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We often see construction ‘Ready Mix’ trucks carrying big ‘concrete mixer tank’, bearing names like Birla Ready Mix, UltraTech Ready Mix, ACC Ready Mix and so on. Adorned with huge spindle-shaped tanks, these trucks catch our attention. Let’s ponder: As home buyers, should we look only for homes/apartments made with the most modern equipment like RMC mixer? If we see an old school manual ‘Miller’ being used for construction of our home, does that mean we are getting a sub-standard home or apartment that lacks sturdiness? What if the ‘columns’ or ‘slabs’ in our apartment/home are crafted with the old-timer manual ‘Miller made concrete’? Would it mean that the builder has gotten us befooled?

Well, let’s explore the answers to these! Fact is, even today, we still see builders using the drum/pan type ‘manual’ concrete mixers or ‘Millers’. Not everyone uses ‘Ready Mix Concrete’ every time. Surprisingly, at times we see builders using both the options- ‘RMC’ as well as the ‘traditional Miller’, with a very specific purpose. Why do they do so? Is there any scientific basis for using both options? Should the home buyer be worried about which ‘concrete-making option’ has been used by the builder for making ‘columns’ and ‘slabs’ of their apartment/home structure?

Is it really a question of ‘which to choose’? RMC vs. Miller?’

When pouring a ‘slab’ or ‘columns’, the builder is faced with a decision. Should the builder use the old school Miller, or move with the times to order RMC (Ready Mix Concrete) trucks from a plant? To answer this question, let’s first understand the ‘pros & cons’ of both these options.

As a home buyer, we might view both RMC and Traditional Millers as mere construction equipment, the former being comparatively newer. Home buyers don’t normally dig deeper to understand the uses of both the options, and implications in the making of our home. To gain a balanced perspective, let us first learn about their ‘pros and cons’ of bot “RMC’ and ‘Miller’. So, let’s understand ‘why, when and where’ these two are used, and their role respective in shaping-up our dream home.

Understanding the basics: RMC & Miller (traditional mixer)

Ready Mix Concrete

Defined by the Indian Standard IS specification, ‘Ready Mix Concrete’ is “concrete mixed in a stationary mixer in a central batching and mixing plant or in a truck- mixer and supplied in fresh condition to the purchaser either at the site or into the purchaser’s vehicles.” 

So, Ready Mix Concrete is a ‘ready-to-use’ material when it arrives at the site loaded in a truck. It is made as per the ‘concrete mix ratio’ recommended by the Civil Engineers or contractors, and delivered directly to the site using ‘cement mixer trucks’. RMC consists of a certain proportion of mixture comprising cement, sand, aggregates and water. A thorough mixing happens in the ‘concrete mixing transport truck’ that carries this mixture. During transit, i.e. from the plant to the construction site, the mixture is made ‘vibrant or alive’. The spiral shaped blade inside the tank of the RMC transit-mixer truck not only mixes the ingredients, but also keeps them in liquid shape during transportation. Once it reaches the destination, the concrete needs to be used within a stipulated time, else the mixture becomes unusable due to ‘setting’. 

RMC is made with the objectives of producing better & consistent quality of concrete, eliminating inconsistencies of storage space at the construction sites, eliminating the conventional hiring of machineries/millers for making concrete, and to avoid the wastages of raw material at the site.

While this technology evolved in 1903 in Germany, in India, RMC was first used in the construction of Bhakra Nangal Dam in the 1950s.

Miller (Concrete Mixer)

A Miller (Concrete mixer) evenly combines ingredients like cement, sand and water to form Concrete. A revolving drum is used to mix the ingredients well. The millers are normally smaller, and portable, and can be easily transported to the construction site. This allows the masons and worker adequate time to apply/use the concrete before it hardens. Concrete components are mixed in a certain pre-determined ratio to give the desired consistency. Consequently, this requires precision and meticulous work to avoid quality issues. 

Pros & Cons: RMC vs. Miller

Both these options have their pros and cons as listed below

Miller:
Pros: 

  • Complete control and flexibility over the type of materials used
  • Control on the consistency, strength and quality of the concrete being churned out
  • It can be tailor made to the requirement, to suit a specific need

Cons:

  • Slow process as it is labour-intensive, has multiple-steps, and is time-consuming
  • Recommended for low-rise structures, since large amount of mixing is difficult
  • Higher wastage owing to a manual process
  • Must be mixed at the exact time, for maximum benefit, else it contaminates
  • Setting-time of each mix may be different due to inconsistencies in manual mixing
  • Requires storage of raw materials on site
  • Requires a thorough calculation and precision before mixing
  • Would have to hire multiple millers and labour for a larger slab, or too many columns

RMC:
Pros: 

  • Comes pre mixed from the plant, delivered ready-to-use, consistent quality owing to automated & controlled environment
  • Construction speed gets quickened, and its less time consuming
  • Efficient planning gets better outputs, for instance, all the trucks can be lined-up sequentially, and a ‘slab’ can be poured very quickly
  • Less manual labour, reduces labour and supervision cost
  • Saves construction costs owing to mechanized operations
  • Reduces wastage of cement, plus large quantities of concrete can be delivered
  • Reduces inventory, since there is no on-site storage required
  • Recommended for high-rise structures
  • Environment friendly

Cons: 

  • One has to trust the company with the materials used
  • Consistency of the concrete is always a gamble as we may get a truck with extra water or less water in the mix
  • Quality of Concrete reaching you dependent on traffic conditions, and slumps can develop in the concrete if it gets delayed due to traffic snarls or vehicle failure
  • Concrete has to be utilized within 210 minutes of starting off from the plant; Hence, a proper dose of admixtures is required to keep the concrete fluid and potent
  • Some of the recommended RMC companies are UltraTech RMC, ACC Limited, Prism RMC, RDC Concrete, Concrete India, India Cements, Godrej & Boyce, JK Laxmi among others.

The verdict

Is it really a question of which is better? With the high ‘cons’ for Miller, and too many ‘pros’ for RMC, it might seem that using RMC alone is the most reliable option. However, the reality is not so. 

Both can be effectively used depending on the purpose. Depending on the scale of the project, the builder may use both Miller and RMC technology to optimize on the advantage accrued. 

Either way, the reality is that majority of the builders out there use miller to fill up their ‘columns’, and the RMC trucks to lay the ‘slab’. Having understood the ‘pros’ and ‘cons’ of both the options (RMC vs. Miller), this reality would make immediate sense to the reader.

By using Miller, the quality of the concrete can be enhanced or optimized to address a specific set of objectives. Considering that the entire load of the building rests on the columns, a Miller used-well is a very safe & sturdy option, and guarantees greater building strength & longevity. 

Similarly, for slabs (roofs) that sometimes run into thousands of square-feet, using RMC effectively within the stipulated timeframe is the best way to cover large areas with a slab within a short span of time. This understanding helps the home buyer gauge the benefits that accrue by using either of these options in varied contexts. To conclude, both RMC and Miller enhance the overall durability and life of our home with an objective-driven deployment and construction-strategy!

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