Should cement be placed under concrete slabs for driveways or is sand enough?


You do not want to just place the concrete tiles on native ground soil. A proper installation would be to dig out the native soil down to a solid base. Then lay in a layer of crushed rock to aid in water drainage. Directly under the concrete tiles would be some sand that makes it possible to level and even out the tile installation.

With the correct materials that are properly packed in and if the water drainage from the area is implemented correctly an installation should stand up well without adding concrete under the tiles. But keep in mind that they will move around if there is winter frost action, an unstable base soil, very large vehicles driving over them or if there is a regular flow of water over and between the tiles down into the base materials. This movement can be mitigated by placing concrete under the tiles but there is a tendency to make this layer fairly thin and this can still crack and allow tile movements.

My recommendation, if you want a driveway...

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Cockburn Cement supply a range of cement products, in different package sizes, to cater for a variety of DIY projects.

We have listed our quality products that may best suit your concreting needs. For estimating your requirements please refer to our easy estimator or try our calculator located in the side panel.

Check out our Home Builders Guide where we have listed the best products available in WA and where to use them for the best result.

Please see below for our step-by-step guide for laying a concrete slab; alternatively you can download our printable copy here:


Concrete requirements

Calculate out the volume of your slab by multiplying the slab’s length x width x depth. This will give you a quantity in m3. Using the chart below you can then work out the materials required.

Mix Design For Slab Floors, driveways and paths:-

1 part cement : 2 parts sand : 4 parts coarse aggregate
(Use only concrete sand to avoid...

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I Курс I Семестр.

Building materials

( 1600 печ. зн. )

Materials that are used for structural purposes should meet several requirements. In most cases it is important that they should be hard, durable, fire-resistant and easily fastened together.

The most commonly used materials are steel, concrete, stone, wood and brick. They differ in hardness, durability and fire-resistance.

Wood is the most ancient structural material. It is light, cheap and easy to work. But wood has certain disadvantages: it burns and decays.

Stone belongs to one of the oldest building materials used by man. It is characteristic of many properties. They are mechanical strength, compactness, porosity, sound and heat insulation and fire-resistance.

Bricks were known many thousands...

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Why build a high quality slab on grade is best answered with, "what happens when you don't!"

If the concrete is out of level (greater than...

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Be sure to scroll down... there may be more than one question on this page!

Dear NH,

My concrete driveway and patio have sunken slightly and water puddles when it rains. is there a way to level it off? I was thinking of using a cement product which will adhere to the existing surface without having to replace the whole drive and patio?


Dear J,

Adding a layer of cement to your driveway and/or patio is one option. There are a number of cement products that can be used… from plain old concrete mix to special Portland cement mixtures that can be applied as an almost paper-thin coating over existing work.

There are a few preparatory steps you should follow to assure the best adhesion of these products. First, the surface of the old work should be cleaned and roughened slightly. Concrete becomes harder and less porous as it ages. Chemical concrete cleaners containing phosphoric acid will both clean and slightly etch the surface and...

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What goes under the concrete in a slab-on-grade home? In the old days, not much — just dirt. Eventually, contractors discovered that it made sense to include a 4-inch-thick layer of crushed stone under the concrete. The crushed stone provides a capillaryForces that lift water or pull it through porous materials, such as concrete. The tendency of a material to wick water due to the surface tension of the water molecules. break that reduces the amount of moisture flowing upward from the damp soil to the permeable concrete.

Since the crushed stone layer provides a fairly uniform substrate, it also may also reduce the chance that a concrete slab will be poorly supported by random pockets of soft, easily compressible soil.

Eventually, polyethylene was invented. Concrete contractors learned that a layer of poly helps to keep a slab dry, because it stops upward vapor diffusionMovement of water vapor through a material; water vapor can diffuse through even solid materials if...

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Concrete is a proportioned mix of sand, gravel, water, portland cement, and various additives depending on your region and the time of year. Concrete is perishable - once it is 'slumped', or mixed together, concrete will become unworkable in 3 to 6 hours without any accelerators or retarders. Adding water at the jobsite to make the concrete more workable is a standard practice in the industry; however, excessive water will weaken the concrete.

A standard residential 3000PSI exterior concrete driveway, under normal wear and tear in our temperate Georgia climate, should last your lifetime. We would say 30-50 years is a reasonable service life for a concrete driveway or patio. We've seen eighty year old concrete parking lots still in servicable shape. Concrete's life span is usually shortened not by its inherent PSI strength but by environmental factors such as tree roots, excessive loads, erosion, and sinking or movement of the sub-grade below.


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The Secret of Strong Concrete

Making concrete is easy. There are many small concrete projects that you as a homeowner can confidently tackle using PPC SUREBUILD Cement 42,5 N with extra strength. Foundations, flooring slabs, fish ponds and driveways are just some reasons to learn how to mix concrete. By doing these projects yourself you can save money.

When learning how to make concrete, remember that the secret to strong concrete is to use a power-packed cement like PPC SUREBUILD Cement 42,5 N with extra strength, and never too much water. PPC SUREBUILD Cement 42,5 N with extra strength makes more concrete than regular class 32,5 general purpose cements.*

*For more details on comparative mixes, see the Affordable Housing page.

What Materials Do I Need?

PPC SUREBUILD Cement 42,5 N Concrete Mixes

How Much Concrete Will I Need?

Concrete is always poured into a ‘form’ or hollow in the ground. To work out how much concrete you need...

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More about Concrete Driveways

Concrete driveways in Winnipeg have long been known to give trouble-free service to homeowners. The reason is simple. Concrete is enduring…many driveways last for 30 years and longer without major maintenance. Just as with many high-quality purchases, a concrete driveway will cost less in the long run.

From the street to the garage, a personally designed concrete driveway not only adds visual satisfaction…but also adds long lasting quality and value to your home as well. IntelCrete will help you design curves and textures as needed to create a higher quality driveway if you would like. Typically, driveways standards in Winnipeg are determined by the neighbour hood look and feel and the standards for that subdivision. Recently, in some of the higher end subdivisions of Winnipeg it is required to use either exposed aggregate or stamped and coloured concrete.

IntelCrete Concrete Works uses minimum 32 MPA and most often...

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1. WHAT is Plastic Shrinkage Cracking?

Plastic shrinkage cracks are cracks that appear on the surface of a freshly placed concrete slab during the finishing operation or soon after. These cracks are usually parallel to each other on the order of 1 to 3 feet apart and 1 to 2 inches deep rarely do they intersect the perimeter of the slab. Plastic shrinkage cracks rarely impair the strength of concrete floors and pavements. Nevertheless they are unsightly. The development of these cracks can be minimised if appropriate measures are taken prior to and during construction.

Note: Plastic shrinkage cracks should be distinguished from other early or pre-hardening cracks caused by settlement of the concrete on either side of a reinforcing bar due to bleeding and resistance to settlement over the bar of because of formwork movement.

2. WHY Do Plastic Shrinkage Cracks Occur?

The most common explanation for the occurrence of plastic shrinkage cracking is that the...

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Develop a plan for your driveway.

You will want to consider a number of things so that the driveway is functional, aesthetically pleasing, and durable. Here are some considerations.

Where will you turn your car around to enter the street? If your home is near a blind corner where oncoming traffic can be hazardous, you may want to create a circle drive, so you have the advantage of facing the street when pulling from your driveway, or make the drive wide enough to turn your car around when pulling out. What is the lay of the land? If you are building on a hill, you will need to pay special attention to drainage to decrease soil erosion, as well as being careful that the contour is not so steep that you will bottom out your vehicle. What obstructions are in the way of your project? Large rocks or trees may be difficult to remove without heavy equipment, and often it is desirable to leave these in place, so determining the path of the drive so it can either curve around...
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Bound or unbound?

There are two classes of bedding material: hydraulically bound and unbound. Hydraulically Bound (HB) materials have the loose aggregate (the sand) held together by a binder, most commonly cement or hydraulic lime, while unbound material, unsurprisingly, have no binder present, meaning that the loose aggregate (sand) remains loose.

There are pros and cons to each type of bedding:

Unbound - unlimited working life - cheap - clean and safer to work with - creates a flexible pavement - prone to movement and settlement - can be mined by invertebrates - requires complete consolidation Bound - firm, robust and solid bed - resistant to movement and settlement - can disguise incomplete consolidation - creates a rigid pavement - limited working life - more expensive than unbound - potentially messy: accidental staining - health & safety implications: dermatitis, cement burns As a very, very general rule, flags 450x450mm...
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How to finish concrete: Placing concrete
Concrete must be discharged in a timely manner upon arriving to the job site. If you are using wheelbarrows to move the concrete from the truck to the forms, make sure you have enough help to finish the project in a timely manner. Concrete delivery should be closely coordinated with placing and finishing operations. Concrete should not be poured faster than it can be worked – spreading, consolidating, bull floating. Instead, concrete should be poured continuously as near as possible to its final position. You should never dump concrete into separate piles and work together.

Consolidation of Concrete
Placing concrete in forms and then consolidating is popular for some types of construction (i.e. Pouring Formed Columns, Beams Etc.). The consolidation process uses vibration and gravity to compact fresh concrete within the forms and around embedded items and reinforcement. This process eliminates unwanted pockets of...

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1. What is VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring? VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring is a system for laying high quality concrete floors where the key is Dewatering of Concrete by Vacuum Process wherein surplus water from the concrete is removed immediately after placing and vibration, thereby reducing the water cement ratio to the optimum level.

VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring increases the Compressive Strength, Tensile Strength, and Abrasion Resistance and minimizes the Shrinkage and Floor Wraps. VDF Flooring results in High Strength, Longer Life, Better Finish and Faster Work. This type of floor is suitable for high abrasion & heavy traffic movement.

2. What is the full form of VDF Flooring? The full form of VDF Flooring is Vacuum Dewatered Flooring. 3. What is the Work Methodology of VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring? (VDF Flooring...
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This could almost be classed as a FAQ given the number of enquiries that roll in each year.

Homeowners want to use Indian Sandstone flags, which are normally considered as 'patio' flagstones, to pave a residential driveway, but worry that the flags may not be strong enough to cope with vehicular traffic.

The good news is that it is possible to use certain flagstones to build a driveway, but that doesn't apply to ALL imported sandstone flags. The flags have to be the right type to be certain of success.

What flags can be used?

There are two very distinct types of flagstone: there are those manufactured from concrete, and then there are those manufactured from natural stone. These two groups have quite different characteristics, so when it comes to driveway paving, careful choice is essential. There is a very wide spectrum of quality in both types.


Generally speaking, for wet-cast concrete flagstones, the cheap or...
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