{"id":75057,"date":"2016-04-12T15:00:53","date_gmt":"2016-04-12T15:00:53","guid":{"rendered":"https:\/\/globalroadtechnology.com\/\/?p=75057"},"modified":"2019-07-08T03:41:25","modified_gmt":"2019-07-08T03:41:25","slug":"subgrade-reactivity-considerations-pavement-design","status":"publish","type":"post","link":"https:\/\/globalroadtechnology.com\/subgrade-reactivity-considerations-pavement-design\/","title":{"rendered":"Subgrade Reactivity Considerations in Pavement Design"},"content":{"rendered":"

Subgrade Reactivity Considerations in Pavement Design \u2013 The performance of a pavement configuration relies heavily on the underlying subgrade strength, stability and reactivity.<\/h3>\n

In pavement design practices, subgrade materials are characterised by their standard classification unit including Clays, Silts and Sands.<\/p>\n

Typically when a clay subgrade is encountered, consideration must be given to the materials \u2018reactivity\u2019 or susceptibility to shrink-swell behavior under changing moisture conditions. This shrink-swell behavior can pose significant detrimental risks to a pavement which include the cracking of the overlying layers and removing the waterproofing, allowing additional moisture to enter the pavement and \u2018snowball\u2019 the problem.<\/p>\n

Where suspected highly reactive subgrades exist, typical practice involves undertaking testing to identify the values of \u2018liquid Limit\u2019, \u2018swell\u2019, \u2018plasticity index\u2019 and \u2018particle size distribution\u2019 of which can be analysed to determine if the soil is reactive. The expansivity and reactivity guidelines as outlined by Austroads: Guide to Pavement Technology<\/a>: Part 2 comprises:<\/p>\n

Liquid Limit: >70%<\/strong><\/p>\n

Plasticity Index: >45<\/strong><\/p>\n

WPI (PI* %passing 0.45mm Sieve): >2200<\/strong><\/p>\n

Swell: >2.5%<\/strong><\/p>\n

In the case where the subgrade is considered reactive, a number of options are typically incorporated to reduce the pavement impact, including:<\/p>\n