I am a firm believer that the subgrade and base are more important for slab performance than the slab itself. No slab will last without a good and even support. The key to good slab performance is ensuring the base is uniformly stiff at the time of placement. Measure, measure, measure in-place...
Can someone tell me what "dynamic stiffness modulus" really is? How is this modulus derived? I see it in a number of papers from Europe but without good explanation. Could this be Young's modulus measured in a cyclic way?
Compaction is loosely used to describe how to change the property of soil. You compact to create a useful structure and to make it stiffer. Measure its mechanical property of insitu stiffness or modulus during the compaction process, rather than its physical property of density. By doing so you...
I am a firm believer in quantifying everything, including proofrolling. Proofrolling basically measures stiffness. I don't mean to sound commercial, but Humboldt Mfg. Co. Norridge, IL manufactures a device that measures both the structural stiffness and soil modulus. Worth checking out.
I think there is confusion regarding the term 'stiffness'. Stiffness, in general, is resistance to deflection or bending and is a property of a soil structure, i.e., subgrade. For this question the more useful term is modulus, (Young's modulus or modulus of elasticity) which is a rate of change...
A good report on the importance of bedding and haunch support for pipes was done by CNA Consulting Engineers, Minneapolis MN, MNDOT and pipe suppliers. I recall that soil stiffness was the critical parameter.
