Tuesday, 24 November 2015
vertical green system through seamless joint between extruded wall panel and plants. Compared with traditional vertical green system, Oxygreen panel vertical green system is more harmony and nicer on appearance, closer joint between wall and plants, which increase the beauty of buildings and take use of the wall limit space to maximum. It changes the “concrete forest” into true natural green forest. And realize the green concept trends from two dimensional space to three dimensional space.
One wall dual purposes, nice and energy saving.
Put soil and plant in the wall to realize the integration of wall envelop structure and greening system. One wall with two purposes reduces the cost invested. Compared with the traditional greening wall, the Oxygreen wall has the thickness reduction more than 60% , because the vertical greening system use the integration panels which integrate wall panel and green plants on a panel..
Stable performance, good weather resistanceOxygreen panel is extruded in vacuum and high pressure , which brings wall panels high density, no leakage, no crack, non deformation, and no need water treatment. Besides, low water absorption rate of the surface gives the panel good freezing resistance and weather resistance.
Fabrication in factory, easy installation“Vertical greening system” is composed of 4 different parts. 1) vertical greening integration panel 2) fixed connection system 3)automatic irrigation system 4)plants arrangement
Good sound insulationOxygreen panel is made as the extruded cement panel, which has very good performance on sound insulation over 45Db.
Energy conservation and emission reduction , widely applicationEvaporation effect and Sunshine shading effect of the plants reach the index of Energy conservation and emission reduction , and mitigate climate warming . can be widely applied in vertical greening, roof greening, tree envelop greening, slope protection greening, elevated greening, subway greening, traffic noise barrier greening.
High benefit, low costVertical greening takes less land, small investment, but produces high benefit. It is one of the effective ways to expand greening area. Vertical greening can reduce wall radiation heat, increase air humidity , reduce dust, clean air , green environment, save energy and protect environment, and beautify city.
Meet requirements of green buildingsVertical greening increases urban greening rate, irrigation system can take use of rainwater recycling, which is energy saving and environment friendly, meet the design requirements of green buildings, meet relevant bonus point criteria of green buildings, and benefit to green building project review.
Monday, 2 November 2015
Monday, 26 October 2015
The following steps should be carried out on site:
• Calibrated dial gauges should be fixed at the bottom of the slab to measure the expected deflection. Five (5) gauges should be used to monitor the deflection in the case of loading.
• The gauges should be set to an initial reading.
• Special precautions should be made to prevent any vibrations in the testing area.
• Test load provided by the contractor should be uniformly distributed on the slab according to the intensities indicated in the cases of loading.
• Test load should be applied in four (4) approximately equal increments.
• Response measurements should be recorded after completion of each Increment
• After completion of four (4) loading increments, the slab should be kept loaded for 24 hours after which deflection readings and response measurement should be taken.
• The slab will be unloaded. Final response measurements should be done after unloading directly then after 24 hrs from removal of test load in order to indicate residual deflection.
the measured maximum deflections shall satisfy one of the following two conditions:
• max ? L2 / 20,000h
• ?rmax ? ?max / 4
?max: is the maximum deflection in mm
?rmax: is the maximum residual deflection in mm
L2: is shorter of:
(a) Distance between centers of supports in mm.
( Clear distance between supports plus thickness of member in mm.
h: is the thickness of the slab in mm.
Friday, 18 September 2015
Fly Ash is a by-product of the combustion of pulverized coal in electric power generation plants. When the pulverized coal is ignited in the combustion chamber, the carbon and volatile materials are burned off. However, some of the mineral impurities of clay, shale, feldspars, etc., are fused in suspension and carried out of the combustion chamber in the exhaust gases. As the exhaust gases cool, the fused materials solidify into spherical glassy particles called Fly Ash. Due to the fusion-in-suspension these Fly Ash particles are mostly minute solid spheres and hollow cenospheres with some particles even being plerospheres, which are spheres containing smaller spheres. The size of the Fly Ash particles varies but tends to be similar to slightly larger than Type I Portland Cement. The Fly Ash is collected from the exhaust gases by electrostatic precipitators or bag filters. Chemical make up of Fly Ash is primarily silicate glass containing silica, alumina, iron and calcium. Color generally ranges from dark grey to yellowish tan for Fly Ash used for concrete.
ASTM C 618 Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use as Mineral Admixture in Concrete has two designations for Fly Ash used in concrete - Class F and Class C.
Class F Fly Ash is normally produced from burning anthracite or bituminous coal that meets the applicable requirements. This class of Fly Ash has pozzolanic properties and will have a minimum silica dioxide plus aluminum oxide plus iron oxide of 70%.
Class C Fly Ash is normally produced from subbituminous coal that meets the applicable requirements. This class of Fly Ash, in addition to having pozzolanic properties, also has some cementitious properties and will have a minimum silica dioxide plus aluminum oxide plus iron oxide content of 50%.
Most state and federal specifications allow, and even encourage, the use of Fly Ash; especially, when specific durability requirements are needed. Fly Ash has a long history of use in concrete. Fly Ash is used in about 50% of ready mixed concrete (PCA 2000). Class C Fly Ash is used at dosages of 15 to 40% by mass of the cementitious materials in the concrete. Class F is generally used at dosages of 15 to 30%.
Advantages of Fly Ash in Concrete
Fly Ash is a pozzolan. A pozzolan is a siliceous or aluminosiliceous material that, in finely divided form and in the presence of moisture, chemically reacts with the calcium hydroxide released by the hydration of Portland Cement to form additional calcium silicate hydrate and other cementitious compounds. The hydration reactions are similar to the reactions occurring during the hydration of Portland Cement. Thus, concrete containing Fly Ash pozzolan becomes denser, stronger and generally more durable long term as compared to straight Portland Cement concrete mixtures.
Fly Ash improves concrete workability and lowers water demand. Fly Ash particles are mostly spherical tiny glass beads. Ground materials such as Portland Cement are solid angular particles. Fly Ash particles provide a greater workability of the powder portion of the concrete mixture which results in greater workability of the concrete and a lowering of water requirement for the same concrete consistency. Pump ability is greatly enhanced.
Fly Ash generally exhibit less bleeding and segregation than plain concretes. This makes the use of Fly Ash particularity valuable in concrete mixtures made with aggregates deficient in fines.
Sulfate and Alkali Aggregate Resistance. Class F and a few Class C Fly Ashes impart significant sulfate resistance and alkali aggregate reaction (ASR) resistance to the concrete mixture.
Fly Ash has a lower heat of hydration. Portland Cement produces considerable heat upon hydration. In mass concrete placements the excess internal heat may contribute to cracking. The use of Fly Ash may greatly reduce this heat build up and reduce external cracking.
Fly Ash generally reduces the permeability and adsorption of concrete. By reducing the permeability of chloride ion egress, corrosion of embedded steel is greatly decreased. Also, chemical resistance is improved by the reduction of permeability and adsorption.
Fly Ash is econoamical. The cost of Fly Ash is generally less than Portland Cement depending on transportation. Significant quantities may be substituted for Portland Cement in concrete mixtures and yet increase the long term strength and durability. Thus, the use of Fly Ash may impart considerable benefits to the concrete mixture over a plain concrete for less cost.
Wednesday, 12 March 2014
- Max allowable temp for all types of concrete is 32 0 c.
- Max allowable fall of pouring 1st 1.2 mts.
- Max allowable slump 100+- 25 mm, water adding should not be allowed.
- Max allowable time is 2hrs after batching
- Normally ‘opc’ used for structural & src used for sub structures.
- Normally types of mix a.40/20, b.30/20, c.25/20, d 20/20.: where ’40’ is compressive strength & 20 is the site of agg.
B. Wet mix
- Minimum cbr should be 80 @ 100 % compaction.
C. Road base
- Normally moisture content should be in between 4.5% to 6.5%.
- Normal grading 70% agg (size = 5mm down) & 30% sand.
- Agg used in wet mix : crushed & in road base natural.
- Minimum compaction required is 98%
D. Prime coat
- Average rate of application should be 0.8 to 1.2 kgs/sqm.
- Temperature should be in between 600 c to 900 c curing time 48hrs.
- Cut back asphalt mc =medium curing rc=rapid curing = sc=slow curing.
E. Tack coat
- Average rate of application should be 0.15 to 0.35 kgs/sqm.
- Temperature should be in between 100 c to 600 c.
- Tack coat should be sprayed min 2hrs before laying aspahlt
- Inter locking paving blocks:6cm thick for footpath:8cm for parking.
- Typical cross section shows:15cm=sub base,5cm coarse sand,6cm=tiles.
- First compaction after paving tiles,final after sand spreading..
H. Kerb stone
- Types upstand kerb,drop kerb,heel kerb,flush kerb(dimension varies)
- Fixing g.l.compacted 7cm con blind.fixed by mortar ,15cm con haunching.
- Pointing gap should be 4mm expansion joint should be at very 10mc.
- All the services should be below 90cm from the frl(finish road level)
- Less than 90cm below frl,should be protected concrete production.
- Normal use :future or spare ductsplit duct,proposed duct
- Normally pvc & upvc pipes used for ducts,dla from 100mm to as required.
- Pipe lines :water =30cm to 60cm a/c irrigation =28cm pvc storm water=225mm .
- Mentral test & pressure tests conducted to confirm clear & lekage
- Test pressure shall be 1, 5 times the max working pressure & bar .
- Ducts above speci level shall be bedded & surrounded with 150mm con 15//20 .
- During backfill warning tape shall be installed over buried pipes.
- All ducts shall be provided std color drancord & std duct markers.
- Trench backfill shall be with appr mat & in 15cm compacted layers.
J. Safety measures:
- Trenches more than 1m deep shall protected with sheet piles (shoring) .
- Construction site should secured with cones, barrier & waring tapes.
- Temporary diversion sign boards, flash lights, should be installed.
K. Test a/c
- Marshal test (for stablity, flow, stifness, vim, vfb, vma) & core test (comp).
- Test for agg grading in asphalt also to find out bitumen content.(e/w)
- Mdd againest omc (proctor test) cbr field density (com) tests
- Slump (workablity) test, test for compressive strength (by cubes).
- Paving blocks & kerb stones shall be tested for crushing value.
- Is a mixture of coarse aggregate, fine aggregate filler material & bitumen binder.
- Mix types /dense mix &stiff mix grad a.40/50 & b,60/70.
- Normal asphaltic layer thickness/b.c=80mm bi.c=60mm w.c =40mm.
- Normal aggregate/ Base Course =37mm & down binder .c=25mm & down wearing c =19mm & down.
- Required min compaction /b.c=97: bi c=97: w.c=98%.
- If compaction is more than 101.8% the asphalt should be rejected
Allowable temp in asphalt
- surface temp before laying =18 0 min
- batching temp=1630c max
- laying temp=1350 c to 1630 min & max
- breakdown temp=1200 to 1400 c
- temp in joints should be 900 c min.
- In logitudinal joints 15cm over lap should be maintained.
- All logitudinal & transverse joints should cut vertical.
- Asphalt laying & rolling should be done from lower to upper.
- Asphalt should be laid max 1.50 m to get req tem in joints.
- Modified asphalt to increase stiffness 10 to 15% of chemcrete is mixed with bitumen while batching also to increase stability.
- Bleeding surface flow of bitumen (occurs due to over spray of tack coat) by placing hot mix over sprayed should be removed.
- Segregation / accumulation of agg. should replaced with fine mix
- To know no of passes required for of min comp, trail area 30mt to be prepared.
- Inspector to check during asphalt, segregation open texture tearing action using straight edge constantly, & tem regularly.
- Pot holes: less asphalt thin asphalt surface, poor drainage & ponding due to oil & diesel patches slippage cracks with form.
- Cracks can be repaired by, bitu- sealant, hot mix asphalt emulsion slurry.
- Camber = two side slope (nor1.5%) cross fall=one side slope(nor2%)
- In long & tran joints between layers 15cm offset is kept for good comp.
- While asphalt paving the speed of paver should be 4 to 6 km/min.
- Weight of STR (Steel Tandom Roller) should be in between 8 to 12 ton.
- Weight of PTR (Pneumatic Tyre Roller) should be 20 to 25 ton/ tyre pressure should be in between 6 to 6.3 kg/sqcm or 80 to 110 psi/
- Rollers speed should 5km/hr, should maintain overlap in passes/
- Staggered rolling should be done in passes, to avoid channeling/
- First & final rolling should be with STR & in middle with PTR.
- First to seal temp, final for smooth finish, PTR for inform comp.
- Veg oil lubrication used on PTR tyre ,should not be excess.
- While rolling at super elevation drive wheel should be forwarded, to avoid pushing of material.
- After 24 hrs re rolling is avoided design period will be reduced.
- Traffic should not be allowed min 7 days on fresh asphalt pavement.
- Transverse joints should be in min 50cm offsets for each line.
- FRL(finish road level) should be 15cm below the kerb stone
- Normal widths c.w=6m 7.3m & 11.5m p.p =2.5m d.p =5.5m s.w.=2.5m:mn=3m.
- Prime coat is sprayed over wet mix to seal the moisture content.
- Asphalt should layer 25% more to get req thickness after compaction.
- String line supported 10m interval pegs to get uniform levels.
- Joints should cut verticaly(900) toget proper compaction in joints.
- Asphalt leveling at joints should done careful to avoid jump & sag.
- Embankment should be in 15cm compacted layers approved material.
- CBR of exist mat should be 15.at formation level.
- Formation level should be compacted 95% and CBR should be 15%.
- Improved sub grade should be compacted 95% and CBR should be 30.
- Use of saline water. Should be avoided in Construction & compaction works.
- Before executing job trial trench's or pits to be excavated to find existing service.
- Construction area shall be checked with cable detector to locate the exist cables.
- Reference point for all levels shall be taken from standard bench mark.
- For trench where water table is high dewatering pump shall be used.
- Before laying pipe lines, 15cm sand bedding should be layed.
- Curing shall be done for min 7 days for all concrete work.
- For emergencies curing compound is allowed to proceed for further job.
- 25 mm grouting shall be done for base of storm water manhole.
- GRP liner shall be provided for all sewer manholes.
- Rock fill layer is used in road const, where the water table is high.
- Earth work= grader, showel, back hoe, static roller & vibrator roller.
- Asphalt works= Paver, STR (Steel Tandom Roller) PTR (Pnuematic Tyre Roller).
- Others: transit mixer, spray tanker, bob cat, dumber, baby roller.
- Equipment used in asphalt should be without leakage of oil & diesel.
- All const works shall execute under: std spec limits & tolerances.
• White cement (O.P.C)
• Silica sand.
• Alkali resistant Glass fiber.
• Others-Marble chips, Mirror glaze chips etc.
- Direct spray: started by weighing (using calibrated weighing equipment) than mixing (using a high shear mixer), Spraying using specialist equipment allowing the simultaneous deposition of known quantities of cementious slurry and chopped glass fiber.
- Premix vibration casting: started by weighing then mixing, pouring the materials in the mould parallel with the vibrating method shall ensure the filling is such that air is expelled from the product and planes of weakness are avoided.
- MOULD: As a first stage mould is prepared to the required element to its exact size and shape in steel, timber, G.R.P (Glass reinforced plastic), rubber or in other material based on the shape and size of the product.
- Casting:The method of casting is with hand spray process. A facing layer of white cement, pigment, silica sand (with required marble or glaze chip if required according to the texture) water and acrylic Polymer is sprayed on to the mould without fiber and then left to harden slightly (not to set). The facing layer is normally 1.5 to 2.5 m.m thick and G.R.Cis then sprayed in to this to the required thickness of normally 9-19m.m based on size and design of element. If the G.R.Cpanel require (for big panels only) the stiffeners, pre-cut polystyrene pads in required profile shape is positioned and again G.R.C is sprayed to form the box type stiffeners to a minimum thickness of 10 to 15 mm . After the initial settings and after demolding keep it up to final setting time and dispatch to site if it is white smooth finish or pigmented smooth finish.
- STONE FINISH After de-molding the face of panel is washed with hydrochloric acid until the required texture is achieved. Brushing on the acid and scrubbing the panel with a stiff brush. Other way the face of whole panel shall be dipped in to a large acid bath. Prior to delivery to site a final wash with dilute acid in normally applied to remove efflorescence (white staining), which may have occurred. Then finally wash with pure water. (Acid, use HYDROCLORICACID diluted 1 part 3 to 4 parts water or required proportion).
- ADMIXTURE "CHROMIX"admixture for color conditioned concrete manufacture by Mis L.M.SCOFIELD EUROPELTD, U.K.
- GLASS FIBER ALKALI RESISTANT glass fiber from EUROPE or JAPAN.
a) G.R.C White smooth finish: - After installation in its place, it shall be painted to required color and texture quality paints. Preferably epoxy based paint.
b) G.R.C Color -pigmented -smooth finish:Pigmented G.R.C not required Paint or it can be painted also later.
c) G.R.C Stone finish &acid washed:This will give rough or fair rough stone finish appearance. It is not required any further painting or finishing. It shall be a unique single color and pattern.
Panels are fixed through steel frame to concrete, with threaded bar (lOx120 mm), nuts, washers and expoxy.
As for G.R.C Pergolas, the G.R.C rafters will be reinforced with 4nos of steel bars (dia=14mm). Some panels required angle brackets (7Sx7Sx7Sx10mm). These angles will be fixed to concrete with anchor bolt (12 mm).
Wednesday, 26 February 2014
Application When fresh concrete is delivered to a site by a truck mixer it is sometimes necessary to check its consistence before pouring it into formwork.
If the consistence is not correct, the concrete will not have the desired qualities once it has set, particularly the desired strength. If the concrete is too pasty, it may result in cavities within the concrete which leads to corrosion of the rebar, eventually leading to the formation of cracks (as the rebar expands as it corrodes) which will accelerate the whole process, rather like insufficient concrete cover. Cavities will also lower the stress the concrete is able to support.
Flow table with a grip and a hinge, 70 centimeters (28 in) square.
Abrams cone, open at the top and at the bottom - 30 centimeters (12 in) high, 17 centimeters (6.7 in) top diameter, 25 centimeters (9.8 in) base diameter.
Water bucket and broom for wetting the flow table.
Tamping rod, 60 centimeters (24 in) long
Conducting the test
- The flow-table is wetted.
- The cone is placed in the center of the flowtable and filled with fresh concrete in two equal layers layers. Each layer is tamped 10 times with tamping rod.
- The cone is lifted, allowing the concrete to flow.
- The flowtable is then lifted up 40mm and then dropped 15 times, causing the concrete to flow
- After this the diameter of the concrete is measured.