Optimized Gradation for
Concrete
WHAT THE HECK IS IT
AND
WHY THE HECK SHOULD I CARE?
Optimized Gradation for Concrete
Discussion Topics
 Specifications and Test Methods
 Lessons Learned
 Summary
 Contacts and Questions
Optimized Gradation for Concrete
Specifications and Test Methods
Optimized Gradation for Concrete
 TxDOT Standard Specification allows the use of ACI
211 or other approved concrete mix design method
 HCCMxDes2.xls is the Xite Manager template used
to document mix design proportions
Optimized Gradation for Concrete
Optimized Gradation for Concrete
 Special Provision 0421-035 allows for Tex-470-A to
be used to furnish concrete mix designs
 Tex-470-A is TxDOT’s procedure to design concrete
with an Optimized Aggregate Gradation (OAG)
 Use the same Xite Manager template and form 2227
in Tex-470-A to document the mix design
 Reference OAG tab to verify compliance with
specifications and test method
Optimized Gradation for Concrete
Optimized Gradation for Concrete
 THE BIG SECRETE - An intermediate aggregate is
used to fill in voids between coarse aggregate
particles
 Typically crusher “waste”
 This will minimize paste content
Optimized Gradation for Concret
Sieve Size Sieve Size (in)
Coarse Agg. 1
% Passing
Coarse Agg. 2
% Passing
Intermediate
Agg. 1
% Passing
Intermediate
Agg. 2
% Passing
Fine Agg. 1 % Fine Agg. 2 %
Passing
Passing
Combined %
Passing
Combined
Combined %
Cumulative %
Retained
Retained
2 1/2 in
2.500
100.0
100.0
100.0
100.0
100.0
0.0
0.0
2 in
2.000
100.0
100.0
100.0
100.0
100.0
0.0
0.0
1 1/2 in
1.500
100.0
100.0
100.0
100.0
100.0
0.0
0.0
1 in
1.000
72.0
100.0
100.0
100.0
95.8
4.2
4.2
3/4 in
0.750
12.0
97.0
100.0
100.0
85.5
14.5
10.3
12.6
1/2 in
0.500
72.0
100.0
100.0
73.0
27.0
3/8 in
0.375
54.0
100.0
98.0
64.5
35.6
8.5
No. 4
0.187
13.0
100.0
92.0
44.5
55.5
19.9
No. 8
0.093
40.0
86.0
34.5
65.5
10.0
No. 16
0.047
20.0
79.0
31.1
68.9
3.4
10.0
No. 30
0.024
61.0
23.8
76.2
7.3
No. 50
0.012
21.0
8.1
91.9
15.8
No. 100
0.006
2.0
0.8
99.2
7.3
No. 200
0.003
0.3
0.1
99.9
0.7
Pan
0.000
0.0
100.0
0.1
Mix Design Percentages
0.0
0.0
0.0
15.0
43.0
3.5
Cementitious
Materials
Weight =
Workability
Factor =
Coarseness
Factor =
611
35.8
54.3
(lb/CY)
0.0
0.0
38.5
0.0
100.0
Optimized Gradation for Concrete
Optimized Gradation for Concrete
Optimized Gradation for Concrete
Optimized Gradation for Concrete
 Increase performance by relying more on the
aggregate strength.
 Enhances concrete workability.
 Minimizes Shrinkage cracking
 Saves money by reducing the amount of paste in the
mix.
Optimized Gradation for Concrete
Lessons Learned
Optimized Gradation for Concrete
 Gradations in ITEM 421 Table 3 no longer apply
 Maximum nominal aggregate determined from




Coarse Aggregate Grades in ITEM 421 Table 5 apply
Fineness Modulus no longer used
Sand Equivalent continues to influence concrete
performance
Statistical variation reduced
Batching tolerance (ITEM 421 table 9 ) versus
staying in the box/meeting strength requirements
Optimized Gradation for Concrete
 Allows the Material Supplier to streamline crushing




and stockpiling operations
Improves mix performance by reducing strength
variability
When used with Concrete Works, mix designs are
crack resistant and have improved performance
OAG has reduced the water demand by up to 1 gallon
per cubic yard
AEA dosage rates are more consistent with OAG mix
designs
Optimized Gradation for Concrete
 Aggregate Stockpiles are not just for DOT usage
 NMDOT uses OAG mixes; Coarseness Factor and
Workability are held constant to control mix designs
Optimized Gradation for Concrete
 Some issues which need to be addressed
 SiteManager and the Guide Schedule are not set up for the
combined aggregate gradation
 Test method relies on strength and “staying in the box” to
control batching
 Guide schedule does not address OAG for sampling and testing
 Sampling and testing aggregate is addressed in test method
 CST-M certification is being developed
 Aggregate must be clean and durable to achieve performance
Optimized Gradation for Concrete
 OAG is not a cure all but a method to maximize
concrete performance
 Continue to use sound concrete practices to ensure
acceptable performance
Optimized Gradation for Concrete
Summary
Optimized Gradation for Concrete
 The El Paso District has used OAG mixes for the last
three years
 The District, Material Suppliers, and Contractors are
pleased with the improvements OAG has brought to
the concrete mix designs
Concrete with Optimized
Aggregate Gradation
 What the heck is it?
 TxDOT’s latest methodology for concrete mix designs
 Relies on aggregate strength
 Presents challenges as well as opportunities
Concrete with Optimized
Aggregate Gradation
 Why the heck should I care?
 Improves performance
 Potential to reduce material cost
 IT’S CONCRETE – IT’S BETTER THAN THE ALTERNATIVE!
(mis-quote from Dale Rand – HMAC guru)
Optimized Gradation for Concrete
Contacts and Questions
Optimized Gradation for Concrete
 Lisa Lukefahr, P. E. 512-506-5858
 Andy Naranjo, P. E. 512-506-5849
 Don’t call me (joking)
 Tomas A. Saenz, P. E. 915-790-4350
 Questions?