Concrete Doesn t Just Come In Vanilla Anymore

feature Part 6: Flowable Fill Concrete Doesn t Just Come In Vanilla Anymore By A. Vance Pool, Senior National Resource Director, NRMCA This is the sixth article in a series on many of the different types of value added concrete you can choose to include on your menu of products to actively promote in a local marketplace. Some of those choices include concrete with fibers, quick setting mixes, decorative concrete, waterproof concrete, flowable fill, self consolidating concrete (SCC), easy finishing mixes, Green concrete, pervious concrete, high strength concrete and corrosion resistant concrete. In our last article, we highlighted the applicability of waterproof concrete and how to actively sell and promote it. This article will take a look at flowable fill. Flowable fi ll is a low strength, highly flowable liquid soil that can be used in lieu of compacted soil. It has been called many things: (CLSM) - Controlled Low Strength Material; (CDF) - Controlled Density Fill; Flowable Compacting Fill; Lean Fill; Unshrinkable Fill; Flow Mortar; Fly Ash Flow; Liquid Dirt. Flowable fi ll is not new. It has been around a long time. Unfortunately, many contractors are still not aware of the speed of construction and cost savings attributes of flowable fi ll, so there is significant growth potential for flowable fi ll in most markets around the country. This article is meant to educate the reader on basic characteristics of flowable fi ll and the way to show its value to contractors. 18 ı JULY/AUGUST 2008

Flowable fi ll is a lean concrete mix which takes the place of compacted soil. It usually contains small amounts of cement, flyash, sand, water, and air or foam generating admixtures. Cementitious amounts vary based on the application involved. To attain hand excavateable fi ll as little as 100 pounds of cement with no fly ash has been used and in some cases many hundreds of pounds of flyash is used in areas where higher strengths or reduced permeability are required. A rule of thumb is that anything below 100 psi strength is generally hand excavatable with a shovel. With fly ash involved you will want to look at numbers from 60- or 90-day strengths as the flyash in the mix will add strength for a period much longer than traditional 30-day cylinder tests account for. These types of mixes can also allow for the use of out of concrete spec sands which may or may not include significant amounts of fi nes. I am personally a big believer in using the air or foam generating admixtures as they can create a 30% air content which may make economic sense based on local material prices but it also allows ready mix producers to ship 10-yard loads. Without the air added at the jobsite, trucks cannot be fi lled fully since the highly fl owable mixture could come out of the back of the truck in transit. By adding the air or foam at the jobsite, a 7-yard haul becomes a 10-yard placement. The economic savings to the ready mix producer as well as the reduced greenhouse gases used in transporting the material make these products a win-win. Using flyash and out of spec sands also has environmental benefits. For the contractor, it is always about saving time or money and flowable fill, in many cases, does both. Traditional fill materials have to be done in lifts and compaction is not always uniform. With flowable fill, both of those issues can be eliminated. Flowable fill can be placed in one lift if no pipes are in the hole. If there are pipes in the hole you must consider the fact that pipes will want to float in the liquid fill due to the buoyancy effects NRMCA Flowable Fill vs. Granular Fill Granular Backfill Placement (2 laborers @ 36.99*) $73.98 Compaction (2 laborers @ 36.99*) $73.98 Heavy Equip. Operator $40.33* Hand Compactor $15.00* Backhoe $25.00* Total labor/hour for granular fill $228.30 NRMCA * National Industry Average incl. overhead costs Flowable Fill vs. Granular Fill Flowable Fill Placement $36.99 Compaction n/a Heavy Equipment n/a Total labor for Flowable Fill $36.99 Total labor for granular fill $228.30 Labor savings $181.31 in a liquid. I have seen a couple of ways to address this issue. One is to place the fill in two lifts with the first coming up about one third up the pipes; you let it harden overnight and it anchors the pipes for the final placement. The other solution is to restrain, weight or tie down the pipes so that they aren t permitted to float. CONCRETE in focus ı 19

All you need to know about concrete color. Cost savings are generally one of the most important attributes a contractor in the United States looks for when selecting materials. Just one call is all it takes to learn how Davis Colors can provide you with the number one concrete color brand in America, the most widely used automatic dosing systems, and the personalized marketing tools that will help you build your business. Call 800-356-4848 ext. 323 or visit www.daviscolors.com. #1 IN SYSTEM INSTALLATIONS WORLDWIDE Tel: 800-356-4848 Fax: 323-269-1053 www.daviscolors.com 2004 Davis Colors, a brand of Rockwood Pigments, Inc. PIGMENTS One of the ways flowable fi ll can speed up construction is to backfi ll even when the hole is wet. Flowable fi ll can be placed in a hole that has water in it. The flowable fi ll will displace the water and fi ll the hole. You have to keep in mind the water is going to come out and run down hill so a little planning can save a big headache. Channel the water where you want it to go if necessary. The big advantage here is that you cannot compact wet soil, so construction can be halted due to rain. But with flowable fi ll the job keeps moving forward. This means the job proceeds immediately after the rains stop and this phase of construction occurs when it normally would not be allowed to. Cost savings are generally one of the most important attributes a contractor in the United States looks for when selecting materials. In order to understand the savings, you need to work with the contractor to understand their cost position on a project. The two slides shown represent some of the cost streams associated with both traditional and flo w a b l e fi l l b a c k fi l l m e t h o d s. Based on oil price changes recently, as well as local market variations in costs, you will want to understand the exact numbers in your markets so you can attack those where flowable fi ll value is high and easy to demonstrate. Other costs which can come into play in a specific project analysis are: Savings due to reduced days to complete the project (especially when fi lling a wet hole) (job trailers staff, overhead, the list is long) Any bonus monies due to speeding the completion of the job Any costs to haul fi ll material off site (if there is extra soil being cut and hauled away) There are many more job specific ones to fi nd Flowable fi ll can be color coded to alert those digging in the future that they are near a pipe or cable with the color telling them what type of pipe or cable they are near. The American Public Works Associations has color codes which are shown in an illustration. By using integral color this can be done easily and will potentially reduce the number of utility problems due to severing them in the future. Because of the amount of water in fl owable fi ll, it is important to take into account the subsidence that will occur 20 ı JULY/AUGUST 2008

QUALITY COMPONENTS HEAVY DUTY CONSTRUCTION ADVANCED DESIGN ERIE concrete batch plants meet the application, production and job size requirements of all ready mix producers, and they re backed by a century of construction equipment manufacturing experience. ERIE STRAYER COMPANY Contact an ERIE representative: P.O. Box 1031, Erie, PA 16512 Phone: (814) 456-7001 Fax: (814) 452-3422 www.eriestrayer.com sales@eriestrayer.com

DOT CAL-TRANS VMMB ASTM C685 Flowable fill achieves full compaction every time and its consistency is unmatched by traditional backfilling methods. your quality CemenTech Volumetric Concrete Mixers produce quality concrete to meet your exacting standards day in and day out, load after load. Expect the best, because CemenTech delivers. when the material sets. A good rule of thumb is to allow for 1/8" of subsidence for every one foot of depth of the placement. This can be especially important on fast track road projects. By accelerating the fi ll and then dropping in quick setting, high early strength concrete on top, airports and roads can be repaired in hours instead of days. Typical applications include anywhere soil backfi ll is used. Some specifi c applications include: Behind retaining walls Trenches Bridge abutments Pipe beddings Building excavations Under concrete slabs Counterweights in drawbridges Filling of abandoned underground tanks, pipes or sewers (if in compliance with environmental regulations) Erosion mats Many others Flowable fi ll achieves full compaction every time and its consistency is unmatched by traditional backfi lling methods. While it has been around a long time, it has barely scratched the surface in penetrating the numerous fi ll applications it is suited for. Keeping up with local fi ll soil and haul prices can allow ready mix industry sales reps to tactically address the cost and value benefits it brings to individual projects. When a ready mix producer wins a project contract, fl owable fi ll should be a standard pre job conversation to see if there are any applications which make economic sense. On rainy days, ready mix sales professionals should be on the lookout for projects being held up due to using traditional fi ll methods and should contact the GC to make it aware that the job can move forward that day. For more information contact Pool at 281/557-8415 or via email at vpool@ nrmca.org. Visit our Buyers Guide online at NRMCA. OfficialBuyersGuide.net 22 ı JULY/AUGUST 2008