Lightweight Concrete for High Strength - Expanded Shale & Clay

More documents

Recommendations

Info

C.2 Girder Construction Prior to lifting the formwork into place, the forms were coated with a form release agent (form oil). It was necessary to recheck the DEMEC embedments and wipe any excess oil from the wing nuts prior to form installation. In a few cases, wing nuts had been knocked off the embedment strips and required replacement. Once properly aligned, the forms were locked into place by large threaded rods beneath the formwork and wishbone struts on top. Figure C.14 shows installation of the formwork. Figure C.14 Formwork with DEMEC Embedment Strips Being Lifted Into Place C.2.1 Batching and Concrete Placement Prior to batching the HSLC, moisture tests were conducted on the lightweight aggregate and sand to determine the exact mix design. The moisture tests were started at least two hours prior to placement to allow time to correctly dry the aggregate and configure the mix design. The concrete was mixed in a rotary auger-type mixer located in an elevated mix station approximately 200 feet from the prestressing bed. The mix station did not have a silo for fly ash or silica fume, thus those two components had to be added manually. The concrete components C-7
were added in a specific sequence for each batch of concrete. The lightweight and normal weight aggregates were added first with all the low range water reducer (LRWR), air entraining agent (AEA), high range water reducer (HRWR), and approximately half the mix water. Next, the Type III cement was added. Additional water was added as necessary to allow proper mixing of the cement. Next the Class F fly ash was added with additional water as required. Last, the silica fume was added. Any remaining water up to the specified mix design amount was added and the result was observed. If the mix was still stiff, additional HRWR was added to bring the mix to a workable state. Upon batching of concrete, it was loaded into the transport vehicle and brought to the quality control station. Tindall personnel performed a slump test according to ASTM C231, a unit weight test according to ASTM C138, and recorded the temperature according to ASTM C1064. Georgia Tech personnel performed an air content test using a roll-a-meter according to ASTM C173. To the greatest extent possible, these tests were performed on each batch of concrete. After delivering concrete to the quality control station, the remaining concrete was transported to the girder line where it was placed into the forms (Figure C.15). The Tindall concrete workers placed the concrete in lifts vibrating each lift with a spud vibrator. One Georgia Tech researcher was present on the girder line at all times during concrete placement to insure the concrete workers did not damage any instrumentation or DEMEC inserts. After all lifts of concrete were in place, the top of the girder was screeded and raked to give it the required ¼-inch variation for good bond between the deck and girder. The girders were then covered with heavy plastic to protect them from rain and hold in heat during the curing process. C.2.2 Concrete Curing The girders were allowed to cure overnight. Temperature was monitored on each girder using the embedded thermocouple and a printing thermometer. A typical temperature curing curve for girder G1A is shown in Figure C.16 together with the temperature in the curing box for test cylinders. C-8
Page 1 and 2:
School of Civil and Environmental E
Page 3 and 4:
ACKNOWLEDGMENTS The research presen
Page 5 and 6:
A statistical evaluation based on f
Page 7 and 8:
5.6 - Transfer Length 5-13 5.7 - Gi
Page 9 and 10:
Report ACI 318- 99 AASHTO Standard
Page 11 and 12:
Chapter 1. Introduction 1.1 Purpose
Page 13 and 14:
Long term properties including pret
Page 15 and 16:
ottom flange. Prestressing strands
Page 17 and 18:
12500 12000 Concrete Strength, fc'
Page 19 and 20:
Chapter 3. Mix Designs, Field Evalu
Page 21 and 22:
Variation of coarse-to-fine aggrega
Page 23 and 24:
3.2.1 Compressive Strength Figure 3
Page 25 and 26:
Table 3.5 Chloride Permeability --
Page 27 and 28:
12,000 11,500 11,000 Compressive St
Page 29 and 30:
1,400 1,300 1,200 1,100 Experimenta
Page 31 and 32:
strength (10L made in the laborator
Page 33 and 34:
The 50% and 90% of the 620-day cree
Page 35 and 36:
700 600 10,000-psi Measured Shams &
Page 37 and 38:
a Creep Coefficient 3.0 2.5 2.0 1.5
Page 39 and 40:
Chapter 5. Behavior of AASHTO Type
Page 41 and 42:
Portion of Girder Damaged During Te
Page 43 and 44:
2” End Cover (Typ both ends) 4 Sp
Page 45 and 46:
5.3 Instrumentation The surface of
Page 47 and 48:
Figure 5.7 Installation of stirrups
Page 49 and 50:
Table 5.3 Girder concrete propertie
Page 51 and 52:
120 100 80 Stress (ksi) 60 40 20 0
Page 53 and 54:
Table 5.5 -Transfer Length Results
Page 55 and 56:
Figure 5.12 Typical flexural failur
Page 57 and 58:
Since G2 girders had a higher concr
Page 59 and 60:
V " pc cw− Pr ed = ft −Pr ed 1
Page 61 and 62:
Test # Table 5.9 Predicted vs. Expe
Page 63 and 64:
this research project, modification
Page 65 and 66:
Chapter 6. Prestress Losses in HPLC
Page 67 and 68:
losses in the 10,000-psi girders to
Page 69 and 70:
Microstrains (in/inx10 -6 ) 0 500 1
Page 71 and 72:
6.3 Conclusions Regarding Prestress
Page 73 and 74: 7.3 Transfer Length An evaluation o
Page 75 and 76: Shrinkage after 620 days of drying
Page 77 and 78: More research is required to examin
Page 79 and 80: Appendix A. Background A.1 Introduc
Page 81 and 82: Raithby and Lydon described the use
Page 83 and 84: are normally recognized as being on
Page 85 and 86: aggregate must be saturated by pres
Page 87 and 88: A.7.2 Strength Ceiling Harmon discu
Page 89 and 90: compared to lower strength specimen
Page 91 and 92: A.8.8 Deatherage, Burdette and Chew
Page 93 and 94: 3. Concrete compressive strength at
Page 95 and 96: findings were comments that the AAS
Page 97 and 98: including strand diameter, embedmen
Page 99 and 100: l d = l t + l fb = f si 3 d b + 1.5
Page 101 and 102: l d = l t + l fb ⎛ = ⎜ ⎝ f d
Page 103 and 104: Table A.1 Summary of Development Le
Page 105 and 106: strand release, the strand attempts
Page 107 and 108: Appendix B. Creep and Shrinkage B.1
Page 109 and 110: Changes in moisture migration: the
Page 111 and 112: t′: age of concrete at loading (d
Page 113 and 114: s: slump (in) γ ψ ⎧ 0.30 −1.4
Page 115 and 116: t: age of concrete (days) t 0 : age
Page 117 and 118: where ε sh ∞ ⎧ 510 µε for st
Page 119 and 120: left girder-end. The dimension L wa
Page 121 and 122: 6” 85” 50” Segment of girder
Page 123: 146” 89” 96” 137” Stirrups
Page 127 and 128: C.2.3 Formwork Removal, Detensionin
Page 129 and 130: Figure C.19 Mostafa Prestressing St
Page 131 and 132: Figure C.22 Ms. Lyn Clements (GDOT)
Page 133 and 134: If significant strand end slip over
Page 135 and 136: CSS at Level of Bottom Strands (µ
Page 137 and 138: Appendix D. Prestress Losses in HPL
Page 139 and 140: E ps : elastic modulus of prestress
Page 141 and 142: D.2.2. AASHTO-LRFD Refined Estimate
Page 143 and 144: ∆f log(24 ⋅t) ⎛ f ⎜ ⎞ 55
Page 145 and 146: P i : initial prestressing force af
Page 147 and 148: References AASHTO (1996), Standard
Page 149 and 150: ASTM C 618, Standard Specification
Page 151 and 152: Guide for Structural Lightweight Ag
Page 153 and 154: Martin, L. D., Scott, N. L., “Dev
Page 155: Shahawy, M. A., Batchelor, B., “S
show all

Lightweight Concrete for High Strength - Expanded Shale & Clay

Create successful ePaper yourself

Delete template?

Save as template?