Lightweight Concrete for High Strength - Expanded Shale & Clay

GVW (kips)
240
230
220
210
200
190
180
170
160
150
140
130
120
110
100
90
SUPERLOAD PERMIT
REQUIRED
100 110 120 130 140 150 160 170
Girder Length (ft)
(f c ' = 8, 10 and 12 ksi)
Type IV (N) Type IV (L) Type V (N) Type V (L)
BT-54 (N) BT-54 (L) BT-54M (N) BT-54M (L)
BT-63 (N) BT-63 (L) BT-63M (N) BT-63M (L)
BT-72 (N) BT-72 (L) BT-72M (N) BT-72M (L)
Figure 2.3 Gross Vehicle Weight (GVW) vs. maximum girder length.
Based on the parameters of this study, AASHTO Type IV and V sections are less
efficient than similar height Bulb-Tee sections, both Standard and Modified. If the
AASHTO Type IV and V sections are removed from the chart, there are noticeable trendlines
for the remaining normal weight and lightweight Bulb-Tee girders.
The primary conclusions from the analytic study are as follows: (1) Use of HPLC has the
potential to increase the length of simple span AASHTO sections up to four percent and
Bulb-Tee sections up to three percent; (2) for spans between 125-ft. (38.1 m) and 155-ft.
(47.2 m), use of lightweight concrete can reduce the gross vehicle weight to less than 150-
kips so that a superload permit is not required for transport of long span girders; and (3)
Bulb-Tee (Standard or Modified) sections provide longer spans at less weight for girders
over 105-ft. (32 m) in length when compared to AASHTO sections.
2-5