Cement is entirely unnecessary throughout the entire process of preparing and laying block paving, except for creating mortar during the installation of the edge course and for setting up a drainage system (linear channel).
However, for some unknown reason, I’ve observed individuals using or recommending the mixing of cement with sand.
Let’s explore the purpose behind using cement in the sand and whether it’s genuinely necessary.
There are two distinct scenarios where cement can be incorporated into the sand. I’ve come across both instances: using cement in sharp sand during screeding and adding it to kiln-dried sand when filling the gaps between the blocks. Let’s delve into the reasons for suggesting cement usage in these situations and whether it’s advisable or not.
Using Cement in Sharp Sand for Block Paving Bed (Dry Mix)
I came across this discussion within a landscaping community where an individual posted about the confusion surrounding various methods for achieving the same outcome.
The scenario involved someone seeking quotes to block paves their 120m2 driveway, and the contractors they consulted had different approaches for accomplishing the identical task.
Some individuals suggested that the preparation should follow the conventional approach, similar to what most people typically do for block paving. This includes using a type 1 sub-base (100-150mm), followed by a layer of sharp sand (30-40mm), with the blocks placed on top.
However, others proposed a thicker sub-base and sand bed, indicating that this is particularly advantageous for those with clayey soil. They also suggested using cement in the sand to prevent block sinking. These varying viewpoints raise several questions, so let’s explore whether you genuinely require a sand and cement mix as a laying course for your block paver or if it will sink without it.
Reasons for its Ineffectiveness
To install block pavers effectively, a flexible bed is essential. Therefore, sharp sand is spread and compacted to establish a suitable foundation for laying the block pavers. However, when you introduce cement into the sharp sand mix, you are essentially going against the fundamental requirement of a flexible bed that is crucial for your paving project.
There are several minor considerations that you can address to ensure a successful job, such as employing a membrane to prevent the sub-base from compressing into the soil, ensuring the appropriate sub-base depth, and conducting proper compaction. These cumulative details significantly influence whether the block paving will sink rather than resorting to an unconventional method like mixing cement with sand.
If you’re a DIY enthusiast tackling block paving on your own, be sure to consult the DIYer’s Block Paving Guide for essential information that can significantly enhance the prospects of success and durability during the paving process.
Utilize kiln-dried sand mixed with cement to fill the joints in block paving.
I’ve authored a collection of articles addressing different facets of block paving, encompassing topics like sanding or resending and the importance of sealing.
If you’re currently engaged in a block paving project, I recommend reviewing the preceding article for valuable insights and guidance.
A common issue I observed while working on this task is that, often, the sand used to fill the joints in block paving gets washed out too quickly after brushing.
Consequently, I’ve come across recommendations from others to incorporate cement into the kiln-dried sand mixture instead of using kiln-dried sand alone for a more lasting joint-filling solution.
Firstly, incorporating cement can result in considerable untidiness and staining of the pavers, potentially jeopardizing the overall aesthetics of the block paving. Addressing these stains may require extensive and, at times, impossible cleaning efforts.
The paramount rationale behind this is that block paving is designed to be a flexible installation, as we’ve previously discussed. In contrast, cement becomes rigid once it dries. Since the surface needs to maintain its flexibility, the joints must also remain flexible. Hence, using only kiln-dried sand stands as the superior choice.
It would be a complete nightmare scenario. Cement wouldn’t effectively fill the gaps, resulting in staining of the paving. It would require water to set, and even with meticulous management, the cement would eventually crack and seep out of the joints due to minor block movements. Apart from these issues, there wouldn’t be any significant problems.
The cement will dislodge itself once it cracks due to any movement in the pavers, necessitating the need to reapply sand to your driveway or block paving. However, this time, you’ll do it correctly, having learned a valuable lesson from the experience.
The most effective and exclusive method for safeguarding the sand-filled joints from erosion is to seal the driveway, which includes sealing the sanded joints. There are additional advantages to sealing a block paving, mainly when using a high-quality sealer. As a result, it is consistently advised to apply a driveway sealant every 2-3 years following the joint sanding process.
Examine this post for insights into the typical expense of cleaning and sealing a block paved driveway using a top-notch sealing product.
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FAQS
What is the best base for block paving?
The optimal base for block paving is a well-prepared and compacted sub-base, typically crafted from crushed stone or concrete. This robust foundation ensures stability, reduces the risk of settling, and enhances the overall longevity of your block paving project.
What materials do I need to lay block paving?
To lay block paving effectively, you’ll need specific materials, including paving blocks or bricks, a solid foundation of sand or crushed stone, edging for containment, a compactor for proper installation, a spade, a spirit level for accuracy, and jointing sand to fill gaps between the blocks.
Should I mix cement with paving sand?
Mixing cement with paving sand is generally discouraged. Paving sand is designed as a base material for laying pavers, while cement acts as a binding agent. Combining the two can lead to a rigid mixture prone to cracking and unevenness over time. To ensure a sturdy and visually pleasing paved surface, it’s best to use specialized paving sand that provides proper drainage and flexibility, avoiding the complications of mixing cement.
Does block paving need sand?
Block paving typically requires sand as part of the installation process. Sand is used as a base layer and for jointing between the individual blocks or pavers. The base layer of sand provides stability and helps with drainage, ensuring that the paving remains level and doesn’t shift over time. Additionally, sand is essential for filling the gaps or joints between the blocks, which helps to lock them in place and prevent weed growth. Adequately laid and maintained block paving with sand can enhance the durability and appearance of your outdoor surfaces.