ABSTRACT Latest innovations have developed new materials and better technologies in the field of construction. The need of the hour is the replacement of costly and scarce conventional building materials by innovative, cost effective and environment friendly alternate building materials. Here we see about the Insulating concrete forms (ICF) Fiber reinforced polymers (FRP) Structural insulated panels (SIP) By implementing these technologies gives birth to many sub level new engineering concepts. These engineering conceptual methods now days become very important, latest practically applied fields in innovative constructions.
The major problem by the conventional structures due to various aspects can be resolved by incorporating these techniques. By using these technologies we can have a great space for research work as how these implemented things work on. INNOVATIVE BUILDING MATERIALS INTRODUCTION India’s present housing shortage is estimated to be as high as 31. 1 million units as per 2001 Census and out of these shortage 24 million units are in rural area and 7. 1 million units in urban areas. The Govt. of India has targeted the year 2010 for providing Housing for All.
In 1998, Government of India announced a National Housing and Habitat Policy which aims at providing “Housing for All” and facilitating the construction of 20 lakh additional housing units annually, with emphasis on extending benefits to the poor and the deprived. Apart from the above housing needs, nearly 1% of the housing stock in the country is destroyed every year due to natural hazards. Such large scale housing construction activities require huge amount of money. Out of the total cost of house construction, building materials contribute to about 70 percent costs in developing countries like India.
Therefore, we need to replace the costly and scarce conventional building materials. The new material should be environment friendly and preferably utilize industrial/agro wastes because as a result of rapid industrialization. Large number of innovative building materials developed through intensive research efforts during last three to four decades satisfies functional as well as specification requirements of conventional materials/techniques and provide an avenue for the construction job to complete faster more durable and to bring down the cost too .
Some of the innovative building materials which are user friendly and cost effective are seen below. INSULATING CONCRETE FORMS Insulating Concrete Forms (ICFs) are formwork for concrete that stays in place as permanent building insulation for energy-efficient, cast-in-place, reinforced concrete walls, floors, and roofs. The forms are interlocking modular units that are dry-stacked (without mortar) and filled with concrete.
The forms lock together serve to create a form for the structural walls of a building. Concrete is pumped into the cavity to form the structural element of the walls. Usually reinforcing steel (rebar) is added before concrete placement to give the resulting walls flexural strength, similar to bridges and high-rise buildings made of concrete The forms are filled with concrete in 1-4 foot “lifts” to reduce the risk of blowouts like with other concrete formwork.
After the concrete has cured, or firmed up, the forms are left in place permanently for the following reasons: Thermal and acoustic insulation Space to run electrical conduit and plumbing. The foam on either side of the forms can easily accommodate electrical and plumbing installations. Backing for gypsum boards on the interior and stucco, brick, or other siding on the exterior Types of systems ICFs can be made from a variety of materials: Expanded polystyrene (EPS) – most common
Extruded polystyrene Polyurethane Cement-bonded wood fibre Cement-bonded polystyrene beads The majority of forms are made of foam insulation, such as expanded polystyrene (EPS), and are either separate panels connected with plastic connectors or ties; or pre-formed interlocking blocks connected with plastic or steel connectors or ties. Most forms have vertically oriented furring strips built into the forms on 6”, 8”, or 12” centres which are used to secure interior and exterior finishes.
Different ICF systems also vary in the shape of the resulting concrete within the wall: “Flat” systems form an even thickness of concrete throughout the walls, like a conventionally poured wall – 3rd Generation ICF: most common “Waffle Grid” systems create a waffle pattern where the concrete is thicker at some points than others – 2nd Generation ICF: somewhat lower structural strength & fire resistance “Post-and-Beam” or “screen grid” systems form discrete horizontal and vertical columns of concrete – 1st Generation ICF: least resistance to fires
Benefits Manufacturers commonly cite the following advantages compared to traditional building materials, especially in residential and light commercial construction. It needs to be said, however, that it is questionable what is meant by “traditional building materials”; this comparison apparently assumes different worst-case alternatives for each point. Minimal, if any, air leaks, which improves comfort and less heat loss compared with walls without an air barrier Thermal resistance (R-value) typically above 3 K•m? W (in American customary units: R-17); this results in saving energy compared with uninsulated masonry. High sound absorption, which helps produce peace and quiet compared with framed walls Structural integrity for better resistance to forces of nature, compared with framed walls Higher resale value due to longevity of materials More insect resistant than wood frame construction When the building is constructed on a concrete slab, the walls and floors form one continuous surface; this keeps out insects.
Concrete does not rot when it gets wet Construction methods are easy to learn, and manufacturers often have training available ICF structures are much more comfortable, quiet, and energy-efficient than those built with traditional construction methods. Designing and Building with ICFs help your construction project attain Leadership in Energy and Environmental Design (LEED) Green Building status. Insulating Concrete Forms create a monolithic concrete wall that is 10 times stronger than wood framed structures. Disadvantages
Adding or moving doors, windows, or utilities is somewhat harder once the building is complete (requires concrete cutting tools). Cost – Depending on design, an average home will cost about 2% – 4% per square foot more than a conventional wood built home. For high-end homes constructed of concrete the insulating concrete form solution is usually less expensive. However, the energy savings of an ICF home usually result in lower cost for utilities. During the first weeks immediately after construction, minor problems with interior humidity may be evident as the concrete cures.
Dehumidification can be accomplished with small residential dehumidifiers or using the building’s air conditioning system. FIBRE REINFORCED POLYMER (FRP) COMPOSITES The Evolution of Composites within Civil Engineering Civil engineers have been in search for alternatives to steels and alloys to combat the high costs of repair and maintenance of structures damaged by corrosion and heavy use for years. Since the 1940s, composite materials, formed by the combination of two or more distinct materials in a microscopic scale, have gained increasing popularity in the engineering field.
Fiber Reinforced Polymer (FRP) is a relatively new class of composite material manufactured from fibers and resins and has proven efficient and economical for the development and repair of new and deteriorating structures in civil engineering. The mechanical properties of FRPs make them ideal for widespread applications in construction worldwide. FRP Laminate Structure FRPs are typically organized in a laminate structure, such that each lamina contains an arrangement of unidirectional fibres or woven fibre fabrics embedded within a thin layer of light polymer matrix material.
The fibres, typically composed of carbon or glass, provide the strength and stiffness. The matrix, commonly made of polyester, Epoxy or Nylon, binds and protects the fibers from damage, and transfers the stresses between fibers. Suitability of FRP for Uses in Structural Engineering The strength properties of FRPs collectively make up one of the primary reasons for which civil engineers select them in the design of structures. A material’s strength is governed by its ability to sustain a load without excessive deformation or failure.
When an FRP specimen is tested in axial tension, the applied force per unit cross-sectional area (stress) is proportional to the ratio of change in a specimen’s length to its original length (strain). When the applied load is removed, FRP returns to its original shape or length. In other words, FRP responds linear-elastically to axial stress. The response of FRP to axial compression is reliant on the relative proportion in volume of fibers, the properties of the fiber and resin, and the interface bond strength.
FRP composite compression failure occurs when the fibers exhibit extreme (often sudden and dramatic) lateral or sides-way deflection called fiber buckling. FRP’s response to transverse tensile stress is very much dependent on the properties of the fiber and matrix, the interaction between the fiber and matrix, and the strength of the fiber-matrix interface. Generally, however, tensile strength in this direction is very poor. Shear stress is induced in the plane of an area when external loads tend to cause two segments of a body to slide over one another. The shear strength of FRP is difficult to quantify.
Generally, failure will occur within the matrix material parallel to the fibers. Among FRP’s high strength properties, the most relevant features include excellent durability and corrosion resistance. Furthermore, their high strength-to-weight ratio is of significant benefit; a member composed of FRP can support larger live loads since its dead weight does not contribute significantly to the loads that it must bear. Other features include ease of installation, versatility, anti-seismic behaviour, electromagnetic neutrality, excellent fatigue behaviour, and fire resistance.
Applications of FRP Composites in Construction There are three broad divisions into which applications of FRP in civil engineering can be classified: applications for new construction, repair and rehabilitation applications, and architectural application. FRPs have been used widely by civil engineers in the design of new construction. Structures such as bridges and columns built completely out of FRP composites have demonstrated exceptional durability, and effective resistance to effects of environmental exposure.
Pre-stressing tendons, reinforcing bars, grid reinforcement, and dowels are all examples of the many diverse applications of FRP in new structures. One of the most common uses for FRP involves the repair and rehabilitation of damaged or deteriorating structures. Several companies across the world are beginning to wrap damaged bridge piers to prevent collapse and steel-reinforced columns to improve the structural integrity and to prevent buckling of the reinforcement. Architects have also discovered the many applications for which FRP can be used. These include structures such as siding/cladding, roofing, flooring and partitions.
Repair and Strengthening of Tanks with Carbon Fiber Reinforced Polymer (CFRP) Carbon FRP offers an ideal solution for repair and strengthening of tanks and silos that are damaged by corrosion. In many cases, leakage of these tanks can be stopped by means of carbon or glass FRP. Moreover, by applying carbon or glass FRP, repair and strengthening of the tank or silo can be achieved to levels that exceed original design strength. This is particularly interesting since such strengthening or repair with FRP will allow additional loads to be imposed on the FRP-retrofitted tank.
Fiber Reinforced Polymer (FRP) is an economical and efficient material for repairing and preventing corrosion and/or leakage problems in metallic, reinforced concrete and fiber glass tanks and silos. Among the advantages of Fiber Reinforced Polymer (FRP) for repair and strengthening of tanks and silos are: FRP provides a continuously bonded liner on the tank’s inner and/or outer surfaces that forms an air-tight seal that effectively prevents corrosion and leakage and strengthens the tank or silo. FRP increases the flexural and shear strength of rectangular tanks.
FRP increases the longitudinal and hoop strength of circular and cylindrical tanks and silos FRP provides electrical insulation for tanks used as electrolytic cells in the mining industry. FRP resists high temperatures of contained substances when bonded with heat-cured resins. FRP resists highly corrosive substances when coated with high chemical resistant toppings. When installed on the inner surfaces, technicians can access through openings (manholes) and no excavation of underground tanks is required.
Seismic Repair and Strengthening of Concrete Columns with Glass or Carbon FRP Reinforced Concrete columns or bridge piers can be efficiently strengthened with Glass FRP (GFRP) or Carbon FRP (CFRP). Older (pre-1970s) columns have two major shortcomings; they are inadequately confined and the ends of the ties are not properly anchored in the core region. During an earthquake, the ties open and allow the longitudinal steel to buckle, leading to failure of the column. Glass FRP and Carbon FRP can provide significant lateral confinement for concrete columns or bridge piers.
While spiral columns have in general performed well in past earthquakes, the above shortcomings have resulted in failure of many tied columns such as the one shown on the right. The solution is to externally confine the column. External confinement increases the strength of the concrete, but more importantly for seismic applications, the strain at failure of the concrete (i. e. ductility) increases significantly. Among the advantages of retrofitting columns with Fiber Reinforced Polymer (FRP) are: Increases Ductility Increases Shear Strength Improves Bond in Starter Bars
Conforms to Various Cross Sections Requires Minimum Access Costs Less than Conventional Methods Slabs Strengthened with Fiber Reinforced Polymer (FRP) Glass or Carbon FRP is a cost-effective system for strengthening concrete floors and decks or correcting design and construction errors that have lead to excessive deflection and sag in the slab. The case history below highlights one such application. Among the advantages of Fiber Reinforced Polymer (FRP) for strengthening slabs are: Increased flexural strength for both positive and negative moment regions in the slab Increased slab tiffness and reduced deflections at service loads Reduced crack widths for enhanced durability Covering a fraction of the slab surface with FRP may be sufficient for strengthening the entire slab No reduction in overhead clearance is caused by application of FRP (e. g. in parking garages) Lower cost for FRP compared to strengthening with conventional methods (e. g. epoxy injection in cracks) Glass or Carbon FRP are very effective in repair and strengthening of slabs and decks.
Because the moment capacity of the slab or deck is the couple resulting from the tensile and compressive forces, FRP can be applied to the tension face of the beam to increase the tension force. In most cases, the deck or slab has sufficient compressive strength and does not require strengthening. However, if needed, FRP can also be added to the compression face of the beam as a part of strengthening and repair. Strengthening of Steel Bridge Girders with Carbon FRP Carbon Fiber Reinforced Polymer (CFRP) is an economical and efficient system for flexural strengthening of steel bridge girders.
Among the advantages of repair and strengthening of steel beams and girders with FRP are: Increased flexural strength in the steel girder for both positive and negative moment regions Restores steel girder capacity after loss of tension flange area due to corrosion Increased stiffness of the steel girder in both elastic and plastic response Eliminates stress concentration in the steel girder due to welding Improved fatigue behavior of steel bridge girder (after retrofit with FRP) Lower cost than conventional methods
The feasibility of strengthening of steel bridge girders with carbon FRP was demonstrated through an extensive research study at the University of Arizona. The girders were constructed using W14x30 steel sections and as shown in the above photos, spanned 16 feet (4. 8 m) during the test. To simulate prior damage, the area of the tension flange for the beam or girder was reduced by 25%. The load-deflection for that damaged beam is shown in red. The tension flange of a similar companion beam was strengthened by applying 3 strips of Carbon Fiber (CFRP).
The behaviour of the steel beam or girder strengthened with carbon FRP is shown in the graph below. As can be seen, the strength of the bridge steel girder that was retrofitted with carbon FRP was significantly increased; this was also accompanied by a profound increase in stiffness of the girder in the plastic region. Carbon Fiber Reinforced Polymer (CFRP) also improves the fatigue behavior of the structure; the CFRP retrofitted beams could resist 2? – 3? times more cycles of loading compared to the cracked bridge steel girders that were not retrofitted with carbon FRP.
Utility Tunnels Repaired with Fiber Reinforced Polymer (FRP) Utility tunnels are concrete box girders that are widely used in major cities to house the various underground utility cables and pipes. Because they are always placed below grade, they are subject to moisture and in many cases the reinforcement in these structures corrodes. This could lead to potential failure and collapse of the tunnel. The case presented here is such a tunnel located below the Arizona State Hospital grounds in Phoenix.
In nearly all cases, the opening to the tunnel is very small, making it difficult to repair the structure with conventional approaches. Carbon fabric was used to strengthen this structure. The fabric was saturated near the tunnel opening. Due to the extreme high temperatures in summer, the contractor provided a chilled room on the site to store the resins. A temporary canopy was also erected to shield the Saturation Machine and to prevent rapid setting of the saturating resin. Saturated fabrics were passed into the tunnel through the manhole and were applied to all interior surfaces of the tunnel.
This slide shows the interior of the tunnel after the repair was completed. The pipes were temporarily covered with protective plastic sheets. The limited space inside the tunnel is clearly evident in this slide. STRUCTURAL INSULATED PANEL Structural insulated panels (or structural insulating panels), SIPs, are a composite building material. They consist of a sandwich of two layers of structural board with an insulating layer of foam in between. The board can be sheet metal or oriented strand board (OSB) and the foam either xpanded polystyrene foam (EPS), extruded polystyrene foam (XPS) or polyurethane foam. SIPs share the same structural properties as an I-beam or I-column. The rigid insulation core of the SIP performs as a web, while the OSB sheathing exhibits the same properties as the flanges. SIPs replace several components of conventional building such as studs and joists, insulation, vapor barrier and air barrier. As such they can be used for many different applications such as exterior wall, roof, floor and foundation systems. Materials
SIPs are most commonly made of OSB panels sandwiched around a foam core made of expanded polystyrene (EPS), extruded polystyrene (XPS) or rigid polyurethane foam, but other materials can be used, such as plywood, pressure-treated plywood for below-grade foundation walls, steel, aluminum, cementitious panels, and even exotic materials like stainless steel, fiber-reinforced plastic, and Magnesium Oxide. Some SIPs use fiber-cement or plywood for the panels, and agricultural fiber, such as wheat straw, for the core. Benefits
The use of SIPs brings many benefits and some drawbacks when compared to a conventional framed building. A well built home using SIPs will have a tighter building envelope and the walls will have higher insulating properties, which leads to fewer drafts and a decrease in operating costs for maintaining a comfortable interior environment for the occupants. Also, due to the standardized and all-in-one nature of SIPs construction time can be reduced over building a frame home as well as requiring fewer trades for system integration.
The panels can be used as floor, wall, and roof, with the use of the panels as floors being of particular benefit when used above an uninsulated space below. An OSB skinned system structurally outperforms conventional stick framed construction in some cases; primarily in axial load strength. With the exception of structural metals, such as steel, all structural materials creep over time. In the case of SIPs, the creep potential of OSB faced SIPs with EPS or polyurethane foam cores have been studied and creep design recommendations exist.
The long-term effects of using unconventional facing and core materials require material specific testing to quantify creep design values. Many asphalt shingle manufacturers will not warrantee their product over a SIP. Shingles tend to overheat and research has shown a shortened life span. Dimensions and characteristics In the United States, SIPs tend to come in sizes from 4 feet (1. 22 m) to 24 feet (7. 32 m) in width. Elsewhere, typical product dimensions are 300, 600, or 1200 mm wide and 2. 4, 2. , and 3 m long, with roof SIPs up to 6 m long. Smaller sections ease transportation and handling, but the use of the largest panel possible will create the best insulated building. At 15? 20 kg/m? , longer panels can become difficult to work with without the use of a crane to position them, and this is a consideration that must be taken into account due to cost and site limitations. Also of note is that when needed for special circumstances longer spans can often be requested, such as for a long roof span. Typical U.
S. height for panels is eight or nine feet (2. 44 to 2. 75 m). Wall panels tend to come in 125–200 mm thicknesses (US: 4. 5–6. 5 inches), but can be made up to 300 mm (US: 1 ft) for roofs. EPS is the most common of the foams used and has an R-value (thermal resistance) of about 4 K•m? /W per 25 mm thickness, which would give the 3. 5 inches of foam in a 4. 5 inch thick panel an R value of 13. 8 (caution: extrapolating R-values over thickness may be imprecise due to non-linear thermal properties of most materials).
This at face value appears to be comparable to an R-13 batt of fiberglass, but because in a standard stick frame house there is significantly more wall containing low R value wood that acts as a cold bridge, the thermal performance of the R-13. 8 SIP wall will be considerably better. The air sealing features of SIP homes resulted in the Environmental Protection Agency’s Energy Star program to establish an inspection protocol in lieu of the typically required blower door test to assess the home’s air leakage.
This serves to speed the process and save the builder/homeowner money. CONCLUSION The technologies which are explained above has been implemented & incorporated in various structures and by various prominent construction companies globally. In order to obtain the core specification in the related fields so as to get the extreme engineering construction. This kind of construction after serving for a decade for the sole purpose for which it is constructed offers us a place of experience & learning and incorporate them with new advanced technologies in it.
So as we can get still more hard core engineering conceptual design buildings, which will serve for more aspects than the conventional buildings. REFERENCES ?Saxena Mohini and Prabhakar J. “Emerging Technologies for Third Millennium on Wood Substitute and Paint from coal ash”, New Delhi, India, February 2000. ?www. quakewrap. com ?WIKIPEDIA ?Taylor, S. B, Manbeck, H. B, Janowiak, J. J, Hiltunum, D. R. “Modeling Structural Insulated Panel (SIP) Flexural Creep Deflection. ” J. Structrual Engineering, Vol. 123, No. 12, December, 1997. ?www. energysavers. gov
