- affordability - provides one of the most efficient and cost-effective means of constructing energy-efficient structure
- Resource efficiency - The predominant raw material for the cement in concrete is limestone, the most abundant mineral on earth. Concrete can also be made with fly ash, slag cement, and silica fume, all waste byproducts from power plants, steel mills, and other manufacturing facilities
- strength - added protection against earthquakes and severe weather.
- durability - gains strength over time, 100-year service life, resists weathering, erosion and natural disasters, long-lasting structures that will not rust, rot, or burn.
- low maintenance - few repairs and little maintenance, adding up to a solid investment
- thermal mass - can harvest natural energy sources such as the sun, and can also capture thermal energy from lighting fixtures and other equipment in the building
- compactness
- Safe - does not burn. It also does not feed rot and mildew. It does not off-gas any volatile organic compounds and provides excellent indoor air quality. Superior quality of construction helps prevent the entry of pollen, dust and other airborne pollutants
- Thanks to solid construction and the benefits of thermal mass, concrete provides superior protection against the effects of outdoor temperature swings, which means a draft-free interior environment and consistent room temperatures, year-round
- A peaceful and quiet building enhances the comfort of occupants and provides a sense of privacy - solid walls and floors make all the difference.
- a type of strong thin wooden board
- consisting of two or more layers glued and pressed together with the direction of the grain alternating
- Plywood consists of three or more layers of veneer.
- Normally, each is glued with its grain at right angles to adjacent layers for strength
- to reduce the shrinkage and improve the strength of the finished piece
- batten board
- lamina board
- metal faced plywood
- multiply, 3 ply
- veneered plywood
- the cost is reduced - Cheap material
- hard material
- the strength is generally increased / increase the stability
- reduce void content and harden the mix
- provide abrasion resistance
Steel transverse reinforcement detailing
- not only take care of structural requirement,, but also hep main reinforcements to remain in desire position
- play a very significant role while abrupt changes or reversal of stresses like earthquake
- should be closely spared as per the drawing and properly tied to the main longitudinal reinforcement
- it is prevention buckling of longitudinal bars and transfer of tensile stresses, that arise in the
orthogonal direction to the direction of compressive force action in the column.
Requirement of mortal during application stage
- must conform to ASM C270 for material weight and recommended properties
- mortal must be cleaned out to a uniform dept
- edges of mansory unit must not be damage
- mortar mix should be used within 2 - 2.5 hours after initial mix is prepared
- repelling - adding water to the mortar mix to maintain consistency
Procedure apply protective paints to timber
- lift the lid of the primer ( undercoat ) . stir the paint and dilute with 5 % -10% water if necessary
- sand down existing timber with coarse to fine grid sand paper
- apply undercoat with a pain brush or roller as evenly as possible
- make sure all surface is painted
- allow 4 hours to dry or according to product information
- sand lightly uneven surfaces
- lift the lid of the finish coat, stir well and dilute with 5% -10% wter if necessary
- apply finish coat with brush or roller and make sure all surface are painted
- allow 4 hours to dry and repeat process until desired effect
- make sure surfaces are clean before every coating application
How precast concrete building product fabricated and installed?
production of reinforced cages and main connections. the precast factory has specialist workshops for manufacture and maintenance of molds and for the production of jig - build reinforceing cages and connections
assembly of moulds
the reinforce cage is positioned in the partly assembled mould, then the remaining mould section is completed
mix being poured
carefully specified concrete is place into the mould, many precast works employ computer controlled batching plants
compaction of concreted using poker / vibrator
to ensure that optimum density is obtained and that specified strength are achieved, concrete is placed and compacted suing high frequency external vibrator or pokers
curing / precast concrete being moved to the storage area
once a n appropriated strength has been reached. Upon the precast is cured, the unit is removed to storage area.
storage of high quality units in works area
the finish precast components are stacked on clean battens or plastic pads positioned to suit the design of the component
transport to site
the components are delivered to the site in pre determined sequence to ensure that hardened concreted are ready for instant erection
erection at site
the components are erected straight from he lorry. this leads to faster erection times with reduced on sited activity
finish building
how air en trained concrete is manufactured and use?
- prepare by mixing aluminum in it is called air en trained, cellular or aerated concrete.
- in this concrete bubbles of hydrogen gas are liberated which forms cell and make the concrete cellular
- used - for lining wall, roofs for heat and sound insulation purpose
- Air entrainment is the intentional creation of tiny air bubbles in concrete
- The primary purpose of air entrainment is to increase the durability of the hardened concrete, especially in climates subject to freeze-thaw; the secondary purpose is to increase workability of the concrete while in a plastic state
- The air bubbles are created during mixing of the plastic (easy flowing, not hardened) concrete, and most of them survive to be part of the hardened concrete
- The primary benefit of entrained air in hardened concrete however is the resistance it offers to freeze-thaw damage and scaling caused by de-icing salts or chemicals
- Most concrete contains some moisture which expands during freezing temperatures. Without room for this expansion, large forces develop that can rupture the surface causing what is commonly called surface scaling.
- The small, entrained air bubbles serve as reservoirs or expansion chambers to relieve these pressures.
key strength of plywood
- better splitting resistance - due to grains in adjacent layers running at the right angle and nailing and screwing even closed to the edges in safe
- it has a good strength both across as well as along the grain
- can easily be bending to a a curvature limited by the tensile and the compressive strength of the other plies
- the face piles made at different heartwood show great aesthetic variety in grain pattern and color.
failure mechanism cause to asphalt road
wearing course
rutting - shear failure
pothole - bond failure
loss of skid resistance ( viscous flow )
lower course
cracking - fatigue failure
breakdown due to failure of lower coarse example : reflected cracking from dry lean concrete
Alligator cracking is a load associated structural failure. The failure can be due to weakness in the surface, base or sub grade; a surface or base that is too thin; poor drainage or the combination of all three. It often starts in the wheel path as longitudinal cracking and ends up as alligator cracking after severe distress.
Block cracks look like large interconnected rectangles (roughly). Block cracking is not load-associated, but generally caused by shrinkage of the asphalt pavement due to an inability of asphalt binder to expand and contract with temperature cycles. This can be because the mix was mixed and placed too dry; Fine aggregate mix with low penetration asphalt & absorptive aggregates; poor choice of asphalt binder in the mix design; or aging dried out asphalt.
Longitudinal cracking are cracks that are parallel to the pavements centerline or laydown direction. These can be a result of both pavement fatigue, reflective cracking, and/or poor joint construction. Joints are generally the least dense areas of a pavement.
Transverse cracks are single cracks perpendicular to the pavement's centerline or laydown direction. Transverse cracks can be caused by reflective cracks from an underlying layer, daily temperature cycles, and poor construction due to improper operation of the paver.
Edge Cracks travel along the inside edge of a pavement surface within one or two feet. The most common cause for this type of crack is poor drainage conditions and lack of support at the pavement edge. As a result underlying base materials settle and become weakened. Heavy vegetation along the pavement edge and heavy traffic can also be the instigator of edge cracking.
Joint Reflection Cracks
These are cracks in a flexible pavement overlay of a rigid pavement (i.e., asphalt over concrete). They occur directly over the underlying rigid pavement joints. Joint reflection cracking does not include reflection cracks that occur away from an underlying joint or from any other type of base (e.g., cement or lime stabilized).
Slippage Cracks
Slippage cracks are crescent-shaped cracks or tears in the surface layer(s) of asphalt where the new material has slipped over the underlying course. This problem is caused by a lack of bonding between layers. This is often because a tack coat was not used to develop a bond between the asphalt layers or because a prime coat was not used to bond the asphalt to the underlying stone base course. The lack of bond can be also caused by dirt, oil, or other contaminants preventing adhesion between the layers.
Pot Holes
Small, bowl-shaped depressions in the pavement surface that penetrate all the way through the asphalt layer down to the base course. They generally have sharp edges and vertical sides near the top of the hole. Potholes are the result of moisture infiltration and usually the end result of untreated alligator cracking. As alligator cracking becomes severe, the interconnected cracks create small chunks of pavement, which can be dislodged as vehicles drive over them. The remaining hole after the pavement chunk is dislodged is called a pothole.
Depressions (bird baths)
Depressions are localized pavement surface areas with slightly lower elevations than the surrounding pavement. Depressions are very noticeable after a rain when they fill with water.
Rutting Ruts in asphalt pavements are channelized depressions in the wheel-tracks. Rutting results from consolidation or lateral movement of any of the pavement layers or the subgrade under traffic. It is caused by insufficient pavement thickness; lack of compaction of the asphalt, stone base or soil; weak asphalt mixes; or moisture infiltration.
Shoving is the formation of ripples across a pavement. This characteristic shape is why this type of distress is sometimes called wash-boarding. Shoving occurs at locations having severe horizontal stresses, such as intersections. It is typically caused by: excess asphalt; too much fine aggregate; rounded aggregate; too soft an asphalt; or a weak granular base.
Raveling (very porous asphalt)
Raveling is the on-going separation of aggregate particles in a pavement from the surface downward or from the edges inward. Usually, the fine aggregate wears away first and then leaves little "pock marks" on the pavement surface. As the erosion continues, larger and larger particles are broken free and the pavement soon has the rough and jagged appearance typical of surface erosion.
There are many reasons why raveling can occur, but one common cause is placing asphalt too late in the season. This is because the mixture usually lacks warm weather traffic which reduces pavement surface voids, further densification, and kneading of the asphalt mat. For this reason raveling is more common in the more northern regions(snow belt).
steel anchorage length in reinforcement
steel anchorage length is the additional length of steel of one structure required to be inserted in other at the junction
for example, main bars of beam in colum at beam colum junction, colum bars in footing
the length requirement is similar to the lap length or as per the design instruction
firmly fix at both end and not slip out
provide sufficient bond strength
how to choose mortar joints
- desired architectural appearance and the weather resistance
- most weather proof and recommended are V shape, weathered and concave
- joins many be formed by using a trowel, steel rod or specialize tool
Concave Joint: The concave joint is the most common joint that is used, as it is also known as the best joint for preventing water penetration. Tooling works the mortar tight into the joints, which produces better weather resistance.
V Joint: The V Joint does not protect from water as well as the concave joint because of its geometry. If it isn’t tooled correctly, water can accumulate in the joint. Similar to the concave joint, tooling works the mortar tight and can help to prevent water penetration if done correctly.
Weathered Joint: The weather joint is used to emphasize horizontal joints. The weathered joint helps shed water from the joint, however it is possible that water can run across the underside of the brick and get through if the mortar is not adhered tightly or if shrinkage cracks develop in the bond line.
Flush Joint: The flush joint is typically used when a wall is going to be plastered-over or when the joints need to be hidden under paint. In order to be weather resistant, this joint will take a little more work and attention. If not given the proper care, water can sit on top of the joint if it sticks out from the brick. It is also difficult to maintain a consistent and sufficient bond to the brick because the mortar is not compressed into the joint with the striking tool.
Squeezed Joint: The squeezed joint is commonly seen in indoor architecture or outdoor fences. It provides a rustic and high texture look, but poses a threat for moisture intrusion because it has three exposed sides exposed to the weather. This can lead to premature deterioration and
floor finishing treatment procedure
- dirt and dust should be first be removed by vacuum or broom
- start grinding marbles floor with a marble grinding machine with metal bonded diamond grit which coarsely grind away the stone leaving it flat
- repeat the process with finer grades of diamonds which are resin bonded
- the level to which grinding takes place depends on color, the of marbles number of scratches, dept of the stained and levelness of marble
- following by the honing process, where silicon carbide or diamond particles are rubbed over the surface. typed of honing depends on floor condition
- honing grit is graded according to tis size and the larger the grit, the more stone it removes from surface
- next step is polishing, is done by industrial diamonds, but smaller graded, than while homing. for shining effect
- crystallization by spraying a fuid onto the marble floor and butting it in with steel wool under butting machine
- apply a coat of marble sealer and let it dries for 45 minutes
how to prevent corrosion to metal pipe
- protection lining on the pipes needs to be provided against corrosion by acidic water
- soil should be tested before laying pipes in ground
- pipes can be wrapped in plastic during installation to protect metal from soil
- organic chemical, especially solvent and gasoline weakens PVC pipes cause pipe to expand and rupture
- the operator in charge should be alert of any unusual odors as it may be a sign of chemical spill that may damage the pipes
- Turn to non-corrosive metals such as aluminum and stainless steel.
- Keep the area around the metal surface dry.
- Use drying agents and moisture barrier products.
- Make sure underground piping is laid in a layer of backfill, such as limestone.
- Make sure any electrical components are cleaned regularly
- Keep in mind that all metal requires maintenance.
- a coating of grease or oil maintained on a metal surface, for instance.
- Painting is another method of preventing metal corrosion.
Carbon fiber coating is another excellent method of preventing the corrosion of metals. In this process, sheets of carbon fiber are sealed around and often inside a metal pipe or on any metal surface. This not only helps to prevent corrosion but strengthens the metal, prevents cracks and stops leaks from forming.
Cathodic protection employs a piece of easily corrodible metal, such as zinc or iron, connected to the surface it is intended to protect. Called a “sacrificial anode” or just “anode,” this metal rusts and corrodes in place of the primary piece of metal.
Primarily, cathodic protection involves galvanizing a metal. Metals such as steel are coated with a more easily corroded metal, like zinc. As corrosion takes place, the zinc is sacrificed to rust and corrosion while the underlying steel is left largely untouched. A natural electrical current forms between the two levels, helping to attract oxidation and corrosion to the sacrificial zinc.
In objects where a solid electrical current cannot be formed between the metal, another method of cathodic protection adds an external, DC electrical current to draw corrosion away from the protected surface
