2019 Scienceline Publication  
Journal of Civil Engineering and Urbanism  
Volume 9, Issue 5: 43-47; September 25, 2019  
ISSN-2252-0430  
DOI: https://dx.doi.org/10.29252/scil.2019.jceu6  
Study on Components of Straw Filler Concrete using  
Orthogonal Experiment  
  
Dang Van Thanh and Pham Van Tinh  
Department of Civil Engineering, Vietnam National University of Forestry, Hanoi, Vietnam  
Corresponding author’s Email: thanhdv@vnuf.edu.vn; thanh40e@yahoo.com  
ABSTRACT  
Study on the use of agricultural residues in the production of construction materials is important in reducing  
construction costs, while minimizing environmental impacts. By using the orthogonal experimental design method  
and the experimental method in laboratory for determining slump of the concrete mix, compressive strength and  
volumetric mass of concrete, this paper shows the designing method of concrete component using straw fillers  
(straw filler concrete - straw concrete). Also, this study analyzes and assesses the influence of three factors: cement  
content, water content and straw content on basic features of designed concrete such as slump, volume and  
compressive strength, thereby determines the reasonable content of the components. Experimental results showed  
that, straw padded concrete meets the basic performance criteria for lightweight concrete when designed with  
reasonable components and the effect of these three factors on the basic features of straw concrete is very  
pronounced. Reasonable values of cement content, water content and straw content used to produce straw concrete  
mixture are: 14.6%; 10% and 2.04% respectively.  
Keywords: Light weight concrete; Straw filler concrete; Agricultural by-product; Orthogonal Experiments.  
INTRODUCTION  
good fire resistance that will create the inner environment  
of a quieter, safer and healthier home. Furthermore,  
materials for fabricating components are easy to use,  
lightweight and do not require much equipment. The  
authors also suggested that more research is needed to  
further promote technology and to make efforts in  
propagating the value of straw construction works and to  
make straw become the main construction material.  
Reducing environmental impacts is an increasingly  
significant requirement in the agricultural production  
activities of people at present, especially after harvesting  
rice. There are six tons of straw per hectare remained on  
the environment after harvesting, and almost of them are  
removed by burning or left in the field. This destructing is  
not only waste but also affecting to our environment. This  
study aims to utilize rice straw - a source of local  
materials available in rural areas to make concrete  
materials and meets the practical requirements of the new  
rural program, while contributing to reducing the negative  
impact of agricultural waste on the environment.  
In fact, there were rarely researches published on  
using straw for building materials, especially aggregate of  
concrete, up to now. Brojan et al. (2013) compared using  
brick and straw bale wall by environmental, economic and  
energy perspectives showed that straw wall can be  
replaced for brick wall. Brick is the most commonly used  
building material worldwide, whereas straw, though  
widely available and having many advantageous  
properties, is still rarely exploited. In terms of  
environmental, economic and energy values, the use of  
straw components is a good alternative to bricks.  
Farooqi and Ali (2016) recommend the wheat straw  
reinforced concrete has the potential to be used for the  
concrete pavement applications due to its post cracking  
behavior as it can elongate the period from the first crack  
up to the complete deterioration. Liu et al. (2012)  
concentrated on the impact of rice straw as additive  
material on physical properties of hollow block. When the  
rice straw amount portion was 0 to 15% of aggregate of  
hollow block, the compressive, flexural strength of hollow  
block decreased gradually. However, it is more suitable  
for building material. Alcorn and Donn (2010); Hall  
(2012) and Sodagar et al. (2011) showed that using straw  
bale as a construction material reduces the CO2 emissions.  
It is estimated that over fifteen tones of CO2 may be  
stored in biotic materials of each of the semi-detached  
houses of which around six tones are sequestered by straw  
and the remaining by wood products. The analysis result  
indicates that the carbon lockup potential of renewable  
materials used in the construction of the house is the  
capable of reducing 61% CO2 emissions in sixty year life  
Brojan and Clouston (2014) through analyzing the  
advantages and disadvantages of straw building material  
concluded that together with natural plaster, the  
"breathing" straw wall has good sound absorption and  
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): 43-47.  
www.ojceu.ir  
43  
compared with the house built with the common  
materials.  
Study plan  
Using theoretical calculation method combined with  
experiments to design basic components of straw  
concrete: by calculating for determination of the base  
concrete composition with the required average  
compressive strength is 20MPa (concrete B15); then, use  
the experimental method gradually (mixing, intuitive and  
test slump) to replace a part of coarse aggregate by straw  
and determine the initial material composition. Based on  
the initial material composition, cement content, water  
content and straw content are changed. Using the method  
of orthogonal experimental design the sample groups are  
manufacture. Afterwards, the indicators included slump of  
mix, volume weight and compressive strength of samples  
at 28 days of age are determined with reasonable contents  
for the material components through experiments.  
In Vietnam, almost there is no official study on the  
use of straw as a material generally and as a concrete filler  
in particular. Using orthogonal test methodology  
(Shaohua and Fenghua, 2003) and the laboratory test  
methods: slump test, volume weight test and compressive  
strength test, this paper introduction of mixed component  
design method and analysed the influences of three  
material composition factors, namely: cement content (X),  
water content (N) and straw content to basic properties of  
straw concrete; thereby determining the reasonable  
content of these three factors for straw padded concrete to  
meet the requirements of lightweight concrete.  
MATERIAL AND METHODS  
Materials  
Orthogonal experimental design method  
Binder: Portland cement PCB-40 manufactured in  
Vietnam was used. The technical properties of the cement  
are in accordance with Vietnam standard TCVN  
2682:2009 and are shown in Table 1. Fine aggregate and  
Coarse aggregate used for this study was produced from  
local sources in Hanoi city of Vietnam. Technical  
properites of fine and coarse aggergates were in  
accordance with Vietnam Standard (2006). Straw fillers  
used new straw (straw immediately after harvesting rice);  
the straw is dried, then cut into small pieces about 3 ÷  
5cm long. Before mixing, the straw is soaked in 20 ÷ 30  
minutes in clean water, then picked out and drained. The  
images and processing of straw fillers are shown in Figure  
1.  
To evaluate the influence of these factors to  
performances of straw concrete, we use the orthogonal  
experimental design method (Brojan et al., 2013). The  
method studies the influence of many factors in  
experiments. Based on methods of scientific experiment,  
orthogonal method has advantages in minimizing numbers  
of experiments, thereby to reduce time and cost for doing  
experiments. In fact, this method is very efficient, fast and  
economical. The order for the design and analysis of  
experimental results according to the orthogonal  
experiment method can be divided into three steps:  
experimental plans design, experiment performance and  
analysis of experimental results.  
Basic testing methods  
Table 1. Typical properties of cement PCB-40  
The basic property tests of aggregates, of concrete  
and concrete mixtures are done according to current  
Vietnamese standards:  
TCVN 7572 - 1-18: 2006 - aggregate tests;  
TCVN 3106: 1993 - method for slump test;  
TCVN 3118: 1993 - method for determination of  
compressive strength;  
No  
Typical properties  
Request  
Compressive strength  
1
3 days (± 45 minutes)  
28 days ( ± 8 hours)  
Setting time  
≥ 21 N/mm2  
≥ 40 N/mm2  
2
3
Initial  
Final  
≥ 45 min  
≤ 375 min  
Fineness:  
TCVN 3115: 1993 - method for determination of  
density.  
The amount of 0,09mm sieve  
Blain rate  
≤ 10 %  
≥ 2800 cm2/g  
RESULTS AND DISCUSSION  
Calculation and basic component selection results  
Determining the amount of mixing water. The  
amount of water (N) was determined based on the  
conditions of the materials and designing requirements.  
Chosen concrete grade was B15 with average compressive  
strength Rb = 20MPa; the coarse aggregate used had the  
largest diameter Dmax = 20mm. The slump of concrete  
mixture and the amount of mixing water was selected by  
the method used in common constructions (Shaohua and  
Fenghua, 2003): For coarse aggregate, crushed stones  
with Dmax = 20mm were used, and the slump of mixture  
Figure 1. Specification and process of straw fillers  
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): 43-47. www.ojceu.ir  
44  
was about 2 ÷ 4cm. The amount of water determined for  
1m3 of the concrete was 200 liters.  
Determining the ratio of cement to water. The  
ratio of cement to water (X/N) was based on the Bolomey  
– Skramtaev fomula (Huy et al., 2011):  
Determine the amount of straw to replace a part  
of coarse aggregate. From the calculation results of  
concrete base components, try gradually by mixing, visual  
observation and slump measurement, the finally amount  
of large aggregate is determined by reducing 40%  
(compared to the volume of initial coarse aggregate) and  
replacing this amount with straw with a content of 1.46%  
(percentage between dry weight of straw and the total  
volume of the mixture). Specifically, the calculation  
results and selected initial materials of straw concrete  
production are shown in Table 2.  
Regular concrete (X/N = 1.4 ÷ 2.5):  
Ryc  
X
N
0.5  
ARx  
In which, Rx – the strength of cement (Rx = 40MPa);  
Ryc – the strength of concrete at 28 days; A – the factors  
of raw materials, choose A = 0.6 (with good quality  
materials) (Huy et al., 2011). The cement –water ratio was  
finally calculated to be 1.42.  
Determining the amount of cement. Determining  
the amount of cement (X) was based on X/N ratio which  
was determined in the above step. From the amount of  
water (N) = 200 litres and the X/N ratio = 1.42 determined  
above, the amount of cement for 1m3 of concrete was  
calculated to be 292 kg. The amount of cement should be  
compared to the amount of minimum and maximum  
cement (Xmin and Xmax) which are based on the design  
standard. The determined cement amount was within the  
range for the minimum and maximum cement in Vietnam  
standard.  
Results of determining orthogonal experimental  
plans  
Based on the calculation results and selection of  
initial material components (Table 2), we selected 4  
experimental levels for each influencing factor, shown in  
Table 3. From the data in Table 3, using the orthogonal  
experimental design method in Alcorn, A. and Donn, M.  
(2010) to design, obtained 16 experimental groups,  
specifically as shown in Table 4.  
Table 2. The original material composition  
Materials  
Mass, kg  
D
C
X
N
R
Total  
29,2 2000  
100  
Determining the amount of coarse and fine  
aggregates. Determining the amount of coarse  
aggregate (D): The amount of coarse aggregate for 1m3 of  
concrete was determined as follows (Shaohua Z and  
Fenghua ed J - 2003).  
718  
761  
292  
200  
Content, % 35,90 38,05 14,60 10,00 1,46  
Table 3. The influence factors, experimental levels and  
composition of manufactured materials  
Influence factors  
1000  
Exp  
levels  
D, %  
(kg)  
C, %  
(kg)  
D   
;kg  
X, %  
(kg)  
N, %  
(kg)  
R, %  
(kg)  
kd.rD  
1
oD  
aD  
1
2
3
4
12.60  
(252)  
9.50  
(190)  
1.46  
(29.20)  
35.90  
(718)  
38.05  
(761)  
Where: 0D – volumetric weight of coarse  
aggregate; aD - density of solid particles of coarse  
aggregate; rD – porosity of coarse aggregate; kd – mortar  
14.60  
(292)  
10.00  
(200)  
1.75  
(35.04)  
35.90  
(718)  
35.90  
(718)  
38.05  
(761)  
38.05  
(761)  
16.60  
(332)  
18.60  
(272)  
10.50  
(210)  
11.00  
(220)  
2.04  
(40.88)  
2.34  
(46.72)  
residue coefficent. From the experimental results: γ0D  
=
35.90  
(718)  
38.05  
(761)  
1.48g/cm3, γaD = 2.8g/cm3 và rD = 0.47; with the amount  
of cement is 292kg, mortar residue coefficient kd = 1.36.  
Substituting all the paramaters into the formula, the  
amount of coarse aggregate in 1m3 of concrete was  
calculated: D = 1197kg.  
Table 4. Tested results of sample groups  
S1,  
cm  
4.0  
5.5  
6.5  
7.0  
1.0  
2.0  
3.0  
9.0  
0
γ0,  
g/cm3  
1.98  
1.86  
1.74  
1.65  
1.76  
1.70  
1.66  
1.83  
1.76  
1.71  
1.89  
1.82  
1.68  
2.04  
1.90  
1.77  
≤
Rb,  
MPa  
4.50  
3.30  
2.70  
2.30  
3.60  
4.78  
2.80  
5.50  
2.70  
2.50  
5.30  
3.95  
3.20  
6.90  
5.50  
3.55  
≥
TT  
X
N
R
01  
02  
03  
04  
05  
06  
07  
08  
09  
10  
11  
12  
13  
14  
15  
16  
1(12.6)  
1
1
1
2(14.6)  
2
2
2
3(16.6)  
3
3
3
1(9.5)  
2(10)  
3(10.5)  
4(11)  
1(1.46)  
2(1.75)  
3(2.04)  
4(2.34)  
Determining the amount of fine aggregate (C):  
After the amount of the mixing water (N), cement  
(X) and coarse aggregate (D) were determined, the fine  
aggregate (C) for 1m3 of concrete was calculated using the  
following formula (Huy et al., 2011):  
1
2
3
4
1
2
3
4
1
2
3
4
2
3
4
1
3
4
1
2
4
1
2
3
X
D
C 1000   
N .;kg  
aC  
aX aD  
0
Where: γaX – weight of solid particles of cement (γaX  
= 3.05g/cm3); γaD – weight of solid particles of coarse  
aggregate (γaD = 2.8g/cm3); γaC – weight of solid particles  
of fine aggregate (γaC = 2.75g/cm3). Substituting all these  
paramaters into the above formula gives the amount of  
fine aggregate: C = 747kg.  
8.0  
7.0  
0
6.5  
4.0  
3.0  
2 -  
4[14]  
4(18.6)  
4
4
4
Request  
1.8[16] 1.0[16]  
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): 43-47. www.ojceu.ir  
45  
and F0.09. 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 (S1), compressive strength  
at 28 days in natural dry state (Rb) and the volumetric  
weight of 28-day-old in the natural dry state (γ0) 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 (%)  
K1  
23.000  
15.000  
15.000  
5.000  
14.000  
21.500  
27.500  
17.500  
11.500  
K2  
K3  
K4  
Slump  
- S1  
13.500  
26.000  
10.000  
The variance  
Optimal  
scheme  
13.92188  
63.42188  
47.29688  
X1N4R1  
K1  
7.230  
6.950  
7.180  
7.310  
7.740  
7.340  
K2  
Volumetric  
weight  
- γ0  
K3  
K4  
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  
X1N4R4  
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 / cm3 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 F0.05  
K1  
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  
K2  
Compressive  
strength  
- Rb  
K3  
K4  
The variance  
Optimal  
scheme  
X4N2R1  
Table 6. Values of the variance analysis (Note: F0.05  
-
significant at 95% probability; F0.01 - significant at 99%  
probability)  
Element  
FS1  
Fγ0  
FRb  
1.05  
0.30  
3.26  
F0.05  
4.76  
4.76  
4.76  
F0.01  
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): 43-47. www.ojceu.ir  
46  
Zealand. Victoria University of Wellington, Master thesis  
of Architecture 2012. Google Scholar  
as the design of straw concrete components according to  
the orthogonal testing method is feasible.  
Huu P D, Quang N T, Loc M D (2011). Building materials.  
Communication and Transport Press, Hanoi,  
Competing interests  
Liu J, Zhou H H and Zhang B (2012). Effect of Rice Straw  
Amount Portion on Physical Properties of Adding  
Admixtures Hollow Block. In Advanced Materials  
Research (Vol. 450, pp. 727-732). Trans Tech Publications.  
Google Scholar  
The author declare that it has no competing interests.  
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47