Exemples of Payback
The following examples are based on actual data for some of the clients most common mixes.
Since concrete is sold by the cubic yard, it is typical to proportion a concrete mix to produce 1 cubic yard (27 cubic feet). This is done by calculating weights of materials based on their specific gravity so that the weights of materials will yield the desired volume. If the materials result in too little volume, the contractor will need to order more material that he expects and will complain. If the material results in too much volume, the contractor will not have to order as much material (resulting in a loss of sales) and the concrete producer will ship more material that is required (resulting in increased material cost).
For example, if a concrete mix yields 27.3 cubic feet, that is .3 cubic feet (or 1.1%) more than is required. If a contractor can reduce his order by 1.1%, at a price of $100 per cubic yard of concrete, the concrete producer will lose $1.10 per cubic yard in sales. Additionally, if the materials for the concrete mix cost $75 per yard, the concrete producer will have to ship $0.82 more material than is necessary. This results in a total loss to the producer of $1.92 per cubic yard. Typically concrete mixes are proportioned to yield between 27.00 cubic feet and 27.2 cubic feet. A slight overyield reduces potential contractor complaints. One potential outcome of this analysis is that the concrete mixes in the batch plants should be evaluated to make certain that the correct material densities are being recorded. In most cases the measured unit weight is actually less than the calculated unit weight. However, these values can change over time and it may be difficult to keep all the mixes updated without a computerized mix management system like LABSYS.
If the client can save $0.05 per yard by monitoring yield, that can result in a savings of $17,500 per year.
Reducing cement is usually accomplished by reducing the strength overdesign for a mix or by increasing the cement efficiency (psi produced per pound of cementitious material). However, if project specifications require a minimum cement factor, it may be impossible to reduce the cement content for a given project. Each project needs to be evaluated on a case-by-case basis. Another way to decrease the amount of cement used in a mixture is to improve the cementitious efficiency, or the psi produced per pound of cementitious material. This can be accomplished in a variety of ways, including improving combined aggregate grading or the appropriate use of mineral additives or chemical admixture. Accordingly, a concrete mix with 7 sacks of cement will have about an 8.7 psi/lb (about 5724 psi). A mix with 6 sacks of cement will produce about 10.5 psi/lb (about 5922 psi). In this example decreasing cement content can actually increase strength. This is based on actual test data. Of course it doesn’t distinguish the variations in admixture. In this example, decreasing cement from 7 sacks to 6 sacks will slightly increase strength and can Cement
Efficiency save approximately $9.40 per yard if cement costs $200 per ton. If the client can save only 10 cents per yard on its cement costs, that can produce $35,000 per year in savings.
Reducing Manpower Requirements
During the year 2007 to date, the client has captured test results for 120 different projects. It can be fairly safely assumed that any project requiring concrete testing also required a concrete mix submittal. LABSYS can substantially reduce the time required to produce a concrete submittal.
If LABSYS can reduce submittal production time by just 15 minutes per submittal, that will translate to 40 hours over a 9 month period or a savings of $1200 (for a man with a $40,000 per year salary at 50% burden).
Improved Batch Tolerance Management:
LABSYS can monitor concrete batch weights and provide notification to QC personnel when batch weights are out of tolerance. The client has already saved over $250 000 by reducing over batching of cement. Future savings can be lost by not maintaining oversight on batching tolerances.