So far all the combined aggregate grading techniques we have discussed have been determined almost solely based on the combined grading. The Total Fineness Modulus method and the Coarseness/ Workability chart have adjustments for cement factor, but the cement content isn’t the driving force. The Mix Suitability Factor (MSF) technique, developed by Ken Day in Australia, directly incorporates both the cementitious content of a mix and the air content. This technique is very easy to use as a mix analysis tool, but a little harder to use as a mix design tool. Continue reading
Hello, readers. I know I am way behind in posting my next blog entry for the “Concrete Mix Design: Art and Science” series, but a lot has been happening in the concrete world lately. I hope to have the next post in the series tomorrow.
One of the biggest happenings has been the World of Concrete, in Las Vegas. http://www.worldofconcrete.com. This year attendance was low again (I’ve heard it said that there were about 40,000 people, down from an all-time high of about 120,000) but this year we attribute it to the fact that ConExpo/ConAgg will be held in Las Vegas this March (about 3 weeks away). The number and size of exhibits was down as well. I would say the show was at about 70% of capacity. I didn’t really get a chance to walk around the show because I was in the Command Alkon booth most of the time. Even though attendance was low, we had a lot of qualified customers come through and the word is that sales resulting from the show will probably be better than projected. The people who came by were ready to buy. We also got a chance to present our new Precision Temperature System, for tighter control of concrete temperatures during summer and winter, and our new Mobile Connect mobile products. There is a tremendous amount of interest in both products.
Another of the high points of the show for me was when ACI revealed its new logo. http://www.concrete.org/News/NewsDetail.aspx?f=51686562 There were so many of my ACI buddies there that it looked like an ACI convention. President Anne Ellis did the honors, presenting the new logo to a group of about 40 people standing in the aisle next to the ACI booth at WOC. In addition, a group of concrete contractors created a decorative pervious concrete pavement with the new logo. Hopefully it will be on display at ConExpo as well.
Speaking of ConExpo/ConAgg, I will be there in the Command Alkon booth in the South Hall, booth S-61229. Drop by if you get a chance and I will show you the latest, greatest stuff in COMMANDqc, including Incident Tracking and ACI 318 Performance Reporting. www.conexpoconagg.com
Another thing that has taken up a lot of my time lately is the Command Alkon Regional Conference that was just held in Columbus, OH. The Regional Conference is a smaller version of our annual Customer Conference, which will be held in New Orleans, LA this year. http://www.commandalkonconference.com/ At the regional conference we conducted hands-on training of many CA products, including COMMANDqc. In addition, I conducted a 1-day seminar on “Developing your QC Department”, which was designed to provide concrete producer QC departments with a structure for developing and enhancing their QC departments. This is the same seminar I did at the last Customer Conference and it has been very well received both times. We plan to hold another Regional Conference in San Francisco April 23-24. http://www.commandalkon.com/rps/sf/index.html
In addition, the beginning of February I conducted 2 days of classes for the Concrete Industry Management Operations class at Texas State University. My host was highly impressed that none of the students fell asleep during my presentations. Considering my recollections of college days, that is high praise, indeed!
A lot more is coming up in the next few months. I expect to be at most of these functions:
- NRMCA Convention, Las Vegas, NV, Mar 1-3, www.nrmca.org
- ACI Convention, Reno, NV, Mar. 23-26, www.concrete.org
- ACI Strategic Development Council, Atlanta, GA,Feb. 20-12 (I won’t be at this one, but the break-out meeting on Nuclear Concrete ought to be interesting.)
- NRMCA Sustainability Forum, Boston, MA, May 12-15, www.nrmca.org (to be held in conjunction with MIT Concrete Sustainability Hub meeting)
- ASTM C09 Committee, Toronto, ON, Canada, June 22-25, www.astm.org
On top of this I will have various meetings at customers’ sites. I guess I just need to figure out how to put more hours in a day.
Hopefully I will see you at one of the industry events. If not, if you get to Dallas let me know and maybe we can get together.
Again, I hope to have the next installment on my Mix Design series out within the next couple of days. I look forward to hearing from you.
So far we have been discussing mix design techniques that rely on the combined aggregate grading. However, we’ve avoided one basic question. Is there a combined aggregate grading technique that will give us the best concrete mix all the time? (In reality the answer is “no”, but let’s assume for a minute there is.) To get one answer to this question, we can turn to the asphalt industry. Their solution is the 0.45 power chart. Continue reading
Back at the end of 2012 I wrote an article for The Concrete Producer magazine entitled “Profiting from Quality Concrete”. http://www.theconcreteproducer.com/testing/profiting-from-quality-concrete.aspx The article appeared in the Jan/Feb 2013 issue and provided an example of how a quality control program can actually improve concrete producer profits.
Last week The Concrete Producer listed its top articles for 2013. My article was rated the “Top Business Story”. http://www.theconcreteproducer.com/concrete/extra-extra-the-most-popular-headlines-of-2013.aspx?dfpzone=home
I just found out that 2 weeks ago The Concrete Producer released its list of the “2013 Most Read Features”. http://www.theconcreteproducer.com/concrete-producers/2013-most-read-features_o.aspx?utm_source=SOA_ALL&utm_medium=SOA_OWNED&utm_campaign=SOA_TRAFFIC My article was at the top of the list.
I post these references not so much as to toot my own horn, but to recognize you, the readers of this blog. Quality Control has long been relegated to the back office – an undesirable cost to the producer. It is because of technically competent and imaginative QC personnel who read this blog that executives are finally recognizing that Quality Control is an essential part of their business and that it should receive the recognition it is due.
Congratulations to you all!
It is December 30, 2013 and now is as good a time as any to review some of the changes that have taken place in the concrete industry. I don’t have the benefit of wide ranging exposure that the large associations and magazine companies have, so this is just the result of what I have seen over the past year. Continue reading
In continuing our series on combined aggregate grading, I want to throw in a new twist – evaluating the combined grading not just of the aggregates, but all the materials, including air content. The Mortar Factor is reminiscent of how ACI 211 works, but it works solely on aggregate grading, material densities and material volumes. The Mortar Factor is something that came about as part of my father’s work on the Coarseness Factor Chart, so it isn’t very old. Continue reading
The Shilstone Blog at www.commandalkonconnect.com just topped 20,000 views! That may not seem like much compared to millions of hits on YouTube for a silly cat, but you must admit my blog has a more limited, and hopefully discerning audience. It has only taken me about 20 months to get to this point. Let’s see how long the next 20,000 views take.
When I finished my first year of posts I created a “Year in Review”. If you want to see it look here: http://www.commandalkonconnect.com/2013/04/08/blogging-the-year-in-review-and-other-inspirations-from-janus/
Here is a partial Table of Contents to my series “Concrete Mix Design: Art and Science”. http://www.commandalkonconnect.com/2013/09/05/concrete-mix-design-art-and-science-table-of-contents/
Probably the most common request I receive is for an explanation of the Coarseness/Workability Factor method of mix design, sometimes called the “Shilstone method”. About 6 months ago I did a survey of concrete producers around the world about mix design methods and was astounded to find out that 50% of them, including international, used the Coarseness Factor method to design concrete mixes. My father would have been very proud of this, since he developed the method. If you want the long, more technical explanation of the method you can download an article my father wrote about it at http://www.shilstone.com/library/ConcMixOpt.pdf. For this blog post I will be giving you a summary of the process. Continue reading
Duff Abrams announced his water-cement ratio theory (or as he called it, the “water ratio”) in Lewis Institute Bulletin 1, “Design of Concrete Mixtures”. While it was the water-cement ratio relationship that gained Abrams historical acclaim, another of his innovations that is used every day in the concrete industry was also introduced in that publication – the fineness modulus (FM). While we primarily use it today to describe the fineness of sand, Abrams used it as a mix design method and addressed the combined fineness modulus of both coarse and fine aggregate. This article won’t attempt to repeat all of Abrams article, but just give you the high points. If you want to use the combined FM to develop your own mix designs, I suggest you read the entire publication. Continue reading
Now that we have finished discussing particle packing techniques (although there is still a lot more to say about the subject) we can turn our attention to the more common combined aggregate grading techniques used in designing concrete mixes. As has been previously discussed, even though particle packing and voids techniques are more directly associated with concrete performance, combined aggregate grading techniques are easier to calculate with minimal testing and they approximate the results of the particle packing technique. For the next couple of months I want to talk about some different combined grading approaches and the strengths and limitations of each. However, before we talk about the combined grading techniques, I think it would be helpful to review how to calculate a combined aggregate grading. Continue reading