In this article, The Concrete Advantage, taken from Green Rooftops website argues, that concrete that undergone hydrophobic technology process will be a better choice for green rooftops as compared to membrane system concrete. This article also mentions the features of the hydrophobic concrete and stating how and why it can benefit the users. Although there are many advantages of having green rooftops on the building, there are some disadvantages too. One of the tremendous disadvantages of having green rooftops is the membrane system concrete. Membrane system concrete increases the additional construction cost greatly and liability for the collaborators. By using hydrophobic technology concrete by removing the membranes, it makes the design, construction, and maintenance processes easier and more effective, thus by eradicating the membranes, it also gets rid the most dangerous factor for the stakeholders.
The five features of the hydrophobic concrete reported on the website are stated in the following below.
Firstly is the permanent "built-in" waterproofing, it is long lasting and does not need to worry about concrete from getting damage throughout the entire building and servicing phase.
Secondly is the elimination for the design and detailing of membranes, time used for designing, constructing phase and cost of the concrete green roofs project can be reduced greatly.
Thirdly is the construction savings, when the membranes are removed, "water-proofing" sub
-contract works can be removed too.
Fourly is the lowering of square-foot cost, hydrophobic concrete is durable, long lasting thus it has higher sustainability rate and lower life cost cycle.
Lastly is that cracks can be quickly repaired with a simple injection from the underside of the green roof deck without affecting its neighbor growing medium or plants. While for the typical membrane system, it can be difficult to trace and expensive to repair.
Overall all these features have the similar benefits which as saving cost, resources and time. Another not proven benefit of having hydrophobic concrete is that it eliminates the use of root barrier in green roof construction where roots will not absorb water in the concrete. Based on the points and features elaborated, although Green Rooftops has stated that the concrete more sustainable, reliable and more efficient, Green Rooftops should have undergone the FLL test before publishing this article to make it valid and more convincing.
The only improvement Green Rooftops shall make is by doing a test, a Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau (FLL) test should have done by Green Rooftops before publishing the article on the website. In the article, Green rooftops mention that "Thus far, there had been no FLL testing done to substantiate whether a root barrier can be eliminated. Roots do not seek water within the concrete because there is none in the waterproof concrete system." However, based on the Green Roof Technology website, it states that "all green roof systems and green roof design must meet the FLL-Guideline and must last as long as the building where implemented. "In my opinion, I strongly believe that the article shall be invalid and contain false information unless Green Rooftops have done and passed the FLL test before publishing the article on the website. Green Rooftops should also meet the requirements for root resistance of the waterproofing membranes. Green Rooftops should have done their FLL test at Center for Innovation and Technology Transfer (CRITT) Horticole and the Scientific and Technical Center for Building, European notified body for construction products (CSTB), CRITT horticole has greenhouses equipment to test the resistance to the root penetration of root protection membrane, roof and waterproof lining sheets and liquid surface treatment material according to the European standard EN 13948 and the FLL guidelines for the planning, construction and maintenance of green roofing. Without the root resistance testing evidence, I am unconvinced that the root barrier can be eliminated. When the plants are growing, there may be a chance that roots will grow towards the concrete causing it to crack and damage. After the concrete is cracked, there is a chance that water can sip in and trap the water causing damage to the concrete over time. With the above improvement, I believe that Green Rooftops will be a much more convincing website with test results and match requirement.
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