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Supplying Ready Mix in Southeast AsiaAdapting concrete mix design for hot, tropical weather
Recently I had the chance to visit with Unique Mix, a ready mix concrete supplier based out of Penang Malaysia. We discussed some of the challenges and local practices that come from supplying concrete in such a unique environment. Unique Mix has provided ready mixed concrete in Malaysia for nearly 20 years. Currently Unique Mix has seven batch plants throughout Malaysia. Four plants are stationed on the island of Penang. Unique mix supplies concrete for the many super condo structures and high end homes currently under construction on the island.
I found the information that was shared by Shamsani Omar (Quality Control Manager) and K S Hong (Plant Manager) regarding ready mix in Malaysia very insightful. Here are the highlights of our conversation:
Brian: What type of aggregates and sand are you using in your base mix designs?
Unique Mix: We are using granite and limestone aggregates. We like the strength that comes from this selection of aggregates. We find that a crushed angular stone provides good compressive strengths while not compromising the workability. The sand is another story. We use river sand here in Penang. One of the issues we face is the cleanliness of the local water found in the rivers and streams. Recently, we have found that the local rivers are quite polluted due to manufacturing. The quality of sand being extracted is not acceptable for use in concrete. We have to ship our concrete sand from Kedah (a state one hour north of Penang) to make sure it's clean.
Brian: What are the typical strengths of concrete being poured in Malaysia?
Unique Mix: For high rise super condo structures we typically start with a grit 50 (7250 PSI) at the bottom of the structure. The higher we get in construction the lower we go in grit. The lowest we go on high rise construction is grit 30 (4350 PSI). For imprint, or stamp, work we see contractors using grit 25 – 30 (3600 – 4350 PSI) and for the guy looking to save money we sell a grit 20 (2900 PSI). Grit 20 is installed on gray sidewalk type applications.
Brian: Do you offer any optimized mix designs?
Unique Mix: We offer mixes with fly ash or blast slag. These mixes are only installed when specified. For example when large structures are being poured and we need to keep the heat low and the concrete setting slowly we will use fly ash in the mix. Also, we do add a retarder to slow the set. Everything we produce has a minimum of 2 hours of delay set in it. The weather here is so hot that this delay is absolutely necessary.
I found these facts noteworthy as most concrete produced in the US has some type of mid range water reducer and maybe 10% cement replacement with fly ash weather you like it or not.
Brian: What standard do you design your concrete to?
Unique Mix: We design our concrete to British Standard 1881. In Malaysia we cast cubes for compressive testing. In the US tube like cylinders are cast for compressive testing.
Brian: Do you offer integral color in your concrete mix?
Unique Mix: No we do not. We specialize in a quality mix and let the decorative contractors worry about the color. Here in Penang integral colored concrete is nonexistent as of now. If concrete has color, it was done with color hardener, or with a stamped powder release.
Brian: What are some challenges you face producing concrete in Malaysia?
Unique Mix: As mentioned before we struggle with the cleanness of the water. This is a big issue, the toxins being dumped into our rivers effect the quality of sand and aggregate we can use. This affects cost as there is a need to wash and ship sand to our plants. No one wins when we have not taken care of our natural resources. Another challenge we have is the difficulty involved in getting permits to build new plants. There are permits, government approval and environmental impact studies that need to be done. Times have changed since we got in the business 20 years ago.
Because of Malaysia's hot weather we use retarders. We also use our own version of a water chiller. We modified our water system to run through ice which cools the water in the production of concrete. A chiller here would cost 300,000 Ringgit or about 94,000 USD. This system works well for us.
What a great experience it was to visit with Mr. Omar and Mr. Hong. I believe some of their challenges are similar to those faced by concrete installers in the rest of the world. At the end of our conversation I asked them what main point they would like me to communicate through this write up. Mr. Omar said, "The contractors of Malaysia need to keep an open mind. We see new technologies in our industry that will better our building practices. For some reason it is hard to embrace change and new systems here." This example was used: "We have the ability to lower water to cement ratios with the use of midrange water reducers. We know the benefits from lower water to cement ratios but we struggle to get our end users to see the value. "
Thank you Unique Mix, especially Mr. Omar and Mr. Hong, for sharing about ready mix production in Malaysia.
Author Brian Farnsworth, BGI Technical Services