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Unformatted text preview: C E M 6 2 C o n s t r u c t i o n M e t h o d s CEM 602 Construction Methods Lecture 4 Compaction Excavation and Side Protect 1 L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Compaction Processes 2 L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Maximum Dry Density/Optimum Moisture One of the first tests to determine soil properties looks at soil gradation Another critical test establishes the laboratory compaction curve From the curve the maximum dry unit weight and percent water to achieve maximum density is determined (Optimum Water Content) The compaction curve plots unit weight vs. water content for a certain compaction effort L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n 3 C E M 6 2 C o n s t r u c t i o n M e t h o d s Maximum Dry Density/Optimum Moisture L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n 4 C E M 6 2 C o n s t r u c t i o n M e t h o d s Compaction Tests The Proctor test is the accepted compaction test by departments of transportation in the US The sample is placed in a steel mold in three layers or five layers (Modified Proctor) The sample is compacted using a 5.5 lb rammer or 10 lb rammer Sample is weighed immediately L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n 5 C E M 6 2 C o n s t r u c t i o n M e t h o d s Compaction Tests Sample is dried to a constant weight and weighed again Test is repeated until water content achieving maximum density is determined L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n 6 C E M 6 2 C o n s t r u c t i o n M e t h o d s Compaction Tests: Compaction Control Contractors are required to a certain field density To verify the compaction level the contractor can test with several methods Sandcone Balloon Nuclear gauge L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n 7 C E M 6 2 C o n s t r u c t i o n M e t h o d s Compaction Tests: Compaction Control Problems with traditional compaction tests Too time consuming to conduct sufficient tests Problems with oversized particles Time delay in measuring water content Tests performed every lift, and testing and acceptance can delay construction operations L e c t u r e 4 C o m p a c t i o n E x c a v a t i o n a n d S i d e P r o t e c t i o n 8 C E M 6 2 C o n s t r u c t i o n M e t h o d s Compaction Tests: Nuclear Test Nuclear methods are used extensively to determine water content and density Provides instant results on soil density Uses the Compton Effect of gammaray Gamma rays are partially absorbed and partly reflect in the soil The reflected rays are counted to determine...
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This note was uploaded on 03/17/2012 for the course CEM 602 taught by Professor Amrkandile during the Spring '10 term at American University in Cairo.
 Spring '10
 AmrKandile

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