All About Bricks
A brick is a single unit of kneaded sand, lime, clay-bearing soil and concrete material, which can be air dried or fire hardened. They are typically used during masonry construction. Lightweight bricks are made from expanded clay aggregate. Bricks are made in different materials, sizes and types, which vary by bulk quantities. The most two basic categories of bricks are non-fired and fired. Fired brick is one of the most durable and strongest building materials. Air dried bricks are an older option then fired bricks; it just has a mechanical binder such as straw added to it.
Types of Bricks
The three basic types of bricks are chemically set bricks, fired and un-fired bricks. Each type of brick is manufactured differently.
This type of brick is burned in a kiln to make them long lasting. The modern fired clay bricks are formed by dry press, soft mud or extruded. This type of brick typically is made of silica, lime, iron oxide, alumina and magnesia.
The soft mud method is the most popular because it is the cheapest. The process starts with raw clay and mixed with 25-30% sand in order to help shrinkage. The clay is first ground and then mixed with water to create the best consistency. The clay then is pressed into steel molds with a hydraulic press. The shaped clay is then burned at 900-1000°C to make it strong.
Dry Pressed Bricks
The method of which dry press bricks are made is similar to how soft mud bricks are. They however start with a thicker clay mix, so there are sharper-edged on the bricks. The more force that used during the pressure, the longer the burn. Because it is longer, it makes them more expensive.
For this type of brick, it is mixed with 10-15% water. The mixture is then forced through a die which creates a long cable of material with the chosen depth and width. The material is then cut into bricks of the desired length. Most of these bricks are made this way because they create hard, dense pieces that help to reduce the amount of clay needed and in turn, the cost too. These hollow bricks are easier to handle and lighter.
Chemically Set Bricks
These types of bricks are not fired, but use a curing process that is accelerated with the use of heat and pressure in an autoclave. Calcium-silicate bricks are a type of chemically set bricks that are made of flintlime or sandlime depending on the ingredients used. Rather than made with clay (like other bricks), they are made with lime, which helps to bind the silicate material. This type of finished brick is more uniform and accurate. They can be made in different colors such as grey-blues, white, black and buff (or natural white).
This type of brick is made with sand aggregate which is made in a simple machine and assembly line. The conveyor belt adds the mixture to make the bricks into the machine, which pours a specific amount of concrete into the form. The form then vibrates to remove the bubbles after which they are raised to create the wet bricks. Then a small elevator stacks the palettes of the bricks. Later, a forklift is used in order to move them to a place to dry. This type of brick is made in a variety of colors. Concrete bricks expand and contract more so then clay or sandlime bricks, so they will need movement joints when used.
Handling and Laying
In order for the most efficient handling and laying experience, bricks must be small enough as well as light enough to be picked up by the bricklayer with one hand. Bricks are typically laid flat and measured by the width of the brick itself. Many times the length of the brick is about twice its width (about eight inches). This allows bricks to be laidbonded, which helps to increase their stability and strength.
When using bricks for wall, a bigger brick helps to cut back the laying time. The correct brick for a job depends on the color, density, weight, width, surface texture, pore structure, absorption, thermal characteristics and fire resistance capabilities. Bricks are used for pavement, block paving and building. They must be able to withstand heavy traffic (when used for roads).
Choosing the Type of Brick
Choosing the type of brick for a home project is a major consideration. It must fit with the décor and style of the home. Brick is commonly used because it is a durable building material and can last for a long time.
Exterior grade modern bricks are used for the exterior. SW is the top grade and is made to withstand below freezing temperatures in moist climates (northern United States). MW is the second exterior grade and is made to withstand the same freezing temperatures in a drier and milder climate (southern United States). A third brick grade is primarily for indoor use although it can be used outdoors too as backup brick, which is laid behind a layer of facing more durable brick. It is used in warmer and drier climates such as places that rarely get a freeze or where there isn’t much rain throughout the year.
The face of the brick is also important. Standard face bricks or exterior ones have smooth surfaces, which are finished on one side with struck faces. Others are sand struck, which are molded against sand to produce a more rough texture. The last type is glazed, which has a ceramic layer on one side of the brick.
Structural bricks are made with two or three holes in the wide face, which reduces the amount of weight of a brick wall without jeopardizing any structural support. The holes create a connection for the mortar which can be used when reinforcing steel bars. These types of bricks are usually used on freestanding walls and not on a house.
Standard or common bricks are normally 2 x 4 by 8 inches, however specific dimensions can vary. King bricks are thicker and longer while Roman bricks are thinner and longer.