What Influences The Curing And Safety Of Exposed Aggregate Concrete?

Exposed aggregate concrete (EAC) is a popular method of concreting where the aggregate is exposed in the laying process for either aesthetic appeal or added traction. It’s commonly used in the construction of footpaths, walkways, and even highways.

Some key attributes of EAC are its durability and the fact that it creates a skid-resistant surface, which is vital when used for roads.

This article takes a closer look at EAC and what influences the curing process and safety of exposed aggregate concrete.

The role of aggregate graduation in EAC

Aggregate graduation refers to the particle size distribution. Aggregate containing particles of varying sizes will provide a mass with fewer voids, whereas when particles of the same size only are used, there is more chance for the development of air pockets. This not only impacts the texture of the finish but also its durability.

Regarding mechanical characteristics, the compressive strength of EAC increases when more coarse particles are used and fewer fine particles. A typical coarse particle is granite, and sand is a common fine particle.

Weather conditions and their impact on curing

Are there specific weather conditions that influence the curing process of exposed aggregate concrete?

During periods of high temperatures, EAC can hydrate (harden) too rapidly. This reduces its strength and durability. Therefore, more water should be added to the mix when concreting in hot weather so it hydrates more slowly.

When laying EAC in cold weather, the opposite is true. The hydration process can sometimes be too slow, resulting in a loss of strength and reducing the concrete’s durability. Adding hot water to the mix and deploying heaters once the EAC has been laid help speed up the hydration process.

Safety precautions when working with EAC

What are the safety precautions to consider when working with exposed aggregate concrete? Let’s take a look.

While concrete in all its forms is one of the most widely used building materials, it does come with some safety risks. For instance, concrete contains hazardous materials such as lime, which is corrosive to the skin. Also, crystalline silica found in concrete is abrasive to the skin and can damage the lungs. Elements such as hexavalent chromium can cause skin and respiratory allergies to develop. Therefore, anyone working with EAC can develop skin problems, eye irritation and respiratory issues. These conditions may be mild or severe in nature.

Other dangers when working with exposed aggregate concrete include incorrect lifting techniques, which can result in a back injury or straining a muscle. As EAC is wet, there is also the risk of a slip and fall accident.

Some best practices for protecting anyone working with exposed aggregate concrete include ensuring everyone has the proper PPE. This includes safety goggles to protect the eyes from concrete dust and chemicals. Workers should wear a N-95 or R-95 face mask to protect the lungs against dust inhalation. 

Wearing full-length pants and shirts with long sleeves provides a layer of protection against the abrasive nature of exposure to concrete. Clothing prevents concrete burns, skin irritation, and the possibility of developing skin allergies. Wearing boots and gloves is also advisable. Hands and feet need to be protected from chemical burns while also protecting them against cuts and abrasions from debris or aggregate. Feet and hands are more susceptible to damage, and a cut from an unsafe source could result in a tetanus infection.

A hard hat or helmet protects workers from falling objects, and if heavy machinery is being used on-site, ear plugs will prevent damage to eardrums.

Innovative techniques for enhancing EAC performance

Adding reinforcement in the form of polypropylene fibre will minimise cracking and increase the strength of EAC. Use a wet cure instead of a disappearing cure and seal for improved results. Never use the slab as a staging or cutting area, as it can damage the finish. For concrete dying, use liquid colour and plastic trowels for optimum results.

Talk to us about your EAC project

Fluid Concrete specialises in laying exposed aggregate concrete for all sorts of projects, from footpaths, walkways, driveways and more. If you’re planning a project that involves EAC, talk to us first.