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Using pine board, 32 mm PVC pipes, cement, and sand in a 4:1 ratio, it is possible to produce handmade eight-hole bricks with side grooves at home, with reduced cost and suitable results for small masonry services and self-construction experiments.
The cement brick with side grooves and eight holes has a more elaborate appearance than the common block and can be produced manually with simple materials, being a viable alternative for those seeking savings in small construction and masonry services.
The eight holes reduce weight and facilitate handling, while the side grooves improve the visual finish, especially when the blocks are exposed on the final face of the wall, without the need for additional coating on the surface.
The typical dimensions are 10 cm wide, 19 cm long, and 19 cm high, measurements that make the piece functional for tests, homemade productions, and masonry services in small buildings or simple residential renovations.
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Building the wooden mold
The mold can be made with thick pine board, which ensures firmness during filling and compaction, combined with metal hinges that facilitate the opening of the structure and the extraction of the brick after initial curing.
A simple latch keeps the mold closed during filling, preventing the sides from opening under pressure and compromising the brick’s dimensions, making it important to check the latch before starting each molding cycle.
The holes are formed by 32 mm PVC pipes fixed in the mold before filling, while half pipes on the sides create the model’s grooves, all needing to be greased with oil before use to ensure demolding without damaging the edges.
Preparing the mix to the right point
The mix follows the 4:1 ratio, with four parts of medium sand to one of cement, a proportion that balances strength and cost, and the dry mixture must be completely uniform before adding water to ensure better distribution of the components.
Water should be added gradually until the mix reaches a moist and loose texture like subfloor crumb, at which point it is possible to form small compact balls in hand without the mixture running when dropped.
Before filling, the internal walls, PVC pipes, and side half pipes should receive a generous layer of lubricant oil — common or used cooking oil — covering all surfaces that will come into contact with the cement mix.
Filling, compaction, and demolding
The mix should be placed in successive layers, not all at once, a practice that facilitates uniform compaction and reduces the formation of internal flaws and voids that compromise the strength and finish of the grooves and edges of the brick.
Hitting the mold against the ground helps the mix settle into the corners and eliminate empty spaces between sand and cement particles, a simple technique that improves the density and uniformity of the internal distribution of the material.
Compaction with iron or wood on each layer increases strength and improves the finish of the grooves, and the alignment of the PVC pipes should be checked between layers to ensure the holes are well positioned.
The top should be smoothed with a trowel after filling, a technique that evens the upper face, improves appearance, and facilitates laying in the masonry course, creating a flat surface that receives mortar more efficiently.
Demolding requires patience to preserve grooves and holes: the piece should be turned with gentle movements, the PVC pipes removed slowly with rotational movements, and the latch opened without abrupt blows after initial curing.
With a well-greased mold, layered compaction, and careful demolding, the handmade brick comes out with defined grooves, clean holes, and uniform finish, a method that uses simple materials to produce strong pieces in small projects with low investment.
An underestimated aspect is the curing time before using the bricks, which varies between seven and 28 days depending on weather conditions, local humidity, and the thickness of the pieces produced in each batch.
Lightly watering the bricks once or twice a day in the first days after demolding slows evaporation and allows the cement hydration to occur completely, improving the final strength of each piece.
Having a second or third mold reduces production time per batch, allowing alternation between filling new molds and curing already molded pieces without interrupting the production process throughout the day.
