CONSTRUCTION EQUIPMENT INTEGRATION

 

 

The TREMIX method, pioneered by TREMIX AB, SWEDEN and introduced by Aquarius in India in 1987, is a system for laying high quality concrete floors with Superior cost-effectiveness. Aquarius subsequently entered into a technical Collaboration with TREMIX AB, in 1991 to start production of Vacuum System in India

A high quality concrete floor or pavement requires not only being level but it should also have high wear resistance; high Compressive strength reduced shrinkage, minimum water permeability and should be free of pores..

The Vacuum Dewatered Concrete Flooring technology has been employed in many projects in the country during last 14 Years and more than 10 million sq. meters. Of work has been carried out. The VD System is increasingly being accepted

as a relevant and totally adaptable technology in the Indian environment. Many leading Architects and Consulting Engineers are now specifying it for their projects.

 

                     Procedure

 

                     The method involves laying the floor in the following sequence:

1.Concreting is done in the conventional way but with a higher slump so    that workability is good and concrete pouring and spreading is done fast.  

2. Poker Vibration (especially on both sides of the panel) is always essential for floor thickness of 100 mm and above.

3. Surface Vibration using double beam Surface Vibrator.

4. Leveling the vibrated surface with a straight Edge.

5. Vacuum Dewatering using Vacuum Pump and Suction Mat Top Cover & Filter Pads.

6. Floating and Trowelling of the concrete pavements using Skim floaters.

 

 

 

 

 

 

 

Why use Vacuum Dewatered flooring?

 

The Vacuum Dewatered (VD) flooring method is a system for laying high quality concrete floors with superior cost effectiveness.

The key to the use of this method is the dewatering of concrete by vacuum process surplus water from the Concrete is removed immediately after placing and vibration, reducing the water: cement ratio to an optimum level.

Therefore, adopting the VD Flooring method facilitates use of concrete with better workability than what is normally possible. A lowered water to cement ratio due to vacuum dewatering leads to improvement in each of the concrete properties listed above.

 

 

 

 

The following paragraphs explain the method and  benefits of this process

v  Through the vaccum treatment, it is possible to reduce the water content in the concrete by 15 – 25% which greatly increases the compressive strength. Thus, by lowering the water/ cement ratio, the tendency of shrinkage and Subsequent cracking is greatly reduced.

v   Lowest water/ cement ratio being at the top part of a vacuum dewatered slab, Gives it the maximum compressive strength.

v   Since the water/ cement ratio is lowered through vacuum dewatering, concrete of higher initial slump can be used while

v  Pouring. This greatly simplifies the job of mixing and pouring concrete.

v  The operational convenience this technology offers, can be very   simply put  as pouring concrete having higher water/cement ratio giving excellent workability and removing the excess water immediately after surface vibration, resulting in a zero slump concrete.

The vacuum treated concrete floor/ pavement, exhibits inherent    advantages like:-

·         Monolithic, Shrinkage free pavements

·          Single panel without joints up to 100 sq. meters.

·          Very high splitting strength

·          Very high quality pavements in terms of strengths i.e. compressive, abrasion, flexural etc.

·          Saving in cement since the compressive strength of the pavement is increased giving flexibility to adopt either leaner mix or design a slab of lesser thickness giving the required strength.

·          Controlled and uniform surface finish

·          Very high output exceeding 100-200 sq. meters in a day

 

 

THE OPERATION

 

 

 

                    

                     In order to obtain a high quality concrete floor using this method, it is essential to follow the various operations in the correct sequence. Initially, poker vibration is essential, especially at the panel edges. This results in proper compaction of the concrete and hence elimination of void sand entrapped air. Poker vibration never really gives a leveled surface. It is therefore essential to combine this vibration with surface vibration (screeding), in order to obtain a vibrated concrete with a leveled surface. Two passes with surface vibrator are normally recommended. Two men, standing on either side of the panel, guide the Surface Vibrator. Vacuum dewatering process removes surplus water always present in the concrete. This is done using the Vacuum Equipment comprising of Suction Mat Top Cover, Filter pads and Vacuum Pump. The process starts immediately after surface vibration

 

 

 

 

 

                      

                       

 

           The dewatering operation takes approx.1.5 - 2 minutes per centimeter thickness of the floor. The dewatered concrete is compacted and dried to such an extent that it is possible to walk on it without leaving any footprints. This is the indication of concrete being properly dewatered and ready for finishing. The finishing operations - Floating &Trowelling take place right after dewatering. Floating operation is done with Floating disc. This ensures after mixing of sand & cement particles, further compaction and closing the    pores on the surface. Floating operation generates skid-free finish. Trowelling is done with Trowelling blades in order to further improve the wear résistance, minimize dusting and obtain smoother finish. Repeated passes with disc and blades improve the wear resistance substantially.

                     . 

 

 

 

Table below shows the list of activities and equipments involved in the    process:-

 

 

 

Sr no

  Activity

Equipment Used

01

        Concreting

R.M.C Plant

Transit Mixer

Concrete Pump

02

        Surface Vibration

Double beam Surface Vibrator.

03

        Vacuum Dewatering

Vacuum Pump and Suction Mat Top Cover & Filter Pads.

04

        Floating and Trowelling

Skim floaters.

 

 

 

 

Sr. No.

Equipment

   Theoretical

     Output

Actual

Output

01

R.M.C Plant

        35m3/hr

30 m3/hr

02

Transit Mixer

        06 m3

05m3

03

Concrete Pump

        20m3/hr

15m3/hr

04

Double beam Surface Vibrator.

           -

     -

05

Vacuum Pump and Suction Mat Top Cover & Filter Pads.

            -

      -

06

Skim floaters.

           -

        -

 

 

 
 
 
 
 
Transit mixer                                 

                                 

 

 

 

 

 

 

 

 

Concrete pump

 

 

Criteria for selecting a concrete pump

 

v  Diameter of the suction pipe should be at least three times the maximum size of the aggregate in the concrete to be pumped.

v  The two primary parameters, which should be known prior to selection of a pump, are

1.      Maximum desired volumetric output of concrete per hour and

2.      The peak pumping pressure, p

                                    Therefore hydraulic output, of the concrete pump

                                    H = Q × p = constant

                                   Where Q is expressed in m3/h and p is expressed in bars 

           assuming a system efficiency of 75 percent, the required power can be      expressed in kilowatts (kW) as :P = 25H= 25Q× p

 

 

 

 

                                             

 

 

 

 

 

 

                                           SKIMFLOATER / POWER TROWEL

 

 

 

 

 

 

 

 

                   

                       

                       

 

 

Double beam vibrator

 

 

 

 

 

 

 

 

 

 

 

 

CASE STUDY:

 

 

Project detail:

 

 

 

Ø  name of PROJECT: PIAGGIO vehicles pvt.ltd.

 

Ø  location               :     m.i.d.c.baramati.

 

Ø  type of work      :     INDUSTRIAL SHED.

 

Ø  R.M.C.PLANT           :     BIRLA R.M.C.

 

Ø  TRAVELLING DIST :      12 KMS

 

Ø  PLANT CAPACITY   :    30M3/HR

 

 

 

 

 

 

 

                                              SITE PLAN

 

 

               

 

 

DETAILS OF POUR

 

POUR 1

43M*4M   

 

 

 

 

 

 

 

 

 

 

POUR 2

43M*4M 

 

 

 

POUR 3

43M*4M   

 

 

POUR4

43M*4M   

 

 

POUR5

43M*4M   

 

POUR 6

43M*4M   

 

 

 

                                

 

        Quantity Of Concrete =(43*24*.15*3)+(1.2*43*.15)-(1*.23*.15*16)

                                                                       = 471.58m3

                                                                                                =472m3

                                             capacity of r.m.c. transit mixer=05M3

                                       Therefore no. of transit mixer         = 95 no.

                                    Therefore 95 no of cycles required

                                   

 

 

 

 

 

 

 

 

 

 

 

 

 


                          

                               DIAGRAMATIC REPRESENTATION OF CYCLIC PROCESS

 

 

 

Time required for 1complete cycle =

Time required for filling the transit mixer + time required for transportation from plant to site + Time required to discharge concrete + Time required for transportation from site to plant

 

·         Time required for filling the transit mixer

= Capacity of RMC Plant / Capacity of   transit mixer                                                          

                                                                        = 30 / 5 per Hr.

                                                                        = 6 per Hr.

= 10 min.

 

·         Time required for transportation from plant to site 

Assume speed of a loaded transit mixer = 30 KM/Hr               

Time required to cover 12 KM distance = 24 min.

 

·         Time required to discharge concrete

Capacity of pump = 15 m3/Hr

            For discharging 5m3 concrete time required = 20 min.

                           

·         Time required for transportation from site to plant

Assume speed of a unloaded transit mixer = 40 KM/Hr               

Time required to cover 12 KM distance = 18 min.

 

Time required for 1complete cycle =

Time required for filling the transit mixer (10 min.) + time required for transportation from plant to site (24min.) + Time required to discharge concrete(20min) + Time required for transportation from site to plant (18min.)    = 72 min.

Concrete pump has discharge of 15m3/hr.so, we could complete only 15 m3 concrete per hour even though the capacity of the RMC plant is 30 m3/hr. The transit mixer has to wait until the concrete is placed & i.e. 15 m3/hr

The time required to complete total concrete work =Total quantity /15                                                             

         = 472/15

                                                               = 32 hrs

To increase the effiencency of the work instead of one pump we go for two pumps of the capacity 15 m3/ hr.

Now as per above information we could easily make out that we can have 30 m3 concrete on site per hour ,as the capacity of the RMC plant & concrete pump will be 30m3 per hour

The time required to complete total concrete work =Total quantity /30

                                                                                 = 472/30

                                                                                 = 16 hrs

 

 

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