Predicting Slump Values of Concrete Made by Pozzolans and Manufactured Sand using ANN

Large amounts of natural fine aggregate (NFA) and cement are used in building, which has major environmental consequences. This view of industrial waste can be used in part as an alternative to cement and part of the sand produced by the crusher as fine aggregate, similar to slag sand (GGBFS), fly ash, metacaolin, and silica fume. Many times, there are issues with the fresh characteristics of concrete when using alternative materials. The ANN tool is used in this paper to develop a Matlab software model that collapses concrete made with pozzolanic material and partially replaces natural fine aggregate (NFA) with manufactured sand (MS). Predict. The slump test was carried out in reference with I.S11991959, and the findings were used to create the artificial neural network (ANN) model. To mimic the formation, a total of 131 outcome values are employed, with 20% being used for model testing and 80% being used for model training. 25 enter the material properties to determine the concrete slump achieved by partially substituting pozzolan for cement and artificial sand (MS) for natural fine aggregate (NFA). According to studies, the workability of concrete is critically harmed as the amount of artificial sand replacing natural sand grows. The ANN model's results are extremely accurate, and they can forecast the slump of concrete prepared by partly substituting natural fine aggregate (NFA) and artificial sand (MS) with pozzolan.

Effect of Calcination on the Chemical and Microstructural Properties of Sugarcane Bagasse Ash (SCBA)

This research study is for the evaluation of the effect of the burning temperature on the chemical and microstructural properties of Sugarcane Bagasse Ash. The Sugarcane Bagasse Ash (SCBA) is a byproduct of sugarcane which is dumped without proper handling and causing environmental issues because of the burning on dump site and loss of the area due to dumping in the commodity. The current research study is conducted for burning of SCBA on different temperatures and duration for finding the optimum burning temperature and duration of burning. The chemical and microstructural properties of SCBA evaluated at burning temperatures of 800°C for the duration of 01 hour, at temperature of 600° for the duration of 03 and 06 hours by conducting the tests of FTIR, XRD and XRF on the samples. The test results show that the burning temperatures of 800°C for the duration of 1 hour contains amorphous silica and also fulfilling the requirement of pozzolanic material (Composition of Silica, alumina and iron oxide is greater than 70%) as compared to other ash samples of sugarcane bagasse.

Mechanical And Durability Properties of HSC Containing Silica Fume And 100% M-Sand

This project is related on the use of Silica fume as a substitution of cement and 100% m- sand as fine aggregate. Concrete is the most widely utilized material in the construction industry and will hold good for years. The credit is attributed to the properties of concrete like excellent strength, durability and less maintenance costs. But in the recent years, the concrete industry is facing a big challenge mainly due to the cement which is a vital component. In order to improve the durability properties many types of special concretes such as High Strength Concrete, High Performance Concrete, Fibre Reinforced Concrete, Self-Compacting Concrete, etc. have been developed. High performance concrete has become an attractive option to Civil Engineers due to the special characteristics like early strength, ease of placement, permeability, mechanical and durability properties. The performance of High strength Concrete (HSC) is enhanced by the addition of admixtures which act as pozzolans as well as fillers, thereby improving the microstructure of the interfacial transition zone making it denser and impermeable. Silica Fume (SF) is a commonly used pozzolanic material owing to its high silicon dioxide content and fineness. This ultra fine property of SF used in concrete to improve its strength and durability.

Review of the Effects of Supplementary Cementitious Materials and Chemical Additives on the Physical, Mechanical and Durability Properties of Hydraulic Concrete

Supplementary cementitious materials (SCMs) and chemical additives (CA) are incorporated to modify the properties of concrete. In this paper, SCMs such as fly ash (FA), ground granulated blast furnace slag (GGBS), silica fume (SF), rice husk ash (RHA), sugarcane bagasse ash (SBA), and tire-derived fuel ash (TDFA) admixed concretes are reviewed. FA (25–30%), GGBS (50–55%), RHA (15–20%), and SBA (15%) are safely used to replace Portland cement. FA requires activation, while GGBS has undergone in situ activation, with other alkalis present in it. The reactive silica in RHA and SBA readily reacts with free Ca(OH)2 in cement matrix, which produces the secondary C-S-H gel and gives strength to the concrete. SF addition involves both physical contribution and chemical action in concrete. TDFA contains 25–30% SiO2 and 30–35% CaO, and is considered a suitable secondary pozzolanic material. In this review, special emphasis is given to the various chemical additives and their role in protecting rebar from corrosion. Specialized concrete for novel applications, namely self-curing, self-healing, superhydrophobic, electromagnetic (EM) wave shielding and self-temperature adjusting concretes, are also discussed.

Impact of diatomite addition on lead immobilization in air pollution control residues from a municipal solid waste incinerator

Air pollution control (APC) residues, which are known to be the byproducts of incineration treatment, exhibit a high leaching potential of toxic metals. Calcium silicate hydrate (C-S–H), which is a major hydration product of hardened cement and immobilizes toxic metal, can be formed by the reaction of Ca with pozzolanic Si in a highly alkaline environment. Toxic metals might be immobilized by the addition of pozzolanic material to APC residues (instead of using cement), which is a Ca source and provides an alkaline condition. In this study, diatomite, which mainly comprises amorphous silica (SiO2·nH2O), was investigated as a pozzolanic material for Pb immobilization in APC residues obtained from a municipal solid waste incinerator. APC residues were cured with and without the addition of diatomite at different temperatures. When diatomite was added to APC residues, pozzolanic phases such as C-S–H gel were formed via the consumption of Ca(OH)2 and CaClOH. Compared to APC residues cured without diatomite, the leaching of Pb decreased by 99% for APC residues cured for 14 days with 10% diatomite at 70 °C. The results of sequential chemical extraction showed that water-soluble Pb in APC residues was reduced from 10.3% to nearly zero by the pozzolanic reaction. Consequently, the leaching amount of Pb dropped below 0.3 mg/L (Japanese criteria for landfill disposal). Overall, these experiments provide promising results regarding the possibility of using diatomite for pretreating APC residues.

A Review on the Performance of Waste Glass as Partial Replacement of Fine Aggregate

Waste glass is one of the biggest contributors in waste production in Malaysia which can be used as partial sand replacement in concrete. Silica exists in waste glass components made it becomes a pozzolanic material and suitable to be used in a concrete mixture. The performance of the waste glass as fine aggregate was reviewed by considering the workability of fresh concrete, the strength, and the splitting tensile of hardened concrete. The range of the replacement waste are 0%, 10%, 20% and 30%. The influence of the waste glass on the microstructure of the concrete also have been evaluated. A total of seventeen previous research papers were collected and review based on the parameters selected. The results shows that replacement of waste glass in concrete give a positive impact for all selected parameters with 20% replacement represent as an optimal percentage replacement. The microstructure of the waste glass concrete resulting that more voids created after 20% replacement of waste glass which affects the compressive strength and split tensile strength of the concrete thus make the optimum replacement percentage is 20% replacement.

Pozzolanic Effect on the Hydration Heat of Cements Incorporating Fly Ash, Obsidian, and Slag Additives

Made up of an engineered mix of ordinary Portland cement (OPC) with artificial pozzolans such as trass, fly ash, and slag, the blended cements have been intensely employed within cementitious materials. The main reasons behind this intensive use can be clarified by enhanced workability/strength, the high resistance to chloride/sulfate, reduced permeability/alkali-silica reaction, and a drop in the heat generated by cement’s hydration. The use of cementitious blends within concrete not only offers durable products but also cuts climate impact by energy saving and falling CO2 emissions. This study presents pozzolanic effect on the hydration heat of cements incorporating fly ash, obsidian, and slag additives. The blended cements were manufactured by three different replacement ratios of 20%, 30%, and 50%. The change in the hydration heat of obsidian-, fly ash-, and slag-based cements was observed by several Turkish standards (TS EN 196-8 and TS EN 196-9). Mortars were used for determining the uniaxial strengths of obsidian-, fly ash-, and slag-based cements. The results show that cement’s hydration heat decreases as the rate of additives (e.g., obsidian) increases from 20% to 50%. The cement’s fineness greatly affects its hydration heat. Increasing the refinement of pozzolanic material to a certain level (30%) leads to an increase in the hydration temperature. After reaching this level, there is no clear relation between the fineness and the replacement rate of pozzolans. As a result, the findings of this work will provide a good understanding of artificial pozzolans on performance and quality of obsidian-, fly ash-, and slag-based cements.

Flexural strength of silica fume, fly ash, and metakaolin of hardened cement paste after exposure to elevated temperatures

The mechanical properties of concrete based mainly on flexural and compressive bearing capacity. Generally, researchers have an interest in the evaluation of compression property through the importance of the flexural performance of the material in the constructions, namely the significance of each mechanical property based upon the position of the structural element. The present experimentally work is directed toward improving the flexural strengths performance of ordinary hardened cement paste (HCP) at ambient and after elevated temperatures exposure. The used parameters were different pozzolanic materials with different replacements ratios to cement mass and different levels of temperature. Results proved the significant contribution of pozzolanic material to enhance the flexural properties of HCP after being exposed to elevated temperatures. The low content of CaO, the high grinding fineness, and the physical morphology of the used pozzolanic materials, made their adoption effective to HCP after exposure to elevated temperatures. Using 3%, 12%, and 15% of silica fume (SF), metakaolin (MK), and fly ash (FA), respectively, showed the highest heat endurance among the other replacements. However, the optimum replacement of MK has shown a better heat endurance than the optimum replacements of SF and FA. On the other hand, the spalling has occurred at high replacements of SF. Finally, the results are supported by means of thermo-gravimetric, SEM, and computed tomography investigations.

Mechanical Properties and Microstructure of Low Carbon Binders Manufactured from Calcined Canal Sediments and Ground Granulated Blast Furnace Slag (GGBS)

This research study evaluated the effects of adding Scottish canal sediment after calcination at 750 °C in combination with GGBS on hydration, strength and microstructural properties in ternary cement mixtures in order to reduce their carbon footprint (CO2) and cost. A series of physico-chemical, hydration heat, mechanic performance, mercury porosity and microstructure tests or observations was performed in order to evaluate the fresh and hardened properties. The physical and chemical characterisation of the calcined sediments revealed good pozzolanic properties that could be valorised as a potential co-product in the cement industry. The results obtained for mortars with various percentages of calcined sediment confirmed that this represents a previously unrecognised potential source of high reactivity pozzolanic materials. The evolution of the compressive strength for the different types of mortars based on the partial substitution of cement by slag and calcined sediments showed a linear increase in compressive strength for 90 days. The best compressive strengths and porosity were observed in mortars composed of 50% cement, 40% slag and 10% calcined sediment (CSS10%) after 90 days. In conclusion, the addition of calcined canal sediments as an artificial pozzolanic material could improve strength and save significant amounts of energy or greenhouse gas emissions, while potentially contributing to Scotland’s ambitious 2045 net zero target and reducing greenhouse gas emissions by 2050 in the UK and Europe.