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What is Porous Concrete?

Porous concrete is designed to trap water and allow it to trickle down to the ground below.
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  • Written By: Mary McMahon
  • Edited By: Bronwyn Harris
  • Last Modified Date: 20 November 2014
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Porous concrete is concrete that is designed to trap water and allow it to percolate through to the ground below. There are a number of advantages to this type of construction, which have caused it to become a popular option for things like sidewalks, driveways, and parking lots. It is especially popular with ecologically conscious construction companies, since it helps to manage water runoff in a sustainable way. Many so-called “green” builders promote its use in their projects.

There are a number of alternate names for porous concrete, including permeable concrete, porous pavement, and pervious concrete. All of the names basically mean the same thing: it's a form of concrete that is permeable, rather than solid. Porous concrete is made by mixing large aggregate material with mortar, creating lots of voids in the cast concrete. When water lands on the material, it trickles through the voids and into the ground below.

For people who are concerned about the environment, porous concrete is attractive because it traps water, rather than allowing it to drain uselessly into the ocean. It can help route storm runoff and rain directly into the soil, where it can nourish gardens and trickle down into the water table. It also comes in a range of colors, and it can be made with recycled materials including recycled concrete rubble. This flexibility and potential for recycling makes it an ecologically friendly and aesthetically pleasing building material.

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From the point of view of a contractor, porous concrete has some distinct water management advantages. Instead of allowing water to pool, it sucks up water and wicks it away. This prolongs the life of the concrete, and it also makes it safer for people driving, walking, and biking on it, since they do not have to contend with pools of water. While extremely wet conditions will eventually overwhelm the concrete's absorption capacity, it is still a better drainage choice than tightly packed concretes.

Because porous concrete does have a lot of empty space, it is not suitable for all building applications. There are specific requirements for structural concrete, for example, to ensure that it will be safe and sound, and porous varieties may not always meet these specifications. It can be used safely for pathways, concrete patios, driveways, sidewalks, and so forth. Some companies also cast bricks and tiles in it for people who want to build their own tiled walkways.

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shell4life
Post 6

I can definitely see why no one would want to build a house out of porous concrete. Anything with cracks and spaces in it is likely to give way under the weight of the house and collapse.

Also, I can't imagine porous concrete would keep a house very warm. Your insulation materials would have to work extra hard to absorb all that cold air that could seep in through the pores, and I'm not sure it could handle the extreme temperatures.

I think that porous concrete would best be used for paving horizontal areas. A house or building would have no need to let water seep through, but a grassy area would.

Oceana
Post 5

@OeKc05 – I absolutely love how porous concrete can keep pedestrians safe from slips and falls. I live in an area that receives a lot of rainfall, and the porous concrete sidewalks keep us from having to walk in puddles all the time.

There are some areas that still have solid concrete sidewalks. For walking on these, you need to wear rain boots, and you have to pull them up over your pants to keep dry.

The porous sidewalks are just a little damp. There is no splashing as you walk across, and the lumpy texture provides something for your shoes to grip.

OeKc05
Post 4

The parking lot of my workplace is covered in porous concrete. This helps keep it from staying frozen and hazardous after a snowstorm.

Regular asphalt can hold onto ice a lot longer than porous concrete. Since there is room for air and sunlight to permeate the concrete, the ice will thaw a lot faster than it will on a solid surface.

I used to worry about parking here in the winter, but since they have repaved the driveway, I haven't had any problems with sliding. It is also nice to feel more secure walking across the lot. It isn't slippery anymore.

cloudel
Post 3

I have porous concrete stones all around the flowers in my garden. They help keep weeds down, but they still allow water to seep through and nourish my flowers.

I never have to yank up weeds anymore, because the stones keep the ground from getting sunlight, so they just don't grow. I don't have to remove them when I water my flowers, because I know that they act as slow release sprinklers to the dirt below.

I would recommend porous concrete to any gardener struggling with weeds and keeping enough moisture in the soil. These stones act as a form of irrigation if you keep them wet.

anon62500
Post 2

is porous concrete safe for structural purposes?

anon9938
Post 1

Is porous concrete more or less expensive to use let's say for a driveway?

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