended by their manufacturers.6

Integral water repellents are available to be incorporated into CMUs as admixtures during manufacturing and into mortar during site mixing to limit water migration through the wall assembly. Since the mortar is mixed onsite and not in the unit plant, it is crucial masons also provide proper admixture quantity and mixing practices for the mortar to avoid a waterproofing weakness within the wall assembly. Integral water repellents also improve efflorescence control. Despite concerns with changes to the concrete’s properties, research has shown integral water repellents do not interfere with the assembly’s bond strength.7

Although it may seem counterintuitive, it is better to use mortar of lower strength to limit cracking.8 High-strength mortars are stiffer; they crack at a lower strain compared to low-strength mortars. Movement related to thermal and moisture changes, as well as foundation shifting, can cause cracking in strong and stiff wall assemblies. These cracks may not impair the wall’s structural performance, but all cracks add opportunities for water’s entry into the assembly.

The mortar’s installation can be as important to the mortar joints’ performance as the materials used. Proper tooling practices help protect concrete masonry walls from unwanted moisture penetration. Choosing a concave or V-joint mortar joint profile will push the mortar against the CMUs to improve bond and provide drainage when the assembly is wet. Raked joints decrease the bond between the CMU and mortar, and provide an area to trap water.9

CS_July_2014.inddIn addition to surface repellents or coatings and integral repellents, NCMA’s other primary recommendation is to provide adequate drainage systems for moisture penetrating the wall assembly. For ungrouted assemblies, through-wall flashing can be installed at bond-beams and floor slabs. Flashing is often eliminated in fully grouted walls to avoid severing the grout which makes it important to consider supplemental waterproofing measures.

These suggestions, along with other considerations found in TEK 19-2B, are given to help ensure moisture will not penetrate the masonry. Although CMUs are characteristically permeable, they can be used successfully in single-wythe walls by following NCMA’s recommendations. Since water penetration can come from various sources, the need for a careful and comprehensive waterproofing approach is essential to providing dry and durable concrete masonry construction.

Laboratory testing
Absorption testing of 24 lightweight CMUs was performed by the authors. Half the units contained an integral water repellent. An informal droplet test was performed initially on selected CMUs from each group; then, all the CMUs underwent a RILEM tube test.10 For additional information about these test methods, see “Field Testing Methods of Water Repellency.”

CS_July_2014.inddThe units tested were smooth-faced CMUs. Split-face blocks, with their more aesthetically appealing surfaces, would likely be even more porous because of the fracturing that creates the appearance (Figure 3).

Absorption testing
To comply with ASTM C90, CMUs must meet maximum absorption requirements dependent on the units—the denser the unit, the less absorption the standard allows. ASTM C140, Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units, outlines the absorption testing procedures to comply with ASTM C90. Each CMU in this study underwent ASTM C140 absorption testing (Figure 4).

The addition of integral water repellent to the CMUs resulted in a 34 percent reduction in absorption (and nearly 50 percent less than allowed by ASTM C90). However, these low absorption values do not correlate with water penetration through the units; the low-absorption CMUs still allowed water to penetrate during water-spray testing. The authors believe this disconnect is a leading reason for leakage in single-wythe concrete masonry walls—the industry standards for the components address absorption, rather than water penetration.

Droplet testing
The CMUs without integral water repellent had droplet test results classified as ‘totally absorbed’—immediately after placing the droplet on the unit, the water was absorbed, but the surface remained slightly damp. For the units with the integral water repellent, the classification was ‘partially absorbed.’ Once the water was placed on the unit, some of the water was absorbed, but there was still partial beading and standing water remaining on the unit. After a five-minute period, most of the beaded water had absorbed into the units with integral water repellent and appeared the same as units without integral water repellent.

CS_July_2014.inddThese observations show an integral water repellent can aid in preventing water from penetrating into the unit. However, the integral water repellent was not impenetrable—some water made its way into the units during the droplet tests. More importantly, there was an extreme range of absorptions on the surface of individual CMUs, which indicates porous pockets of less consolidated concrete were present as described earlier (Figure 5).

RILEM tube testing
The second procedure conducted on the concrete masonry units was RILEM tube testing. When tested using a standard 5-ml (0.16-oz) tube, all 24 specimens failed. However, units containing an integral water repellent were able to hold the water column of a short RILEM tube test for more than 20 minutes with little to no reduction in the water level, thus passing the less-severe testing method.

The units without integral water repellent quickly failed even when tested with a short RILEM tube. In a matter of one to two seconds, the entire water column had been depleted, and significant water penetration could be seen in the unit surrounding the RILEM tube and putty. These results clearly indicate the necessity for CMUs to have deliberate waterproofing components to avoid catastrophic leakage.

Medium- or normal-weight CMUs would be expected to perform better than their lightweight counterparts because research indicates water repellents’ effectiveness correlates with concrete density. This is another reason for water ingress in single-wythe concrete masonry walls—the repellents most commonly employed are least effective on lightweight CMUs. In some regions, lightweight units dominate the market despite their poor water penetration performance. This point alone indicates the benefit of using redundant waterproofing components.

CS_July_2014.inddConclusion
Concrete masonry units are porous structural elements that need to be properly installed with appropriate components to prevent water infiltration in single-wythe exterior walls. High-quality CMUs and mortar (complying with ASTM standards), integral water repellents, and good design and construction practices (following NCMA recommendations) are important steps. However, these measures may not suffice.

Redundant waterproofing components are required because of the likelihood of cracks, mortar joint separations, and variable absorption characteristics in a single-wythe concrete masonry wall (Figure 6). The variability of available materials in a given region supports the need for tailoring the design to achieve the desired performance. Field testing during the construction phase is recommended to confirm performance. Even adding a surface-applied repellent will not stop water from migrating through cracks. An elastomeric wall coating should be considered for crack-bridging ability.11

Notes
1 The authors gratefully acknowledge the continuing support and leadership of David W. Fowler, PhD, PE—the faculty advisor for the research being performed at The Durability Lab, a testing center at The University of Texas at Austin. Also, the authors thank Featherlite Building Products for donating concrete masonry units for lab testing. (back to top)
2 For more, see Failure Mechanisms in Building Construction, edited by David H. Nicastro, PE (ASCE Press, 1994). (back to top)
3 See Note 2. (back to top)
4 See NCMA’s TEK 19-2B, Design for Dry Single-wythe Concrete Masonry Walls. (back to top)
5 See NCMA’s TEK 19-1, Water Repellents for Concrete Masonry Walls. (back to top)
6 See the article, “Testing the Test: Water Absorption with RILEM Tubes,” by Adrian Gerard Saldanha and Doris E. Eichburg in the August 2013 issue of The Construction Specifier. (back to top)
7 See NCMA TEK 19-7, Characteristics of Concrete Masonry Units with Integral Water Repellent. (back to top)
8 See Note 4. (back to top)
9 See Note 4. (back to top)

Robert M. Chamra, EIT, is a project engineer with Building Diagnostics Inc., specializing in the investigation of problems with existing buildings, designing remedies for those problems, and monitoring the construction of the remedies. He participates in the research being performed at The Durability Lab—a testing center established by Building Diagnostics at The University of Texas at Austin (UT). He can be reached by e-mail at rchamra@buildingdx.com.

Beth Anne Feero, EIT, is completing her master’s degree in architectural engineering at UT. She serves as the graduate research assistant for The Durability Lab, which researches and tests the durability of building components, identifying factors causing premature failure. She can be reached via e-mail at bfeero@buildingdx.com.

Don’t Put All your Eggs in One Waterproof Basket

by John Chamberlin, MBA

This photo shows above-grade moisture protection with coating over joint treatment and rough opening protection. Photos courtesy Sto Corp.

“A building is only as strong as its foundation,” is a common idiom uttered across the construction industry. Time can be spent applying this to anything, in the metaphorical sense, but in the construction business it can be taken literally. The foundation is literally the building block on which the rest of a building will rely for long-term function and performance. Continue reading

Protecting Infrastructure from Major Floods

All photos courtesy Kryton International

All photos courtesy Kryton International

by Jeff Bowman, B.Sc., Greg Maugeri, and Sarah Rippin

Major flooding has dominated international news in recent years. While it may not be occurring more frequently than it was 50 years ago, due to growing infrastructure, the impact is certainly greater. Since 1949, the U.S. population has doubled, leading to a rapid increase in the construction of the urban environment. Most cities are unprepared for these rare increases in water levels—initiatives to protect infrastructure from major damage too often occurs only after the destruction.

Concrete is the modern world’s most commonly used building material, employed twice as much as other major building materials—steel, aluminum, wood, and plastic—combined.1 Concrete walls naturally protect against structural damage that can be caused by the effects of nature.

Looking back in history, many century-old structures stand longer than those erected in the last 50 years. This is largely due to reinforcement methods—instead of using solid stone, most U.S. infrastructure contains reinforcing steel embedded within poured concrete. As the priorities of construction methods shift to increase productivity and streamline scheduling, long-term durability often takes a backseat.

Feeling the effects of flood damage
In 2012, Hurricane Sandy ravaged the Atlantic coastline. The ferocious storm was among the worst disasters to ever hit the United States, causing tens of billions of dollars in damages and losses. The storm surged more than 4 m (13 ft) above the average low tide, leaving millions without power, causing severe flooding, and leaving properties destroyed.

One such flooded building happened to house the server farm for a well-known company’s global financial transactions. The server farm was located in a large warehouse building on West Street in Manhattan, more than two blocks from the Hudson River.

The most damaging issue in the storm’s aftermath was the street-level power plant running the server infrastructure was dramatically flooded. The mechanical room took 750 mm (2 ½ ft) of flooding during the hurricane, which was foreseen by neither owners nor builders when the servers were installed.

After the waters receded, engineers worked with waterproofing experts to come up with a way to protect the vital systems from potential flooding in the future. They opted to surround critical systems with waterproof concrete half-walls that could stand up to hydrostatic pressure.

For this Manhattan server room project, the concrete-to-concrete joints of the walls were constructed using the same crystalline technology to fully tank the room. To provide extra protection, a slurry coat containing the same crystalline properties was applied to the outside of the walls.

For this Manhattan server room project, the concrete-to-concrete joints of the walls were constructed using the same crystalline technology to fully tank the room. To provide extra protection, a slurry coat containing the same crystalline properties was applied to the outside of the walls.

Even under normal circumstances, if soil around a below-grade structure’s foundation is saturated with water to 1 m (3 ft) or more above the ground level, the water’s force causes pressure on the concrete. The walls absorb the moisture like a sponge, leading to cracks and ensuing water infiltration, rebar corrosion, and mold. In a flash flood, similar water pressure is applied to concrete structures.

Waterproofing concrete from the inside out
The project team knew waterproofing the server farm would require a robust assembly that could withstand the sudden onset of a large volume of water. Typical concrete structures built in the past 50 years are waterproofed solely on the positive side (i.e. wet side) using surface-applied paints or membranes. These surface barriers are vulnerable to damage during construction, which can lead to waterproofing failure. In the case of the server farm, the water pressure of a flash flood (and the debris it carries) could damage a membrane and leave the servers vulnerable at the most critical moment.

The slow effects of water damage to an aging building can be accelerated by flooding, which adds force to aging materials and pushes moisture into concrete. This moisture stays within the concrete even after the building is cleaned up, and can cause mold and mildew growth over time. The moisture can also collect around the steel reinforcing rebar within the concrete, causing corrosion that spreads throughout the structure. Additionally, the rebar expands as it corrodes, cracking the concrete and adding to the deterioration.

To make concrete truly ‘waterproof’—which means both preventing water passage and resisting hydrostatic pressure—many contractors have embraced a long-term, permanent approach. Using an integral system, usually in the form of a powdered admixture added directly to the concrete itself, the entire mass of concrete can be made the waterproofing barrier. The system should include properties which work to protect steel from corrosion, saving structures which incur water damage fewer repair or replacement costs down the road.

In late 2010, the American Concrete Institute (ACI) published a new report on chemical admixtures for concrete called ACI 212.3R-10, Report on Chemical Admixtures for Concrete. This document contains a new chapter focused entirely on permeability-reducing admixtures (PRAs). Chapter 15 embodies research dating back nearly five years, with volunteers from across the industry spending countless hours and untold effort into its development.

The result is a valuable resource for concrete users, with the greatest value of the new chapter being its clear categorization of permeability-reducing admixtures into two divisions:

  • permeability-reducing admixtures for non-hydrostatic (PRAN) conditions; and
  • permeability-reducing admixtures for hydrostatic (PRAH) conditions.

Dampproofing admixtures
Used for PRAN conditions, dampproofing admixtures reduce water absorption via treatment with repellent chemicals (e.g. soaps or oils) or partial pore-blocking (i.e. fine particle fillers). Since resistance to water under pressure is limited or non-existent, these admixtures are not suitable for concrete exposed to this situation.

For the Manhattan data center project, the critical systems were surrounded by waterproof concrete walls, which incorporated a crystalline concrete waterproofing admixture.

For the Manhattan data center project, the critical systems were surrounded by waterproof concrete walls, which incorporated a crystalline concrete waterproofing admixture.

Waterproofing admixture
Waterproofing admixtures are specified for PRAH conditions. They reduce water penetration via a pore-blocking mechanism (e.g. crystalline growth or polymer plug). Given these materials are sufficiently stable to resist water under pressure, they are suitable for use in watertight construction, such as basements and water tanks.

Corrosion considerations
Not all flood damage to concrete structures is immediately apparent. Even after the water recedes, there is still a risk of rebar corrosion, especially if the flooding involved salty ocean water.

Corroded rebar can weaken a buildings vital support network, and the damage can quickly spread. Reducing water permeability effectively lowers opportunity for this, thereby increasing the structure’s longevity. Of course, not all corrosion-inhibiting admixtures (waterproofing or otherwise) are created equal.

The University of Hawaii recently released the results of a 10-year study on the corrosion of reinforced concrete exposed to a marine environment.2 Concrete panels were placed in the tidal zone of Honolulu harbor—a highly corrosive environment due to chlorides in the ocean water, as well as constant weather fluctuations.

Corrosion can be prevented in concrete in two primary ways. If the permeability of the concrete is very low, the penetration of water and chlorides will be minimized, preventing corrosive conditions from developing. Alternatively, the concrete can be treated with corrosion-inhibitors that act to chemically inhibit corrosion at the surface of the steel once corrosive conditions develop. For real projects, both methods can be used, but for research purposes only one additive was used in each test mix.

The Hawaii program used a good quality, control concrete (water/cement [w/c] ratio of 0.40) that would be considered durable. Even so, the control (i.e. plain concrete) showed corrosion induced cracking and rust residue after 10 years. The other materials evaluated included two supplemental cementitious materials (SCMs)—fly ash and silica fume—as well as four corrosion-inhibitors and three PRAs.

By implementing long-term waterproofing solutions to key areas, the Manhattan server room will withstand high water exposure caused by any future massive flooding.

By implementing long-term waterproofing solutions to key areas, the Manhattan server room will withstand high water exposure caused by any future massive flooding.

At the study’s conclusion, the report published in 2012 made the following recommendations to minimizing corrosion:

  1. Use a W/C ratio as low as possible, but not greater than 0.40.
  2. Include fly ash with at least 15 percent replacement of cement, or silica fume with at least five percent replacement of cement. Mixing must ensure the fly ash and silica fume, in particular, are well-distributed throughout the concrete.
  3. Include a calcium nitrite admixture at minimum dosages of 20 L/m3 (4 gal/cy).
  4. As added protection, consider including a proprietary hydrophilic crystalline product at two percent by weight of cement.

These findings are particularly relevant because they are based on field exposure in a harsh costal environment. This is the best type of testing because the exposure simulates the actual service conditions of a real structure. Laboratory tests are generally designed to provide accelerated results using conditions that do not always model real life. Many products may perform well in a short-term laboratory experiment, but perform poorly over the long term in actual conditions.

Wall joints and entryways
Certain water entry points are particularly sensitive when exposed to hydrostatic pressure. For example, water can easily penetrate through the joints where walls meet in a corner, or where the wall meets the floor. Tie-holes should also be treated as possible leakage points, and with a product that is effective under hydrostatic conditions, especially if in a below-grade location.

It can be difficult to predict how vulnerable a concrete joint is until it is too late, so it is important to mitigate any concerns well in advance by administering a permanent jointing system that can permanently withstand high water pressure, without breaking down and becoming an entry point for moisture.

Unsuspecting entryways are another issue. Insufficient waterproofing of the concrete is not the only way water can infiltrate an interior space during a major flood. In many cases—including the aforementioned building housing the server farm in New York—there are strong enough winds and water pressure to simply break through windows or doorways.

Boarding up these entrances is an effective protection measure in many cases, but this is time-consuming and, in some cases, impossible. Installing flood-resistant doors, gates, and window protectors upon the construction of the building helps ensure the structure can be protected quickly and efficiently when facing a flood.

If all entrances cannot be flood-proofed, protecting below-grade concrete from water damage from both the positive and negative side is a vital step in ensuring a building’s longevity.

Not all flood damage is immediately apparent. Even after the water recedes, there is still a risk of rebar corrosion for concrete structures.

Not all flood damage is immediately apparent. Even after the water recedes, there is still a risk of rebar corrosion for concrete structures.

The concrete barriers, designed by engineers for the server building in Manhattan, contained a system that would work with water under pressure, rather than against it. Hydrophilic technology (from the Greek hydros, meaning water and philia, meaning friendship) absorbs water rather than repelling it, effectively using the water contact to its advantage.

This process is employed in crystalline admixtures and surface-applied cementitious crystalline products, which transform water into microscopic crystals. These crystals permanently block the pores of the concrete, preventing water from penetrating and moisture from remaining within the wall. As time goes on, the crystalline product remains dormant in the concrete, and reactivates upon the presence of moisture, throughout the entire life of the structure.

For the New York project, the finished wall took on crystalline waterproofing in three different applications:

  • as an admixture added directly to the concrete mix;
  • as a surface-applied brush-on (i.e. to the positive side—on the outside of the walls facing any potential water penetration into the building); and
  • within the concrete joints as a two-part physical and chemical barrier.

By using these extra enforcements, engineers could guarantee the protection of this vital server farm should a flooding event at the level of Hurricane Sandy occur again.

Preparing for the future
With climate change and the increases in water-related damage to cities and areas around the world, it is becoming more apparent drastic steps need to be taken regarding the way we build, and the materials we use. In order to gain full insight, it is critical to pay attention to new innovations based on proven techniques, which reflect both sustainability and durability. Staying up to date with the new tools, research, and reports can help us to know what we can do to protect our structures from costly damage and early deterioration.

Notes
1 Visit cementtrust.wordpress.com/a-concrete-plan. (back to top)
2 For more see the report, “Performance of Corrosion-inhibiting Admixtures in Hawaiian Concrete in a Marine Environment,” by Joshua Ropert, MS, and Ian N. Robertson, PhD, SE. Visit www.cee.hawaii.edu/reports/UHM-CEE-12-04.pdf. (back to top)

Jeff Bowman, B.Sc, is a technical manager at Kryton International Inc. He earned his bachelor’s degree in chemistry from the University of British Columbia, and has extensive experience in the development and use of various construction products for the repair and waterproofing of concrete, specializing in crystalline admixtures and repair materials. Bowman has written numerous articles on waterproofing technologies and has contributed to international publications on this topic. He can be reached at jeff@kryton.com.

Gregory Maugeri is the CEO and managing partner of New England Dry Concrete, which specializes in solving cementitious waterproofing problems with crystalline materials. He has decades of construction and waterproofing experience; his company has been awarded the (ICRI) Project of the Year. Maugeri can be contacted via e-mail at greg@dryconcrete.com.

Sarah Rippin is a multimedia coordinator for Kryton. Over the past eight years, she has worked within the construction and marketing industries, and now uses both visual and written communications to promote and draw awareness to the importance of concrete waterproofing. She can be contacted at srippin@kryton.com.

Energy-efficient Building with EIFS: Retrofitting at Silver Creek Resort

Silver Creek in Snowshoe, West Virginia, used an EIFS system which included a fluid-applied waterproofing air barrier to restore the high-rise resort. [CREDIT] Photos courtesy Sto Corp.

Silver Creek in Snowshoe, West Virginia, used an EIFS system which included a fluid-applied waterproofing air barrier to restore the high-rise resort. Photos courtesy Sto Corp.

by Tom Remmele

Far away from any major city, the nine-story, 239-unit, high-rise Silver Creek Resort in Snowshoe, West Virginia, has undergone a complete claddings renovation.

The resort’s exterior was a panelized exterior insulation and finish system (EIFS) that had been experiencing water leaks since its 1985 installation. Incorrect installation and maintenance was the cause of the leaks, according to Sam Collins, general manager.

Once there was a decision to restore the building, the team worked with an architect and considered

metal panels, fiber cement, and other claddings. In the end, however, a 127-mm (5-in.) drainable EIFS was specified because it was deemed to be the best fit and had the best R-value (i.e. approximately R-19 of continuous insulation [ci].)

Specifying EIFS
The system includes a fluid-applied waterproofing air barrier, and finish with a pronounced self-cleaning effect. This project consisted of 11,612 m2 (125,000 sf) of wall cladding.

Snowshoe’s climate includes some of the most extreme wind, snow, and rain in the Southeast. Prior to the renovation, whenever a severe storm came through, management had to deal with damages and continue to ‘Band-Aid’ additional problems.

According to Collins, when the original EIFS was installed there was no option for substrate protection, air barriers, or drainable systems, but this has since changed and staying informed is key.

Before starting the project, building sections had to be opened up to identify the existing condition behind the wall. Issues such as how the EIFS panels were hung on the building, window leakage, and imperfect seals had to be identified so a solid, watertight building with the new cladding could be created.

“We had to remove all the original exterior skin including the EIFS, exterior sheathing, and wet wall cavity insulation before we could begin,” said Gabriel Castillo, of EIFS-installer Pillar Construction. “The trend now is to insulate outbound of the exterior sheathing taking the insulation out of the cavity, and we did just that.”

The renovation begins
Members of the resort’s board of directors knew something had to be done. The building had been leaking for more than 25 years, and the damage would only escalate. After looking at various cladding options, they decided to employ EIFS.

After the initial drawings, they worked with architect Peter Fillat who came up with the design plans to maintain the building’s strong architectural façade.

Adding a continuous air and moisture barrier—now code in most states—gave the building a R-value not compromised by the thermal bridging effect of stud framing. The air barrier was connected to the windows to give it a tight seal. West Virginia has adopted the 2009 International Energy Conservation Code (IECC), which requires both ci and air sealing.

All 740 windows needed to be replaced. The new assemblies were thermal break horizontal sliding and fixed, and played a big part in energy savings. Without thermal breaks, the window frame becomes a thermal bridge to the exterior and a conduit for energy loss and a possible source of condensation in the wall section.

The previous installation had expansion joints between each panel, but because the renovations removed everything down to the studs, the panel-to-panel joints in the substrate were eliminated. This allowed the air barrier to run continuously between the panels and provided less opportunity for water and moisture to get in.

Challenges
The project was completed in two phases over more than two years. The building was occupied during the entire transition with full-time residents and vacationers. Getting all the ownership together was the first challenge, according to Castillo. However, something needed to be done immediately.

The next challenge was the climate. Silver Creek is located on the ski slopes and sits at 1280 m (4200 ft) above sea level. The average annual snow fall is 4572 mm (180 in.). The decision to renovate was made in early 2011, however, because of the winter, construction had to wait.

The final challenge was location. Even the closest hardware store was three hours away, according to Castillo. There is also limited use of cell phones, because of its proximity to the National Radio Astronomy Observatory (NRAO) located in nearby Green Bank. The construction crew committed to work for two to three months at a time, and stayed on the property.

Craig Swift of the project’s structural engineering firm, Keast and Hood, focused on repairing the metal stud backing. Much of the metal stud cladding wall system had deteriorated, though the primary structural system was in fairly good shape.

By using the versatile EIFS system, it allowed the logo and signage to be built into the building. The front logo letters are up to 2.4 m (8 ft).

By using the versatile EIFS system, it allowed the logo and signage to be built into the building. The front logo letters are up to 2.4 m (8 ft).

Testing—One, two, three
Scott Johnson, an inspector with Williamson & Associates, performed window water testing during phase one and tested windows and claddings related to the openings in phase two. The EIFS, windows, and installation all performed well.

“The building tested out fine,” said Johnson. “There was a major storm during the final phase of construction, with 85-mph [i.e. 137-km/h] winds and hard rain. There were no leaks.”

Johnson and his team conducted ASTM E1105, Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls, by Uniform or Cyclic Static Air Pressure Difference. This evaluates water infiltration performance, capabilities of windows, and related building construction.

The new primary cream color, with a separate forest green color insert, gives the building a distinct profile and more depth, according to Fillat. This was the first time the architect had ever worked with a drainable EIFS cladding, and he feels it solved this longstanding problem.

After the renovations, residents began noticing drastic changes in their utility bills, with savings of 20 to 50 percent, said Collins.

“There has been a big noise reduction from the outside— most likely due to the ‘air-tightening’ of the building envelope,” he said. “Another benefit is from inside my residence I can no longer hear the wind blowing or have snow in my living room each morning when I wake up.”

Tom Remmele, CSI, is the director technical services/R&D for exterior insulation and finish system (EIFS) producer, Sto Corp. He has held technical management positions in the construction industry for more than 25 years. Remmele is a past Technical Committee chair of the EIFS Industry Members Association (EIMA). He can be reached at tremmele@stocorp.com.

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