THE CONCRETE BRIDGE MAGAZINE

Winter 2019

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

Issue link: http://www.aspiremagazinebyengineers.com/i/1064399

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S A F E T Y A N D S E R V I C E A B I L I T Y 32 | ASPIRE Winter 2019 O wners and designers of many new structures are specifying a design life of 100 years or more to ensure durability and sustainability. Tourney Consulting Group LLC (TCG) in Kalamazoo, Mich., recently conducted a study 1 for the Expanded Shale, Clay and Slate Institute (ESCSI) to determine the effects of lightweight coarse and fine aggregates—100-year-old technology— on the transport properties and other durability-related properties of concrete. Ten expanded shale, clay, and slate lightweight coarse aggregates from across the United States were used i n "s a n d l i g h t w e i g h t " c o n c r e t e mixtures that were compared to a normalweight concrete control mixture with respect to transport properties. Transport properties of concrete are measurements of the ability of ions and fluids to move through the material. I n a d d i t i o n , o n e m i x t u r e w i t h n o r m a l w e i g h t c o a r s e a g g r e g a t e and lightweight fine aggregate (an "inverted" mixture); one mixture with lightweight coarse and lightweight fine aggregates ("all-lightweight" concrete); and one mixture with normalweight aggregate with a partial replacement of normalweight sand by lightweight fine aggregate (an "internally cured" mixture) were also evaluated for transport properties. All mixtures used 658 lb/yd 3 of Type I portland cement. No supplementary cementitious materials were used. Table 1 lists the 14 concrete mixtures t e s t e d a n d t h e i r p ro p e r t i e s . T h e transport properties from the TCG tests were used in several service-life prediction software models, including STADIUM ® and Life-365 ™ , and analysis according to fib Bulletin 34: Model Code for Service Life Design. A bridge deck subjected to deicing salts in Detroit, Mich., was modeled using the two software programs. The results for the analysis using STADIUM showed that the concrete bridge deck's service life would be i n c r e a s e d i n c o m p a r i s o n t o t h e normalweight concrete control mixture as follows: • By approximately 22% when using the "sand lightweight" mixtures SIGNIFICANTLY IMPROVE CONCRETE DURABILITY AND SERVICE LIFE BY USING A 100-YEAR-OLD TECHNOLOGY by Ken Harmon, Stalite and Chair of the Structural Committee of the Expanded Shale, Clay and Slate Institute Table 1. Concrete Mixture Proportions and Properties 1 Mixture description LW1 LW2 ALW LWF IC C Lafarge Alpena Type I cement, lb/yd 3 658 658 658 658 658 658 658 658 658 658 658 658 658 658 Aggregate Resource Midway Pit NW FA, lb/yd 3 (SSD) 1360 1342 1320 1119 1119 1074 1568 1346 990 1465 — — 846 1294 Bay Aggregates Cedarville Pit NW limestone CA No. 67, lb/yd 3 (SSD) 450 350 150 — — — — — — — — 1800 1800 1800 LW CA, lb/yd 3 (SSD) 500 650 862 1215 1209 1209 862 1038 1273 875 1115 — — — LW FA, lb/yd 3 (SSD) Total water, lb/yd 3 250 250 244 243 243 243 242 243 243 246 243 243 243 243 Designed air, % 6.5 6.5 6.0 7.0 7.0 7.0 6.5 6.0 6.0 6.0 6.0 6.0 6.0 6.0 Designed plastic density, lb/ft 3 120.5 120.4 118.9 119.7 119.5 117.8 123.3 121.7 117.2 120.1 108.7 130.9 142.6 148 Water-cement ratio 0.38 0.38 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.37 Admixtures BASF Master Air AE100, oz/cwt 0.15 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.2 0.2 0.4 0.5 BASF Glenium 7500, oz/cwt 3.2 3.6 3.7 3.9 4.3 3.9 5.2 5.8 3.5 5.0 4.3 5.3 5.0 4.4 Physical properties Slump, in. 4.00 5.00 3.50 3.00 8.75 5.00 2.75 5.25 3.00 4.00 3.00 5.00 7.50 4.00 As-tested air, % (volumetric) 6.75 8.00 7.50 7.25 6.50 6.50 7.00 6.25 6.25 7.00 6.25 6.00 7.00 7.10 Plastic density, lb/ft 3 (concrete) 120.5 123.0 118.8 119.1 122.6 122.2 125.7 123.5 121.4 120.7 109.8 133.3 141.6 146.2 Oven-dry density, lb/ft 3 (concrete) 111.9 113.8 108.9 109.2 109.8 108.2 115.7 114.0 109.1 114.1 95.6 130.1 137.2 142.1 Equilibrium air dry density, lb/ft 3 (concrete) 118.6 119.9 115.4 117.3 117.7 115.9 122.3 120.7 117.1 120.3 104.8 136.5 142.9 147.3 No. of days to reach equilibrium (average 2) 112 84 84 140 140 140 112 112 112 56 140 84 84 67 Compressive strength Average Average 1-day strength, psi (3 each) 2870 3370 2700 3500 3570 3310 28-day strength, psi (3 each) 5650 6540 6160 7120 6760 5470 90-day strength, psi (3 each) 6260 7240 7140 8040 7743 5950 Note: For compressive strength tests, three cylinders were tested for each mixture at each age and the average compressive strength is reported. For LW1 mixtures, the compressive strength value shown is the average of the average values for the three mixtures of this type. For LW2 mixtures, the compressive strength value shown is the average of the average values for the seven mixtures of this type. ALW = one "all-lightweight" mixture with LW CA and FA; C = one control mixture with NW CA and FA; CA = coarse aggregate; FA = fine aggregate; IC = one "internally cured" mixture with NW CA, NW FA, and some LW FA; LW = lightweight; LWF = one "inverted" mixture with NW CA and LW FA; LW1 = three "sand lightweight" mixtures with LW CA, some NW CA, and NW FA; LW2 = seven "sand lightweight" mixtures with LW CA and NW FA; NW = natural, normalweight; SSD = saturated surface dry.

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