Evaluation of the slip resistance of modified wood decking products

With increasing global concerns on environmental issues, Chromated Copper Arsenate (CCA) treated wood decking products have been step by step replaced by Wood Plastic Composite (WPC) lumber and heat-treated lumber. The slip resistance of decking is no doubt a critical safety index. Overall, there has not been a proper standard for measuring the slip resistance of WPC products. Canadian Construction Materials Centre (CCMC) uses the static coefficient of friction (μs) to evaluate the slip resistance of WPC products, which stipulates that μs should be larger than 0.50. This study was aimed at measuring the slip resistance of WPC decking products in terms of μs and then comparing with others. There were four types of testing specimens including WPC lumber (WPC), CCA treated spruce lumber (CCAS), heat-treated spruce lumber (HTS) and untreated spruce lumber (UTS). μs was measured, according to ASTM D2394 standard, under two surface conditions (SCs) (dry and wet), two weights of sliding block (WSB) (14 and 20 kg), and three sliding speeds (SSs) (10, 50 and 250 mm/min). It was discovered that (1) The μs values of CCAS and HTS were always larger than those of UTS and WPC, and only at some specified testing conditions, the μs values of them could reach or exceed 0.50; (2) The μs values of all specimens under wet SC were larger than those under dry SC, and the increase of μs under wet SC was less significant than that under dry SC as the WSB increased from 14 to 20 kg; (3) The μs values increased, regardless of the types of specimens, with increasing the WSB from 14 to 20 kg; (4) There was no statistically significant difference in μs among three SS values used, 10–50 or 250 mm/min.

► The μs values of CCA treated and heat treated spruce lumber were larger than those of untreated spruce lumber and WPC lumber.
► The μs values of all specimens under wet surface condition were larger than those under dry surface condition.
► The μs values increased with increasing the weight of sliding block from 14 to 20 kg.
► There was no significant difference in μs among three sliding speeds, 10–50 or 250 mm/min.