CONCRETE BATCHING & MIXING PLANT

10 PRINCIPAL FUNCTIONS OF CONCRETE BATCHING & MIXING PLANT

The two main criteria determining the quality of concrete are its strength and durability. The process of achievement of strength and durability of concrete begins with its production. The ease with which quality control measures can be implemented at the production stage is not available in later stages of transportation and placement of concrete.

Ready-mix concrete is a type of concrete that is manufactured in a factory or in batching plant, according to a set recipe, and then delivered to the work site. A Concrete Batching and Mixing Plant, combines various ingredients like sand, water, aggregates, chemical and mineral admixtures (fly ash, plasticizer etc), and cement by weight to form concrete. Capacity of the plant is measured in cum per hour. It depends upon capacity of mixer, number of mixers, charging, mixing and discharge time of each mixer. The purpose of Concrete Batching and Mixing Plant is to produce homogenous and uniform concrete, as indicated by physical properties such as unit weight, slump, air content, and strength in individual batches and successive batches of the same mix proportions.

FUNCTIONS OF CONCRETE BATCHING AND MIXING PLANT:

The main functions of the concrete batching and mixing plant are as under:

1. To coat the surface of all the aggregates with cement paste, and to blend all the ingredients of the concrete into a uniform mass.
2. To mix homogeneously the cement, water, coarse and fine aggregates, admixtures (if required) and fibers (when provided in mix design) and other material as per job mix formula in proportion as per predetermined specification to make concrete cohesive and plastic which is easy to transport, place, compact, texture, finish and which will set, and harden, to give a strong and durable concrete structure.
3. To measure the cement, water, coarse, fine aggregates and admixtures within specified tolerance limits and to maintain the desired grading of aggregates.
4. To provide greater freedom in design.
5. To achieve the production of concrete at a faster rate.
6. To provide concrete at any location
7. To maintain the quality of mix through monitoring various processes like mixing, batching, etc. and controlling the variations e.g. ingredients proportion, moisture, etc.
8. Cooling and heating of dry aggregates in the mix (before adding water), if required, to produce concrete within specified temperature limits.
9. View and print the report of concrete production, report of produced concrete, batch wise, recipe wise etc.
10. To maintain batch wise, date wise data of the concrete produced in the on board computer.

33 MUST HAVE CHECKS FOR MAINTENANCE OF BATCHING PLANT

MAINTENANCE OF READY-MIXED CONCRETE BATCHING PLANT

For an effective production & delivery of concrete, all plant & equipment should be maintained in a clean and efficient working condition. To achieve this, checklists are used by the batching plant personnel. These checklists include daily checks, weekly checks, monthly checks and quarterly checks. Checklists must be prepared in such a manner so that they cover the following 3 basic components of ready-mixed concrete batching plant.

1. Storage & handling equipment
2. Batching & mixing equipment
3. Transporting equipment (Mixer & Agitator)

CHECKS FOR STORAGE AND HANDLING EQUIPMENT

7 WEEKLY CHECKS

1. Check the area under plant for spillage and trace source
2. Check all drains and traps are clear. Check cleanness of yard
3. Check to maintain settlement pits, recyclers and wash down areas in efficient working order
4. Check all storage bins and doors for efficient operation
5. Check conveyors, boom scrapers and bucket elevators for free running and wear, and adjust as necessary
6. Routine checks and servicing on loading shovels
7. Routine checks and servicing on compressors

CHECKS FOR BATCHING AND MIXING EQUIPMENT

3 DAILY CHECKS

1. Check and adjust tare weights and clean weigh dials (if applicable)
2. Check to ensure that weighing hoppers empty properly
3. Check to washout central mixer drum or pan

14 WEEKLY CHECKS

1. Check and maintain all hoppers and doors are in clean and efficient working order
2. Check central mixer blades, paddles or arms for wear and tightness and adjust as necessary
3. Check and remove any cement or concrete build up in the mixer
4. Check and shack out cement silo filter sock (if applicable) and maintain in efficient working order.
5. Check dust seals on cement hoppers for wear
6. Check and clean knife edges or load cells on weighing equipment
7. Check calibration of moisture meter if applicable
8. Check oil levels on air line lubricators
9. Drain water traps on air lines
10. Check rams and air lines for leaks
11. Check pipe-work for leaks and wear
12. Check wiring and electrical apparatus for correct operation and over heating
13. Routine checks for greasing of bearings and gears
14. Routine checks and servicing on central mixers

3 MONTHLY CHECKS

1. Check calibration of all weigh scales
2. Check calibration of water meter
3. Check calibration of admixture dispenser

2 QUARTERLY CHECKS

1. Inspection and testing of all weigh scales over their complete operational range
2. Routine oil changes in gearboxes and oil baths

CHECKS FOR TRANSPORTING EQUIPMENTS – MIXER & AGITATOR UNITS

1 DAILY CHECK

1. Check and wash out truck mixer drum

3 MONTHLY CHECKS

1. Check mixer unit for blade wear
2. Check operation of revolution counters, if fitted
3. Check calibration of truck mixer water meter

READY MIXED CONCRETE – WHAT INFORMATION TO BE SUPPLIED BY THE PRODUCER?

Ready Mixed Concrete

INFORMATION TO BE SUPPLIED BY THE PRODUCER

Before supplying any concrete, the producer should provide the following information to the purchaser.

• Nature and source of each constituent material
• Source of supply of cement
• Proposed proportions or quantity of each constituent/m3 of fresh concrete

If any admixture is to be used to produce concrete, then following information about admixture should be provided.

• Generic types of the main active constituents in the admixture
• Whether or not the admixture contains chlorides and if so, the chloride content of the admixture expressed as a percentage of chloride ion by mass of admixture
• Whether or not the admixture leads to the entrainment of air when used at the adopted dosages
• Where more than on admixture is used, confirmation of their compatibility
• Initial and final setting time of concrete when admixture is used at adopted dosages