A superplasticizer is an admixture used in the preparation of concrete. It improves the flow characteristics of concrete, increasing its workability without affecting its mechanical properties. Superplasticizers therefore reduce the water/cement ratio in the concrete mixture, which increases its mechanical strength and makes it easier to install.

Ask for an added superplasticizer rather than water to ensure easier concrete installation.

Water is one of the four essential components of concrete, the others being cement, coarse aggregates and sand.

Water is also the most crucial component, because the water-cement ratio determines the concrete’s compressive strength and durability. To ensure a perfect reaction between the water and cement, water is added at the plant following the quantity specified in the formula, while respecting CSA standard requirements.

Water should NEVER be added imprecisely at a worksite or at home. Adding water could cause problems in the future, because water has a direct impact on the strength of your concrete.

Fibre-reinforced concrete provides three-dimensional reinforcement due to its fibre density. It can mean you don’t have to reinforce floor slabs with steel frames, thus saving time and money. The tensile strength of fibre-reinforced concrete is comparable or superior to that of standard reinforced concrete.

Fibres can be added to concrete to increase its post-cracking strength. A “fibre” is a material from 5 to 60 mm long that can be metal, organic or ceramic. Based on their type, these fibres have different characteristics and do not react the same way. Their impact on concrete can therefore vary.

Fibre-reinforced concrete is used in many applications similar to standard concrete.

USE
Fibre-reinforced concrete is easy to use. It produces an excellent finish, and is easy to pump. It is recommended for commercial, industrial, agricultural and residential floor slabs. It is also used in concrete patching and for many other applications, such as foundations and flooring.

FINISH
Fibre-reinforced concrete can be finished using conventional techniques, but some precautions must be taken to prevent the fibre from appearing on the surface and to minimize the risk of cracking at the edges when sawcutting control joints. These precautions include:

• using a double trowel;
• placing the trowel as flat as possible against the concrete surface;
• bull floating after screeding;
• using screeds and laser equipment.

To avoid any rapid or excessive loss of moisture at the surface of freshly poured concrete, it is recommended that concrete surfaces be protected from the damaging effects of the wind. Wind can increase the loss of surface moisture and lead to surface flaws.

To avoid this:

• moisten formwork and supports;
• cool the concrete;
• place the concrete at the end of the day or early in the morning;
• cover the concrete surface (polyethylene, tarps, or other);
• begin curing the concrete as soon as possible.

(source: ABQ’s Guide du chantier)

Concrete curing is the amount of time required to allow the freshly poured concrete to set in adequate temperature and humidity conditions to ensure that it achieves the desired properties.

The cure must begin as soon as the concrete surface is hard enough not to be damaged. Respect the concrete curing period before form removal and backfilling.

Concrete curing method:

• formwork left in place;
• ponding or immersion;
• sprinkling water;
• steam or hot water curing;
• water soaked canvas;
• waterproof paper;
• plastic film;
• curing compounds, etc.

(source: ABQ’s Guide du chantier)

Abrasives are recommended (for example, sand and fine gravel) instead of deicing salt.

1. Values from common practice
2. Values from standard CSA A23.1-09, referred to in the Quebec Construction Code based on the CNB 2010 (reference 7.5)
3. The nominal maximum size of aggregate is generally 20 mm, but it may be smaller to allow for use by pumps with a small diameter, and for application in thin spaces
4. Air content between 3 to 6% according to standard CSA A23.1-09