Q1. What is the white haze that randomly forms on the bricks after a couple of weeks?
This white haze is called efflorescence. Water reacts with cement inside bricks that produces water soluble calcium oxide. It is a natural phenomenon that appears randomly. Click here to read more in depth about the topic
Q2. How do I remove the white haze that randomly forms on the bricks after a couple of weeks?
Usually the rain washes it away in about 1 to 2 years. The quick solution is to wash the bricks with diluted hydrochloric acid (1 part hydrochloric acid, 20 parts water). WARNING- Washing with hydrochloric acid may change the brick shade and/or cause the surface of brick to become rougher. Click here to read more in depth about the topic.
Q3. What is the difference between Dry and Wet cast paving?
THE DIFFERENCES BETWEEN WET CAST AND DRY CAST PAVERS
Getting ready to install a new or replacement paver patio or walkway?There are two main types of concrete pavers and you should know a little bit about each one before making a final decision on what material to use. Here are the major differences between wet cast and dry cast pavers.
Wet cast pavers
Wet cast concrete is fairly liquid and has a high slump.
To manufacture wet cast pavers, concrete is poured into a mould and then vibrated to release air bubbles. After the concrete has cured the product is de-moulded. Wet cast pavers can be made with various stone textures and in many different colours. Surface finishes are smooth or textured depending on customer requirements
Dry cast pavers
The dry cast manufacturing process uses heavy, complex machinery.Dry cast concrete has very little water and has zero slump.It contains only enough water to hydrate the cement.The mix is compressed in a mould using pressure and vibration.After de-moulding the product is cured before being transported.Products are manufactured with a coloured topping. Surface finish is not as smooth as wet cast pavers, but has better non slip properties. Dry cast products are mass produced and are generally cheaper than wet cast, but shapes are more limited.
Both wet cast and dry cast pavers are suitable for residential projects (i.e. driveways, walkways, pool decks, and patios). Dry cast pavers have an optimal water to cement ratio making them very strong. For large-scale commercial projects dry cast pavers are the more popular choice due to their strength, durability, and load capacity.
Wet cast pavers typically tend to be more expensive than dry cast. For projects with budget restraints, dry cast pavers will most likely be the more economical option.
Q4. What is the recommended paving installation procedure? CMA Installation Manual - Concrete Block Paving
We would always advise contracting a paving specialist.
For clients that want to install the paving themselves, or supervise a contractor, we recommend the
CMA illustrated guide to paving installation. Click here
Q5. Delivery times on orders
Zenzele Brix will aim to deliver 2 to 3 working days after payment reflects in our account, this is also subject to availability of stock, scheduled deliveries, weather conditions and any unforeseen events.
Q6. What is the correct plate compactor to achieve a professional finish on wet cast products?
For best results use a brick roller attachment on the plate compacter. The rubber rollers will protect the paving and give a professional finish. Alternatively a rubber mat or carpet can be attached to the base of the plate compacter to protect the surface finish of the paving during the compaction process. Direct use of a steel plate compacter can cause damage. Compacting equipment can be hired at all reputable plant hire companies.
Q7. Do copings around pool need to be sealed?
Products installed around a salt chlorinated pool MUST be sealed.
Concrete products can be damaged by excessive exposure to salt.
This reaction is known as “salt attack” and therefore the products must be sealed upon installation.
Q8. Important information on Courtyard paving
10mm open formation, size does vary, not to be laid butt joined.
Perfect for Courtyards, Patios, Lapa’s, Pathways, Walkways and Swimming pools.
Q9. Why does the product seem to stay wet/stain in either the centre or around the edges? Why is my product showing dark/black areas and can this be prevented or cleaned?
Blackening or darkening of concrete products.
What is “black efflorescence”?
In some rare area-specific cases, certain pavers become black or darker. This may occur within a time-frame of two to 18 months after installation. The blackening does not affect all the pavers on a site. In fact, one will see a patch of dark pavers surrounded by normal ones. This is usually a permanent condition and may happen to any concrete products (pay attention to discolouration on concrete bridges and building façades, for example).
The blackening products manufactured with concrete is random and not yet well understood by the concrete industry. The blackening is beyond the control of manufacturers and does not affect the pavers’ structural performance. At present, the theory is that the blackening of concrete has something to do with the specific soil conditions in an area. Evidence of this is that neighbouring sites installed with concrete products will generally also show blackening.
Discolouration or “differential curing” in especially larger products:
An obvious variation in the colour of individual pavers, with a distinct light or dark-hued “frame” and a light or dark-hued “core” on the paver’s surface, might develop or be present when unpacking your pavers. This condition is called “differential curing”. One should be aware that the “curing” of concrete is not simply the evaporation of water – it is a chemical process that takes years. Therefore the “stains” will become less profound and almost invisible over time. Initially though, some might consider it unsightly.
Picture framing on concrete bedded flagstones:
This phenomenon normally only comes to light a few days after installation has been completed and some flagstones are more prone to it than others. The common denominator is that joints were filled using a wet cement slurry grout.
Basically, what happens is that cement-contaminated water from the slurry grout is absorbed by the flagstones and carried through internal capillaries.
Evaporation then takes place, creating a “transport chain” within the body of the paver, with cement-laden water being absorbed from the underside and joint faces of the pavers, and evaporation from the upper surface, particularly from the edges of the pavers. Cement, however, does not evaporate; it cures and leaves a stain. This stain often resembles a picture frame around the flagstone.
We do not recommend using cement grouting, as cement staining is nearly impossible to prevent with this grouting method. We recommend using a resin bound mortar, like Romex, which is supplied by Cretesol. Unlike cement grouting, there is no chance of staining with this method. It is incredibly strong and long-lasting. Most importantly, Romex allows for a flexible joint between your pavers, unlike cement grouting – which eventually breaks and pops out.
Q10. Are paver surfaces slippery.
Zenzele dry cast bevel and interlocking pavers are manufactured with a surface that is not slippery.
Wetcast pavers can be chosen with a smooth or a textured surface depending on the application.
Q11. Is the product sealed
Q12. How can we clean paving
Paving can be easily cared for by either broom sweeping or hosing with a water spray. DO NOT USE A HIGH PRESSURE SPRAYER, A STEEL BRUSH, ANY STRONG DETERGENTS OR ACID TO CLEAN. This may damage the surface and colour of the product.
When laying dry cast paving the gaps between the pavers should be filled with fine sand only. Do not use cement as this may discolour the surface of the pavers. Gap filling should be done when pavers are dry and with dry sand to enable the sand to flow into the gaps.