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Everything There Is to Know about Ready-mix Concrete

Ready mix concrete is concrete batched, mixed, and delivered in its unhardened plastic state. It provides tremendous value by saving time and labor compared to mixing concrete from raw materials on the job site. This guide covers everything about this essential construction material.

What Is Ready-Mix Concrete?

Ready-mix concrete is a combination of basic ingredients such as:

  • Cement
  • Aggregates
  • Water
  • Optional admixtures

However, instead of being mixed on-site, it is batched at a plant into its plastic form and delivered by truck to the construction site. This eliminates the need to mix concrete from raw materials at the job location.

History of Ready-Mix

The ready-mix industry emerged in the early 1900s to improve construction efficiency. In 1913, the first ready mix concrete plant opened in Baltimore, using horse-drawn carriages to deliver batches of fresh concrete. A breakthrough came in the 1920s-30s with motorised transit mixer trucks that could combine and agitate the concrete continuously during transport. This extended the delivery range and improved concrete quality. Innovations in truck mixers and batching plants drove growth into today’s multi-billion dollar global industry.

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Composition Basics

Like standard concrete, ready-mix contains cement, aggregates, and water as primary ingredients. Cement acts as the binding agent that reacts with water to harden and hold the mix together. Aggregates make up the bulk and include coarse gravel/crushed stone as well as fine sand particles. The exact ratio of cement to aggregates depends on the application’s required strength and performance.

Along with the basic ingredients, ready-mix may include chemical admixtures. Admixtures are added to modify properties like setting time, workability, strength enhancement, or protection against environmental factors. Common admixtures are plasticisers, accelerators, retarders, air-entraining agents, and others.

Batching and Mixing Process

Instead of combining ingredients at the job site, ready-mix concrete is precisely batched and mixed at a centralised plant. This specialised process involves:

  • Measuring prescribed amounts of cement, aggregates, admixtures, and water into the plant’s huge rotating drum.
  • Thoroughly mix these raw ingredients into a uniform, homogeneous plastic concrete mixture inside the drum.
  • Loading the fresh concrete into a transit mixer truck to transport to the job site.
  • Key factors in batching are carefully measuring and combining the raw materials to meet performance specifications. Plants can produce countless mixed designs for different project requirements.

Delivery and Timing

Once batched, ready-mix concrete remains in its plastic state and must be delivered promptly to the job site before it starts setting and becomes unworkable. Transit mixer trucks keep the concrete agitated and rotating during transport.

Concrete has an “open time” window when it must be discharged and put into place after batching. Open time depends on factors like temperature, humidity, and travel distance. Truck drivers closely monitor the open time to ensure loads aren’t wasted or rejected upon arrival.

Once on site, the concrete mixer discharges the load precisely where needed. The plastic concrete goes directly into formwork, onto surfaces for flatwork, or into equipment like concrete pumps to be placed.

Applications and Uses

Thanks to its versatility and performance capabilities, ready-mix concrete spans practically every construction sector:

  • Residential – Foundations, slabs, driveways, walls, footings, columns, etc.
  • Commercial/Industrial – Office buildings, warehouses, manufacturing facilities, tilt-up concrete, precast components
  • Infrastructure – Bridges, highways, roads, runways, dams, tunnels, water/sewer pipes
  • Repairs/Maintenance – Patching deteriorated concrete, resurfacing floors, overlays

Site Placement and Finishing

After discharge, ready mix concrete still requires proper placement, consolidation, finishing, and curing just like site-batched concrete. Techniques depend on the application but may include:

  • Pumping – Using a concrete pump to place into formwork or across a worksite
  • Screeding – Leveling and striking off flatwork surfaces
  • Bull-floating/troweling – Smoothing and densifying slabs
  • Vibrating – Consolidating and removing entrapped air voids

Proper finishing and curing exponentially increase concrete’s service life, strength, and durability.

Key Advantages Over Site Mixing

Ready-mix provides significant benefits compared to mixing concrete from raw materials at the job site:

  • Consistency – Batching plants ensure uniform quality control across loads
  • Time/Labor Savings – No hauling, measuring and mixing raw materials
  • Quality Assurance – Meeting strict industry testing and standards
  • Environmental – Option to use recycled/waste materials like fly ash
  • Mix Flexibility – Easy changes to mix composition and properties
  • Safety – Reduced manual material handling and less heavy equipment

Overall, ready-mix operations boost productivity while maintaining high quality.

Standards and Specifications

To ensure structural integrity and performance, industry standards strictly govern ready-mix:

  • ACI 318 – American Concrete Institute’s “Building Code Requirements for Structural Concrete”
  • ASTM C94 – Standard specification for ready-mix materials, batching, mixing, and delivery
  • NRMCA – National Ready-Mix Concrete Association certification programs

Meeting all standards for ingredients, batching, mixing time, delivery, placement, and testing is mandatory. Most projects specify minimum design strengths required.

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Sustainability Efforts

The ready-mix industry aims to reduce its environmental footprint through:

  • Recycled Materials – Using recycled concrete aggregate (RCA), fly ash, slag cement, and other materials reduces CO2 and raw material usage.
  • Water Recycling – Plants recycle and reuse water from production and washout.
  • More Efficient Vehicles – Deploying vehicles with improved fuel economy and lower emissions.
  • Optimised Transportation – Batching at the ideal plant location and routing deliveries to minimise transport.

While concrete itself is durable and sustainable, the industry continues exploring sustainable practices from raw material sourcing through product usage.

Innovations and New Technology

Along with environmental efforts, innovations are modernising ready-mix:

  • Self-Consolidating Concrete (SCC) – A highly flowable, pumpable mix that consolidates under its weight without vibration.
  • Fiber Reinforcement – Adding steel, glass, and synthetic fibers during batching for improved strength and crack resistance.
  • Nanomaterials – Exploring nanoparticles like carbon nanotubes or nano-silica to enhance concrete performance.
  • Digital Monitoring – Electronic tracking systems monitor slump, temp, and revolutions, and issue alerts to drivers and batch plants.
  • 3D Printing – Development of specialised printable concrete mixes and techniques for construction 3D printing.

The future of ready-mix involves further sustainability efforts combined with digital monitoring, advanced material science, and new construction methods like 3D printing.

Wrap Up

As construction practices continue to evolve, Ready-Mix Concrete remains at the forefront, shaping the skylines of cities around the world. Its time-saving benefits, consistent quality, and versatility make it an indispensable building material for projects of all scales and complexities.

Ready Mix Concrete Near Me

At Pro-Mix, we pride ourselves on being leaders in providing top-notch Ready-Mix Concrete. From residential developments to commercial complexes and infrastructure projects, Pro-Mix stands ready to partner with you. 

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