This article addresses the effects of a rushed project submittal process and shows the benefits to beginning the process early.

At PMI we value our customers so much that we are often hesitant to point out areas where our relationships could be improved.  We have many customers who have been with us the entire 15 years that we have been in business, and we have a deep level of gratitude for you!  It is this appreciation of your business, our relationships, and our future endeavors that has caused me to sit down and write this article.  Currently, the way that our customers are requesting Project Submittals is not allowing them to appreciate the full potential of what PMI has to offer.  Often times the Project Submittal Process is rushed, and in many cases, we do not get the opportunity to review the specifications or conduct research and development in order to provide the best mixes.  

PMI now has 4 CMEC accredited laboratories around the State of FL, one in each of our operating Regions.  As you know, each Region has a highly skilled and certified QC Manager.  Our newest development in the QC Dept is that three of our four Regions now has a highly skilled, highly experienced, and certified Laboratory Manager.  These new Laboratory Managers allow us to provide the highest level of research, development, and support to our customers.  It is these individuals who are tasked with creating new mixes and assuring those mixes meet project specifications.

So many projects today include “special” requirements of the concrete mix.  Special requirements could include heavy-weight, light-weight, surface resistivity, shrinkage coefficient, pigment, or maybe the need for extended slump life.  Of course, we would love to pull a mix off the shelf and have it perfectly meet your requirements!  All of these special requirements need time for R&D in the laboratory, and many of them require a certain amount of curing time before the testing can even be conducted.  Here are a few examples that will help you understand the time requirements:

ASTM C-156 Standard Test Method for Length Change Of Hardened Cement Mortar And Concrete

This test may be modified by specifying engineers to require a 30, 60, or 90 day reading; however the full test method takes 64 weeks.

ASTM C-567 Standard Test Method for Determining Density of Structural Lightweight Concrete

This test requires concrete to be cured for 7 days, and then tested at 28 day intervals up to and beyond 90 days old to ascertain the equilibrium density.  The process can be sped up by using the calculations for oven dry density, if allowed by specification.

Slump-Life and Set-time – These are tests conducted on a trial batch of the mix in question.  We keep the mix in the mixer and test it at intervals to observe the rate at which it is losing slump.  Set-time is tested after the mix is removed from the mixer, it determines initial and final set.

Special Temperature Requirements – If a specification requires a maximum allowed temperature or a maximum temperature differential between the core on a pour and the outside then we must have time to perform a mock up.  A mock up is simply forms built to simulate the thickest part of the pour where we place the mix and then measure temperature throughout the curing process.  This data can not be forecasted or determined formulaically; it must be tested in the conditions that it will be poured.

Another challenge that we are faced with is specifications which contain contradictory requirements.  Examples of this are a heavy-weight mix which requires a low strength.  Another example would be a mix that requires corrosion inhibitor but also requires a low heat of hydration and mass concrete requirements.  These contradicting attributes are not insurmountable!  To overcome a contradictory specification requires R&D, which means we need time to study the mix and measure these special requirements.

What is the result when we are not allowed sufficient time to research a mix design?  I would surmise that in most cases where we have job-site issues it is caused by a disconnect between the specification, the contractor’s needs, and our mixes’ ability to meet both.  When we rush the process of selecting and qualifying a mix, we bypass all the testing that we are capable of, and we make assumptions based on anecdotal data.  Often those assumptions are incorrect, and it could cause pumping problems, finishing issues as a result of unexpected set-times or slump life, concrete temperature issues, lower than designed strength, and concrete unit weight discrepancies.  We have the resources internally to study and perfect mixes for any application, we simply need the time to conduct this work.

For any one of our customers who has struggled with job-site issues, please think back to the submittal process and consider if we were given enough time to provide these critical answers.  At PMI we are eager to take on any mix designing challenge and we take a lot of pride in our Team and their abilities.  The key to our success is being afforded enough time to provide you these answers.  We have a QC Submittal Manager who is focused on preparing your submittals correctly and including all pertinent data.  We also have QC Managers who specifically cover Block and Gunite.  Whatever your project requires we have the experienced personnel to assure our products meet your expectations.