![]() ![]() Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops. The practical implication of this is that concrete elements subjected to tensile stresses must be reinforced with materials that are strong in tension (often steel). As a result, without compensating, concrete would almost always fail from tensile stresses even when loaded in compression. In other words we can say concrete is made up of sand (which is a fine aggregate), ballast (which is a coarse aggregate), cement (can be referred to as a binder) and water (which is an additive).Ĭoncrete has relatively high compressive strength, but significantly lower tensile strength. ![]() The compressive strength is typically controlled with the ratio of water to cement when forming the concrete, and tensile strength is increased by additives, typically steel, to create reinforced concrete. Classes include professionally produced videos taught by practicing craftspeople, and supplementary downloads like quizzes, blueprints, and other materials to help you master the skills.Concrete has relatively high compressive strength (resists breaking, when squeezed), but significantly lower tensile strength (vulnerable to breaking, when pulled apart). MT Copeland offers video-based online classes that give you a foundation in construction fundamentals with real-world applications, like house framing. For either poured or block walls, using rebar is an effective way to bolster lateral strength. Block foundations are simpler to build, but might be prone to leaks if they’re not mortared evenly. Poured concrete tends to be less vulnerable to water, though it does require special equipment, more preparation, and potentially more money. How to determine which foundation is right for youīoth types of foundation are popular, so deciding between the two really comes down to factors like moisture, budget, and timeline. Large wooden forms are harder to move and might require cranes to install, which can increase building and labor costs. Also, the concrete-pouring process, which takes place in one step, may create weak spots or air pockets. Pouring concrete and inserting wooden forms requires a lot of preparation, and bulldozers, soil compactors, and cranes may be needed to move heavy loads. Poured concrete walls don’t have multiple openings like block foundations, which can increase the likelihood of a joint weakening over time.ĭisadvantages of poured concrete foundations Solid concrete walls can withstand pressure from all sides. Solid concrete walls are less prone to water damage. Poured walls take less time than concrete block foundations to build since most of the work is done with machinery. Advantages of poured concrete foundations Once it cures, or solidifies, the wall forms are removed, leaving concrete shaped like a wall that holds back the earth surrounding the home. Next, concrete mixed on-site is poured into the wall forms. These wooden walls are built around steel rebar supports, both vertical and horizontal, which strengthens the foundation walls. These forms act like molds, shaping foundation walls. Poured concrete foundations use wooden wall forms built on top of foundation footings. Block walls without rebar may bow from groundwater or shifts in the soil (lateral pressure). Gaps in the mortar between cinder blocks can make concrete block foundations vulnerable to water damage. Concrete is prone to cracking and air pockets, which can compromise a foundation’s integrity.ĭisadvantages of concrete block foundations Some block foundations use concrete to fill in cinder blocks and rebar, although the concrete doesn’t need to be precisely poured and cured. Block foundations, especially ones reinforced with rebar, can bear heavy vertical loads. Cinder blocks are lighter than poured concrete, making them easy to move from one place to another. Laying walls one block at a time helps avoid mistakes, and special equipment and machinery aren’t required. Rebar isn’t necessary for structures like garden walls, but is often used for block foundations that support heavy structures. Once the rebar is threaded through the cinder blocks, the surrounding gaps are filled with concrete. ![]() The process is repeated until a foundation wall is formed.īecause cinder blocks are hollow, block foundations are often reinforced with rebar––vertical steel bars that strengthen concrete. Using the CMU method, the footings are coated with mortar-a mixture of sand, water, and fillers to bind masonry-then cinder blocks are layered evenly on top. Concrete block foundations, or Cinder Masonry Units (CMUs), are made from stacked cinder blocks. ![]()
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