and F_{0.09}. This shows that the effect of all three factors on
the performance characteristics of straw concrete is very
clear.
Orthogonal experiment results
Based on the orthogonal experimental plan designed
and experimental procedures, experiments are carried out
to determine the initial slump (S_{1}), compressive strength
at 28 days in natural dry state (R_{b}) and the volumetric
weight of 28dayold in the natural dry state (γ_{0}) of the
concrete sample groups. From Table 4 shows, the sample
group were satisfactory on the minimum compressive
strength with lightweight concrete regulations. The
maximum compressive strength reaches the highest value
when the contents of X, N and R are 18.6%, 10% and
1.46%, respectively; the compressive strength reaches the
smallest value when the contents of X, N and R are:
12.6%, 11% and 2.34%, respectively. Therefore, the
selection of reasonable values of X, N and R content is
mainly based on the consideration of two criteria: Slump
and Volumetric weight.
Table 5. Results of general equilibrium analysis
Parametric
analysis
Indicator
X (%)
N (%)
R (%)
K_{1 }
23.000
15.000
15.000
5.000
14.000
21.500
27.500
17.500
11.500
K_{2 }
K_{3 }
K_{4 }
Slump
 S_{1 }
13.500
26.000
10.000
The variance
Optimal
scheme
13.92188
63.42188
47.29688
X_{1}N_{4}R_{1 }
K_{1 }
7.230
6.950
7.180
7.310
7.740
7.340
K_{2 }
Volumetric
weight
 γ_{0 }
K_{3 }
K_{4 }
7.180
7.190
6.970
7.390
7.070
6.700
The variance
0.02482
0.00722
0.15337
Analysis of optimal options
Optimal
scheme
X_{1}N_{4}R_{4 }
From the results of experiments conducted
orthogonal analysis of factors affecting the criteria to
select the optimal concentrations, respectively; analysis
results are shown in Table 5. Results of the general
equilibrium analysis in Table 5, shows that the slump of
the mixture will be greatest when the contents of X, N and
R are 12.6%, 11% and 1.46%, respectively; the volumetric
weight will be greatest when the contents of X, N and R
are 12.6%, 11% and 2.34% respectively; the compressive
strength will be greatest when the contents of X, N and R
are 18.6%, 10% and 1.46%, respectively. Also, it can be
preliminary assessment that as the cement content
increases, the compressive strength increases; the water
content increases, the slump increases; the straw content
increases, the volumetric weight decreases. This is
completely consistent with the structural principle of
concrete.
Combined with the experimental results in Table 4,
it is very clearly that there are 3 sample groups can satisfy
all 3 criteria simultaneously (Slump, Volumetric weight
and Compressive strength), that are the sample groups in
order: 06, 07 and 16. In which, sample group No. 06 has
the advantage of small cement content, high straw content,
but the highest compressive strength and reasonable
volumetric weight.
Finally, we choose reasonable values for the cement
content, water content and straw content, respectively:
14.6%, 10% and 2.04%. For component materials with
selected content, the designed straw type has the slump,
the volumetric weight and the compressive strength
respectively: 2cm, 1.7g / cm^{3 }and 4.78 MPa.
To assess the degree of influence and reliability, we
conducted variance analysis. Analysis results are shown in
Table 6. From Table 6, it can be seen that the F values
correspond to the influence of cement content, water
content and straw content on slump, volumetric weight
and compressive strength are greater than values of F_{0.05 }
K_{1 }
12.800
16.680
14.450
19.150
5.70395
14.000
17.480
16.300
15.300
1.63970
22.200
16.350
13.730
10.800
17.63595
K_{2 }
Compressive
strength
 R_{b }
K_{3 }
K_{4 }
The variance
Optimal
scheme
X_{4}N_{2}R_{1 }
Table 6. Values of the variance analysis (Note: F_{0.05 }

significant at 95% probability; F_{0.01 } significant at 99%
probability)
Element
F_{S1 }
F_{γ0 }
F_{Rb }
1.05
0.30
3.26
F_{0.05 }
4.76
4.76
4.76
F_{0.01 }
9.78
9.78
9.78
Cement content  X
Water content  N
Straw content  R
0.69
3.12
2.33
0.59
0.17
3.66
CONCLUSION
Taken the B15 mixture as a basic concrete, straw padded
concrete components are designed and analyzed to assess
the effect of cement content, water content and straw
content on the performance of this mixture. The study
results showed that the effect of all three factors on the
performance characteristics of straw concrete is very
clear. Through a general analysis of the effect of
orthogonal experimental results, reasonable values for
cement content, water content and straw content were
selected: 14.6%, 10% and 2.04%. With the selected
component contents, the type of straw concrete is
designed to ensure the slump, volumetric weight and
compressive strength of lightweight concrete. Thereby, it
can be determined that the type of straw concrete as well
To cite this paper: Thanh DV and Tinh PV (2019). Study on Components of Straw Filler Concrete using Orthogonal Experiment. J. Civil Eng. Urban., 9 (5): 4347. www.ojceu.ir
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