What is Concrete?

Concrete is a composition of cement (most commonly Portland cement, defined by ASTM C 150 as a "hydraulic cement" given that it not only hardens with water but forms a water-resistant product after hardening), water, aggregates (typically a course aggregate such as crushed rocks of various and certain sizes, combined with a fine aggregate such as sand) and other cementitious materials such as fly ash and slag.

Concrete is formed after the above are combined as a result of a chemical reaction called hydration. The water in the mix reacts with the cement which bonds the other materials together producing a stone-like material capable of creating bridges, skyscrapers, pavements, dams, and much, much more.

The word concrete comes from the Latin word "concretus" (meaning compact or condensed), the perfect passive participle of "concrescere", from "con-" (together) and "crescere" (to grow), and has been around for over a thousand years - made famous by the Romans in structures such as Hadrian's Pantheum.

Key Things To Look For During Concrete Placement

When looking for concrete placement, there are certain key factors you should consider:

• Has the subgrade been properly prepared and compacted?
• Ensure the area is properly drained and sloped to prevent water build-up. 
• Ordering the proper concrete. 
• Place the concrete within 120 minutes of batching. 
• Do not allow the addition of water to the concrete after the concrete placement has started. 
• Has the contractor prepared a control joint layout to prevent uncontrolled cracking?
• How will the concrete be properly cured? What curing method will be utilized to protect the concrete and how long will the protection be applied?

To learn more about concrete placement and to ensure your pour provides the results you desire, call us and speak to one of our conrete experts. 

Pouring Concrete Driveways

A concrete driveway represents an investment that is designed to last a lifetime, provided proper procedures are followed. Having the assistance of an expert assistant is recommended when installing a driveway in order to ensure a satisfactory job, but there are six general steps to success when pouring a new concrete driveway:

When followed correctly, and with the assistance of a qualified contractor, these six steps will lead to a visually appealing driveway that will last a very long time. So call us and we'll be glad to recommend a contractor to you. If you're after a quote for concrete, call us or click the 'Need a Quote' button at the top of your screen, and don't forget to use our Concrete Calculator to help you figure out how much concrete your new driveway requires.

For keeping your driveway clean and looking great - free of messy oil and fuel drips, check out Micro 50^TM, Sarjeant's EcoLogo^TM certified cleaner and degreaser that biodegrades petroleum stains. 

• 1) Determine the Required Thickness

  a) For cars and pick-ups - 100mm

   

  b) For light trucks - 125mm

   

  c) For occasional heavier trucks - 150mm

   

  (placed on a competent subgrade)

• 2) Site Preparation

  Concrete can be placed directly on uniform subgrade after moving the topsoil, or on deteriorated asphalt pavement. Excavate the surface or bring to grade as necessary using granular ‘A’ as leveling course (typically 100mm).

   

  a) Make sure the subgrade is uniform, well compacted and contains no frozen material

   

  b) Slope away from buildings at 2%

   

  c) Install isolation joints using asphalt impregnated board strips (see figure 1). 

   

  d) To form driveway, use stiff wood forms kept in position with stakes no more than one meter apart. Top of stakes should be flushed with, or slightly below the top of form at finished grade.

   

  e) Plan exact position of concrete joints before starting the project and mark the locations on the formwork prior to concrete placement. 

• 3. Plan Your Requirements for Labour & Material

  a) Concrete: Class C-2; 32MPa; 0.45 water to cement (w.cm) ratio; 5-8% air entrainment; 100mm slump (max), for all exterior slabs on grade as required by CAN/CSA-A23.1 & OBC using quality proven aggregate. 25 hour advance notice of delivery should be provided. 

   

  b) For colored concrete, it is recommended that the color be integrally mixed with concrete at the time of batching. Air entrainment (5-8%) must be measured after the colored is mixed in.

   

  c) Make sure adequate labor is on hand when concrete will be delivered. Generally a minimum of 3 peeople, but plan for more for larger jobs or when placing the concrete on hot, dry days.

   

  d) Checklist of tools and materials needed:

   

  - large roll of plastic sheeting (protection from rain)

   

  - wheelbarrows and shovels

   

  - water supply for curing and wetting subgrade

   

  - long handled bullfloat about 120mm wide minimum

   

  - straight rigid board for screeding

   

  - vapor retardant

   

  - concrete broom for texture

   

  - curing materials

• 4. Order & Place the Concrete

  For tips on ordering concrete, click here.

   

  a) Dampen the subgrade without leaving freestanding water. Oil the forms before placing concrete

   

  b) A 100mm slump is adequate for placement. Adding water to increase the slump or workability has a very detrimental effect on both the strength and the durability of the concrete. 

   

  c) Distribute the concrete; use shovels to bring rough grade avoiding segregation. 

   

  d) Strike off the concrete to finish grade by using a straight board in edge between the forms – use “sawing” motion. Tap the forms to consolidate the concrete. 

   

  e) Screeding: smooth the surface using the long handled bullfloat – DO NOT USE STEEL SHOVELS 

   

  f) For final non-slip finish use a concrete broom, burlap drag, magnesium float or impressed mat finish. 

   

  g) IF PLACED ON A HOT, DRY OR WINDY DAY, TAKE SPEICAL PRECAUTIONS:

  - Protect fresh concrete from rapid moisture low by covering with plastic after screeding to keep surface moist, or use wind screens, fog nozzles, vapor retardants, etc.

  - Be prepared for fast setting during warm weather

  - Protect hardening concrete by curing concrete immediately after final finish. 

   

  h) During cold weather, longer time is required before performing final finish. Do not perform final finish while concrete is still bleeding.

   

  Note: Improper procedures can result in a poor quality job. 

• 5. Curing & Sealing

  a) For proper curing, moisture must be retained in the slab for an extended period. Curing must start immediately following the final finish and is accomplished by using:

   

  - curing membranes/compounds, which can be easily rolled or sprayed on as soon as the finishing operations are complete.

   

  OR

   

  - wet burlap, soaking hoses, waterproof paper or polyethylene film to keep the surface constantly wet for 7 days. Do not hose on surface. 

   

  b) DO NOT APPLY DE-ICERS UNTIL THE CONCRETE HAS GONE THROUGH ITS FIRST WINTER. DO NOT USE AMMONIUM BASED DE-ICERS AT ANYTIME. 

   

  c) If the concrete is placed in the late part of the year below 5ºC, use polyethylene film or another cold weather curing method. An air drying period of one month after the curing period is required before de-icing salts can be applied. A PENETRATING SEALER can be applied as caution against chloride penetration. 

   

  d) Under normal conditions the concrete may be sealed with a PENETRATING SEALER according to the recommendations of the manufacturer:

  (i) After 30 days of a curing member has been used;

  (ii) After a period of air drying of water-cured

• 6. Control Joints

  As concrete ages, it initially shrinks because of water evaporation and cooling of the concrete. Cracks will occur at random locations unless they are controlled in a pre-determined manner, typically using control/contraction joints. These joints create weakened plains where the concrete can crack in a straight line, providing for pleasing aesthetics because the cracks have occured below the finished surface.

   

  The concrete has still cracked which is nromal behaviour, but the absence of random cracks at the concrete surface gives the appearance of an un-cracked section.

   

  Certain conditions must be met in order to achieve this result, however. Control joints shall be:

   

  - Cut as soon as possible without pulling the aggregate out, usually within 4-12 hours after concrete has been placed (can be longer in cold weather)

   

  - cut ¼ the thickness of the slab – this is the minimum depth.

   

  - no more than 3m apart for 100mm thick slab, 4m apart for 125mm slab, and 4.5m apart for 150mm or thicker slab.

   

  - control joints should be cut in a square pattern. 

Concrete Pavement

Concrete pavement is the most versatile pavement available. They are used as sidewalks that support foot traffic to runways that support 350,000 pound aircraft. They may be designed for a life of 5, 10, 20 and even 50 years - a range that far exceeds what is possible with any other pavement material.

Read about the benefits of concrete paving below, then call us to discuss how it will work for your project.

The benefits of concrete pavement can be organised into fve categories; Value; Safety; Durability; Smoothness and; Versatility.

• Value

  Oil Inflation – Concrete Will Save You Money

  Flexible pavement prices are related to oil refining processes and Statistics Canada shows that flexible paving prices are increasing during this continued period of oil inflation. This has led to the concrete pavements being more financially beneficial on a first cost basis (in addition to the life-cycle cost benefits) 

  Noise Control

  Sound level is primarily a function of the surface finish not the material is it construction from. Many types of concrete pavement surface textures have been developed to reduce concrete pavement noise related problems. The concrete pavement textures shown on the right all produce different noise levels and different frequency spectrums (tones). 

• Safety

  Increased Visibility

  Concrete is naturally brighter and more reflective than flexible pavement. This requires less energy to illuminate comparable areas, which is good for the environment, pedestrian safety, and can save on street lighting costs. 

  No Rutting

  Concrete under normal use will not rut, so there is no risk of water accumulation in ruts and causing hydroplaning. 

  Superior Traction

  Plastic concrete surfaces can be text red to provide skid resistant surfaces that are needed to allow safe vehicle breaking action and directional stability. This texture surface also improves drainage. 

• Durability

  Continues to Gain Strength

  After its first month in place, concrete continues to slowly gain 10 percent in strength during its life. 

  Minimal Maintenance Requirements

  Concrete pavements provide long-term value because they will frequently outlast their design life expectancy and traffic loads. 

• Smoothness

  Specifying Road Characteristics

  Technology in today’s road design and placement equipment allow for owners to specify the ride characteristics of their concrete road. Any future road cut repairs when finished properly, can be completed quickly without affecting ride quality. 

  Smoother for Longer

  The rigidity of concrete pavements allows it to keep its smooth riding surface long after construction

  Longer Lasting Roads

  Concrete can withstand even the heaviest traffic loads, without the worry of ruts, shoving or washboard effects that are common with flexible pavements. Also, Concrete roads will offer forgiveness when future traffic expectancy is underestimated. 

  Utility Cuts – No Problem

  There is a common misperception that concrete cannot be removed for repairs or utility cuts. The reality is that concrete pavement repairs are easily made with readily available equipment and materials. By using quality concrete and following full-depth repair techniques, it is relatively easy to construct long-lasting, durable patches that can extend the concrete pavement’s life for many years. 

• Versatility

  

  Variable Design

  Concrete pavements can be designed for any load and traffic for streets and roads, parking lots, intersections and entrances. 

  Fast-Track Concrete

  Concrete pavement can be open to traffic in as little as 12 hours.

• Pavement Properties

  Concrete Pavement Properties 

  Flexural Strength	4MPa
  Reliability	80%
  K-Value	100
  Design Life	30 years

   

  Flexible Pavement Properties

  MAAT	7°C
  Modulus of Resilience Sub-Grade Support	20MPa
  Design Life	30 Years

Cold Weather Concrete

Weather conditions can have a dramatic effect on both the setting time and concrete placing, finishing and protection systems that must be followed for proper concrete placement. Cold weather concreting conditions are typically defined as:

- When the air temperature is ≤ 5°C

- Or when there is a probability that the temperature may fall below 5°C within 24 hours of placing the concrete

Click here and expand 'Sarjeant ProSeries' to see how Sarjeant's WINTER Pro specialty concrete can help meet your cold weather concrete needs.

• General Procedures for Cold Weather Concreting

  General procedures for cold weather concreting include:

   

  - Removing all ice and snow from the subgrade or formwork

  - Supplying the necessary supplemental heat required to ensure that forms, subgrades, and reinforcing steel is maintained a minimum temperature of 5°C well prior to the concrete placement

  - Ordering concrete with a temperature between 10°C – 25°C

  - Concrete should be ordered using the lowest practical water slump since this will reduce bleeding and setting times. Chemical admixture can still be used to improve the workability of the concrete

  - Chemical admixtures and mix design modifications can be used to offset the slower setting times and strength gain of concrete during cold weather conditions. Considerations should be given to ordering concrete that will obtain higher early strengths

  - Concrete temperature must be maintained at a minimum of 10°C for the full curing period

  - The surface of the concrete should not be allowed to dry out while it is still plastic since this may cause plastic shrinkage cracking. The longer set times encountered during cold weather combined with the effects of hot dry air from heaters being blown along the top surface of the concrete significantly increase this risk

  - Wet curing methods are typically not recommended during cold weather conditions since the concrete will not have a sufficient time period to air dry before the first freeze/thaw cycle

  - The possibility of thermal cracking must be considered when the heating supplied during the curing period is going to be suspended. Concrete should not be allowed to cool at a rate outside the limits listed in CSA A23.1. See below:

   

  

   

  Special care should be taken with concrete test specimens used for the acceptance of the concrete. The initial test specimens shall be stored in a controlled environment that maintains the temperature at 20 ± 5°C as per CSA A23.1/.2 requirements. 

• Caution Regarding the Use of Portable Gas Fired Heaters

  Plastic concrete exposed to a carbon dioxide source (CO₂) during the concrete placing, finishing and curing period will develop a soft, chalky, carbonated surface (known as dusting).

   

  Carbon Dioxide is an odourless and colourless gas that is heavier than air and is produced by all forms of combustion. Typical sources include open flame heaters (stacks must be vented to outside) and internal combustion engines (e.g. on trucks, power trowels, concrete buggies, etc.).

   

  Precautions must therefore be taken to properly vent the placement area.

Hot Weather Concrete

Weather conditions can have a dramatic effect on both the setting time and concrete placing, finishing and protection systems that must be followed for proper concrete placement. Hot weather concreting conditions typically include:

- High ambient air temperatures (≥ 28°C)

- Low relative humidity conditions

- High wind speeds

- Solar radiation or heat gain

These conditions can result in the following challenges for the concrete contractor:

- Increased concrete water demand

- Accelerated concrete slump loss

- Increased rate of setting leading to placing and finishing difficulties

- Increased tendency for plastic shrinkage cracking

- Increased concrete temperature resulting in lower ultimate strength

- Increased potential for thermal cracking

The first step that must be taken is to identify when hot weather concreting conditions may apply and modify the normal concrete placing and finishing procedures accordingly. Browse the steps that may be taken below, and call us if you have any questions or would like us to recommend a contractor. If you would like a quote, you can call us or click the 'Need a Quote' button at the top of your screen

• Preparation

  ACI (American Concrete Institute) recommendations regarding the pre-wetting of the subgrade have recently changed so that this procedure is not typically recommended. The only exception is during hot weather conditions were plastic shrinkage cracking may be an issue. The subgrade should be pre-wetted and forms and reinforcing steel should be dampened prior to concrete placing (there should be no standing water). The purpose of these actions is to prevent the absorption of water from the concrete into the subgrade.

• Ordering

  Inform the ready mixed concrete producer of your placing schedule and whether a chemical retarder will be required. For exposed flatwork the use of retarding admixtures or supplementary cementing materials should be discussed with the concrete producer. In extreme cases the concrete temperature may also be lowered by using chilled water, ice or liquid nitrogen.

   

  Click here for helpful tips on ordering concrete.

• Slump

  A concrete consistency (slump) which allows for rapid placement and consolidation should be considered. Chemical admixtures such as super-plasticizers can dramatically improve the concrete slump and reduce placement times.

   

  Sarjeants offers a range of testing services in its fully-equipped concrete laboratory - the only local Ready Mix producer to have one in Simcoe County. Call us to dicuss a the range of services our Quality Control department can provide.

• Placing

  After the concrete is properly mixed ensure that it is discharged as soon as possible. Consider the use of large crews to accelerate placement rates.

   

  See 'Key Things to Look For During Concrete Placement' above for more information. 

• Finishing

  In cases where protection against rapid evaporation of water from the concrete surface is a concern, consider the use of one or more of the following actions: 

   

  - Erect sunshades and wind breaks

  - Cover the surface with white polyethylene sheets

  - Apply fog spray

  - Place and finish at night or early morning

  - Apply temporary evaporation retarder after the screeding operation

• Curing

  Curing should be started as soon as the concrete has set enough to avoid any surface damage. Concrete should be cured for at least 7 consecutive days after placing. Ensure that the concrete is kept moist throughout the curing process (see technical bulletin on curing options).

• Testing

  To avoid inaccurate strength test results, the initial test specimens shall be stored in a controlled environment that maintains the temperature at 20 ± 5°C as per CSA A23.1/.2 requirements. Concrete test cylinders that exceed these temperature requirements typically exhibit much lower 28 day strengths.

   

  Sarjeants offers a range of testing services in its fully-equipped concrete laboratory - the only local Ready Mix producer to have one in Simcoe County. Call us to dicuss a the range of services our Quality Control department can provide.

Stamped Concrete Guidelines

Stamped concrete is concrete that is patterned and/or textured to resemble brick, slate, flagstone, stone, tile, wood and various other patterns and textures.

Commonly used for patios, driveways, interior flooring and around swimming pools, stamped conrete's aesthetics mean it can be used as a less expensive alternative to the real materials it's replicating. 

Click here and expand 'Sarjeant ProSeries' to see how Sarjeant's ProSTAMP specialty concrete can help meet your cold weather concrete needs.

Browse the guidelines below for using stamped concrete, and call us if you would more information. If you would like a quote, you can either call us or click the 'Need a Quote' button at the top of our screen.

• Concrete Specifications

  For Exterior application concrete shall conform to C.S.A. A23.1 – M94 for class C-2 exposure:

   

  - Minimum 28 day compressive strength – 32MPa

  - Maximum water/cement materials ratio – 0.45

  - Air content category – 7-10% for 10mm Coarse Aggregate or 6-8% for 20mm Coarse Aggregate.

   

  Slump shall not exceed 100mm.

• Colour

  Trial batch for colour match is possible. Colour can be integral or top shake.

   

  Click here and expand 'Coloured Concrete Options' for a list of colour samples, and call us or your contractor if you would like more information on concrete colouring options.

• Testing

  All concrete shall be tested in accordance with C.S.A. A23.1 – M94 and any air test must be done after color has been introduced and immediately prior to placing concrete.