The pressure to build on suboptimal land is growing as the availability of optimal buildable land begins to decline. With less than preferable lot offerings ahead, like brownfields, the need to look for creative ways to support building structures against nature and moisture at the base is crucial.
To address these challenges GCP released the following examination to show the benefits of using waterproofing and gas membrane between the ground and structures in the future.
Water intrusion is a perennial concern due to its impact on the long-term structural integrity of concrete foundations and walls, and of the building itself. Concrete is vulnerable to groundwater and chemical contaminants in the soil. These can leach into the pores and cracks of the concrete and degrade its integrity, causing spalling and corroding the reinforcing steel. Moisture migrating into the building can also degrade structural elements over time and lead to mold and other hazards to occupants’ health.
In addition, there is growing concern regarding the intrusion of methane and other gases and chemicals, such as trichloroethylene (TCE) and perchloroethylene (PCE), from the soil. Methane, a hydrocarbon (CH4), is a potent greenhouse gas (GHG) and can have serious health implications for building occupants. In some jurisdictions, this concern is driving regulations requiring proactive mitigation. In the U.S., California is leading the trend with methane mitigation standards issued by the Los Angeles Department of Building and Safety (LADBS). To comply with these standards, any methane barrier must have Los Angeles Research Report (LARR) approval, certifying that it meets testing requirements defined by the city.
Meeting these challenges demands a pre-applied or post-applied membrane that meets a host of functional and performance requirements. It must be:
GCP has two proven solutions that meet these requirements for both pre-applied and post-applied applications: PREPRUFE® 300R Plus and BITUTHENE® 8000.
PREPRUFE® 300R Plus is a composite sheet membrane composed of a thick high-density polyethylene (HDPE) film, pressure-sensitive adhesive, and weather-resistant protective coating. As a pre-applied membrane, it is installed directly against the formwork or other soil retaining system before the reinforcement is placed. Concrete is then poured directly onto the membrane, forming a permanent, continuous bond with the PREPRUFE® 300R Plus membrane. The membrane’s waterproofing system does not require water activation, confining pressure, or chemical hydration to bond with the concrete.
Once installed on the formwork, the PREPRUFE® 300R Plus membrane can be trafficked immediately, allowing placement of reinforcement using standard concrete spacers. The installed membrane is unaffected by typical jobsite conditions, including wet or freeze/thaw conditions.
BITUTHENE® 8000 is a self-adhesive, cold-applied sheet membrane for above- and below-ground applications. It can be used either horizontally or vertically. BITUTHENE® 8000 features a thick, HDPE composite carrier film. BITUTHENE® technology has been proven in more than 50 years of use in the field across countless projects, under a wide range of conditions.
Key to the long-term performance of PREPRUFE® 300R Plus and BITUTHENE® 8000 is the optimal thickness of their HDPE and HDPE composite carrier film material, respectively. This thermoplastic polymer has distinct performance characteristics that make it ideal for use as a waterproofing and gas barrier membrane.
HDPE is an inert material that resists degradation over time. Some waterproofing membranes are made of materials that have higher levels of degradation due to their polymer structures. These include linear low-density polyethylene (LLDPE), PVC (polyvinyl chloride), EPDM (ethylene propylene diene polymer) and CSPE (chlorosulphonated polyethylene). LLPDE, PVC and EPDM are at particular risk of oxidation, while CSPE suffers from dehydrochlorination. HDPE has greater resistance to oxidation, hydrolysis and stress than these other materials, making it an ideal choice for use as a geomembrane.
Independent scientific testing1 has shown that HDPE offers longer life than other commonly used membrane materials in both unexposed and exposed applications
Figure 1: Total lifetime prediction of HDPE (non-exposed) at various field temperatures. Stage “B” is induction time; Stage “C” is the time for 50% change in mechanical properties.
Figure 2: Exposed lifetime prediction results of selected geomembranes to date (2011).
Proper installation is crucial to ensure the long-term performance of a water or gas membrane. Complex or unclear processes increase the chances of installation errors that can lead to leaks. PREPRUFE® 300R and BITUTHENE® 8000 are thoughtfully designed for ease of installation.
PREPRUFE® 300 features a kick-out roll for simple installation against concrete forms. ZipLap™ selvedge seams allow for an adhesive-to-adhesive bond at membrane sheet overlaps to create a continuous membrane, without the need for heat, power or specialized equipment. The membrane can be installed to permanent formwork, allowing maximum use of confined sites. Detailing watertight penetrations is easy with BITUTHENE® liquid membrane.
BITUTHENE® 8000 is easy to apply by simply peeling back the protective release paper and applying to the properly prepared concrete surface. Surfaces (except those below ground-bearing slabs) should be primed with a single coat of the specified primer. Installation can be performed over a wide temperature window — from -5°C to +35°C (a hot climate variant is rated to 55°C) — and is tolerant of damp surface, helping avoid delays. The exposed surface is reflective, reducing solar heat absorption by more than 20% while the membrane is exposed, preventing degradation due to UV rays. Printed lines help ensure the correct overlap (minimum 50mm) and provide a continuous membrane when well rolled using a lap roller with firm pressure. Detailing can be performed using cut sections of BITUTHENE® 8000 or BITUTHENE® liquid membrane.
GCP helps building engineers, architects and contractors meet the challenges of today’s construction site realities with advanced solutions for above- and below-grade waterproofing and methane barriers. PREPRUFE® 300R Plus and BITUTHENE® 8000 offer two compelling solutions for mitigating risk, ensuring regulatory compliance and protecting the health of building occupants, today and into the future.
Original article source: GCP
GCP is a leading global provider of construction products that include high-performance specialty construction chemicals and building materials. GCP partners with producers, contractors, designers and engineers to achieve performance and sustainability goals. The company has a legacy of first to market and award-winning solutions that have been used to build some of the world’s most renowned structures. GCP is focused on continuous improvement for its customers, end-users and the environment. For more information, visit GCP's website at www.gcpat.com.
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