Mechanical and durability properties of bagasse ash-blended high-performance concrete
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The use of supplementary cementitious materials has become an integral part of high-strength and high-performance concrete mix design, which may be natural by-products or industrial wastes. Some of the frequently used supplementary cementitious materials are fly ash, silica fume, ground granulated blast furnace slag, rice hush ash and bagasse ash (BA). BA (sugarcane industry waste product) is considered to be an active pozzolan because of its large surface area with significant amount of amorphous SiO2. The mix design for high-performance concrete is done as per the method proposed by P. C. Aitcin. This method is simple and follows the same approach as ACI 211-1 standard practice for selecting proportion of normal, heavy and mass concreting. Ordinary Portland cement was replaced at different levels of 0%, 5%, 10%, 15% and 20% by BA. This investigation presents results on the strength and durability properties of high-performance concrete with and without BA, which includes cube compressive strength, splitting tensile strength, flexural strength, saturated water absorption, sorptivity, porosity, impact test and alkalinity measurement. The test results indicate that the incorporation of BA up to 10% provides improved properties of hardened concrete.
KeywordsBagasse ash High-performance concrete Mechanical properties Durability properties
Major construction projects today around the world use ordinary Portland cement as a binder for manufacturing of mortar and concrete . Production of cement emits carbon dioxide worldwide, which causes environmental issues such as dust pollution and thinning of ozone layer, which leads to global warming . Utilization of supplementary cementitious materials as a partial replacement of cement mortar and concrete is the most effective way of reducing the environmental impact, which also minimizes energy, cost and waste emission [3, 4]. The wastes from various industries such as silica fume, fly ash and blast furnace slag were used as mineral admixtures. Bagasse ash, rice husk ash and wheat straw ash were also being used as pozzolanic materials in various forms [5, 6]. Mineral admixtures as partial replacements of cement improve the mechanical and durability properties of concrete .
In India, sugarcane production was about 300 million tons per year  and plenty of bagasse is available in sugar industry. Bagasse is partly used as fuel in sugar industry and the remaining was dumped in ground. Silica content present in the pozzolan reacts with the free lime during hydration and forms calcium silicate hydrate (CSH) . During hydration process, formation of C–S–H gel improves properties of blended (cement and supplementary cementitious material) hardened concrete. However, hydration time is inversely proportional to the porosity, which also increases pore structure and permeability of mortar and concrete. The waste from agro-industry was burnt in incinerating temperature of below 700 °C for 1 h which converts the silica content of the ash into amorphous phase . In order to achieve the required size, ash was grinded in laboratory ball milling. The grinded ash mixed with ordinary Portland cement produces blended cement. The characteristics of agricultural industry waste ash purely depend on the following process such as burning, maintaining constant temperature, drying and grinding.
The objective of the present study is to assess the performance of bagasse ash as supplementary cementitious material in mechanical and durability properties of high-performance concrete, as well as to make out the optimal level of replacement.
2.1 Cement and bagasse ash
Chemical composition of cement and bagasse ash (%)
Coarse aggregate in surface dry condition of size confirming to 20 mm was used. River sand was used as fine aggregate in saturated surface dry condition. Coarse aggregate and fine aggregate specific gravity is found to be 2.85 and 2.66. Water absorption of coarse aggregate and fine aggregate was 0.85% and 3.09%, respectively. All the aggregates were conforming to IS 383: 2016  specifications.
2.3 Super plasticizers
The properties of super plasticizer were given as polycarboxlic ether-based super plasticizer, colour—light brown, and specific gravity—1.08 ± 0.01 at 25 °C, pH ≥ 6. The dosage of super plasticizer is adopted is 10 L/m3 of concrete. It was primarily developed for application in high-performance concrete for reducing water content.
3 Experimental work
3.1 Mix proportion and casting of HPC specimens
Bagasse ash (%)
Water binder ratio
Bagasse ash (kg/m3)
Fine aggregate (kg/m3)
Coarse aggregate (kg/m3)
Super plasticizer (L)
Ordinary Portland cement was replaced with bagasse ash of proportions 5, 10, 15, 20% by weight of cement. Five different concrete mixtures including control mixtures were prepared with a water binder ratio of 0.28. Concrete was mixed for about 5 min in laboratory drum mixer. The details of the number of concrete specimens cast for the present study are as follows: cube specimens of size 150 mm of 30 Nos., cylindrical specimens of size 150 mm diameter and 300 mm height of 30 Nos., prism specimens of size 100 mm × 100 mm × 500 mm of 30 Nos., cube specimens of size of 100 mm of 63 Nos., and disc specimens of size of 152 mm diameter and 62.5 mm thickness of 21 Nos. After 24 h of casting, the test specimens were demoulded and immersed in water for curing, till the age of test.
3.2 Mechanical properties
The cube compressive strength was calculated as per IS 518-2004  for bagasse ash-blended high-performance concrete. Splitting tensile strength was carried out on bagasse ash-blended high-performance concrete cylinders as per IS 5816-2004 . Prism specimens were cast to determine the flexural strength of bagasse ash-blended high-performance concrete. The test was carried out at the age of 7 and 28 days curing.
3.3 Durability properties
Saturated water absorption (SWA) tests were carried out on bagasse ash-blended high-performance concrete cube specimens as per ASTM C642  at the age of 7 and 28 days curing. SWA of bagasse ash-blended HPC is used to assess of the pore volume or porosity in hardened concrete which is occupied by water in saturated condition. It represents, in saturated bagasse ash-blended HPC specimens, the amount of water which can be separated on drying. The porosity obtained from absorption tests is designated as effective porosity. The formula used to calculate the effective porosity: (volume of voids (Ws–Wd)/bulk volume of specimen (Ws–Wsub)) × 100, where Ws is weight of specimen at fully saturated condition, Wd is weight of oven-dried specimen and Wsub is submerged weight of specimen in water . Sorptivity measures the rate of infiltration of water into pores available in concrete. The sorptivity values of bagasse ash-blended high-performance concrete specimens after 28 and 90 days were calculated using the formula I = S × T0.5, where I is absorption per unit area (mm), S is sorptivity (mm/h0.5) and T is the time elapsed . The impact strength tests were carried out on bagasse ash-blended high-performance concrete specimens at the age of 28 days curing using drop weight testing device as per ACI Committee 544. 2R-89. By using hammer, tested bagasse ash-blended high-performance concrete cube specimens were broken into small pieces. Further, the small pieces were powered using laboratory ball milling and pulverizer. For all the mixes, processed powder sample was tested for alkalinity.
4 Results and discussion
4.1 Compressive strength
Mechanical properties of bagasse ash-blended HPC
% Increase in strength
4.2 Splitting tensile strength
4.3 Flexural strength
4.4 Saturated water absorption
Durability properties of bagasse ash-blended HPC
Reduction compared to conventional concrete
The transformation of large pores into fine pores was achieved in fly ash-blended concrete due to the low permeability, which increases the pore reinforcement. Occurrence of pore reinforcement is due to the conversion of calcium hydroxide into calcium silicate hydrate gel by silica content (pozzolanic), which fills the large voids in hydrated cement and liberates some amount of calcium hydroxide. Similar pozzolanic reaction takes place in BA-blended HPC, in which BA converts calcium hydroxide into calcium silicates. Thus, due to the effect of BA between cement paste phase and aggregate phase in transition zone, HPC gets lower permeability. Generally, transition zone is less dense in plain cement concrete than the cement paste and has minimum amount of crystal of calcium hydroxide, which gets reduced due to the addition of BA. The pores (micro and macro) present in HPC are filled by finer particles.
4.7 Impact test
Alkalinity measurement and impact strength of bagasse ash-blended HPC
pH value of samples (28 days curing)
Number of blows
Energy absorbed for ultimate failure (N m)
pH indicating papers
4.8 Alkalinity measurement
The early compressive strength development may be due to the reaction of bagasse ash with CaO, which improves the hardening process in bagasse ash-blended HPC.
The splitting tensile strength increases gradually from 12.92 to 25.17% for the cement replacement of 5–10% of bagasse ash at the age of 28 days.
The flexural strength was increasing gradually from 2.09 to 3.08%, respectively, for the bagasse ash replacement level of 5–10%. Therefore, inclusion of bagasse ash improves strength properties of concrete up to 10%. Bagasse ash acts as micro-filler and improves the density of cement paste. The bond between the cement paste and the aggregate particles is enhanced and improves the concrete strength.
Due to the reduced permeable voids after 90 days of curing, the percentage of water absorption values of bagasse ash-blended HPC mix decreased reasonably.
Sorptivity of bagasse ash-blended HPC at 28 and 90 days curing gradually reduced with the increase in the bagasse ash content up to 20%, when compared with the control mix specimen.
The porosity of the HPC mixes varies from 2.20 to 2.70% at the age of 28 days. Similarly porosity varies from 2.10 to 2.40% at the age of 90 days. The porosity of the bagasse ash-blended HPC mixes was lower than the HPC mix without bagasse ash. Durability properties of HPC mixes blended with bagasse ash show significant improvement between 10% and 15% of replacement of cement.
Due to the formation of constant C–S–H in HPC mixes, impact resistance of bagasse ash-blended HPC mixes showed higher values compared to that of mixes without bagasse ash.
The pH values of HPC powder sample blended with bagasse ash showed lower value of 13.05 to 13.23 compared to sample without bagasse ash, where there is no loss of alkalinity significantly. The reduction in the pH is due to the presence of high magnesium content, which gradually replaces calcium hydroxide in HPC.
The authors wish to thank UGC, New Delhi, for their financial support under minor research Project MRP-6458/16(SERO/UGC) and Dr. R. Rudramoorthy, Principal, PSG College of Technology, Coimbatore, for the facilities and support provided in carrying out this research work at Advanced Concrete Research Laboratory.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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