Posts by Luis Babler

The idea of aggregate piers was initially conceived in 1988 as an effort to make stone replacement more efficient and easily implementable at a larger scale. The processes to design and construct aggregate piers have since evolved by quantum leaps, making aggregate piers a reliable and widely-accepted ground improvement method well beyond stone replacement. Aggregate…

Good building sites have become somewhat rare as more and more projects involve redevelopment or re-tasking of existing sites either incumbered by existing buildings or impacted by contaminated soil and/or groundwater from previous site activities. In many cases, sites contain loose soils, buried demolition debris, or other less-than-desirable materials that are not reliable to support…

In some instances, either as part of design or during construction, special circumstances require the use of fill materials other than traditional structural fill soil. In most cases, performance requirements, weight (load) restrictions, or both dictate the need for special or unconventional fill materials. Common situations requiring fill or backfill materials other than soil include…

Engineering+Experience+Common Sense = Good Pavement. We all know what asphalt is – or do we? There are many names to refer essentially to the same thing: Asphalt, Asphaltic Concrete, Blacktop, Tarmac, Macadam, Hot-Mix Asphalt, etc.  What is it?  One short definition from the Asphalt Pavement Alliance says: “Hot Mix Asphalt (HMA) is a combination of…

Modulus of Subgrade Reaction: What is it?  The modulus of subgrade reaction (k) is primarily a mathematical expedient.  Essentially, it is an attempt to reduce the behavior of soil subjected to loading to an equivalent, and convenient, “spring constant”.  However, one thing (k) is not is a fundamental soil property.  The same subgrade conditions and…

What is a Rule of Thumb? From Dictionary.com: “a general or approximate principle, procedure, or rule based on experience or practice, as opposed to a specific, scientific calculation or estimate.”  The one explanation from English Common Law which states that “a man is allowed to beat his wife with a stick no thicker than his…

I want to say one word to you. Just one word. Yes, sir. Are you listening? Yes, I am. Karst There are many definitions of Karst.  Following are some of the more succinct ones:  Dictionary.com: “an area of limestone terrain characterized by sinks, ravines, and underground streams”; Merriam-Webster.com: “an irregular limestone region with sinkholes, underground…

We have been shaping the earth to suit our needs ever since we stopped being hunter-gatherer nomad folk.  Properly shaping the ground and making sure it stays the way we intend requires moving soil and compacting soil.  Some call it “dirt”.  Dirt is the stuff under your fingernails.  When we use it as an engineering…