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OCR for page 27
A-1 APPENDIX EXAMPLES OF MIXTURE DESIGNS There are many ways to achieve high early strength while Accelerator Type: calcium chloride maintaining durability of EOT concrete. The goal is to select Water Reducer: none the most cost-effective combination of materials that will Coarse Aggregate: 1,030 kg/m3 (1,736 lb/yd3) crushed produce a mixture meeting strength criterion while achieving limestone the desired level of durability. To some degree, this will Fine Aggregate: 425 kg/m3 (716 lb/yd3) natural sand depend on the environment in which the repair is to be made. Average Slump: 65 mm (2.5 in.) For example, in some states, issues of freeze-thaw durability Average Air Content: 5.6 percent and scaling resistance are not big concerns, and the need for 8-hour Compressive Strength: 17.0 MPa (2,465 psi) air entrainment is reduced. For the vast majority of states, 28-day Compressive Strength: 53.8 MPa (7,800 psi) however, air entrainment must be considered because of the 8-hour Flexural Strength: 2.4 MPa (350 psi) freeze-thaw environment and use of chemical deicers. In this study, several mixture designs were found to provide appro- Mixtures 4, 5, and 6, all of which were made using a vin- priate fresh and hardened concrete properties. sol resin air-entraining agent, provided good performance for Mixtures 1, 2, and 3, all of which were made using a vin- 20- to 24-hour EOT concrete: sol resin air-entraining agent, provided good performance for 6- to 8-hour EOT concrete: Mixture 4 Cement Type: Type I Mixture 1 Cement Content: 400 kg/m3 Cement Type: Type I w/c ratio: 0.43 Cement Content: 525 kg/m3 (885 lb/yd3) Accelerator Type: calcium chloride w/c ratio: 0.40 Water Reducer: none Accelerator Type: non-chloride Coarse Aggregate: 1,030 kg/m3 (1,736 lb/yd3) crushed Water Reducer: none limestone Coarse Aggregate: 1,030 kg/m3 (1,736 lb/yd3) crushed Fine Aggregate: 628 kg/m3 (1,060 lb/yd3) natural sand limestone Average Slump: 85 mm (3.35 in.) Fine Aggregate: 427 kg/m3 (720 lb/yd3) natural sand Average Air Content: 6.6 percent Average Slump: 140 mm (5.5 in.) 20-hour Compressive Strength: 24.5 MPa (3,550 psi) Average Air Content: 5.0 percent 28-day Compressive Strength: 46.0 MPa (6,670 psi) 8-hour Compressive Strength: 16.4 MPa (2,375 psi) 28-day Compressive Strength: 44.0 MPa (6,400 psi) 20-hour Flexural Strength: 3.4 MPa (490 psi) Mixture 5 8-hour Flexural Strength: 2.4 MPa (350 psi) Mixture 2 Cement Type: Type I Cement Type: Type I Cement Content: 400 kg/m3 Cement Content: 525 kg/m3 (885 lb/yd3) w/c ratio: 0.40 w/c ratio: 0.36 Accelerator Type: non-chloride Accelerator Type: non-chloride Water Reducer: none Water Reducer: none Coarse Aggregate: 1,030 kg/m3 (1,736 lb/yd3) crushed Coarse Aggregate: 1,030 kg/m3 (1,736 lb/yd3) crushed limestone limestone Fine Aggregate: 659 kg/m3 (1,110 lb/yd3) natural sand Fine Aggregate: 482 kg/m3 (812 lb/yd3) natural sand Average Slump: 50 mm (2 in.) Average Slump: 70 mm (2.75 in.) Average Air Content: 5.7 percent Average Air Content: 5.0 percent 20-hour Compressive Strength: 19.9 MPa (2,890 psi) 8-hour Compressive Strength: 20.4 MPa (3,000 psi) 28-day Compressive Strength: 40.6 MPa (5,890 psi) 28-day Compressive Strength: 56.3 MPa (8,150 psi) 20-hour Flexural Strength: 3.8 MPa (550 psi) 8-hour Flexural Strength: 3.0 MPa (435 psi) Mixture 6 Mixture 3 Cement Type: Type I Cement Type: Type I Cement Content: 475 kg/m3 Cement Content: 425 kg/m3 w/c ratio: 0.43 w/c ratio: 0.40 Accelerator Type: none

OCR for page 27
A-2 Water Reducer: none 28-day Compressive Strength: 39.3 MPa (5,700 psi) Coarse Aggregate: 1,030 kg/m3 (1,736 lb/yd3) crushed 20-hour Flexural Strength: 3.6 MPa (520 psi) limestone Fine Aggregate: 659 kg/m3 (1,110 lb/yd3) natural sand These examples of cement mixtures were identified from Average Slump: 150 mm (6 in.) the investigations conducted in NCHRP 18-04B. Other suit- Average Air Content: 5.9 percent able mixtures could be proportioned with the same or differ- 20-hour Compressive Strength: 17.8 MPa (2,580 psi) ent cements, aggregates, and admixtures.