Cold Weather Concrete

When freshly poured concrete is exposed to freezing temperatures before it has set, the water within the concrete can freeze. This expansion disrupts the setting process, delays chemical reactions necessary for hardening, and increases the volume of pores within the hardened concrete, which weakens its overall structure. If the concrete manages to reach an appreciable strength before it freezes, the damage can be somewhat mitigated. To counteract the negative impacts of cold weather, ensuring...

Concreting at elevated temperatures accelerates the hydration process, leading to quicker setting but potentially reducing the long-term strength of the concrete structure. Additionally, low air humidity fosters rapid moisture loss from the concrete, resulting in reduced workability, pronounced plastic shrinkage, and a higher likelihood of crazing. Mitigating the heat increase in concrete can be economically achieved by shading aggregate stockpiles to prevent heating from solar radiation,...

In cold weather, masonry construction requires specific precautions to ensure mortar does not freeze before curing, as this can significantly weaken its strength and watertightness. Mortar temperature should be maintained between 60°F and 80°F to support proper hydration and curing. Below 40°F, mortar water must be heated, but should not exceed 120°F as high temperatures can reduce mortar's compressive and bond strength. Other key practices include keeping masonry units and sand dry and...

Overview Weather refers to the current state of atmospheric conditions at a specific time and place. Weather is temporary and is influenced by the interactions between the sun, atmosphere (gases around the Earth), hydrosphere (the water bodies of the Earth), and geosphere (the land portion of the Earth). As all of these factors differ across location and time, different weather can be observed across the planet. Solar Radiation and the Greenhouse Effect Solar radiation penetrates the...

Source: Roberto Leon, Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA Concrete consists of two phases, a cement paste phase comprised of cement, water, and air, and an aggregate phase comprised of coarse and fine aggregates. There are two key considerations when designing a concrete mix. First, the concrete must be workable and easy to cast in the forms in its fresh condition, even when the forms are packed with steel reinforcement. In this condition, it is the...