The use of composites in the building industry is growing rapidly. Traditional benefits offered by composites are being recognized and utilized to address design limitations and can be used to reduce life cycle environmental and cost impacts. Composites are nothing but an engineered combination of materials that result in a finished material with better overall properties than the starting constituents. The biggest advantage of modern composite materials is that they are light as well as strong. By choosing an appropriate combination of matrix and reinforcement material, a new material can be made that exactly meets the requirements of a particular application. Composites also provide design flexibility because many of them can be molded into complex shapes. The downside is often the cost. Although the resulting product is more efficient, the raw materials are often expensive. Typical engineered composite materials include : Composite building materials, such as cements, concrete ;Reinforced plastics, such as polymer; Metal composites and Ceramic composites (composite ceramic and metal matrices).Composite materials are generally used for buildings, bridges, and structures such as boat hulls, swimming pool panels, race car bodies, shower stalls, bathtubs, storage tanks, imitation granite and cultured marble sinks and counter tops. The most advanced examples perform routinely on spacecraft and aircraft in demanding environments.
Composites are light in weight, compared to most woods and metals.
Composites can be designed to be far stronger than aluminum or steel. Metals are equally strong in all directions. But composites can be engineered and designed to be strong in a specific direction.
Composites resist damage from the weather and from harsh chemicals that can eat away at other materials. Composites are good choices where chemicals are handled or stored. Outdoors, they stand up to severe weather and wide changes in temperature. Composites offer very good corrosion resistance and find widespread use in corrosive environments.
- Cladding for roofs & walls
- Seawalls, decks & railings
- Duct work and ventilation
- Water handling systems
- Salt water environments
- Underground applications
Composites can be molded into complicated shapes more easily than most other materials. This gives designers the freedom to create almost any shape or form. Most recreational boats today, for example, are built from fiberglass composites because these materials can easily be molded into complex shapes, which improve boat design while lowering costs. The surface of composites can also be molded to mimic any surface finish or texture, from smooth to pebbly.
Composite materials are usually classified by the type of reinforcement they use. This reinforcement is embedded into a matrix that holds it together. The reinforcement is used to strengthen the composite. For example, in a mud brick, the matrix is the mud and the reinforcement is the straw. Common composite types include random-fiber or short-fiber reinforcement, continuous-fiber or long-fiber reinforcement, particulate reinforcement, flake reinforcement, and filler reinforcement.
MUD BUILDING BLOCKS
Mud building bricks are examples of a composite material invented by ancient humans.
CONCRETE AND REINFORCED CONCRETE
Concrete is a composite material made of cement, sand, stones and water. A chemical reaction that occurs when you combine these materials makes concrete stronger than any one of its components. Concrete is commonly used in building and road construction. When you add reinforced steel rods to the concrete, you create another composite with greater strength and flexibility called reinforced concrete. Concrete is the most common artificial composite material of all and typically consists of loose stones (aggregate) held with a matrix of cement. Concrete is a very robust material, much more robust than cement, and will not compress or shatter even under quite a large compressive force. However, concrete cannot survive tensile loading (i.e., if stretched it will quickly break apart). Therefore, to give concrete the ability to resist being stretched, steel bars, which can resist high stretching forces, are often added to concrete to form reinforced concrete.
Fiberglass is made of tiny glass shards held together by resin and other components. In the automotive industry, fiberglass is important for making body kits. The body shell for a car is made up of different layers of fiberglass, such as a gel-coat layer, tissue layer, matting and cloth. The final product is a complete, waterproof, lightweight and strong body kit. Fiberglass can also be a less expensive alternative to other materials.
Composites can be easily found in nature. Wood is an example of a composite because
cellulose fibers are held together by a substance called lignin. These fibers can be found in cotton and thread, but it’s the bonding power of lignin in wood that makes it much tougher. Certain types of large rocks can also be regarded as natural composites when they are composed of a variety of smaller rocks and minerals.
Wood is a naturally occurring composite comprising cellulose fibers in a lignin and hemi cellulose matrix. Engineered wood includes a wide variety of different products such as wood fibre board, plywood, oriented strand board, wood plastic composite (recycled wood fibre in polyethylene matrix), Pykrete (sawdust in ice matrix), Plastic impregnated or laminated paper or textiles, Arborite, Formica (plastic) and Micarta. Other engineered laminate composites, such as Mallite, use a central core of end grain balsa wood, bonded to surface skins of light alloy or GRP. These generate low weight, high rigidity materials.
FIBRE REINFORCES POLYMERS
(Francesco Tornabene, 3/7/2015)In both new construction projects and renovation work, design professionals are continuing to discover the advantages of plastic composite building products, including durability, light weight, corrosion resistance, high strength, and low maintenance requirements. These plastic materials obtain much of their versatility because they can be engineered to provide specific performance characteristics. Technically known as fiber reinforced plastics or fiber reinforced polymers (FRP), plastic composites generally comprise two components: a reinforcement fiber and a polymer binder (often called a matrix). The size, shape, proportional weight/volume, and material of the reinforcing fibers typically determine the plastic composite’s mechanical properties, such as stiffness and strength. The type and proportion of the plastic resin matrix, on the other hand, lends the finished plastic composite its physical characteristics, including resistance to impact.
(Sharma, 23 February 2015)Bamboo is a rapidly renewable material that has many applications in construction. Engineered bamboo products result from processing the raw bamboo culms into a laminated composite, similar to glue laminated timber products. These products allow the material to be used in standardized sections and have less inherent variability than the natural material.
With more & more realization on conversation of nature & natural resources, scarcity of wood looms large for the construction & housing sector. This calls for an immediate attention for developing suitable wood substitutes. From the point of view of wood substitution, natural fibre composites would enjoy wider acceptance. India enjoys a niche for the natural fibre composites as the country is endowed with large varieties of natural fibre. Some of the important projects launched by the Mission in the civil engineering sector include FRP profiles, jute-coir composite boards as wood substitute, FRP door & door frames etc. The Mission has been quite instrumental in bridging the knowledge gaps and bringing together the industries & the users for technology development, transfer & subsequent commercialization.
Such an objective oriented, demand driven and time bound programme on composite technology with the involvement of stake holders would go a long way in developing innovative composite applications meeting international quality and wider acceptance by the users thus contributing to the growth of knowledge-based business in India.