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Lightweight insulating concrete (LWIC) is a material used for insulation purpose as a substrate for attachment or support of roofing membranes on slope roofs. Insulation is the process of introducing a barrier to a delicate component to save it from damages. LWIC systems are derived from cellular concrete or a composition of aggregate materials. LWIC has mostly been used in roofing as a roofing base or a form of insulation for all types of buildings, including commercial and industrial building structures, which have low-sloped roofs. The systems were non-structural in the sense that they had no definite outlook. However, due to their technological advancement, LWIC systems have been shaped into various structural forms. The current paper describes LWIC by considering its uses in construction, reinforcement, its benefits, and disadvantages.
Understanding LWIC
LWIC installations are a result of a combination of various constituting elements, which have their unique function. The main components include the substrate, LWIC, and molded expanded polystyrene (MEPS), which form LWIC systems (Wang, Feng, & Wang, 2013). Most often, the galvanized metal deck, the pre-cast structural concrete, or an existing built-up roof layer serve as the substrate. The substrate should be strong, light, durable, and environmentally friendly.
LWIC is formed from such composite elements as cement, air entrainment, water, and aggregate. The main function of cement as a component of the system is to bind together other constitutes and make the whole system strong. The cement of high quality is preferred for making the systems generate enough strength. In fact, once it is installed, one can claim that LWIC can last as long as the building lasts (Yun, Jeong, Han, & Youm, 2013).Furthermore, sufficient air entrainment in the LWIC is crucial in strengthening the system (Yu, Spiesz, & Brouwers, 2015). The air is used to generate air cells that help control the density of the material. It also assists in creating a homogenous mixture that does not easily segregate. Clean and portable water is another important component of LWIC, which provides moisture that is essential in hydration, as well as fluidity that helps pump and finish the system. Finally, the b aggregate is another constitute of LWIC. Usually, it is a nonreactive filler, which helps prevent shrinkage and control density. The proportions of the mixing of the composite components are considerably important.
The concrete material in the system is used to bind all constitutes together. MEPS is a most preferred material for the system, which assists in making boards of various thicknesses. The boards can go to a maximum of sixteen inches. Then, the boards are perforated so that LWIC can flow through the holes, which helps strengthen the system, making it well bonded. The MEPS material serves as a core component of LWIC system. It has a nominal R-value of up to four inches. The lightweight material is used to generate thickness and develop slope-to-drain.
Design of LWIC System
Considering the design of LWIC system, encapsulation is the most important concept of the system’s design. It presupposes that the lightweight material encapsulates the MEPS. In most designs, a layer of insulated concrete is applied to the substrate, which is considered the slurry coat. Therefore, MEPS is embedded in the first layer. The thickness of the MEPS board is stepped to form a positive drainage. The slope is generated when the stairs are placed on the mounted slurry coat (Wang et al., 2013). To create a good slope, the topcoat thickness of LWIC is adjusted to the desired inclinations. The top coat of the LWIC is also essential in creating a smooth sloped monolithic layer of the surface for the use of the roof membrane.
The density of most materials is 22-38 pounds per cubic foot, which makes LWIC thick and strong. An average of 8000 square feet can be installed daily for reroofing purposes. The concrete has a density of about 105 pounds per cubic foot, which is not the case with other forms of concrete. LWIC can have many designs, which include Insulcel, ZIC, Zonocel, and NVS.
Uses in Construction and Reinforcement
LWIC has been widely used in making the roofing decks and for insulation purposes. It has been commonly used since there are deficiencies, shortages, and even delimitation of the roofing solutions in the market. The lightweight material is placed by pumping equipment and mixing the components. However, this material can be used in reroofing by placing it on top of another roof. As a result, the slurry is used in correcting the irregularities and low spots. If it is effectively used, it can help solve the roofing problems. It is also used in fabricating roofs. Moreover, it provides a positive slope to drain which is aesthetic. The installation of LWIC either for the first time or as a fabrication is used to eliminate the irregularities of the surfaces (Wang et al., 2013). The material also assists in preventing the destruction from noise and debris. Moreover, it is essential in creating a potential barrier for asphalt fumes, which are highly destructive. The encapsulated membranes provide a strong covering that cannot be easily disturbed, hence being a long lasting solution. In addition, LWIC is also used in composite slabs and as a topping slab over the earlier structural concrete decks (Yu et al., 2015). In its application, the slurry layer coat is set up a day earlier. The concrete material is then poured over the following day.
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Characteristics of Lightweight Insulation Material
The substrate materials used for the formation of the LWIC system possess high-quality features. Vermiculite is one of the most used aggregate materials, which is strong, durable, and easy to use. It is suitable for installation over other roofing systems and is compatible with other kinds of structural decks of metal or even wood. The material can also be galvanized with steel to make it stronger. LWIC is recommendable to numerous construction structures, as it shows high resistance against the strong and destructive winds, which helps keep buildings safe from being stormed down (Wang et al., 2013). Thus, LWIC systems have been used in coastal areas since they can sustain the strong wind. The systems are highly reusable and hence are preferred in places experiencing acid rain. Moreover, the material shows a high resistance against the fire, which ensures the safety of the building against burning down to ashes. The reroofing capability of the material has improved the usability of LWIC and has enabled constructors to solve the roofing problems. Furthermore, the longevity of the material is outstanding since it is concrete and substrate; thus, the LWIC systems are expected to last longer than other roofing materials. Therefore, LWIC assists in providing long-lasting roofing solutions due to its overall durability (Wang et al., 2013). Finally, LWIC has displayed the exemplary impact on insulation capabilities as it has been mentioned as a long lasting membrane.
Advantages of LWIC
LWIC has been widely used due to its outstanding performance. Firstly, it provides slope-to-drain, which enables the roof to be effective as a barrier. Moreover, the LWIC systems have been used in correcting surface abnormalities. Consequently, all problems with earlier irregularities can be dealt with by installing LWIC. Particularly, the material has been the best protection against the disruptive factors, which include fumes or water intrusion (Yu et al., 2015). In addition, it is also durable in nature.
Most importantly, LWIC is light, which contributes to a great reduction of labor costs. The material is also easy to install, which results in a higher workability easy since LWIC is light and easy to install. Comparing with other structural concretes, LWIC is fifteen percent lighter because most of LWIC systems are made from the vermiculite aggregate. Most substrates used in making LWIC are comparatively lighter. As a result, constructors benefit from using LWIC due to the reduction of cost of foot steel for building structures.
Furthermore, as mentioned earlier, LWIC also serves as a fireproof, hence making buildings safer (Yu et al., 2015). The fireproofing capability of the concrete has improved its popularity and contributed to its wide use in thermal insulation. Moreover, LWIC is highly versatile and thick. The materials used in its construction, like vermiculite, are strong and everlasting, which allows the concrete to sustain various obstructions. The thicknesses of the substrate material also give a good slope to drain features of the insulation materials.
With regard to the features of the LWIC systems mentioned above, it is clear that the materials can provide better insulation. Where vermiculite material has been used as the aggregate, the whole LWIC system becomes comparatively strong. There is a belief that a single inch of the vermiculite concrete is equal to twenty inches of the regular concrete, which is a clear indication of its outstanding insulation capabilities.
Ease of application has also been an advantage of choosing the lightweight insulation material over others. The concrete material is easily placed during construction by the use of modern designed pumping equipment. The material can be installed largely in one day. The reroofing capability of the material is advantageous to the constructors (Wang et al, 2013).
Another advantage is the benefits that come with installing the LWIC. In this case, most companies providing the materials have developed a manner of replacing the roofs through a method known as re-roofing at no cost as long as the client had initially used their concrete (Yun et al., 2013).
Finally, LWIC systems are environmentally friendly. The utilization of the concrete materials will ensure that the environment is safeguarded. Its use can make sure that the roofing solutions are satisfied in an economical and environmentally friendly manner.
Disadvantages of LWIC
The application of the lightweight material is associated with some limitations and liabilities. Firstly, the proper installation of the material requires good skills, which are not known to the majority of contractors (Wang et al., 2013). The quality of the whole system is highly dependent on the expertise of the applicator. Secondly, the material has some additional constraints since its success is determined by the mix ratio. Where the mix ratio is not good, voids among other faults occur, causing the deficiency. Another disadvantage of the lightweight concrete is an inability to provide consistent compressive strengths and appropriate density throughout the entire area since the concrete material has its compressive strength from molecules of the foam when properly mixed. If the foam additive is improperly mixed, it may collapse, hence lowering the strength of the product (Wang et al, 2013). The effectiveness of the material depends on human skills and aloofness. Human error can easily occur, hence resulting in a poor insulation material formed (Wang et al., 2013).
Conclusion
Over the years, LWIC has made a remarkable difference in roofing activities. Particularly, it has been widely used in reroofing and recovering substrate products. The lightweight has been rated as the best insulating material. Due to its characteristics, LWIC assists in preventing damages due to fire, wind, or water. It is advisable to use LWIC since it is economic and environmental friendly.
