Do Que O Tijolo É Feito

What bricks are actually made of

Brick manufacturing is one of those old industries where people still argue about the right way to do things. The basic recipe has not changed much since Roman times, but the details matter more than most builders realize. A standard clay brick contains around fifty percent silica sand, thirty percent clay, and smaller amounts of lime, iron oxide, and sometimes shale. The exact mix depends on where you get your materials and what strength rating you need. I spent years dealing with brick suppliers who claimed their product was "premium quality" while the chemical analysis told a different story. One batch I received had forty percent more potassium than specified, which caused severe efflorescence after installation. The white salt deposits appeared six months later when moisture worked through the wall. I learned to always request a recent lab report rather than trusting the sales pitch. The manufacturing process starts with mining the clay, then mixing it with water to reach a plastic consistency. Some manufacturers use the soft-mud method where the clay is extruded through a die, while others use the dry-process method with lower water content. The formed bricks then go through drying tunnels at controlled temperatures before entering kilns that reach between nine hundred and one thousand two hundred degrees Celsius. The firing time varies from twelve to thirty hours depending on the brick type and size.

What most people miss is that the color comes from the iron content in the clay, not from added pigments. A high iron percentage produces those classic red colors, while low iron clays yield pale yellow or buff bricks. Some manufacturers add manganese or chromium to get darker shades, but this is less common than you might think. The surface texture also depends on the mold material and whether they use sand as a release agent. Here is the thing nobody tells you: not all bricks are suitable for every application. Facing bricks require tighter tolerances and more consistent color than structural bricks. Waterwork bricks need lower absorption rates for below-grade applications. Paving bricks must withstand freeze-thaw cycles and heavy traffic. Using the wrong type for the job leads to failures that are expensive to fix later. I once saw a project fail because someone used common bricks for a retaining wall in a freeze-thaw zone. The water absorbed into the porous clay expanded when it froze, causing spalling within two winters. The repair cost three times the original material cost. Always check the absorption rate specification when buying bricks for exterior applications in cold climates.

The strength rating you see stamped on each brick refers to compressive strength measured in megapascals or pounds per square inch. A typical residential brick might rate around ten to fifteen megapascals, while engineering bricks can exceed fifty megapascals. Higher strength does not always mean better quality for every situation. Sometimes you need bricks with higher absorption for plaster adhesion or better thermal insulation properties. Sizing is another area where mistakes happen frequently. nominal brick sizes include allowances for mortar joints, but actual fired dimensions vary between manufacturers. A brick marketed as eight inches long might measure seven and three-quarters after firing. Always check actual dimensions rather than assuming nominal sizing when planning your layout. If you are looking to buy bricks, check for certifications like ASTM C216 for face bricks or BS EN 771 in Europe. Reputable suppliers will provide test reports showing compressive strength, absorption rate, and efflorescence potential. Do not accept samples alone as proof of quality. Request documentation that matches your specific application requirements.

The environmental impact of brick production has improved significantly with modern kilns and recycling programs. Many manufacturers now use fly ash or slag as partial clay substitutes, reducing the energy required for firing. Some facilities capture and filter emissions more effectively than regulations require. Look for suppliers who publish environmental product declarations when sustainability matters for your project. Cost varies widely based on type, origin, and order quantity. Standard common bricks might run between fifty and one hundred fifty dollars per thousand, while specialty facing bricks can exceed five hundred dollars per thousand. Shipping costs can double the material price for remote locations. Buy from regional suppliers when possible to reduce transportation costs and support local industry. Storage before installation matters more than most builders realize. Bricks should be stored on level ground with adequate drainage to prevent water absorption. Stack them with spacers between layers for air circulation. Do not cover them with plastic unless you need to protect from rain during storage, as trapped moisture can cause efflorescence. Cover with breathable tarps if protection from weather is necessary.

The mortar you use should match the brick specifications. Higher strength mortars can trap moisture in low-absorption bricks, causing spalling during freeze-thaw cycles. Type N mortar works well for most residential applications, while Type S provides higher strength for below-grade work. Follow manufacturer recommendations and local building code requirements when selecting mortar. If you encounter bricks with inconsistent color or sizing, do not install them without checking with your supplier. Some variation is normal between batches, but excessive differences indicate quality control problems. Request replacement materials rather than trying to work around issues. The labor cost of removing and replacing failed bricks far exceeds the material cost of proper quality control.