Study on Combination of Stainless Steel Reinforcementand Lightweight Concrete in Structural Members
Concrete Laboratory
Adrian Leonardo Ferrino Patino
Professor: Takumi Shimomura

3. Case study
The case study consists in a comparison of 4 vehicularbridge designs in corrosive environments, using the 4
combinations of materials stated before following the“AASHTO LRFD Specifications”. The objective is toevaluate L+S which is expected to reduce the size ofthe structure, the reinforcement and weight.

50

Volume of concrete(m3)2. Research method
The research method of this study consists in theevaluation of 4 combinations of materials which arenormal concrete + carbon steel (N+C), normal
concrete + stainless steel (N+S), lightweight concrete+ carbon steel (L+C), lightweight concrete + stainlesssteel (L+S). In this case, L+S is the main combination
to evaluate. However, the other 3 combinations willserve as a comparison group to analyze differences in
the obtained results. This research consists inperforming to these 4 combinations of materials anexperimental study to evaluate the mechanicalperformance and corrosion resistance, and a casestudy to evaluate its use in an example of a bridge
design.

3.1. Results and discussion
After the analysis of loads and computation of thedimensions, a design section of each material
combination was obtained. Then, estimations of thetotal weight, amount of reinforcement and volume ofconcrete were performed for each design to observe
differences in these values. In Figure 2, it can beobserved a table with the volume of concrete neededfor each material combination and when using
lightweight concrete and stainless steel (L+S), almost
the lowest value of the necessary volume of concrete
can be obtained which is 37.54 m3. If this value iscompared with the 39.69 m3 of concrete volume
required by N+C, it can be observed that L+S saves
2.15 m3 of concrete which is an important saving if
the bridge have several sections to build.

4030
20
10

0
N+C

N+S

L+C

L+S

Figure 2: concrete volume of bridges.
In Figure 3, it can be observed that the L+S
combination has a very low total weight equal to62.67 Ton when it is compared with the total weightequal to 95.24 Ton of N+C. It was verified that L+S
could reduce 30% the total weight when it iscompared to N+C.

100Weight (Ton)

1. Introduction and objective
This study intends to evaluate the effectiveness of
combining stainless steel and lightweight concrete in
RC structural members. The expected merits of using
this combination of materials are the high resistanceto corrosion of stainless steel which permits to have asmaller concrete cover thickness and reduce thecross-section size of the member, and the low densityof lightweight concrete which can be approximately30% lighter than normal concrete and can reduce
dead-loads, which decreases the size andreinforcement of structural members. The objectiveof this research is to observe and analyze with anexperimental study and case study if the mechanicalbehavior of lightweight concrete and stainless steel issatisfactory and can be applied to structural members.
Also, verify if the application of lightweight concreteand stainless steel in the design of structural members
can produce reductions in the size, weight and amountof reinforcement.

8060
40
200
N+C

N+S

L+CL+S

Figure 3: total weight of bridges.

Figure 1: view of the dimensions of the bridge.

In Figure 4, it can be observed that L+S needs 95223
mm2 of steel area, while N+C requires 115504 mm2.
With this it was also verified that L+S decreased theamount of reinforcement in the structure if it iscompared with the N+C combination.

each concrete type. The objective of the loading test
is to measure the load, strain on concrete and steel,deflections, and crack development in all 4 specimens
to target the differences in the mechanical behavior.

Area of steel (mm2)12000090000
60000

Averagecompressive
strength(MPa)Modulusofelasticity(MPa)

Density(kg/m3)

Normalconcrete

54.6

38451

2280

Lightweight
concrete

35

20134

1580

30000
0
N+C

N+S

L+C

L+S

Figure 4: steel area of bridges
4. Experimental study
The experimental study consists in a loading test toevaluate the mechanical performance of thespecimens to confirm if L+S can offer a satisfactorymechanical behavior. Then, since the diffusivity ofchlorides in lightweight concrete must be studied, thecorrosion behavior of the reinforcing steel mainly
inside lightweight will be evaluated with anaccelerated corrosion test. Regarding the corrosion
test, it is currently being done and results haven’t
been obtained.
4.1. Specimens and loading test
The 4 specimens are reinforced concrete beams basedon the Bench Mark Test by JSCE 311 Committee [2].
The specimens consist in a main steel bar D13 with 2
strain gauges to measure its strain, stirrups
D6(SD345) or D5(SUS304) every 100 mm as shownin Figure 5.

Table 1: concrete properties.
4.2 Results and discussion
The strains in the main steel bar of the specimens canbe observed in Figure 7. According to the table it isobserved that the shape of the slopes of the lines of all
the specimens depends mainly in the type of the steel.
The specimens with stainless steel had less strains
than the carbon steel at initial stages during the sameloads, and a bigger ultimate strength than thespecimens with carbon steel. Also, it can be observedthat specimens of lightweight concrete presented
bigger strains than specimens of normal concrete at
similar loads. However, this differences were notdrastic and may be due to the variation of 19.4 MPain the compressive strength of lightweight concreteand normal concrete.
30

Load (kN)

25

Figure 5: characteristics of specimens.
Figure 6 shows the setting for the loading test which
consists in a load-cell, hydraulic jack, the specimen
simply supported, deflectometers and 3 strain gauges
placed on each face of the specimen to measure its
strain.

Figure 6: setting of loading test.
Table 1 shows the properties of the concrete obtainedwith a compression test to 3 cylindrical specimens of

20
N+C
N+S
L+C
L+S

15
10
500

5,000
Strain(μ)

10,000Figure 7: strains in the steel bar of specimens.
Regarding the deflections of the specimens, theFigure 8 shows the deflection development of thespecimens during the loading test. It was observedthat specimens using lightweight concrete presented
very similar deflection values under similar loads likenormal concrete specimens. There were somedifferences in the maximum deflection value, since
lightweight concrete specimens had less ductility anddeflected less than normal concrete specimens at
ultimate load. However, this difference was not
drastic and may be due to the variation in thecompressive strengths of the concrete mixes showedin the Table 1. Regarding the crack development,
according to the sketches of cracks in Figure 9, it canbe observed that crack development was similar sincethe spacing and deepness of cracks were equivalent
between combinations of lightweight concrete andnormal concrete during the loading test.
30

Load (kN)

25
20
N+C
N+S
L+C
L+S

151050051015
Deflection at center (mm)20Figure 8: deflection development of specimens.

Figure 9: crack sketches of specimens.
4.3 Expected results for corrosion test
Since lightweight concrete is a more porous material
it is expected that it presents a faster ingress ofchlorides than normal concrete. However, since theexperiment is currently being done results haven’t
been obtained.
4.4 Conclusion of obtained results
Case study: in the case study it could be observedthat when using lightweight concrete and stainlesssteel in a vehicular bridge under same loading andsupport conditions, same dimensions and the sameenvironmental conditions (marine environment),
there was a 30% reduction of the total weight and adecrease in steel reinforcement. In addition, thisreduction of weight may have a positive effect toreduce the dimensions and necessary reinforcementof other structural members that will carry these loads.
Also, since stainless steel is used it can be expected
to have a longer service life of the structure and lessmaintenance and repair frequency [1].

Experimental study: it could be observed that L+S
showed a very similar cracking load like N+C. Some
differences were obtained in the deflection
development, however they were minimum and may
be due to the differences of the compressive strength
between the concrete mixes. Regarding the crackdevelopment, if the sketches are observed, cracks hadvery similar spacing and deepness which may
indicate that in this experimental study lightweight
concrete and normal concrete developed cracks on
similar ways during the loading stage.
5.

References[1] ACI Committee 222, 2001, Protection of Metals
in Concrete Against Corrosion, American Concrete
Institute.
[2] ACI Committee 213, 2003, Guide for Structural
Lightweight-Aggregate Concrete, American Concrete
Institute.