CHAPTER 6
CASE STUDY
6.1 Concrete walls and floors
Concrete walls is an eclectic category with options for everything: seat walls; decorative interior or exterior finishes; sound walls that abut a freeway; retaining walls to hold back the earth; to the very walls that comprise the exterior of a home. Concrete has become the new flooring material of choice for designers and homeowners across the United States. Concrete floors are popping up in retail stores, trendy restaurants, offices, and homes everywhere. Whether it's acid-stained, painted, overlays, micro toppings, radiant floors, or a unique personal floor, concrete floors offer a range unlike any other material. Concrete flooring, sometimes referred to as cement flooring, no longer has to be gray and boring. Now coloring concrete or applying textures, patterns, saw cuts, etc., can bring new life to this traditional substrate.
One of the major benefits of concrete floors is their affordability compared to other flooring options. Installing a decorative concrete floor can be quite cost-effective, particularly if you already have a concrete slab that’s ready for staining, polishing or application of a coating or overlay. A basic concrete floor will carry a comparable price tag to linoleum, vinyl, ceramic tile or carpet. While a more complex concrete floor design will run you about the same or slightly less than marble, granite, slate, or high-end wood. Furthermore, the lifetime cost of a concrete floor is very low because they require little upkeep and last for years.
A second thing that attracts business and homeowners to concrete flooring is its ease of maintenance. When properly sealed, concrete floors can be cleaned with a quick pass of a dust mop. For an occasional deep clean a neutral cleaner and water can be used. The frequency of maintenance is dependent on the amount of traffic the floor receives. Restaurants and businesses with considerable foot traffic may want to use a sacrificial floor wax in addition to a sealer to further protect from abrasion.
Here are some additional benefits of concrete floors according to Barbara Sargent of Kemiko Concrete Floor Stains:
• They enhance the integrity of architect's designs.
• They are easy to change, especially if you sell your home; the next owner can place carpet or wood on top of the concrete slab.
• They are great in regions with a lot of sand or snow.
• They are a good alternative to carpet if you have allergies.
Fig 6.1 Concrete wall
6.2 Precast Cladding Panels
Precast concrete panels are reinforced concrete units available in a wide range of mixes, colours and finishes. Finishes can include acid-etched, smooth or coarse ground, grit or sand-blasted, rubbed or polished. Mixes designed to resemble natural stone can also be produced. Highly articulated designs can be accommodated by the mouldable concrete mix.
Benefits
• Faster programme times - not affected by weather or labour shortages.
• Improves buildability.
• Early enclosure of dry envelope enables follow-on trades to start sooner.
• Produces a high standard of workmanship in factory conditions - reduces potential for accidents, addresses on-site skill shortage.
• Has a high quality finish that can be left exposed - concrete's thermal properties can
• be exploited in low-energy buildings
Fig 6.2 ACP Cladding
6.3 Precast Flat Panel System
Floor and wall units are produced off-site in a factory and erected on-site to form robust structures, ideal for all repetitive cellular projects. Panels can include services, windows, doors and finishes. Building envelope panels with factory fitted insulation and decorative cladding can also be used as load-bearing elements. This offers factory quality and accuracy, together with speed of erection on-site
Fig 6.3 Panel system
6.4 Volumetric modules
3D Volumetric construction (also known as modular construction) involves the production of three-dimensional units in controlled factory conditions prior to transportation to site.
Modules can be brought to site in a variety of forms, ranging from a basic structure to one with all internal and external finishes and services installed, all ready for assembly. The casting of modules uses the benefits of factory conditions to create service-intensive units where a high degree of repetition and a need for rapid assembly on-site make its use highly desirable.
Fig 6.4 Volumetric Module
6.5 Twin Wall Technology
Twin wall technology is a walling system that combines the speed of erection and quality of precast concrete with the structural integrity of in-situ concrete to provide a hybrid solution. The prefabricated panels comprise two slabs separated and connected by cast-in lattice girders. The units are placed, temporarily propped, then joined by reinforcing and concreting the cavity on site. Twin wall is usually employed in association with precast flooring systems.
The panels are manufactured to exacting tolerances, have a high quality finish, and can incorporate cast-in cable ducts, electrical boxes and service ports. Installation rates are of up to 100m2 per hour. Twin wall has excellent inherent fire resistance and acoustic performance.
Fig 6.5 Twin Wall Technology
6.6 Flat Slabs
Flat slabs are highly versatile elements widely used in construction, providing minimum depth, fast construction and allowing flexible column grids. Because this is one of the most common forms of construction, all construct members and many other concrete frame contractors can undertake this work. Flat slabs are particularly appropriate for areas where tops of partitions need to be sealed to the slab soffit for acoustic or fire reasons. Flat slabs are considered to be faster and more economic than other forms of construction, as partition heads do not need to be cut around down stand beams or ribs.
Flat slabs can be designed with a good surface finish to the soffit, allowing exposed soffits to be used. This allows exploitation of the building’s thermal mass in the design of heating, ventilation and cooling requirements, increasing energy efficiency. Flat slabs provide the most flexible arrangements for services distribution as services do not have to divert around structural elements.
Fig 6.6 Flat Slab
6.7 Thin Joint Masonry
In masonry, mortar joints are the spaces between bricks, concrete blocks, or glass blocks that are filled with mortar or grout. Mortar joints can be made in a series of different fashions, but the most common ones are raked, grapevine, extruded, concave, V, struck, flush, weathered and beaded.
In order to produce a mortar joint, the mason must use one of several types of jointers (slickers), rakes, or beaders. These tools are run through the grout in between the building material before the grout is solid and create the desired outcome the mason seeks
Thin joint block work (thin joint masonry) is a fast, clean, accurate system for construction using autoclaved aerated concrete blocks of close dimensional tolerance with 2mm-3mm mortar joints. Thin layer mortar is a pre-mixed cement-based product that only requires the addition of water to make an easily-applied mortar. The benefits offered by thin layer mortars are provided by a system with many of the characteristics of traditional block work construction.
Fig 6.7 Thin Joint Masonry
6.8 Concrete Formwork
Formwork is a structure, usually temporary, used to contain poured concrete and to mould it to the required dimensions and support until it is able to support itself. It consists primarily of the face contact material and the bearers that directly support the face contact material. Formwork systems used for concrete frame construction have continued to develop significantly since the early 1990s. The major innovations have focused on on-site efficiency of production, health and safety, and environmental issues, driving the concrete construction industry towards ever-increasing efficiency. Different formwork systems provide a wide range of concrete construction solutions that can be chosen to suit the needs of a particular development.
Traditional formwork for concrete construction normally consisted of bespoke solutions requiring skilled craftsmen. This type of formwork often had poor safety features and gave slow rates of construction on-site and huge levels of waste.
The main types of formwork systems in use now are:
• Table form/flying form
• System column formwork
• Horizontal panel
• Slip form
• Tunnel form
The modern formwork systems listed above are mostly modular, which are designed for speed and efficiency. They are designed to provide increased accuracy and minimize waste in construction and most have enhanced health and safety features built-in.
Fig 6.8 Concrete Formwork
6.9 Precast Foundation
Precast concrete foundation and wall panels can take many forms. Some consist of steel-reinforced concrete ribs that run vertically and horizontally in the panels. Others are solid precast concrete panels. Panels are precast and cured in a controlled factory environment so weather delays can be avoided. A typical panelized foundation can be erected in four to five hours, without the need to place concrete on site for the foundation. The result is a foundation that can be installed in any climate zone in one sixth of the time needed for a formed concrete wall.
Some manufacturers cast the concrete against foam insulation that provides the form during manufacture and added R-value in the wall. Panels range in size from 2'-12' in width by 8' - 12' in height and are typically installed with a crane on top of 4" to 6" of compacted stone. The stone facilitates sub-slab drainage and adequately carries and transfers the load from the foundation wall. Panel connections consist of bolts and sealant. The foundation can be backfilled as soon as it is braced per manufacturer's specifications.
The controlled temperature of the processing plant allows the manufacturer to work with concrete admixtures that focus on ultimate strength rather than cure time and temperature. Manufacturers are able to produce mixes that harden to 5,000 psi, which is stronger than concrete block or concrete walls formed and cast in the field. Better control of the concrete mixture and curing environment allows the use of low water/cement ratios that results in a dense material that prevents water penetration.
Fig 6.9 Precast Foundation
CHAPTER 7
CONCLUSION
As can be seen through-out the above report, the use of a precast frame and a thin coat spray on plaster finish on this development can produce significant reductions on the overall construction programme while also not only maintaining, but excelling the standards set out in the original specification.
The precast frame exceeds specification as it will be 60N concrete and manufactured to a very high specification in a factory controlled environment. Tight factory production control ensures that the re-enforcement is located accurately and the panels are made to tight dimensional tolerances. Structural connections are also accurate which assists in the accurate installation of cladding, windows and other elements thereafter. Furthermore precast concrete improves structural efficiency as longer spans and shallower construction depths can be obtained using prestressed floors and/or beams. Most importantly, there will be no additional work created for the design team as the precast manufacturer produces their own in-house precast drawings for approval by the architect thus design costs do not change or increase.
The limitations of the topic “Modern Construction Technology” is very enormous and massive. Therefore, it not possible to covers all the topic and chapters in this report. Therefore , this report has limited topics related to “Modern Construction Technology” which are as follows:-
1. Concrete Walls and Floors.
2. Precast Cladding Panels.
3. Precast Flat Panel System.
4. Volumetric Modules.
5. Twin Wall Technology.
6. Flat slabs.
7. Thin Joint Masonry.
8. Concrete Formwork.
9. Precast Foundation.
The benefits of modern methods of construction are too positive to be ignored.. Modern methods of construction can provide large numbers of sustainable, well-designed homes in a short period of time. Modern methods of construction also afford an opportunity to overcome the skills shortage in the construction industry through factory production.. Modern methods of construction will be a key tool in addressing this challenge and should be viewed as an opportunity for the house building sector to increase capacity and choice in the housing market.Modern construction technology have evolved from the more conventional methods to a large extent. Modern construction technology is those that provide greater efficiency in the construction process, resulting in increased production, better quality, in less time and with less waste, so reducing the environmental impact. Modern construction technology is a process to produce more, better quality homes in less time.
REFERENCES
1. Modern methods of constructions and their components (Lenka Kyjaková , Tomáš Mandičák & Peter Mesároš)
2. Modern methods of construction: a solution for an industry characterized by uncertainty (Ylva Sardén1 And Susanne Engström)
3. Study on modern methods of constructions used in Srilanka H.M.M.Uthpala1, T.Ramachandra.
4. Modern methods for cost management in construction enterprises Peter Mesároš, Tomáš Mandičák, Jozef Selín
5. Acceptance theories of innovation and modern methods in construction industry Daniela Ma˘Ckov´ A, Tom´A˘S Mandi˘C´Ak
6. www.google.com
7. www.wikipedia.com
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