Ahad, 18 Mac 2012

Ready-Mix Concrete Batching Plant

Politeknik Merlimau Melaka

My first project as civil engineer began in July 1999 just after Malaysia's economic hit by currency crisis. I still remember during  an interview with the Project Director, he come to a room and only said that the company only can pay RM 1,200 as basic salary and  no further negotiation. I took the job because the work area nearby with my village.

I was assign as Site Engineer for the construction of new Politeknik at Merlimau Melaka Project with total project cost  about RM 146 million.






Merlimau is one of small town under district of Jasin Melaka. It is situated about 22 kilometers south-east of Melaka Historical City. Until 40 years ago, it used to be the main town travelers passed when traveling south of West Malaysia.  Merlimau is between Melaka Town and Muar. There are housing areas in Merlimau and in nearby areas such as Air Tawar and Batu Gajah.





The famous historical Penghulu Nattar's House is located here. About 3 kilometers away in Kampung Simpang, visitors can also have a look at the Tun Teja Grave. The Tun Teja story goes back to the Malacca sultanate era.

 

Since these project began during currency crisis,  minimize of  cost overhead with control in budgetary  need to be implemented by my top management in order to maintenance the company survival.

Therefore the level of building platform to be revised in order to suit and optimize the existing quantity of earth and also to reduce  the imported suitable earth quantity required for cost saving purpose. Since the major cost of the building works contributed by large volume of concrete, the decided have been made to setup  in-house concrete batching plant since the negotiation with out source is too expensive.

 
Concrete is a mixture of portland cement, aggregates, and water that forms a hard, strong, stone-like material after curing. Concrete may also contain “admixtures” which are special chemicals designed

Ready-mix concrete, also known as “ready-mixed concrete,” is delivered to jobsites in concrete mixer trucks that agitate and mix the material during transport. At the jobsite, it is “ready to use” and is generally specified for larger pours and slabs.

There are two types of ready mixed concrete plants: central plants (sometimes called "wet" plants) and dry-mix (traditional) plants. In central plants, a concrete batch is made up by an operator at the plant before it is loaded into the truck. At dry plants, the dry components of concrete are weighed and loaded separately into the truck mixer; water is then added and the final mix is made. Central plants offer producers more control over quality and consistency of the concrete mix, but require that a load be dropped in a shorter time, usually in 90 minutes or less.

However , in this project the dry mix method have been adopted. The Installation of concrete batching plant is not difficult because it come by component part. Except the Silo's installation due to solid ground required  with need more attention compared with the others component where the installation work can be done smoothly.

The operation system of the batching plant by push button (manual) and it based on weight of the cement,aggregate and sand. So during batching process, the batcher must know total weight of mixture component by refer  to table of concrete design provided. Actually it very simple for example, if you need to batch 1 meter cubic of concrete Grade 30N,  by referring the table you known the  weight of component to be required.


Cem
W/C
Water
Sand
20mm
10mm
Admix
400
0.43
172
635
619
564
1.2
1
0.43
1.6
1.547
1.36
0.003











First the open up the aggregate hooper until it reach the weight required then repeated the same method to the sand hooper by adding the weight ( 619kg  + 564kg + 635kg) .  please make sure that mixer lorry in position. then you just release the mixture slowly together with cement into the truck mixer. during this process the lorry drum's mixer must in rolling position. The water to pump inside the mixture together with admixture and finally the batching work done.

Then the lab technician will take a sample for concrete cube compression test and checking the workability of concrete with  the slump test  before the concrete can deliver to site.




At that time our deliver of concrete supply supported with 4 nos of mixer truck ( because in-house concrete plant ). I learned one of important thing regarding on mixer truck from my Site Manager, "do not forget to clean up your drum before leave the site".  it happened when one of lorry still have 2  cubic meter inside 
the drum and we only realise the matter on the next day. My Site  Manager blown up with "  f " word to everybody including myself.  It very difficult because the foreman need to cut the drum in order to allow our worker goes inside to hack up the concrete.  I remember my worker need to stand in narrow confine space during hacking works. It so miserable but need to be done due to cost saving.

The best part for the batching plant is about the Cement Silo. As batcher, it shall reminded that the usage of cement in Silo must in balance.  What is the method to measure balance of cement contain in Silo?  This is the best part, because you need to climb up the silo and knocked it by hammer in order to measure the cement balance.  If you try it by the first time , it so scary because the ladder is too straight.  for me, climbing up is not the big deal but when you going down, it too scary because you will feel that you leg always miss the ladder stand.

The last time I was remember about this project an experience driving the Showel.  This machine  had important role  to make sure the aggregate and sand to be uploaded inside the hooper.  it was interesting machine and easy to control.   Some time we not use the brake only playing with the gear. A broken pile will laid down and to be positioned so that the showel tyre will  hit it in order  slowing down the machine before release the bucket.  it so sad because  this great memories cannot be repeated again and it a journey of life.