3 MAJOR COMPONENTS OF QUALITY CONTROL OF READY-MIX CONCRETE

Quality control of ready-mixed concrete could also be divided into three components,

 1. Forward control, 

2. Immediate control and 

3. Retrospective control.

               Quality control of Ready-mix concrete

FORWARD CONTROL:

 Forward control and consequent corrective action are essential aspects of internal control. Forward control includes the subsequent. • Control of purchased material Quality 

• Control of Materials storage 

• Mix design and blend design modification 

• Transfer and Weighing Equipment: The producer shall be ready to demonstrate that a documented calibration procedure is in situ. the utilization of electro-mechanical weighing and metering systems, that is, load cells, flow meters, etc. is preferable over the pure system, that is, knife edge and lever systems. 

• Plant mixers where present and truck mixers used shall be in an operational condition. 

IMMEDIATE CONTROL: 

Immediate control cares with instant action to regulate the standard of the concrete being produced or that of deliveries closely following. It includes assembly control and merchandise control. 

A) PRODUCTION CONTROL: 

The production of concrete at each plant shall be systematically controlled. This is to make sure that each one the concrete supplied shall be in accordance with these requirements and with the specifications that have formed the idea of the agreement between the producer and purchaser. Each load of mixed concrete shall be inspected before dispatch and before discharge. The workability of the concrete shall be controlled on an endless basis during production and any corrective action necessary taken. For each load, written, printed or graphical records shall be made from the mass of the materials batched, the estimated slump, the entire amount of water added to the load, the delivery ticket number for that load, and therefore the time the concrete was loaded into the truck. Regular routine inspections shall be administered on the condition of plant and equipment including delivery vehicles. 

B) PRODUCT CONTROL: 

Concrete mixes shall be randomly sampled and tested for workability and where appropriate, plastic density, temperature, and air content. Where significant variations from target values are detected, corrective action shall be taken. It is important to take care of the water-cement ratio constant at its correct value. the quantity of added water shall be adjusted to catch up on any observed variations within the moisture contents within the aggregates. Suitable adjustments should even be made in masses of the aggregates thanks to this variation (see IS 456). Any change in water content thanks to changes in aggregate grading shall be taken care of by forwarding control by suitable modifications to combine design.

RETROSPECTIVE CONTROL:

 Retrospective control cares with those factors that influence the control of production. Retrospective control may cover any property of materials or concrete, like aggregate grading, slump, or air content, but is especially related to 28-day cube strength because by its very nature it's not property which may be measured before, or at the time of, manufacture.

Er.SP.ASWINPALANIAPPAN., M.E.,(Strut/.,)

Structural Engineer

Madras Terrace Architectural Works

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