REBLOCKPermeable paving blocks made from recycled ceramics
1reblock1@gmail.comFAQ · As of October 2026
A plain summary of the Korean standard for permeable paving blocks (KS F 4419), permeability grades and Seoul's permeability retention grades, based on official sources. It also covers REBLOCK's own test results.
On regular paving, rainwater runs off the surface into storm drains.A permeable paver has connected pores (voids) that let rainwater soak through the block, then through the sand bedding and crushed-stone base below, and back into the ground.The Korean standard (KS) requires a permeability coefficient of at least 0.1 mm/s for permeable pavers only.
Permeable pavers follow the requirements in KS F 4419 (Concrete interlocking blocks for sidewalks and roadways).The permeability coefficient must average at least 0.1 mm/s over three specimens, and flexural strength for sidewalk blocks must be at least 4.0 MPa.Blocks are typically 60 mm thick for sidewalks and 80 mm for roadways.
Blocks are graded by permeability coefficient, the speed at which water passes through: Grade 1 (1.0 mm/s or more), Grade 2 (0.5 to under 1.0) and Grade 3 (0.1 to under 0.5).These grades are used in Korea's Ministry of Environment eco-area ratio calculation, where fully permeable paving is weighted 0.4 for Grade 1 and 0.3 for Grade 2, and Grade 3 does not count.Since the second half of 2024, Korea's Public Procurement Service lets suppliers enter a permeability coefficient in Multiple Award Schedule (MAS) product listings, and suppliers who do must submit a certified test report for each size.
A permeability grade describes a new block, while a permeability retention grade describes the block after its pores have been clogged with dust and debris.Seoul's permeability retention test recreates clogging with fine debris, measures the permeability coefficient again, and grades it on the same scale (Grade 1 at 1.0 or more, Grade 2 at 0.5 to 1.0, Grade 3 at 0.1 to 0.5 mm/s).Blocks that drain well at first can clog over time, so it is worth checking both grades.
They can.When dust fills the pores, permeability drops, which is why Seoul grades blocks with a retention test that recreates clogging.In a follow-up study by the Seoul Institute, Grade 3 sidewalk products clogged within three years, while Grade 1 products stayed in good condition for more than five years.REBLOCK received Grade 2 in the clogged-state test, and we keep monitoring long-term performance at our pilot site.
Since March 2026, the City of Seoul has used products with permeability retention Grade 2 or better as a rule.Before that, the minimum was Grade 3.Products certified by an accredited body are exempt from testing at delivery, and the certificate is valid for one year.
The testing bodies listed by the City of Seoul for permeability retention are the Seoul Metropolitan Quality Testing Center, the Korea Testing & Research Institute (KTR), the Korea Construction Quality Testing Institute, and Korea Conformity Laboratories (KCL).KS items such as permeability coefficient and flexural strength can be tested at any KOLAS-accredited testing laboratory.
Testing at the Korea Testing & Research Institute (KTR) confirmed a permeability coefficient of 1.12 mm/s, a flexural strength of 4.4 MPa and permeability retention Grade 2.The permeability coefficient falls in the Grade 1 range (1.0 mm/s or more), and the retention result meets Seoul's Grade 2 rule.We continue to check long-term performance at our pilot site.
Choose 'Test report request' in the inquiry form on our Resources page and send it.We will check your request and email you the original KTR report (Korean and English).
Yes.REBLOCK uses the standard installation system for permeable sidewalk pavers, laid on sand bedding over a crushed-stone base.No special equipment or method is needed.
Our standard size is 200 × 200 × 60 mm (sidewalk), and our standard colours are white and grey.If you need another size or colour, we can make it to suit your site, so please get in touch.
Roadways usually use 80 mm thick blocks, and the KS flexural strength requirement is higher than for sidewalks (5.0 MPa or more, compared with 4.0 MPa).REBLOCK has already reached roadway-level strength with 60 mm blocks, so producing an 80 mm roadway block is well within reach.Please contact us about roadway projects.
Sources · As of October 2026
Values summarise public sources as of October 2026. Before design or procurement, please check the latest original documents from each body. All sources are in Korean.
We answer directly, from how to read the standards to site applications and test report requests.