High-Performance Concrete's Compressive Strength with Fly Ash as a Mineral Admixture and Replaces Natural Sand by Manufactured Sand

Abstract

Manufactured sand-based concrete has gained popularity as green construction materials. It has been recognized by studies that low strength concrete, this setback could be reduced by the augmentation of fly ash. Similarly, the requirement for natural sand has a great hike and eventually becomes expensive and scarce in accessibility. Environmental aspects are better obtained if locally available the development of cost-effective state-of-the-art procedures for producing, evaluating, and designing with MSHPC will enhance the performance for each performance characteristic and can be reliably achieved in the field. This investigation assesses the effect of cement being partially substituted by fly ash and natural sand by M-sand for high-performance concrete. The water to binder ratios (W/B) of 0.30, 0.35, and 0.40 and an aggregate to binder ratio (A/B) of 2 were adopted. Fly ash were replaced in the range from 0% ,10%, 20% and 30% manufactured sand were added in volume percentages from 0%,20%,40%,60,80% and 100%.The outcome of replacement of cement by fly ash 10% and natural sand by M-Sand at 60% to the W/B:0.30 was found to be the optimal strength, production minimizes enormous cement production and reduce using of normal sand  and extraction from water bodies  resolve the impact environment to maintain the sustainable environment in coming day.

Keywords: M-Sand, Natural Sand, Aggregate binder ratio, Fly ash (FA) and High-Performance concrete

1. Introduction

HPC is a type of concrete that is made for a specific use and environment. It works very well for the entire life of the building in which it is installed, as well as in the environment and under the loads to which it will be exposed.[1]. These days, it is necessary to use high-performance concrete to meet design standards and speed up the country's growth. Making one metric ton of ordinary Portland cement (OPC) is thought to release about one metric ton of carbon dioxide. This makes the cement industry one of the biggest sources of greenhouse gas emissions in the world.[2].At the same time, taking too much normal sand from the streams to make concrete has caused a lot of damage to the environment, such as riverbank erosion, groundwater depletion, and the loss of aquatic habitats. Satellite-based studies in major river basins have shown a big rise in sand mining, which shows how important it is to find other fine aggregates.[3].The use of manufactured sand (M-sand) instead of natural river sand has become a viable and long-lasting option for making concrete. Because M-sand has a controlled particle size distribution, an angular shape, and a lower impurity content, it improves particle packing, lowers void content, and improves the characteristics of ITZ. This makes HPC stronger and more durable.[4-6]. The interaction between M-sand-based concrete and additional cementitious ingredients and the W/B ratio, on the other hand, has a big effect on how it behaves mechanically. This means that the mix proportions need to be optimized in a systematic way. Fly ash (FA), silica fume (SF), and metakaolin (MK) are all mineral admixtures that are often used to partially replace cement in order to improve both performance and sustainability. These pozzolanic materials improve the pore structure, help make gels of calcium silicate hydrate (C–S–H) and calcium–aluminosilicate hydrate (C–A–S–H), and make the cement matrix denser. This makes the cement stronger in compression, tension, and bending, and it lasts longer. [7-12].Binary and ternary blended systems that use OPC with SCMs greatly lower permeability and make them more resistant to damage from chemicals and mechanical stress. Among these materials, metakaolin has the best pozzolanic reactivity and micro-filler effects, especially in high-performance and high-strength concrete systems. [13-17].The current study examined M40 grade HPC mixes with changing replacement levels: 25%, 30%, 35%and 40% cement replaced by fly ash, and 60%, 65%, 70%, 75%and 100% of stone dust replaced by sand, utilizing a water-binder ratio of 0.35. For high-performance concrete, super plasticizer (BASF) is used to make it easier to work with. The HPC mix grade M40 concrete is made according to IS: 10262-1982 and IS: 456-200, which is normal. We looked at mechanical properties like compressive strength, split-tensile strength, and flexural strength. The outcome of these studies illustrates the strength attributes of stone dust and the characteristics of concrete mixtures incorporating fly ash. Based on the results, it was found that replacing 100% of the stone dust and 25% of the fly ash with 1.2% of super plasticizer, which has better properties, was the best option.[18]. showed better compressive, flexural, and split tensile strengths than river sand concrete in most cases. Alccofine with M-sand was the best of the admixtures. At 56 days, it was 21% stronger than the target mean strength.[19-20].

2. Methods and Materials

2.1. Materials and Properties

The specific gravity of OPC43 grade cement is 3.08, while the specific gravity of natural sand is 2.50 and M-Sand is 2.56. There were 40% of the aggregates that were 12.5 mm and 60% that were 20 mm. The coarse aggregates had a specific gravity of 2.70. The fly ash used had a specific gravity of 2.17, a specific surface area of 0.398 m2/g, and concentrations of SiO2 and Al2O3 of 59.16% and 30.64%, respectively. To mix concrete, you needed fresh drinking water that didn't have any organic or acidic parts. Fosroc's Superplasticizer (SP) was used, and it didn't have any chloride in it.

3. Experimental Procedure

For each water binder ratio, make 24 mixes to see how MSHPC acts. The MSHPC mixes have W/B ratios of 0.3, 0.35, and 0.40, and the A/B ratio stays the same at 2.0. There are FA levels of 0%, 10%, 20%, and 30% to replace cement, and there are also levels of 0%, 20%, 40%, 60%, 80%, and 100% to replace natural sand with M-Sand. SP stayed the same at 0.8% of the weight of the binder. The used an absolute volume method to find out the mix ratios. The first letter in the mix designation shows how much manufactured sand is in the mix. For example, M0 and M20 mean that 0%, 20%, 40%, 60%, 80%and 100% of the sand is manufactured. The second letter shows the percentage of mineral admixtures. For example, MA0 means there are no mineral admixtures, and F10, F20, and F30 show that the fly ash content is 10%, 20%, and 30%, respectively. The last letter of the alphabet shows the water-to-binder ratio. For example, M0MA0A means a plain high-performance concrete mix with 0% M-Sand (100% natural sand) and 0% mineral admixture (100% cement) for 0.3 W/B.  Table 1 shows the names and compositions of different mixes. It also shows how to keep design principles the same across different W/B ratios to make sure that the whole thing is worth it. the absolute volume method used to find the quantity of materials for the plain mix (M0MA0A) is as follows: cement = 719.88 kg/m3, natural sand = 575.90 kg/m3, CA = 896.37 kg/m3 with a W/B ratio of 0.3. For the other mix (M20F10A), the amounts are as follows: cement = 672.28 kg/m3, fly ash = 74.70 kg/m3, natural sand = 478.06 kg/m3, M-sand = 119.52 kg/m3, and CA = 896.37 kg/m3 with  W/B ratio = 0.3.

Table 1:Mix Detail

*Similarly designs of constituents are used for other W/B ratios W/B= 0.35 (B) and 0.40 (C).

3.1 Experimental methods

Before adding coarse aggregates, portable water, and a superplasticizer, people mixed dry mixes of cement, natural sand, M-Sand, and FA by hand to make sure they were all the same. We mixed these parts together to make samples. To find out how strong the concrete was, we cast cubes that were 100 × 100 × 100 mm in size. To test split tensile strength, we made cylindrical samples that were 150 mm in diameter and 300 mm tall. To test flexural strength, we made beam samples that were 500 × 100 × 100 mm. After being removed from the mold, cube samples were kept in water for 7 and 28 days. Cylindrical and beam specimens were kept in water for 28 days under normal water-curing conditions.

All mechanical tests were done in accordance with the Indian Standard (IS) rules that apply. We used a compression testing machine with a capacity of 2000kN to do compressive strength tests according to IS 516:2018. The rate of loading was 14 N/mm2/min. The split tensile strength was measured at a loading rate of 1.2 N/mm2/min to 2.4 N/mm2/min, as per IS 5816:1999. We used a universal testing machine (UTM) to test flexural strength according to IS 516:2018. The loading rate was always 0.7 N/mm2/min. Three samples were tested for each mix combination, and the numbers shown are the averages of those three tests.

4.Results and Discussion

This section presents the experimental performance of MSHPC and establishes the influence of W/B ratio, fly ash dosage and M-sand replacement level on compressive, split tensile and flexural strength is systematically analyzed.

4.1 Effect of Water–Binder Ratio for fly ash and M-sand replacement.

Figure 2 shows how the W/B ratio, the amount of manufactured sand (M-sand) that replaces it, and the amount of fly ash affect the compressive strength of MSHPC after 7 and 28 days. As the W/B ratio goes up from 0.30 to 0.40, all six subplots show a steady and consistent drop in compressive strength, regardless of the amount of fly ash and M-sand. This behavior shows how important water content is in controlling capillary porosity and paste densification. Higher W/B ratios make it easier for continuous pore networks to form, which makes the cementitious matrix weaker. Figure 2 shows that the strength order among the M-sand replacement levels stays the same at all curing ages. The 60% M-sand mixtures always have the highest compressive strength. The main reasons for the better performance at W/B = 0.30 are better particle packing and stronger bonding between the aggregate and paste phases. The strength increase from 7 to 28 days is another sign of the delayed pozzolanic reaction of fly ash. This reaction slowly eats away at calcium hydroxide and helps build secondary C–S–H gel, which makes the microstructure denser.

Fig.1:7&28days Compressive strength vs W/B Ratio. 

4.2 Effect for Replacement Level of fly ash.

Fig .2: 7 & 28-Days Compressive strength Vs. % of fly ash.

As the percentage of fly ash used additionally goes up from 0% to 10%, Fig. 2 shows how the compressive strength of MSHPC changes over 7 and 28 days. After that, the strength starts to decrease again as the amount of fly ash used as a replacement goes up from 20% to 30%. This illustrates that there is a distinct best volume of fly ash to employ.  The MSHPC mix is strongest at 7 & 28 days for all W/B and M-sand ratios when 10% of the cement is substituted with fly ash. When there is more than 10% fly ash, the value of compressive strength decreases down.  The strongest concrete is made up of 10% fly ash and 60% M-sand. The mix M60F10A was stronger than the basic concrete mix (M0MA0A) after 7 days (23.36%) and after 28 days (24.90%).  The micro filler effect and the delayed pozzolanic reaction are what cause the first improvement in fly ash replacement mixes. These actions make the particles fit together better and help the secondary C–S–H gel develop at later curing ages. The reduction beyond 10% replacement exhibits a dilution effect, wherein diminished clinker complicates early hydration and binder continuity[21-22]. 

4.3 Effect of replacement Natural sand by Manufactured Sand.

Fig.4: 7&28 days Compressive strength Vs % of M-sand 

The compressive strength after 7 days and 28 days rises up as the amount of artificial sand goes up. It is possible for the amount of produced sand to be between 20% and 100%. The tight link between M-Sand and the cement matrix may be what makes the compressive strength go up. The combination with 60% M-Sand had the most strength when it was pushed together. At 60% M-Sand, the M60MA0A mix was 16.12% stronger than the M0MA0A mix. At 7 days and 28 days, it was 13.78% stronger. When cured for 7 days and 28 days, the mix with M-Sand (M0F10A) was 11.40% stronger than the mix without it (M0F10A).

Conclusion

This experiment looked at how well manufactured sand and fly ash worked in high-performance concrete. The subsequent conclusions were reached after looking over the facts.

1. It was initiated that the compressive strengths of the M-Sand and fly ash combination went down as the water binder ratio went up. All the other mixtures did the same thing. For a mix with a W/B of 0.30 and 28 days of curing, the maximum strengths were initiated for all mixtures with different amounts of fly ash and M-Sand added to replace cement.

2. The analysis of experimental data shows that the mechanical properties of the 60% M-Sand and 10% Fly ash mix improve compared to the other mix for all water binder ratios and concrete testing ages.

3. It was shown that the compressive strength of concrete increased with the amount of M-sand up to 60%, but it decreased after that. However, concrete with a 100% M-sand mix showed more strength than concrete with 100% natural sand mix.

4. It was noted that as the quantity of fly ash rises, so does the compressive strength, up to 10%. Beyond that, the compressive strength goes down.

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