Fresh and hardened properties of self consolidating concrete
Proportioning pervious concrete mixtures is different compared to procedures used for conventional concrete and the mixture proportions are somewhat less forgiving than conventional concrete mixtures—tight controls on batching of all of the ingredients are necessary to provide the desired results.
When developing pervious concrete mixtures, the goal is to obtain a target or design void content that will allow for the percolation of water.
A handful of pervious concrete formed into a ball will not crumble or lose its void structure as the paste flows into the spaces between the aggregates (see Figure 5). As a general rule, water that is drinkable is suitable for use in concrete.
Recycled water from concrete production operations may be used as well, if it meets provisions of ASTM C 94 or AASHTO M 157.
It imparts added strength and durability to concrete, and can replace 20-70% of the cement in the mix. Pervious concrete is made with a narrow aggregate gradation, but different surface textures can be obtained through the use of different maximum sizes. (6.5-mm) top size, while that below used a larger top size, 3/4 in. Fine aggregate content is limited in pervious concrete, and coarse aggregate is kept to a narrow gradation. However, extra water in aggregates contributes to the mixing water and increases the water-to-cement ratio of the concrete. Samples of pervious concrete with different water contents, formed into a ball: (a) too little water, (b) proper amount of water, and (c) too much water.
Commonly-used gradations of coarse aggregate include ASTM C 33 No. Water-to-cement ratios between 0.27 and 0.36 are used routinely with proper inclusion of chemical admixtures, and those as high as 0.40 have been used successfully.
ASTM C 494 governs chemical admixtures, and ASTM C 260 governs air-entraining admixtures.
Generally as the void content decreases, the strength increases and permeability decreases.