Experimental study on different properties of cenosphere based concrete using calcium lactate

Abstract

Keywords: Calcium Lactate; Cenosphere; Compressive Strength; Flexural Strength; Microstructural Analysis; Plastic And Dry Density; Split Tensile Strength

Introduction

Concrete is the most extensively used building material and has contributed a significant amount to contemporary civil infrastructure over the past century. Concrete is a mixture of versatile materials which make it strong and durable [1]. Cenosphere, as a cementitious material, represents a novel technological advancement that forms the foundation for concrete development [2]. Cenospheres are derived from coal-fired power stations, it may also known as fly ash cenospheres (FAC). Cenospheres are valued in

the construction industry for their lightweight, low-density, high compressive strength, and thermal insulation properties. Their chemical composition, primarily silica, contributes to their durability and resistance to chemical reactions. Their physical attributes, such the dispersion of their particle sizes [3–10], specific surface area [11,12], shell thickness [13], diameter [13–15], colour [14, 16], particle bulk density [17,18], specific gravity [19,20] and water absorption [16, 20] may affects workability, strength and overall performance of concrete. These chemicals and physical properties make cenospheres a valuable additive for improving

*Corresponding author. *E-mail address: zanjadnilesh13484@gmail.com This paper was recommended for publication in revised form by Editor-in-Chief Ahmet Selim Dalkilic Published by Yıldız Technical University Press, İstanbul, Turkey Copyright 2021, Yıldız Technical University. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

Sigma J Eng Nat Sci, Vol. 42, No. 6, pp. 1786−1796, December, 2024

Table 1. Particle size distribution (wt.%) of cenosphere Sieve

Table 2. Chemical structures (wt%) of cenosphere materials Description

the performance of construction materials like concrete and composites. The average particle density of the cenospheres utilised in the concrete is about 850 kg/m3. Table.1 shows the particle size distribution of the cenospheres, with the majority of the particles falling between 63 and 150 μm in size. Cenosphere is versatile material utilized in construction industry for lightweight concrete [8,21], energy saving building design [12], ceramic construction [17], internal curing agent [15,22–24] and manufacturing composite materials [23, 25, 26]. The qualities of both freshly poured and hardened cenosphere concrete will be discussed, and any differentiations observed will be compared to more conventional concretes. It aims to provide a deeper comprehension of the possible benefits and drawbacks of cenosphere concrete. This concrete investigates the ideal cenosphere component to take into account when designing concrete mixes. Concrete uses the cenosphere as a binding agent in place of some of the cement. The chemical composition of cenospheres shows high combined SiO2 and Al2O3 content of 96.5% but low CaO content equal to 0% as shown in Table 2. The use of fly ash cenosphere is highly helpful for lowering density and bettering concrete’s performance; utilising hazardous trash to alleviate environmental issues, and lowering the utilization of cement and hence lower the carbon footprint of the manufacture of concrete while only slightly reducing compressive strength. Utilizing industrial waste, cenosphere is employed in mixes up to about 10% by volume of total cement materials, calcium with 0.010 and 0.015 mol/lit gives concrete density under 2550 kg/m3, Owever, they share many of the same mechanical characteristics as regular concrete (Figure 1).

also supports the hollow spherical shape and size variation of the FAC, which ranges from 63 to 150 µm as shown in Figure 2. A versatile mineral called calcium lactate is utilized to meet the need for calcium required by cenosphere and bacteria in concrete at different stages of development. The calcium lactate has a chemical compound of (C6H10CaO65H2O) with a molar weight of 308.31 g/lit. Calcium lactate’s physicochemical compositions are shown in Tables 3 and 4. The calcium lactate that is included in the mix design is added in hydrated form and is precisely soluble in the water together with the other ingredients of concrete. Calcium lactate molar weight quantity is utilised as 0.01(CL0.010) and 0.015(CL0.015) mol/lit shown in Table 6. The concrete mixtures are made in the lab using a pan mixer. According to IS’s recommendations, the physical characteristics of coarse and fine aggregate (CA and FA) are examined shows in Table 5. The potable water is utilised as instructed by IS 456.

Materials And Methods

In accordance with Indian Standard (IS) 12269, the experimental work is done on concrete specimens made of fly ash cenosphere and ordinary Portland cement (OPC) as the binder ingredient. Cenosphere-based low-density concrete achieves good workability of concrete mix. According to the FAC grading, the majority of the particles are between 63 to 150 µm in size. Additionally, the SEM examination

Sigma J Eng Nat Sci, Vol. 42, No. 6, pp. 1786−1796, December, 2024

MIX Proportion

In the cement-based system, pozzolanic reactions might benefit from the presence of amorphous silica and a tiny amount of lime. Due to the dehydroxylation and decarbonization processes in the cement hydration, cement paste incorporated of FAC composites exhibits weight loss. still, it will give better mechanical properties even at lower density levels [2]. Calcium oxide is a dominant compound that is observed in the chemical analysis of FAC, to overcome that calcium lactate is precisely soluble in the water together with the other ingredients of concrete. To know the effect,

the Concrete mix was categorized into two groups, the first specimen set with five combinations of FAC and cement percentages of replacements, those five combinations are Normal Concrete (CN), Concrete with FAC 2.5% (CN2.5), FAC 5% (CN5), FAC 7.5% (CN7.5), and FAC 10% (CN10). The second specimen set with two combinations of FAC with different contents of calcium lactate, those two combinations are Concrete with FAC (0%,2.5%,5%,7.5% and 10%) with

Experimentation

Concrete mixtures were divided into two groups; the first specimen set consisted of five concrete mixtures that were made by using FAC instead of OPC, in different combination of 0%, 2.5%, 5%, 7.5% and 10% each & second specimen set consist of two combinations of FAC with different contents of calcium lactate, those two combinations are Concrete with FAC (0%,2.5%,5%,7.5% and 10%) with calcium lactate (0.01 mol/L) and FAC (0%,2.5%,5%,7.5% and 10%) with calcium lactate (0.015 mol/L). The control mix was the concrete mix that did not contain FAC or calcium lactate. Table 6 lists the precise mix proportions along with their names. As the two sets of mixes were prepared, in the first set FA and CA well mixed together to get uniformity then cement and FAC add as a binder in composition. Dry mixing time is increased by 5-7 minutes over the control concrete mix. Finally calculated the exact amount of water added to the dry mix to get homogeneous and workable concrete. In the second set dry mix was prepared in the same way as that of the first set, but before adding water

to the mix, calcium lactate by weight is added to the water and uniformly diluted for 4-5 min afterward the water was added in the dry mix. The obtained fresh mix was utilized right away to perform a slump cone test to determine its workability; the results are listed in Table 7. Utilizing the special qualities of cenospheres to promote flow and lessen friction within the mixture, cenosphere concrete with a slump range of 104111mm exhibits high workability and is appropriate for a variety of building applications. According to IS 1199, the slump cone examination is carried out on new laid concrete; the W/C ratio is kept at 0.5 in each mix. Fresh concrete was then poured into the designated mould needed for the various tests. A table vibrating machine was used for achieving the compactness of poured concrete. After 24 h ± 1 h of air curing, specimens were taken out from the molds and placed for curing in water. The test specimens were taken out from the curing tank after receiving enough curing and allowed to dry at room temperature. At the ages of 7 and 28 days, the specimens are subjected to the standard test using the instructions outlined in IS 516.

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Result And Discussion

Plastic and Dry Density The density is a key index for evaluating the physical and mechanical properties of concrete. The density of material affects the consumption and utilization of the material in the mix, which directly affect the cost of the structure. The density of the concrete mix was measured for freshly laid concrete after 24 hours, for surface saturated concrete after 28 days, and for oven-dry concrete after 24 hours. Table 8 shows the impact of various circumstances noticed on the sample. The use of FAC and calcium lactate in the mix shows little variation in density. FAC is hollow in nature due to which concrete loses density when the proportion of FAC rises. The addition of calcium lactate in the mix shows linear changes in the density of concrete. From the obtained result it is observed that at FAC 10% replacement of cement shows a 4.62% reduction in density, simultaneously when calcium lactate of 0.010 mol/lit and 0.015 mol/lit is added to the mix it shows 4.69% and 4.80% reduction in density. The obtained result shows density at various percentages of FAC shown in Figure 3. Compressive Strength Testing a 150 x 150 x 150 mm cast cube on a compression testing equipment yields information about concrete’s

compressive strength. Concrete mixes were categorized into two groups to check the effect of FAC replacement with cement and adding of dissolved Calcium lactate on the compressive strength of concrete. Employing IS 10262, the concrete mix was built for M25 grade, and then FAC is added to the mix as a partial substitution of 2.5%, 5%, 7.5%, and 10% for OPC. According to the results, FAC 2.5% replacement provides stronger strength when compared to regular concrete because of cenosphere fineness. But it exhibits a loss of strength when the proportion of FAC rises, this may happen because of its hollow shape and less amount of calcium elements present in FAC. The variation of compressive strength at various percentages of FAC shows in Figure 4. Further to this two concentrations of calcium lactate were added to the mixture of 0.010 mol/lit and 0.015 mol/ lit. For a uniform mixture of calcium lactate in the mix, calcium lactate was dissolved in water and afterward, it was added to the concrete mix. The obtained result shows compressive strength improvement after the inclusion of CL. The variation of compressive strength at various percentages of FAC shows in Figure 5. The obtained normal strength of concrete is 32.96N/ mm2. Addition of FAC 2.5%, 5%, 7.5% and 10% shows linearly decrease in strength, 10% FAC replacement with cement shows strength 30.78 N/mm2 which is 6.61%

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Figure 5. Compressive strength of concrete (Mpa) Vs FAC (%) at 28 days. decrease in strength, after addition of calcium lactate with 0.010 mol/lit & 0.015 mol/lit shows strength 34.31 N/mm2 and 35.73 N/mm2 which is 4.09% & 8.40% higher strength than normal concrete. Failure pattern A concrete cube was tested on a compression testing equipment with a steadily increasing force, the concrete cube was placed between upper and bottom plate of loading frame afterward hydraulic pressure was applied on the cube which observed from dial gauge of the control panel. The dial gauge shows incremental readings up to the failure of the concrete cube. The failure sample of a cube was taken away from the loading frame and the failure pattern

was observed as shown in Figure 6, the matrix shows all ingredients mixed well at the time of mixing and compacted properly. The surface shows no tension zone was observed on the concrete cube. Fine and coarse aggregate shows proper bond with other materials of the matrix, it was also observed that aggregate failure or break in the central portion of a cube, this means all the material used in mix perform well within the limits. Flexural Strength To examine the flexural properties of FAC, two points load test was conducted on a beam specimen of size 100 x 100 x 500 mm. After completion of the curing period, the beam specimen sample was thoroughly checked for defects

Sigma J Eng Nat Sci, Vol. 42, No. 6, pp. 1786−1796, December, 2024

Figure 6. Failure pattern of compression member. then demarcation was done on the beam, 50 mm cover was left from both ends of the beam and the remaining span was equally divided into 3 spans of each length of 133 mm. The universal testing machine of force capacity 250 KN was used for the application of uniform loading at the rate of

Conflict Of Interest

The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Cenosphere is waste material increasing its own volume day by day and simultaneously creating problems for the environment. The cenosphere has an advantageous physical property of being light in weight which makes economical and sustainable concrete for the construction industry. The main focus is given on studying the behavior of the cenosphere with other construction materials, its application, and its limitations. Chemical study of cenosphere shows absence of calcium mineral in its composition this affect mechanical property of concrete. The observation of experimentation, results, and discussion gives following conclusion;

1. The findings indicate that using cenosphere in place of

cement results in a reduction in the weight and density of concrete, making it economical and sustainable.

2. Fly ash cenosphere adds incrementally (2.5, 5, 7.5 &

10%) replacing cement into the mix, showing a linear strength reduction due to the absence of calcium in cenosphere concrete.

3. Strength may be enhanced at specific percentages due

to the cenosphere’s involvement in pozzolanic processes and its extremely fine particles. Concrete strength increases little (1.51%) at FAC 2.5 percent.

4. FAC 10% replacement of cement shows a 4.62% reduction

in density, simultaneously when calcium lactate of 0.010 mol/lit and 0.015 mol/lit is added to the mix it shows a 4.69% and 4.80% reduction in density after 28-days.

5. FAC 10% replacement of cement shows a 6.61%

decrease in compressive strength, after addition of calcium lactate with 0.010 mol/lit & 0.015 mol/lit shows 4.09% & 8.40% higher compressive strength than normal concrete.

6. Flexural strength of typical concrete at 28 days is up

to 4.03 N/mm2, when FAC 10 % added in replacement with cement it shows 8.70% reduction in strength, after addition of calcium lactate in the mix it shows 2.86% and 6.34% increase in strength.

7. FAC with 10% replacement to cement gives 10.34% less

tensile strength than the result expected from normal concrete, whereas the addition of calcium lactate gives a 4.02% and 9.77% increase in tensile strength.

Authorship Contributions

There are no ethical issues with the publication of this manuscript.

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