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MODERN CONSTRUCTION TECHNOLOGIES IN ENGINEERING PERSPECTIVE

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Some new and emerging building construction technologies and materials are presented.

Veröffentlicht in: Ingenieurwesen
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MODERN CONSTRUCTION TECHNOLOGIES IN ENGINEERING PERSPECTIVE

  1. 1. MODERN CONSTRUCTION TECHNOLOGIES IN ENGINEERING PERSPECTIVE Dr K M Soni ADG(TD), CPWD, N. Delhi
  2. 2. Advantages of Modern Technologies • Faster Construction • Quality • Non availability of Economic Conventional Technologies and Workers • Non availability of Skilled Workers or highly costly workers • Environmental consideration • Use of Waste Materials • Aesthetic considerations and Innovation
  3. 3. Applications of Modern Technologies • Buildings • Roads and Highways • Tunnelling • Retaining Walls • Irrigation Structures • Nuclear Installations • Development Works and Services
  4. 4. Buildings • Conventional Buildings • Pre-fab / Pre cast Buildings • Pre-engineered Buildings
  5. 5. Conventional Buildings • Load bearing structures, • RCC framed structures, • Steel structures and • Temporary/semi permanent structures
  6. 6. Load Bearing Structures Brick/stone masonry structures • Modern materials and technologies may include; • CC blocks – Solid/hollow – With blocks made of stone dust – With C & D waste recycled concrete blocks, AAC Blocks or fly ash bricks • Cavity walls • Mortar/Adhesives • Robotic Laying of block/brickwork, Plaster and Painting
  7. 7. RCC Framed Structures • Formwork • Slab/beams/Columns • Plaster • Flooring • Ceiling • Painting • Services
  8. 8. Components • Floorings • Roofing • Cladding • Panelings • Casting of concrete • PT Slabs • Confined Masonry Construction
  9. 9. Services • Anchoring • Trenchless Technologies • Recycling Asphalt • Reinforced Soil • Robotics • 3 D Printing • Energy Efficient Technologies • Tree Plantation
  10. 10. Formwork • Conventional shuttering Jump formwork, aluminium formwork, aluminium-plastic composite formwork, Tunnel formwork, Plastic formwork or of similar other materials For Monolithic construction
  11. 11. Monolithic Construction • Monolithic construction means in situ casting of slab, beams and columns / walls simultaneously. • Such construction is carried out by specialized shuttering/formwork normally for RCC walls. • Therefore, new technology is in the use of shuttering only and other construction may be conventional.
  12. 12. Advantages • As the construction is with RCC walls, wall thickness is less than masonry members or columns having advantage of higher carpet area. • Also, it has few construction joints and even may not require cement plaster on the walls and • Provide better seismic resistance than conventional RCC construction. • Construction is faster, and • Highly suitable for repetitive multi-storeyed construction particularly in housing.
  13. 13. Limitations • Limited modular sizes in some cases, • High cost in case of non-repetitive units, • Changes not feasible after casting or during life time of the building, • Feasibility of limited architectural features, • Less energy efficient due to façade having low insulation characteristics, and • Difficulty and higher cost in repair and rehabilitation of services and structure during its life time.
  14. 14. Formwork • Jump formwork • Aluminium formwork, • Tunnel formwork
  15. 15. Jump Shuttering • Central core (Generally core housing lifts, staircase etc) is constructed first using a climbing or jump formwork system • A frame is constructed over the central core and steel formwork hung from it. Once the climbing formwork is in position, the formwork panels are closed and concrete wall is casted. After the walls are casted, the formwork is released. • Jacks then lift the whole frame up to next level. All the formwork panels are then attached to the frame and the process continued. The formwork get supported on the concrete casted earlier and thus does not rely on supports or access from other parts of the building or permanent works. • Suitable for multi-storeyed vertical concrete such as shear walls, core walls, lift shafts and stair shafts in buildings thus advantage in high rise construction as central core can be effectively used for other activities.
  16. 16. Aluminium Formwork • Allows casting of a floor in single operation. • Advantage of such formwork is that architectural features like projections, cornices, planters, curved beams etc can also be casted in one operation though it cannot be combined with other formwork materials such as plywood and steel. • The formwork is largely hand held and does not need the services of a crane for movement either vertically or horizontally. • These can be effectively used for repetitive works like multi-storeyed construction or row houses
  17. 17. Aluminium Formwork
  18. 18. Tunnel Formwork • It comes in half units in the form of an inverted “L”. When two halves are bolted together at the top, they form the tunnel (Fig. 3) hence the name.
  19. 19. Tunnel Formwork • The inbuilt wheels and the jacks help the formwork move in and out of the position and adjusted to the final height to cast walls and slabs in one operation in a daily cycle. • In casting process, prefabricated wall reinforcement is placed by crane along the entire wing prior to casting the kickers used to position wall formwork then two and a half tunnel placed in position by crane, bolted together and ties added. • The formwork system provides for a pour to be wrapped in tarpaulins and for the use of butane heaters to maintain a sufficiently high temperature for the concrete to reach its desired strength overnight for removal of formwork next day. • The process is repeated for the next two bays.
  20. 20. Tunnel Formwork • Apart from limitations described earlier, in tunnel formwork, walls are to be planned in same alignment of the formwork, external projections avoided and shaft openings to be provided from inside.
  21. 21. Tunnel Formwork
  22. 22. Prefab/Pre-cast Buildings • Pre-cast concrete buildings, or steel buildings. • Precast concrete buildings use precast RCC structural members such as beams, slabs, columns, walls, staircases, footings etc. • Normally such members are fabricated at the casting yard or in the factory with in-situ jointing and foundation casting. • Structurally, connectivity of the members is to be ensured and designed suiting to loading requirements including seismic and lateral loads, if any. • Advantage of such construction is pollution and dust control, quality assurance of precast products, faster construction and less storage space required at the site. • Limitations are of module sizes, limited architectural features, constraints of service lines and assurance of connectivity particularly during lateral loads.
  23. 23. CPWD Constructed Building at Hyderabad • Costly compared to conventional • Better quality • Uniform sizes • Faster • Limited storage space required at site
  24. 24. Pre-Cast Construction It uses standard steel sections and is widely adopted in crowded areas having space constraints and noise pollution restrictions particularly for industrial set ups, large span structures, and even high rise construction of any type of usage where RCC members requires large sections though welding may be required at site in many cases. In such construction any module size is feasible but special precautions are to be taken for fire safety and as such fire retardant coatings/paints are to be applied on structural members or to be made composite. False ceiling may be required due to aesthetic considerations. After 9/11 incidence in US, impact due to collision of air strike has also become of concern.
  25. 25. Pre Engineered Buildings • They are custom designed having varied sections as per the loading requirements, fabricated in factory, without welding (only bolting). • Saves rection time, erection cost, and maintenance cost. • In case column of free structures like exhibition halls, large convention centres, auditoriums etc, PEBs have the advantage over other type of conventional buildings.
  26. 26. Confined Masonry Construction • Concept of confined masonry construction is similar to Assam walling or ekra walling construction used long time back in semi permanent buildings in north eastern India, difference being that in place of wooden vertical posts and horizontal members in ekra walling construction, members in confined masonry construction are casted in reinforced concrete while infill walls are replaced with masonry work in place of bamboo mat. Like ekra walling construction was having higher seismic resistance, confined construction also exhibits similar properties.
  27. 27. Stamped Finish Concrete Flooring Technology Modern floorings, i.e. stamped or textured or imprint concrete, a decorative finish in desired colours and surface resembling to bricks, stones, tiles or even wood. The process includes preparation of sub-grade, placing of forms, providing reinforcement for stability, placing the concrete, screeding and finishing the concrete, applying colour and in the last stamping the concrete using desired moulds.
  28. 28. Stamped Finish Concrete
  29. 29. Post Tensioned Slab Technology • PT construction technology has advantage of elimination or reduction in sizes of beams hence has the advantage of larger headroom or more floors in same height hence highly suitable for high rise and air-conditioned buildings. The tendons are pre-stressed hence immediately tested for maximum loading conditions and leads to material saving, fast construction and increased performance.
  30. 30. PT Slabs
  31. 31. HPC Technology • HPC is a high strength concrete made by lowering the water-cement (w/c) ratio than 0.35, utilizing fine pozzolanic materials. Low w/c ratio and the use of silica fume make concrete mixes significantly less workable. To compensate the reduced workability, super plasticizers are commonly added to high-strength mixtures. • High strength concrete like self compaction concrete is normally used in post tensioned construction, and even in monolithic construction.
  32. 32. Cool Roof Technology • Cool roof is the one that reflects the sun’s heat back into the atmosphere. The roof thus, becomes cooler. • Such roofs offer advantages of reducing heat- gain, and improving energy efficiency of buildings, improving thermal comfort in buildings or reducing air conditioning load. Though there is a criticism that cool roofs enhance outside air temperature or reflect heat on some other surface.
  33. 33. GFRC Technology • Architectural features are essential components of any building. Some of the constructions like monolithic have no or limited architectural features. Such features can be added in the buildings by applying GFRC construction technology being very light in weight, weather and corrosion resistant and crack resistant. • GFRC is also used in various other applications like water storage tanks, septic tanks, domes for the buildings, roofing sheets, door frames and shutters, canopies, chimneys, pipes, gratings, column claddings, cooling towers, sculptures and statues, dustbins, furniture, external claddings and for rehabilitation and retrofitting of structures.
  34. 34. Reinforced Soil Technology • Reinforced soil concept is applied by providing reinforcement in frictional soils as the principle is based on friction between soil and the reinforcement. • Reinforcement is generally in the form of metallic strips or sheet generally of geostextiles or geogrids.
  35. 35. Anchoring technology • Mechanical Anchoring • Chemical Anchoring
  36. 36. Robotics • Robots can be used in buildings to roads, railways to underground structures, nuclear structures to disaster rescue operations, demolition of structures to inspections of deep sewer lines. • Maintenance of roads, railway tracks and electric power lines.
  37. 37. 3D Printing Technology • It refers to various techniques that use 3D printing as a core method to fabricate buildings or the components though at present in nascent stage. • Such technology is going to be integration of owner’s design acceptability, architect’s vision, on site but mainly off site fabrication, robotics and use of IT.
  38. 38. Trenchless Technology • Trenchless technology largely avoids cutting of roads and paths to pass through utility services in soils. Such technology avoids disruption of traffic and also helps in pollution control. The technology includes “no dig” methods like micro tunnelling, horizontal directional drilling, pipe ramming, auger boring, moling etc.
  39. 39. Energy Efficient Technologies • Building materials produced from such technologies include PPC, flyash based bricks, blocks and concrete, light weight and waste containing products, wood substitutes, C&D waste products, low VOC paints, and low water consuming faucets. • Similarly in E&M services, LED technology, solar power generation, regenerative lifts, IBMS, occupancy and other sensors, smart equipment and gadgets, energy efficient chillers and geo thermal heat exchange system for air- conditioning.
  40. 40. Re-plantation Technologies • The tree transplanter works on hydraulically operated spades. Conical shaped blades penetrate into the soil. Once all the blades penetrate inside soil, then the earth ball is lifted above ground level, and a pit is dug lifting the tree along with roots and soil. Trees of even one meter basal girth can be re- transplanted.
  41. 41. Conclusions • New Technologies will continue to come due to innovations. • Due to ICT, new and modern technologies will be less dependent on workforce . • “Smart” concept will be part of new technologies. • Though little costlier, new technologies will have to qualify for quality, better finish, green concept, aesthetics, less maintenance and faster construction. • Each technology has some limitations and as such should be chosen as per the requirements.
  42. 42. Acknowledgements • Photographs have been taken from internet sources and mostly not taken by the author. The original sources are gratefully acknowledged. Thank you

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