3 transport

7/31/2019 3 Transport

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3. TRANSPORT

3.1. TRANSPORT IN CONSTRUCTIONS

For execution of civil works, large amount of materials, precast elements have tobe transported, cost of transport being 20-25% of total costs of the constructionworks.For some materials, (e.g. aggregates for concrete and plasters) transport cost is40-50% of their total cost.Choice of the most appropriate transport vehicle in a certain case, can insure aminimum transport cost.Transports in constructions are:

Horizontal transport Vertical transport (exclusive vertical) Vertical transport with limited horizontal transport Specific transport for workshops

3.1.1. Horizontal transportHorizontal transport can be:

- transport at long distance- transport at short distance

3.1.1.1. Horizontal transport at long distance

Long distance transport can be made on:a) Railwayb) Road wayc) Unprepared way

a) Transport on RailwayA regular railway or a narrow railway can be used for materials transport.

Transport on regular railway uses locomotives with platform wagons, boxwagons, tank wagons for liquids or special wagons for aggregates or cement.

Besides these, transport on light railway uses light rail motor tractors(locotractoare) with the following rolling stock:

Platform cars (1-2 tons capacity) (vagonete cu platforma fixa) Side discharging cars (vagonete cu basculare laterala) with capacity of 0.5,

0.75, 1m3 for 600 mm railway gauge, and 1.5, 1.75 and 2 m3 for 760 mmrailway gauge

Metallic discharging cars (vagonete basculatne metalice) of 0.5 m3 capacity

Maximum slope for light rail motor tractors is 4%.


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Transport on normal railway is used of material supply to main warehouses ofcompanies or earth bringing in or evacuation. It has the advantage of large rangeof transport, being economic on long distances and large volumes of materials

Transport on narrow railway is used only on large sites for evacuation ormovement process of earth or other materials between fixed points. A narrowrailway becomes economic when transport is made on a fixed route for a periodlarger then 2 years, in order to return the investment (amortizarea investitiei) ofrailway building

b) Transport on Road way

It is realized with vehicles. The vehicles achieve big velocities (2080 km/h) withvariable transport capacities (from 3 tones for tractors to 120 tones for lorries),

which makes them appropriate for transport of large volumes of materials ataverage distances. They have the possibility of easy access in almost anyworking point, and easier maintenance then other transport means.

Large quantities of materials and large variety of materials to transport, necessityof their mechanized dump and quality insurance for transported materials leadedto a large variety of road transport means.

After the possibility to transport one or many kinds of materials, the roadstransport means are:

- nonspecific vehicles

- specific vehicles

Nonspecific vehicles are the ones that can carry several types of materials (inpieces, in bulk etc.) In this category can be included:

- platform lorries- dump lorries (with possibility of lateral or back dumping)

Specific vehicles can carry only one kind of materials, but insure better conditionsthen nonspecific vehicles (ex: cement trucks, agitating trucks).

In order to use the traction force of the motor as much as possible, there can beuse multiple-unit trains, containing track tractors, trailers and/or semi trailers.

The difference between a trailer and a semitrailer is that the last one sends a partof its weight to the vehicle frame at the back axle, increasing vehicle adherence.

Multiple-unit train


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In some countries, ruttier transports use multiple-use trains has increased to 85%of total because of following advantages:

- increase of transport capacity (live load being 1.52.5 times higher)- decrease of fuel consumption- one or two trailers can be used in order to reduce the loading-unloading

time

For transport of large elements as precast elements, heavy equipments etc.,large capacity low-bed trailers are used. Their load capacity can reach 50100 t.

Semi-trailer

When the road is not fit for lorries, here can be used dumpers, tractors withtrailers or semitrailers, Tractors can be wheels tractors or chain tractors.

Tractor with trailer


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Dumpers

Dumpers are vehicles with dumping bucket of special shape characterized bylarge mobility, high maneuver capacity, easy handling, high productivity.Usual dumpers have 24 m3 transport capacity being recommended for highmaterial volumes transported on medium distances.Medium dumpers have a 0.51 m3, transport capacity being recommended forsmall material volumes transported on medium distances.

Tractors on wheels are characterized by small velocities 2040 km/h. They areused on small and medium distances on difficult roads.


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c) Transport on Unprepared ways

Chain tractors are used for heavy unprepared ways, with trailers and semi-trailers. They are indicated for short distances, and are characterized by:

- small velocities: 515 km/h- low mobility

3.1.1.2. Determining the traction force on the horizontal transport

Fig. 3.1 Vehicle scheme

Calculus of traction force is necessary for determination of maximum load thatcan be carried by a vehicle. In order to find the traction force Ft the vehicle

scheme is considered (fig. 3.1). The vehicle motor is characterized by indicatedpower Pi, indicated force Fi, and developed at motor level. The effective power Peand traction force Ft are developed at the boundary of driving wheel.

The effective power has the expression:

ie PP where

efficiency; =0.750.95, depending on the vehicle type

The value of traction force results from the equality between the mechanical work

developed at the level of driving wheel in 1 second and effective power of themotor developed at the same level:

eFt PL s

mN750CP1

et P7501vF3600

1000

v

P2700F et [N] where


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v

h

km- vehicle speed

Pe [CP] effective power

To start the car (provided that the wheel does not slide) the traction force at thewheel level shall not exceed the friction force (Fad) at the wheels level:

adadt Q1000FF where

Qad [kN] normal weight to the contact surface

- friction coefficient between driving wheel and rolling track; depends on wheelnature and road type and condition

PGQad

- coefficient that takes into account the unfavorable action of working load onthe friction forceG[kN] dead load of the vehicleP[kN] working load of the vehicle

3.1.1.3. Determining the maximum transport load

The basic condition for a vehicle to be able to move on a certain road is that thetraction force to overcome the resistance movement, meaning:

wQF tt ; rip wwww

Qt total weight of the vehicle; Qt = G+Pwp rolling resistance; it depends on wheel nature and road type and conditionwi supplementary grade resistancewr supplementary curve resistance

The value of grade resistance can be found

from fig. 3.2, as follows:

sinPG1000w i or

sinPG

Ww ii

In case of small slope, sin tg i wi = 1000iwhere i = the slope

Fig. 3.2.


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The value of supplementary curve resistance can be found with relationsestablished experimentally. In case of transport on roads wr = 0 because thecurves are calculated so the additional forces to be canceled one by another.

The general expression can be written:

ripRRripTTt wwwQwwwGF , where

GT [kN] weight of the traction vehicleQR [kN] total weight of the trailed vehicles and

ripR

ripTTtR

www

wwwGFQ

Special cases:

Transport with tractors and trailers wr = 0

ipR

ipTTtR

ww

wwGFQ

Transport with lorries wr = 0; QR = 0; GT = G+P

Gww

FP

ip

t

Number of trailed vehicles can be found from the condition:

RRR pgnQ RR

R

pg

Qn

where:

gR dead load of a trailerpR working load of a trailer

3.1.1.4. Organization of horizontal transport

The horizontal transport is a cyclic process, consisting in: loading, transport withfull load, unloading, empty transport, maneuver operations.

Duration of a transport cycle (tc) is:

m2

d1

ic t2v

lt

v

ltt where:


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ti [h] loading durationtd [h] unloading duration

v1

h

km- vehicle speed at transport with full load

v2

h

km- vehicle speed at empty transport

tm maneuver durationl transport distance

If an average vehicle speed is considered, the cycle duration becomes:

mdm

ic t2tv

l

2tt

It is recommended that the traction vehicles to work with trailers or semi-

trailers 0tt di ; the duration of transport cycle for a traction vehicle is now:

mm

tc t2

v

l2t

In order to avoid waiting times of base equipment (for loading or unloading) at thearrival of transport vehicles, a correlation between cycle times of equipmentssystem by means of traffic chart (fig. 3.3).

Inclined line in the graph corresponding to motor traffic line is called running line,

and the tangent of angle is the average speed of traffic. On that portion:

1

11

1 v

vl

l

t

ltg

For base equipment to have a continuous operation is necessary to organizetransport using several sets of trailers. From the traffic chart, results the numberof sets of trailers (Ng) in order to insure the continuity at loading point:

cig ttN i

mdm

i

gt

t2tv

l2t

N

The number of transport vehicles results for the same condition:

tcit ttN

i

mm

tt

t2v

l2

N


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Fig. 3.3

The result is rounded up to the first round number both for N g and Nt. Theserounded numbers insure the continuity but leads to a waiting time for trailers (t gs)and/or vehicles (tts), with the values:


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ciggs ttNt

tcit

ts ttNt

The relations are similar for continuity at unload point:

cdg ttN d

mdm

i

gt

t2tv

l2t

N

tcdt ttN

d

mm

tt

t2v

l2

N

cdggs ttNt

tcdt

ts ttNt

Finally, the shift carrying capacity can be found. First, the number of sets oftrailers (Ng

s) transported during a shift is found:

tc

ssg K

t

tN where:

ts shift durationKt vehicle usage rate during a shift; Kt = 0.850.95

The shift carrying capacity results as follows:

pgtc

spg

tgtp KPK

t

tKPNQ where

Pg [kN] carrying capacity for one set of trailers; Pg = n x pRKp - loading capacity usage rate (Kp = 0,91,0)

3.1.1.5. Horizontal transport at short distances

For small distances, following equipment can be used:

- equipment with cyclic service, stationary or mobile: drag bucket (lopatamecanica), small dumper, etc.

- equipment with continuous service, between 2 fixed points: drag chainconveyor (transportor cu lant), belt conveyor (transportor cu banda) etc.

The drag bucket is made of a shovel tied to a steel cable placed around apowered winch (troliu). It is used for transport on small distances, for aggregatesdump from wagons, supply of belt conveyors, etc.

Small dumpers have transport capacity of 0.250.5 m3 and reduced speed(1040km/h) and are recommended for small or medium volumes on small or


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medium distances. As disadvantage, they need asphalt roads or concreteplatforms, etc.

Belt conveyors are used for horizontal transport of grain materials between 2fixed points, in workshops, in gravel pits (balastiera) etc. The transport distanceis around tens of meters, or more, when 4-6m sections connected are used.Being equipments with continuous operation, it has high efficiency: 50-200 t/h, upto the belt width and speed.

Drag shovel

Chain conveyor


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Belt conveyor

3.1.1.6. Technical and economic criteria for choice of transport means forhorizontal transport

The choice of the most suitable vehicle for horizontal transport, several factorsshould be considered: volume of transported materials, transport distance, kindof material, road existence and type, cost of transported ton of material, etc.

Taking into account the cost of transported ton of material, the following arerecommended:- For transport on short distances - 200300m the most suitable vehicle is the

small dumper- For 13 km, on sites with short life span it will be preferred: tractors with

trailers, lorries or 5t dumpers, in specified order- For distances larger then 3 km: lorries- For long span life sites, fixed transport routes and 0.53 km distances, light

rail motor tractors with wagons are preffered.

3.1.2. Vertical transport (exclusive)

3.1.2.1. Classifications of equipments for vertical transport

The most of construction materials must be lifted at a certain height. Followingequipments are used for this purpose:

1) With cyclic operating waya. Fixed

With small span arm (window crane, light crane for finishingworks)

With no arms (vertical platforms, mast elevator lift pe catarg)


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b. Mobile- With small span arm (mast crane macara catarg)- With no arm (mast elevator with platform installed on a 4 wheels

carriage)2) With continuos operating way (bucket hoist)

Window crane Mast elevator

3.1.2.2. Technological considerations (consideratii tehnologice)

The equipments used for vertical transport (exclusively) are provided withfollowing devices:

With 1 hook and 1 arm 2, 3, 4 m long With one or two platforms With tipping buckets (cupe basculante)

The materials to be lifted are loaded in baskets (cosuri), boxes, pallets(containers), wheelbarrows (roabe), platform wagons or in tipping buckets.Excepted are long materials tied reinforcement bars , precast concreteelements, isolated objects.

The containers are hanged on the crane hook or are manually pushed on theplatform that is to be lifted. The containers that cannot be moved alone andpushed on the platform are moved with special carriages (ex.: bricks transport inpallets).


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The long materials can be lifted only with equipments provided with hooks.Because the hooks can also be used for hanging the containers for smallmaterial transport, the equipments with hooks can be considered that cover thelifting procedures for all necessary materials.

The equipments provided with tipping buckets can be used only for bulkmaterials lift. The bulk materials are poured into the bucket through a gutter(jgheab).

The lifting equipment with small arms, with platform or with tipping buckets caninsure only transport on vertical line. Because the material should reach theplace of installation, these transport means should be combined with equipmentof minor mechanization. The materials transshipment between the 2 equipments

should be reduced to minimum possible, so it has to be done as closest aspossible to the lifting equipment. For this reason, the place of the fixed liftingequipment will be near the edge of the floor level. The mobile lifting equipmentwill be placed in the middle of the long side of working front. They have theadvantage the movement possibility alongside the building. The fixed equipmentcannot be moved, but it can be used at higher distances then the mobile ones.

3.1.3. Vertical transport with limited transport on horizontal line(Transportul pe verticala cu transport limitat pe orizontala)

3.1.3.1. Classifications of equipments for vertical transport with limitedtransport on horizontal line (Clasificarea mijloacelor de transportpe verticala cu transport limitat pe orizontala)

The equipments from this category have a great advantage compared toprevious ones, because they can bring alone the materials to the place of finalinstallation, or they can leave the material in the weight centre of the workingfront. In this way the necessity of minor mechanization equipment use iseliminated. This characteristic leads to economy in manpower, equipment andcost.

These equipments are classified in:- tower cranes- other equipments

The tower cranes are classified after their load-carrying capacity:- light tower cranes (0.5 1.5 t capacity)- medium tower cranes (1.5 5.0 t capacity)- heavy tower cranes (> 5 t capacity)


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Tower crane

The last category is used mainly for heavy precast elements handling andinstallation, both on site and on the storage place. Also are used for handling ofheavy equipments.

The light and medium tower cranes can be classified after their technicalparameters and the way they are used, as follows:

tower cranes with constant mast height , which are used for working frontsplaced at 40-45 m height

tower cranes with possibility of mast uplift, used for working fronts placedat 70-80 m height

self-lifting tower cranes can be used for working fronts placed over 70-

80 m height, up to the cable length that can be coiled over the barrel(tambur)

The classification other equipments includes all other equipments besidestower cranes that are used for the combination vertical + horizontal transport.They can be:

equipments:o belt conveyorso pumps: insure the transport of materials in liquid, paste or dust

state through pipes


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transport installations:o inclined plane (plan inclinat)o cableway crane (funicular)o gantry crane (macara portal = electropalan pe masina sustinut pe

cadre sau console pe stilpi)

Gantry crane

3.1.3.2. Technological considerations (consideratii tehnologice)

CRANES: The light and middle tower cranes with constant tower mast height

have the following characteristics: Span range (raza de actiune) 8-20m Lifting height 20-40m Lifting carrying capacity 0.5 5 t

There is a strong connection between the three parameters in the way of thefollowing parameters being in inverse proportion:

a. span range and working lifting heightb. span range and lifting carrying capacity

In order to insure the materials transport to the place of final installation, a tower

crane does the following maneuvers: moving along the rolling track (with or without load, after the

construction type) arm rotation with tower mast rotation in horizontal plane together

with the arm (after the construction type)

Some cranes are provided with trolleys that drive the cable with the hook; thetrolley is also moving along the arm or crane runway. These cranes are easier tomaneuver. In order to bring the container at the final position, the rotationmaneuver in horizontal plan done together with the horizontal move of the trolleyalong the crane runway.


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The rolling track for tower cranes is done from 2 parallel rails with 2.60 4.00 mgauge (ecartament). The distance between the rolling track axis and buildingfront varies with the gauge and structural solution (basement for instance).

Generally, the 5 tons capacity tower cranes are used mainly for the materialtransport from the storage place on site to the final destination over the structure,meaning materials lifting and horizontal movement; they can be also used forloading unloading operations, handling in storage places, installing processesin civil engineering.

The average capacity tower cranes are used at buildings with large amount ofworks, because they allow the use of heavy duty containers (2-5 t). the lighttower cranes are indicated for structures with lower volume of works.

The disadvantage of cranes use can be considered a kind of rigidity duringoperation process, because of its fixed rolling track. There is the tendency toreplace these cranes with truck cranes on wheels or chains.

truck crane

EQUIPMENTS

BELT CONVEYORS (TRANSPORTOARE CU BANDA) are used for thecontinuous transport of bulk materials (materiale in vrac) with grading(granulometrie) up to 150mm. the belt conveyors are used in warehouses,quarries, and construction sites.


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Belt conveyors

PUMPSused for civil works can have continuous operating system (pump withscrew conveyor (snec) for cement transport, centrifugal pump for transport ofwater, cement milk, lime milk) or cyclic operating system (pumps with pneumatictransport for concrete and mortar).

Generally, the pumps have the following advantages: Insure the easy access of materials inside the buildings, in hard to reach

places. have a high efficiency insure transport at long distances and heights with small amount of labor

They also have disadvantages: pipes clogging (infundarea conductelor) fast pipes wear (uzura rapida a conductelor)

TRANSPORT INSTALLATIONS are used for materials supply in areas hard toaccess with usual vehicles. They insure the transport between two fixed points

INCLINED PLANES are used both for materials supply and earth evacuationfrom diggings in large areas. The length range is 10 200m. The rolling trackhas thin gauge (600 to 700 mm) and it can be simple track or double track. Therolling stock (material rulant) consists in dump cars (vagonet basculant) orplatform cars (vagonet platforma) pulled by a winch with cables.


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1 simple rolling track2 platform car3 mechanic winch4 traction cable

5 roller for traction cable6 materials storage placeA construction object

Fig. 3.4. inclined plane with simple rolling track

This installation has the advantage that it needs little arrangements and therolling track is recovered almost integrally.

CABLEWAY CRANESare used for materials transport for bridges construction,dums construction or other works situated in places hard to reach.

3.1.4. Specific transport for warehouses (Transporturi specifice atelierelor)

The transport inside warehouses is done with: Bridge cranes (Poduri rulante), used in warehouses for precast

elements production and storage, in warehouses for reinforcementmanufacture, etc. the bridge cranes with hooks are built for 5-50 tons loadand lifting heights 12-16m.

3.1.5. Technical and economic criteria for choice of transport means forvertical transport (Criterii tehnico-economice pentru alegereamijloacelor de transport pe verticala)

The types of structures realized nowadays have a great variety of heights andwidths, constructive systems (masonry, cast in place reinforced concrete, precastreinforced concrete, etc.), all these factors influencing the type of optimumequipment to be used for materials lifting transport.


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For instance, the choice of crane type is done from technical and economicalcriteria.The technical criteria are:

Building height Width and shape of the building (the length of the building influences only

the number of the equipments used) Maximum load to be lifted Dimensions of the elements to be lifted

The economic criteria are: The cost of the crane or the rent payment for one The cost of crane installing and uninstalling The cost of arrangement for rolling track

The technical characteristics of the building to be built eliminate a part of theequipment that does not comply with the objective conditions. The equipmentsremained are examined from the economic point and helps taking the finaldecision.

3.2. LOADING AND UNLOADING WORK OF MATERIALS AND PRODUCTSIN CONSTRUCTIONS (LUCRARI DE INCARCARE DESCARCARE AMATERIALELOR SI PRODUSELOR DE CONSTRUCTII)

The loading unloading works in constructions use a large volume of work. It

can be considered that only the handling of materials and precast elements onsites means 20-30% of the total works without materials. The cost of handlingworks is about 8-10% of the total costs without materials.

The loading unloading works are used for transport processes.

The equipments used and the flow chart (schema tehnologica) used for themechanization of operations of loading transport unloading of the mainmaterials and products are different, according to the materials nature: grains,powdery, in pieces, etc.

3.2.1. Flow charts for loading unloading works of grain materials(Scheme tehnologice pentru lucrari de incarcare descarcare amaterialelor granulare)

The aggregates (sand, gravel, crushed stone) and other necessary grainmaterials as earth, rubble, etc. can be loaded in vehicles with equipments andvehicles that sometimes can insure the materials transport on medium distances.The following types of equipment are used:

Loaders with cyclic operation way (with bucket)


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Loaders with continuous operation way Installation composed of drag bucket and conveyor belt

a) Flow charts for loaders with bucket (schema tehnologicapentru incarcatoare cu cupa)

The loaders are moving on wheels or chains.The loading operation has 3 phases:

Bucket loading Going next to the transport vehicle Bucket unloading

Wheel loader with auxiliary equipment

The working charts (schema de lucru) for loaders differ according to themaneuver movement and the unloading method (fig. 3.5.)

The maneuver can be a front movement. In this case, the unloanding can bedone by:

Frontal tipping of the bucket (basculare frontala) Frontal and lateral tipping of the bucket Reverse running with bucket pull-over


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a, b,c Wheel loader. Frontal unloadd Wheel loader. Lateral unload

e Wheel loader.Lateral unload

f Wheel loader.

Bucket pull-overdischargeg, h Chain loader.Bucket pull-overdischarge

Fig. 3.5. Loading charts for different loader with 1 bucket

The loaders with frontal discharge do the most maneuver movements. The most

efficient are the ones with pull-over discharge. Though, during the last years, themost used ones where the wheel loaders with frontal discharge because there isthe possibility to adapt other equipments to the same tractor.


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b) Flow charts for loaders with continous operating way (schematehnologica pentru incarcatoare functionare continua)

The loaders with continuous operating way have as working device buckets onchains, shedders (rotor port cupe), etc. The material discharge into the truck isdone through a gutter or a conveyor belt.

1 loader2 conveyor belt

3 railway car4 usual railway

Fig. 3.6. Working charts for loaders with continuous operating way

This loader can be used only for loading operations. Because of the continuousdelivery of the loader and the calm unloading process, it results a highproductivity and there are avoided the shocks that affects the transport vehicles

in case of loader with bucket. They are very efficient for loading the aggregatesinto vehicles.

A comparison between the cyclic and continuous loaders leads to the followingconclusions:

The cyclic loaders have a simpler construction path, are less costly, havemobility and can provide transport on short distance, are harder to break,and by the interchange of the working devices, they can handle a widerange of materials.The continuous loaders works from a fixed position, handle only bulkmaterials (grains or powder), but have a higher productivity.


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c) Flow charts for systems with drag buckets and conveyor belts(schema tehnologica pentru instalatie compusa din lopatametalica si banda transportoare)

The mechanical discharge of aggregates from railway cars or trucks is done ingood conditions with systems made of drag buckets and conveyor belts.

1 conveyor belt on railway2 railway car

3 drag bucket on railway4 storage pile

Fig. 3.7. Aggregates discharge from railway cars using drag bucket and conveyorbelt

The aggregates discharge into a storage place is done as follows: the lateral side

of the railway car is partially open and loads the conveyor belt through a cone.

3.2.2. Flow charts for loading unloading works of powder materials(cement) (Scheme tehnologice pentru lucrari de incarcare descarcare a materialelor pulverulente)

The cement is about 6% of the total weight of construction materials andproducts.The supply transport of cement can be done using 3 different technologicalsolutions:

In paper bags In containers In bulk: with transport vehicles on road or railway station; the vehicles

must be provided with pneumatic recipients (fig. 3.8.)The pneumatic recipient is charged by gravity free fall, and discharged with thehelp of compressed air. It is installed on special cars, semi-trailers, in storageplant for discharging normal cars, or on cars that moves below a line of silos anddoes the cement unloading and transfer from the auxiliary silo to the supply silo.


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1 metallic tank2 charge hole cover3 loosening plate (placa de afinare)4 inferior pressure room with cover5 inferior air duct (conducta de aer)6 superior air duct7 supplementary air duct8 cement evacuation pipe into thebunker

Fig. 3.8. Pneumatic recipient for cement

The technological solutions for bulk cement transport and storage with pneumaticequipments should take into account the railway car type that insure the transportto the concrete mixing plat: special cars or normal box cars.

a. cement discharge from special cars

1 special car3 auxiliary metallic silo4 compressing air plant5 compressing air pipe6 cement flexible duct7 metallic cement duct for silocharging

As superior airAi inferior airAa auxiliary air


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b. cement discharge from normal boxcars

2 box car3 auxiliary metallic silo4 compressing air plant6 cement flexible duct7 metallic cement duct for silocharging8 buried concrete tank9 metallic recipient with impulse role

10 drag bucket11 metallic cone for gravitationalcharge of the impulse recipient

Fig. 3.9. Cement transfer from cars to auxiliary silos

The special cars consist of rolling system only, being flat cars. On top of the flatcar, two pneumatic recipients for cement will be installed.

Cement unloading from special cars is done directly into the auxiliary silo,

meaning in one step. Cement unloading from normal cars is done in two steps:1. from wagon to the impulse recipient: it is done with mechanic

means - the drag bucket and metallic cone2. from the impulse recipient to the auxiliary silo with pneumatic

means

The normal cars are used only in times when the special ones are not available.

According to the distance between the auxiliary silo (siloz de rezerva) and supplysilo (siloz de consum), two technological solutions for cement transfer can beadopted:

for distances below 100m: pneumatic transfer with mobile recipient (fig.3.10..a)

for long distances: road transport with semi-trailer for bulk cement (fig.3.10.b)


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a. Pneumatic transfer with pneumaticmobile recipient

1 Auxiliary silo2 Supply silo3 Tram (carucior CF ingust),1500mm gauge4 pneumatic recipient installed ontram5 flexible compressed air duct6 flexible duct for cement7 metallic duct for cement8 metallic scaffolding for cementduct support

9 supplementary air jets installed onduct route

b. Toad transport with gravitationalloading and pneumatic discharge

1 Auxiliary silo2 Supply silo

10 semi-trailer for cement transport

Fig. 3.10. Cement transfer from auxiliary silo to supply silo

The pneumatic transfer of the cement from auxiliary silo to the supply one can bedone with a metallic mobile recipient of 6 tons capacity, installed on a narrowrailway tram that can be used for a line of 19 auxiliary silos. The system can beused as it is for 50m distance, or with supplementary air jets for distancesbetween 50-100m.

For distances over 100m, the cement transport is done on roads, with trailers forbulk cement that are equipped either with one vertical cement recipient of 9 tonscapacity, or two vertical recipients with 18 tons total capacity. The unloadingprocess from the auxiliary silo is done gravitationally. The loading process of thesupply silo is done with pneumatic means, with the compressed air supplied bythe pneumatic discharge equipment of the cement recipients installed on thesemi-trailer.


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The mechanized means for concrete loading, transport and unloading lead tohigh productivity by eliminating almost all the cement losses during theseoperations.

3.2.3. Flow charts for loading unloading works of materials in pieces(Scheme tehnologice pentru lucrari de incarcare descarcare amaterialelor in bucati)

This category of materials in small pieces represents 13% of the total weightof materials and products incorporated into a building.The procedures transport and storage of materials in pieces are:

package (impachetare) transport with pallets

transport with containers combined transport

The advantages of these procedures are: increase the works productivity by reducing the manpower consumption simplifies the operations of weigh, sorting, paperwork, control of materials

and products decrease materials losses produces economies at packing process, loading-unloading process,

transport and storage (ca. 25-40%) increase the used capacity of transport vehicles

increase the storage capacity

Package (impachetarea)The following solutions are used for packing:

packs with no ties (free packs) the stability is insured byimmobilization of the pack into the transport vehicle

packs with ties the stability is insured with auxiliary materials

The solution packs with no ties is used for movement of water supply pipes,heating pipes, gas pipes, etc.

The solution packs with ties uses non-recoverable materials for ties: bailingband (banda de otel pt. impachetare), plastic band, wooden blocks, foil, etc.The solution of packaging differs after the way of hanging during loading-unloading operations, as follows:

packs taken with handling devices with metallic cross bars (traversemetalice)

packs taken with handling devices in shape of a tongs (cleste) (fig. 3.14for BCA)

packs with holes for transport, handled with a forklift, or holding devices ofthe cranes, with adjustable forks (fig. 3.15, for bricks)


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1, 2 wooden beams (storagesupports)3 tie band4 handling device with metallic crossbars5 support cross bars (they areremoved after pack placement into thetransport vehicle)

Fig. 3.11. Pack with ties, handled with device with metallic cross bars

a. pack with tiesb. device in shape of tongs

1 plates of gas-formedconcrete (BCA)2 protection angles (coltar deprotectie)3 tie band

Fig. 3.12. Pack with ties, handled with device in shape of tongs

1 bricks2 hard board angles - 12mm thick3 tie band (steel or plastic)4 fasten staples (capse de stringere)5 holes for fork with 2 adjustableteeth

Fig. 3.13. Pack with ties, handled with device with forks

Another solution for bricks transport is the packs of bricks wrapped in contractiblefoil (folie contractabila), solution used for combined transport road railway. Theprinciple of the method consists in wrapping the whole charge unit in contractiblefoil and curing the foil by crossing a thermal chamber or with a mobile heatinginstallation moved around the foil. The contact with hot air leads to foilcontraction and insure a perfect stability of the package.


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Transport with palletsThe pallet is a support of wood,metal sheet, etc. that is used tomake a load unit with a shape thatwill not be changed during thehole circuit loading transport unloading. The load units (unitatide incarcatura) are moved withpallets placed below the unit. Thepallets are taken to be moved byforklift trucks (motostivuitoare) that can carry several rows of loadunits. The pallets can be alsomoved with pallet trucks, which

can move only one row of loadunits. For this purpose, the palletsare provided with holes at thelower side, holes needed to insertthe forks of the transport device.

The pallets can be classifiedaccording to their destination:

standardized pallets (forgeneral purpose) that cancarry several kinds of products:

plane pallet, box pallet specialized pallets designed

for a certain type of products

Plane pallet is built as a load platform, and consists in one or two deck boards(made of wood, metal) that are supported by stringers with the height adapted tothe forks height. The plane pallet can carry products encased in boxes, bags(cement, lime), or not encased products, correlated with the pallets size andhaving a regular shape that can allow a even arrangement (free bricks).

The plane pallet ca be also built with specialized superstructure for carryingspecific materials.

Forklift truck

Hydraulic pallet truck


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1 deck board (1 or 2 rows)2 stringers

h maximum height of material placedon the pallet

Plane pallets - photo Fig. 3.14. Plane pallet

Box pallet is a box with fixed ortilting walls, made of wood, metalsheet or wire net, supported bystringers.It is used for transport of

rolled materials: tar boards(carton bitumat), rubbercarpet (covor de cauciuc)

liquid materials in canisters:dyes (vopseluri), lacquers(lacuri), ant throw agents(adezivi)

Specialized pallet it is used for materials or products that need specialtransport or loading unloading conditions.

The glass support pallet is a pallet specialized for glass transport. It consists in awooden and metal racking (stelaj) with 2 inclined sides and supports for glasspacks.

The transport, handling and storage of materials on pallets, is insured with thefollowing equipments:

Box pallet


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- equipments for taking, movement and storage: forklift truck, pallettrucks

- lifting equipments with hooks and special devices: wheel crane,tower crane, portal crane

- road transport vehicles: platform truck, track lorries with or withouttrailers, tractor with trailers, etc.

- railway transport vehicles: flat cars, cars with fixed walls, cars withtilting walls, etc.

The plate truck is a special truck equipped with lifting platform made of 2 forks.The plate truck can move and arrange the pallets in one row, at the level of theplatform.

1 platform lifting arms: 2 forks at 650-

900 mm distance2 control lever3 movement roles (one or two pairs)4 driving wheel

Fig. 3.15. Pallet truck

Transport with containersThe container is a transport device made of boxes, frames open or closed ofstandardized dimension so that, placed on a transport vehicle to allow themaximum use of the platform and vehicle capacity.

There are 3 types of containers: for road transport directly:1.25 t capacity, 1.22.0m height for railway transport: 1.5 t capacity, 2.5m height for combined traffic road and railway: 2.55 tons capacity

3 transport

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