Experimental investigation for RCC structural element using the sustainable material like Fly ash and Rice husk ash.
 
Rohini V. Chavan1*, Dr. M. M. Pawar2, Dr. S. P. Patil3, P. B. Bhaganagare4, S. P. Padole5
1 PG Student, Sveri’s College of Engineering, Pandharpur, Maharashtra, India
Email: rohichavhan11@gmail.com
2 Associate Professor, Sveri’s College of Engineering, Pandharpur, Maharashtra, India
3,4,5 Assistant Professor, Sveri’s College of Engineering, Pandharpur, Maharashtra, India
Abstract - Both the strain capacity at fracture and the tensile strength of unreinforced concrete are low. Traditionally, concrete has been strengthened by adding rice husk ash (RHA) to address these deficiencies. It is commonly recognized that Aggregate mixtures are heterogeneous in concrete, water, and cement. To create the desired properties in concrete, a variety of sustainable ingredients are added, including rice husk ash and fly ash. Proper component proportioning, mixing, and compacting are essential for producing strong, long-lasting concrete. A thorough experimental examination will be conducted to examine the impact of partially replacing cement in concrete with rice husk ash. Ash made from burning rice husks is an agricultural waste product with a high degree of reactivity. A by-product of the agriculture sector, rice husk ash (RHA) has a high silicon dioxide (SiO2) content. An effort was made to figure out the ideal burning temperature and duration. The ideal combination, according to the results, is 650 degrees Celsius and a burning time of 60 minutes. Afterwards, a number of tests were run to ascertain the characteristics of concretes with the ideal RHA.
Keywords: Rice Husk Ash ,Fly Ash, Compressive Strength, Pozzolanic materia

INTRODUCTION

The shells formed when paddy rice dehisces are called rice husks. About 200 kg of husk can be produced from one tone of paddy rice, and 40 kg of ash can be produced when the husk is burned. Before 1970, uncontrolled burning was the usual method used to make rice-husk ash (RHA), which was typically crystalline and had poor pozzolanic characteristics. The impact of pozzolanic reactivity of RHA on pyroprocessing parameters A fluidized-bed furnace was designed based on the research to allow for the controlled incineration of rice bran. The rice husks were burned in an environment and temperature regulated to produce a highly reactive RHA. According to studies, rice husks are burned at 600°C yields an ash that is ideal for pozzolanic material. The silica that forms below this temperature is pozzolanic in nature. The study's second section examines the RHA's performance in concrete. India is a global leader in rice production, and the leftover husk from milling is often burned in boilers to process paddy and generate energy. Table 1.1 illustrates the yearly production of rice husk ash (RHA), which amounts to about 120 million tonnes. How varying the amount of rice husk ash added to concrete can affect its mechanical and physical characteristics. Sample cubes were tested with varying w/c ratios and RHA percentages, substituting quantity of cement. Evaluations were done on characteristics including compressive strength, water absorption, and slump.
METHODOLOGY
This research examines methodology using experimental analysis to examine the mechanical characteristics of fly ash and rice husk ash concrete. The current study intends to perform a reliability analysis of the concrete mix by substituting fly ash and rice husk ash for ordinary Portland cement in amounts of 0%, 4%, 8%, 12%, 16%, and 20%, respectively, for M25 grade concrete. The material properties will be taken into consideration.
 

Table 1 : The physical attributes of cement

Sr. No
Test Name
Result
1
Brand
ACC 53 Grade
2
Fineness By dry sieving (%)
1
3
Consistency (%)
30.50
4
Setting Time Initial (minutes)
Final (minutes)
111
221
5
Soundness (mm)
0.8
6
Strength in Compression After three days (N/mm2),
seven days (N/mm2), and
twenty-eight days (N/mm2)
30.210
38.248
54.200
 
Table 2: Fine Aggregate's physical attributes
Sr.
No.
Description
Sand / Fine Aggregate
1
Sender’s Identification
Sand
2
General Description
Natural Sand
3
Particle Shape
Rounded & Coarser
4
Surface Texture
Rough
5
Color
Black
6
Fineness Modulus
3.895
7
Specific Gravity
2.820
8
Absorption %
1.270
 
Table 3 :Physical Characteristics of Coarse Aggregate
Sr.
No.
Description
Metal/Coarse Aggregate 20 mm
Metal/Coarse Aggregate 10 mm
1
Sender’s Identification
Metal
Metal
2
General Description
Crushed Basalt
Crushed Basalt
3
Particle Shape
Angular
Angular
4
SurfaceTexture
Rough
Rough
5
Color
Grey
Grey
6
Fineness Modulus
7.136
5.829
7
Specific Gravity
2.90
3.016
8
Absorption %
0.85
0.65
 
9
Bulk Density (kg/ltr)
A
Loose
2.100
1.898
 
B
Compacted
2.340
1.967

 

Rice Husk Ash Properties

Table 4 :Chemical Characteristics of Rice Husk Ash
Sr. No.
Content
Result Analysis
1
pH
7.21
2
Bulk Density
0.37 (gm/ml)
3
Sp. Gravity
1.04
4
SiO2
93.80%
5
Al2O3
0.74%
6
Fe2O3
0.30%
7
TiO2
0.10%
8
CaO
0.89%
9
MgO
0.32%
10
Na2O
0.28%
11
K2O
0.12%
12
Loi
3.37%
 
Table 5: Characteristics of Rice Husk Ash Physically
Sr. No.
Content
Result Analysis
1
Physical State Solid
Non Hazardous
2
Appearances
Very fine powder
3
Particle size
25 microns-mean
4
Color
Grey
5
Oduor
Odorless

 

Fly Ash Properties :

Table 6:Chemical Characteristics of Fly Husk Ash
Sr. No.
Content
Result Analysis
1
pH
6.12
2
Bulk Density
0.994gm/cm3
3
Sp. Gravity
2.40
4
SiO2
65.6 %
5
Al2O3
28.0 %
6
Fe2O3
3.0 %
7
TiO2
1.0 %
8
CaO
1.0 %
9
MgO
1.0 %
10
Na2O
0.71 %
11
K2O
1.15 %
12
Loi
0.29 %
 
Table 7: Physical Properties of Fly Ash
 
Sr.No
Content
Result Analysis
1
Physical State Solid
Non-Hazardous
2
Appearances
Very fine powder
3
Particle size
6.92 microns-mean
4
Colour
Grey
5
Odour
Odourless
 

Mix Design Stipulation for Rice Husk Ash Concrete :

Table 8: Concrete Mix Design Stipulation
Sr. No.
Particular
M25
a)
Grade designation
25
b)
Type of cement
OPC 53 Grade
c)
Maximum nominal size of aggregate
20
d)
water-cement ratio
0.47
e)
Workability
Medium
f)
Exposure condition
Moderate
g)
Method of concrete placing
Manual
h)
Degree of supervision
Good
i)
Type of aggregate
Crushed angular aggregate
j)
Chemical admixture type
-
k)
Proportions
C
S
M
1
1.932
3.057
100%
20mm

 

Experimental Details:

The experiments are performed on concrete grade of M25. In first phase normal concrete and in second phase high strength concrete were used .The test specimens were divided into categories depending upon the total percentage of volume of Rice Husk Ash (RHA) and Fly Ash (0%, 4%, 8%, 12%, 16%, and 20%) for both grade of concrete. The casting and tests were conducted to find the compressive strength on the cubes of size150mm X 150mm X 150 mm and also compressive strength on cylinder of size 150 mm in diameter& 300 mm & to find the split tensile strength on cylinder of size 150 mm in diameter & 300mm inlength. In addition to this the flexural strength on beams of size 700mm X 150mm X 150mm with a c/c distance of 600 mm under two point loads.
Figure 1.Testing of C Specimen on CTM

RESULTS & DISCUSSIONS

Every category sample undergoes testing and analysis to determine its fresh concrete qualities, such as density, compaction factor, and slump. These samples are also used to measure the deflection values, flexural strength, split tensile strength, and compressive strength of the hardened concrete.
The samples are called sample F (FA), where The first category M25 grade is indicated by the letters F0 (0%), F1 (4%), F2 (8%), F3 (12%), F4 (16%), F5 (20%), and so on. FA stands for the percentage of fly ash in the sample.Ratio: - Cement: 1: 1.932: 3.057 = F.A.: C.A.
Table 9 :Slump, Compaction Factor & Density for M25 Grade of FA Concrete with Different % of Fly Ash
 
SeriesF (FA)
Slump Value
(mm)
Compaction
Factor
Density of concrete
(kg/m3)
F0
120
0.94
2654.81
F1
101
0.94
2648.88
F2
96
0.90
2640.88
F3
91
0.89
2637.04
F4
76
0.88
2634.07
F5
62
0.83
2604.44
 

    Compressive Strength of cube

Figure 2: Compressive strength at different age of M25 grade of Fly Ash concrete

OBSERVATIONS & DISCUSSIONS

  1. F1 to F4 has given performance for achieving reasonable workability & good strength.
  2. In all series for M25 grade concrete, we get M30 grade concrete strength only due to addition of Fly Ash.
  3. It is observed that F1 & F2 FA content is 4% & 8% respectively as compared to F5 20% which FA content is more. It seems as % of FA increases, the homogeneity of mix affected due to which workability as well as strength reduces.
  4. From the result of 7th & 28th day compressive strength it is observed that series F5 (20%) got poor strength as compared to other series, because % of FA is high which makes mix non homogeneous.
  5. From the result of 45th & 90th day compressive strength it is observed that strength of concrete increases 7% of 28th day compressive strength.

    6. . Compressive Strength of cylinder

Figure 3. Compressive Strength at Different Age of M25 Grade of FA Concrete
Table 10 : Flexural Strength for M25 Grade FA Concrete with Various Fly Ash Content at Day 28
Series F (FA)
Flexural Strength(N/mm2)
F0
4.72
F1
4.67
F2
4.55
F3
4.49
F4
4.45
F5
3.96
 
Figure 4: Flexural Strength at 28th Day for M25 Grade of FA Concrete with % of Fly Ash Content
Sample F (RHA) is the name given to the samples, where F0 (0%), F1 (4%), F2 (8%), F3 (12%), F4 (16%), F5 (20%), and so on indicate the first category M25 grade. RHA stands for the percentage of rice husk ash in the sample.
Proportion: - Cement: F.A.: C.A. = 1: 1.932: 3.057
I. Compressive Strength of cube
Figure 5: Compressive strength at different age of M25 grade of RHA concrete

Flexural Strength for Rice Husk Ash Concrete

Table 10: Flexural Strength at 28th Day for M25 Grade of RHA Concrete with Different % of RiceHusk Ash Content
Series F (RHA)
Flexural Strength(N/mm2)
F0
2.67
F1
2.72
F2
2.55
F3
2.49
F4
2.45
F5
1.96
 

CONCLUSIONS

The investigation into the effects of varying proportions of fly ash and rice husk ash has potential because concrete's brittleness and workability are persistent issues that need to be resolved. The current study allows for the deduction of the following conclusions.
Few Prominent General Conclusions for Rice Husk Ash (RHA) Concrete:
  1. The workability of concrete decreases as the percentage of RHA rises. This decrease is somewhat significant.
  2. 3% to 6% more amount of water is required in comparison with normal concrete for gettingdesired workability using RHA.
  3. The weight of Rice Husk Ash concrete is reduced up to 4% to 6% in comparison withnormal concrete.
  4. Rice husk ash can replace cement up to 20% of the cement content with safe outcomes.
  5. The cube's maximum 28-day compressive strength of 32.16N/mm2 was achieved with 4%, or rice husk ash, in the mixture.
  6. The highest 28-day compressive strength of the cylinder was achieved by adding 4%, or 25.52N/mm2, of rice husk ash to the mixture.
  7. The highest 28-day split tensile strength of 2.80 N/mm2 was achieved with 4% of rice husk ash in mixture.
  8. The highest 28-day flexural strength of 2.72 N/mm2 was achieved with 4% of rice husk ash in mixture.
Few Prominent General Conclusions for Fly Ash (FA) Concrete:
  1. Concrete becomes less workable as the percentage of FA rises. This decrease is somewhat significant.
  2. 4% to 6% more amount of water is required in comparison with normal concrete for gettingdesired workability using RHA.
  3. In the case of fly ash, the replacement rate may exceed 20%.
  4. The cube's maximum 28-day compressive strength of 34.16N/mm2 was achieved with 4% fly ash in the mixture.
  5. The maximum 28-day compressive strength of the cylinder was achieved with 4% fly ash in mix, or 27.50 N/mm2.
  6. The highest 28-day split tensile strength of 2.82 N/mm2 fly ash in mix was achieved at 4%.
  7. The highest 28-day flexural strength of 4.67 N/mm2 was achieved with 4% fly ash in mixture.

REFERENCES

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