A Concrete Experience
by Engr. Adnan Asdar,
It's been over 25 years since I first experienced the use of Ready Mix Concrete at a site near Chicago in the USA. Since then I had always dreamt of this service being made available to the construction industry here in Pakistan. When I was told of launching of ready-mix business backed by to two respectable names, Paragon Constructors & Lucky Cement, it was almost like a long awaited dream come true for me.
The availability of Ready Mix Concrete on a commercial basis, in Pakistan, ushers a new milestone in the history of our construction industry. It is definitely a welcome development for all stakeholders, from contractors, suppliers, consultant as well as owners and sponsors of projects. While concrete through batching plants have been in use in Pakistan for quite some time, however, its use has mostly been projects specific and limited.
Consistent quality and guaranteed strength are the two single most important advantages of ready mix concrete delivered and pumped at the site, all over the world. These two factors alone enable the designers to design efficiently and, thus assuring huge savings for the owners/clients.
Furthermore, the capability of consistently delivering guaranteed strength concrete from batch after batch for thousands of cubic meters at a stretch enables contractors to accomplish improved construction schedules with substantially less labour costs, reducing on site material storage space, saving time and eventually money for the clients
A ready mix batching plant generally ensures consistent quality of concrete. It is not only important for the batches to be calibrated in terms of volume or weight, as is generally done here in Pakistan, it is extremely important that all the ingredients are of consistent quality as well. The aggregates crush and sand should be properly graded and sufficiently stock piled for the entire batch, the admixture dosage and the mixing temperature during batching and till the time of delivery to the site all have to be suitability monitored and controlled. These challenges have all been adequately understood by the sponsors and have been catered to on this important project. Structural Engineers can reduce column sizes by using high strength concrete and thus improving the net usable space for developers and clients to sell or lease. Reducing the column size by 10 to 15%, can bring in savings on each floor, and making it a more profitable proposal for the developers and as well as the owner or users of space.
When I left the Chicago area in the mid eighties, ready mix concrete companies were satisfactorily delivering 11,000 to 14,000 psi concrete to projects in the greater Chicago area. Few years down the road I was told that they had reached up to 17,000 psi.
In Pakistan in the last 20 years we are still struggling to deliver satisfactorily 5,000 to 7,000 psi concrete only. The Structural Engineers cannot take the risk of specifying higher strength due to the lack of comfort on the contractors' capabilities for delivering quality. This ready mix concrete project should hopefully provide them with the satisfaction of guaranteed strength and quality.
As a professional from the field, I feel personally indebted to the sponsors of this project for raising the bars for the industry and I strongly pray to Allah for their success and for the success of Pakistan.