What Can Happen If It Rains On New Concrete In San Marcos?

5 Situations Can Happen If It Rains On New Concrete In San MarcosRain can hurt concrete that hasn’t dried enough. When the surface of a newly-laid concrete slab is exposed to precipitation, a number of detrimental effects can occur that compromise its strength and longevity.

  1. Due to chemical reactions between the water and the minerals in the cement, raindrops that land on uncured concrete can create etching or discoloration of the surface. In addition, when heavy rain falls on an exposed concrete slab, the top layer can be eroded, leaving the slab more susceptible to discoloration and breaking over time.
  2. When it rains heavily on a freshly poured concrete slab, water can pool and produce pockets of moisture beneath the surface, which can cause cracking when the water evaporates. This is of particular importance on sloping surfaces and in areas with inadequate drainage, such as near gutters and downspouts.
  3. When the top layer of the slab becomes saturated with water, the general strength of the concrete is weakened, which can eventually lead to crumbling, cracking, and shifting.
  4. The combination of rainwater and alkalis in cement can result in alkali-aggregate reaction, which causes concrete to expand and crack. This is more likely when specific aggregate kinds are combined with specific cement formulations.
  5. If it rains on new concrete, unprotected concrete can become a breeding ground for mildew, mould, and other microorganisms due to moisture buildup. In addition to altering the appearance of the concrete, this can eventually weaken its structure.


How Long After Pouring Concrete Is Rain OK?

As a general rule, you should wait at least 48 hours after laying concrete before exposing it to wet conditions. The curing time needs to be much longer in places with a high water table or heavy precipitation.

Can You Pour Concrete When It Looks Like It Might Rain?

Yes, you can pour concrete when it might rain as long as the area is well protected and the risk of damage is kept to a minimum. Before you pour concrete, you should know what the weather is going to be like and have the right protection in place.

In The Event Of Rain, Should I Protect Freshly Poured Concrete?

Protecting freshly poured concrete from the elements by covering it with plastic or a tarp is a good idea any time rain is in the forecast.


It is always ideal to avoid pouring concrete when rain is forecast; nevertheless, if this cannot be prevented, appropriate protection must be employed in order to decrease the danger of damage. For more information, contact Concrete Contractor San Marcos at (760) 289-3555.