Amount Of Concrete Research Articles

Improvement of crushed returned concrete aggregates by wet carbonation

A considerable quantity of pre-mixed concrete is returned from construction sites which is usually dumped directly into pits. While this concrete may possess lower quality attributes due to inadequate compaction and curing, the crushed hardened concrete can be potentially used to produce recycled aggregates. Carbonation is regarded as a significant way of improvement of recycled concrete aggregates. This study investigated the effectiveness of wet carbonation method for the improvement of crushed returned concrete aggregates (CRCA) to reuse in concrete productions. Recycled concrete aggregate (RCA) obtained from crushing of old conventionally cast concrete was also subjected to the same treatment, and its properties were compared with those of CRCA to understand the improvement in each type of recycled aggregate. The effectiveness of wet carbonation was evaluated by the aqueous chemistry during carbonation, development of microstructure, depth of calcium carbonate deposition, the mineralogy, water absorption, and compressive strength for both treated and untreated CRCA and RCA for different carbonation durations. The results showed that, although the water absorptions of both uncarbonated and carbonated CRCA were higher than those of RCA, the rate of reduction of water absorption of CRCA after carbonation was higher than that in RCA. Due to the long exposure to open environment, CRCA showed less initial alkalinity and conductivity than RCA but at the end of carbonation, both pH and conductivity were almost same as those of RCA. Wet carbonation successfully produced well shaped calcite in both CRCA and RCA where the deposition depth of calcite was higher in CRCA than in RCA. Mineralogical analysis showed higher calcium carbonate formation in CRCA indicating its potential of sequestrating more CO2 than by RCA. The improvement of concrete compressive strength was more pronounced for CRCA, with a 28 % enhancement observed after 2 hours of carbonation, compared to an 18 % enhancement for RCA. These findings demonstrated that wet carbonation can be regarded as an effective strategy for enhancing CRCA.

Enhancing Onshore Wind Tower Foundations: A Comprehensive Automated Design Approach

The realm of green energy is in constant flux, drawing considerable attention from stakeholders dedicated to minimizing environmental impact, reducing costs, and developing structures that align with stringent standards. This study introduces an innovative approach aimed at improving onshore wind tower foundation systems, emphasizing both engineering and financial feasibility. The approach involves a comprehensive analysis of design load cases, particularly emphasizing resistance against overturn, while ensuring compliance with Eurocode guidelines. The foundation system is conceptualized as a beam slab with voids filled by soil material. High reduction in concrete quantity is achieved by reaching 30%, while the steel reduction reaches 90%. It is worth mentioning that the total cost is reduced by up to 70%. Furthermore, as a future trend, this study aims to integrate the new foundation system with steel 3D printing technology in the manufacturing process of the wind tower’s structural elements. This integration is expected to enhance the precision and customization of the superstructure-foundation system, thereby improving overall performance and efficiency. The optimized design not only significantly reduces construction costs but also streamlines installation, saving time. Simultaneously, this study enhances the structural behavior of the wind tower foundation by focusing on elements crucial to its efficiency.

MOAAA/D: a decomposition-based novel algorithm and a structural design application

When real-world engineering challenges are examined adequately, it becomes clear that multi-objective need to be optimized. Many engineering problems have been handled utilizing the decomposition-based optimization approach according to the literature. The performance of multi-objective evolutionary algorithms is highly dependent on the balance of convergence and diversity. Diversity and convergence are not appropriately balanced in the decomposition technique, as they are in many approaches, for real-world problems. A novel Multi-Objective Artificial Algae Algorithm based on Decomposition (MOAAA/D) is proposed in the paper to solve multi-objective structural problems. MOAAA/D is the first multi-objective algorithm that uses the decomposition-based method with the artificial algae algorithm. MOAAA/D, which successfully draws a graph on 24 benchmark functions within the area of two common metrics, also produced promising results in the structural design problem to which it was applied. To facilitate the design of the "rectangular reinforced concrete column" using MOAAA/D, a solution space was derived by optimizing the rebar ratio and the concrete quantity to be employed.

Assessing the Sustainability of Alternative Shaft Construction Methods

Reducing carbon dioxide (CO2) emissions is a global priority. The concrete industry has a major role in this reduction since it accounts for about 8% of global CO2 emissions. Despite significant improvements in the sustainability of the production of concrete, one of the best solutions is still to improve the design and construction methods, such that the required quantities of concrete are reduced. Using, as a reference, a real case study, this study compares alternative shaft construction methodologies from engineering and sustainability points of view, highlighting the advantages and drawbacks of each solution. To achieve this purpose, a back analysis is performed to ensure that the numerical model is accurately calibrated and the shaft construction methods can be adequately assessed. The results show that, while the considered methods are applicable and satisfy engineering requirements, the characteristics of the lining of the shaft could have been optimized, resulting in a reduction in CO2 emissions by at least 50% without compromising the safety of the construction.

Multi-steps integrated mathematical MCDM model for construction material selection of Addis Ababa high-rise building infrastructure

ABSTRACT The construction industry is confronted by resource constraints. It affects the initial costs and environment that requires resource and method optimization. The objective of the research is to design a mathematical MCDM model that would enable to select economically and ecologically suitable building material. To achieve this, the researcher designed, evaluated, and selected the suitable concrete grade using a combined mathematical MCDM. The objective sampling technique is used in Addis Ababa to collect samples of high-rise structures and materials. The study used objective-weighed MCDM and fuzzy-AHP to create specific concrete grades. The amount of the objective was fitted by 95% sensitivity analysis cost and quantity of concrete using a combination of MCDM, linear programming, and Monte Carlo simulation. The result demonstrates that, although the unit cost of concrete increased as strength grew, the project’s overall cost was reduced by reducing the project quantities. It will also add more space with environmentally friendly, sustainable structures. In conclusion, the integrated mathematical MCDM model is a helpful tool for selecting urban structure cost-effective materials

Comparative analysis of the impact of design and detailing provisions for RC moment resisting frames under the first- and second-generation of Eurocode 8

Eurocode 8 is undergoing a thorough revision process encompassing a significant number of changes. In this work, the novel ductility classes, drift limits for damage limitation, local ductility conditions, and corresponding detailing prescriptions are presented and discussed. It is paramount to analyse and contrast these modifications with the current provisions of Eurocode 8. In order to assess the impact of such revisions, an extensive examination was conducted on ten symmetrical moment-resisting frame (MRF) buildings. These buildings are regular in plan and in elevation and are not torsionally flexible. The analysis was carried out following both the current and the second-generation Eurocode 8 provisions, with the results being compared in order to evaluate the effectiveness of the new design and detailing provisions. The study outcomes revealed that the DCM, DC2, and DC3 structures demonstrated different trends in their detailing demands for local ductility and capacity design. Differences in reinforcement quantities were observed between DCM and DC2, as well as DC2 and DC3, for 5-storey and 10-storey buildings. The design approach focused on individual member detailing requirements, to optimize design, while maintaining the overall concrete quantities. These insights offer valuable economic considerations for various structural configurations under strong seismic actions.

Experimental investigation of the effect of horizontal construction joints on the behavior of deep beams

Abstract Construction joints serve as interruption points in the concrete placement process, which is necessary because it is often not feasible to pour concrete continuously in many structures. The quantity of concrete that can be poured at a single instance depends on the batching and mixing capacity, as well as the strength of the formwork. An effective construction joint must ensure sufficient flexural and shear continuity across the junction. Many studies investigated the construction joints in the reinforced concrete (RC) normal beams, but there are no studies investigating the effect of construction joints on the behavior of the RC deep beams. This study was prepared to show the behavior of deep beams having horizontal construction joints (HCJs) extended through their entire length. The parameter studied in this research was the location of the HCJ within the beam height. Four simply supported RC deep beams were tested under a two-point static load up to failure. One of these beams was without a construction joint and was considered a reference beam. Each one of the other beams has only one horizontal construction. The location of these joints was below, at, or above the beam mid-height. The crack patterns, the strain distributions, the mode of failure, deflection, and failure load are discussed. It was found that the existence of construction joints below, at, or above the beam mid-height results in a decrease in load failure load by 9, 11, and 1% compared with the reference beam. It can be concluded that the best location of the HCJ in the RC deep beam is in the upper part of the beam.

Impact of unit prices on the optimal costs of reinforced concrete beams: A comparative study

Numerous studies have been conducted on optimizing reinforced concrete (RC) structures. However, the existing literature focused on reducing the overall costs of the structural members based on materials' local prices, neglecting that these prices could vary from region to region. Thus, this article investigates the impact of materials' unit prices on the optimal costs of RC beams, considering the prices of three countries: Egypt, the UK, and Brazil. The evolutionary algorithm provided by MS Excel Solver was employed to obtain the optimum designs based on three target functions: total cost, steel weight, and concrete weight. Unlike earlier studies, we provided a sufficient number of discrete design variables that significantly influence the total cost and weights of concrete and steel; these variables include the concrete class, cross-sectional dimensions, and details of reinforcing bars at all the critical sections of the beams. Two benchmark examples were presented to illustrate the robustness of the proposed optimization model in dealing with different span lengths and continuity conditions. The results showed that the optimal designs could significantly vary based on the materials’ unit prices. In Egypt, minimizing the steel weight could save up to 50% of the total cost, compared to reducing the beam concrete dimensions. The optimal steel-to-concrete and span-to-depth ratios were as low as 0.7% and 9, respectively. On the other hand, in the UK and Brazil, cost-effective designs could be achieved by minimizing the concrete dimensions, with higher reinforcement ratio (up to 1.3%) and span-to-depth ratio (up to 11.5). The study outcomes could assist designers in the building sector estimate economical concrete quantities based on the materials’ unit prices during the conceptual stage, enabling more informed decisions.

Computation of embodied energy and carbon dioxide emissions of geopolymer concrete in high-rise buildings: a case study in Chennai city

The total primary embodied energy (EE) and carbon dioxide (CO2) emissions (ECO2e) of geopolymer concrete (GPC) in high-rise (60 m height) residential buildings located at Chennai city, India, were carefully examined in this study. The buildings were analysed and designed with the same aspect ratio and loading with two structural systems; Reinforced concrete (RC) framed and Shear wall type. The computation was performed for floor area, building volume, and concrete quantity. The results show that for the same grade of concrete, compared with conventional concrete (CC), GPC's EE is reduced by 46%, ECO2e is reduced by 42%, and the cost is reduced by 7%. The primary energy consumption (EET) and CO2 emissions (ECO2eT) towards material transportation in GPC shear wall and framed structures are 8% lower and associated cost is 22% cheaper than CC buildings. Compared to CC, the total primary EE and ECO2e of GPC RC shear wall and framed buildings are 46 and 55% lower, respectively. From the study, it has been observed that GPC is more environmentally beneficial than that of using CC in high-rise structures.

Improving the engineering properties of sustainable recycled aggregate concrete modified with metakaolin

This study investigates the potential of metakaolin as a mineral admixture to enhance the performance of concrete mixtures with varying proportions of recycled aggregates (RA). Sixteen distinct concrete combinations were formulated by substituting natural aggregates (NA) with RA at 0 %, 50 %, 75 %, and 100 % and incorporating metakaolin at 0 %, 5 %, 10 %, and 15 % as a replacement for cement. Experimental investigations were conducted to evaluate the effects of metakaolin (as a cement replacement) and RA (as a replacement for NA) on key concrete characteristics, including density, water absorption, compressive and tensile strength, and acid resistance. The results revealed that an increase in RA reduced mechanical properties, such as compressive strength, tensile strength, and dry density. Additionally, RA-based concrete mixtures exhibited higher water absorption and void volume than those with natural aggregates. However, including metakaolin in RA-based concrete significantly reduced the void volume and water absorption. The optimal proportion of metakaolin substitution was 15 %, resulting in the best overall performance for RA-based concrete mixtures. Notably, the highest compressive and splitting tensile strength (41.6 MPa and 4.3 MPa, respectively) were observed at 90 days in mixtures with 0 % RA and 15 % metakaolin. Similarly, the highest hardened density and lowest water absorption (2494.7 kg/m3 and 4.7 %, respectively) were recorded in samples with 0 % RA and 15 % metakaolin. Furthermore, concrete mixes containing 15 % metakaolin and 50 % RA demonstrated comparable qualities to conventional concrete, indicating that sustainable concrete can be produced by utilizing a significant quantity of waste concrete (15 % metakaolin and 50 % RA) without compromising strength criteria. This study sheds light on the potential of incorporating metakaolin and recycled aggregates as environmentally friendly alternatives in the construction industry, contributing to sustainable and eco-conscious practices.

An Experimental Study on Partial Replacement of Cement by Dolomite Powder

Abstract: Currently India has taken a major initiative on developing the infrastructures such as express highways, power projects, and industrial structures to meet the requirements of globalization in the construction field, which involves the construction of buildings and other structures. Concrete plays the key role in the construction field and a large quantity of concrete is being utilized in every construction practices. To increase the strength of concrete the water/cementratio has to be reduced, which in turn increases the cement content. To overcome low workability problemdifferent kinds of admixtures are used to achieve the required workability. The dolomite powder which is usually disposed can be used as an alternate for cement, since dolomite powder is rich in magnesium carbonate content and also sufficient calcium content. The dolomite powder is used in different combination to find the feasibility of using the dolomite powder as an alternate to cement. The cement is replaced by 0%, 5%, 10%, 15%, and 20% by the weight of cement and by keeping the replacement of dolomite powder for cement as constant that is 10% by weight of cement. The concrete cubes are casted and compression and split tensile tests were carried out to find the best combination which results in optimum percentage of strength.

Comparison of the post-tensioned, solid, hollow block, and flat slabs in terms of economy considering different span lengths

From among the several types of slabs, there is uncertainty about the most cost-effective one for structures with short, medium, and long spans. A study comparing the cost of the solid, flat, hollow block (HB), and post-tensioned (PT) slabs for 4, 6, and 8m spans was conducted using SAFE software. For each span length, the total quantities of concrete and steel bars were found and compared for 4 slabs. Then, the total cost of steel bars, concrete, blocks, tendons, and formwork was tabulated and compared. The findings revealed that the quantity of concrete in slabs with 4 and 6m spans is the least in the HB slabs, while for slabs with 8m spans, the quantity of concrete is the least in the PT slab. Besides, the quantity of steel bars in slabs with 4, 6, and 8 spans is the least in PT slabs. In terms of economy, the most cost-effective option is the flat slab for 4m spans, with savings of about 14, 9, and 17% compared to solid, HB, and PT slabs, respectively. On the other hand, for 6 and 8m spans, the most cost-effective option is the PT slab, with savings of about 10, 6, and 6% for the 6m span, and 10, 20, and 22% for 8m span compared to solid, HB, and flat slabs, respectively. Therefore, for 6m spans and more, PT slabs offer significant cost savings.

Performance evaluation of concrete mixtures using mining & industrial byproducts

Concrete plays an important and rightful role in the construction of buildings and other structures, and a large quantity of concrete is being utilized. Currently, India had already taken a massive effort on continuing to develop the infrastructures like expressways, flyovers, hydroelectric dams, and industrial projects, etc. to satisfy the specifications of global economy. For such massive development huge amount of natural resources were extracted and utilized. One of the most commonly used stone is marble for the infrastructure building works. The mining, refining, polishing, cutting, and transporting of a large quantity of marble all result in the generation of waste, which has a cumulatively detrimental effect on the natural environment. Marble is almost entirely sourced from the Indian state of Rajasthan, accounting for approximately 95 % of the requirement supply. The coarse-grained slag produced in the foremost extraction of zinc is ISF (Intrinsic Slag) is a nuisance. The focus of this investigation was to produce sustainable concrete by using the mined marble waste in concrete as a substitute for coarse aggregate and industrial waste i.e. ISF slag as a substitute for fine aggregate. Natural aggregate was used in this analysis instead of coarse aggregate. Marble aggregate produced from Marble Quarry Waste (MQW) replaced 75 % of the natural aggregate, and ISF sand replaced the remaining 40 % by mass. The flowability, compressive strength, permeability and Ultrasonic tests were conducted on the modified concrete mixture. The results of the study were compared to conventional concrete. The concrete flowability was not much affected. The strength properties showed slight reduction. The permeability of the modified bled was increased significantly. The findings showed that blends made of marble and ISF slag recyclable materials did not affect concrete mechanical propertie

Geopolymer Concrete Mix Design Efficiencies BY Taguchi Method

Abstract: Geopolymer concrete has had an extra edge over normal concrete for the past 2-3 decades. According to research, geopolymer concrete offers improved strength, modulus of elasticity, and durability. In this work, Ordinary Portland cement is fully replaced by a mixture of Sugar Cane Bagasse Ash(SCBA) and Ground Granulated Blast Furnace Slag(GGBS), with alkaline liquids added for reactivity. Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3) are used for the polymerization to achieve good workability in the geopolymer concrete. The combined quantities of geopolymer concrete were optimized using the Taguchi method to meet the specified strength parameters for the concrete grade of M30 with nine mixes. Binder content, which included three proportions of SCBA and GGBS, NaOH/Na2SiO3 ratios (1:2, 1:2.5, and 1:3), molarity(4M,8M,12M), and alkaline activator to binder content ratio(AAC/BC) of 0.4,0.5,0.6 were among the various parameters of study. Compressive strength and split-tensile strength was investigated using these components and variables during the work.

Mix proportioning of M25 grade concrete by replacing normal aggregate with light weight aggregate (Pumice)

Day to day a large development in construction activities are happening. All constructions require huge quantity of concrete. All we know that conventional concrete has density 2400 kg/m3.This type of concrete is not at all required in all aspects. So that new era concretes are developed to solve more problems. In general Components of buildings have concrete density 2400 kg/m3. In high rise buildings the components are large in size. Thus, by making the components lighter, a concrete needs to have a lesser density while still retaining its adequate compressive capacity. Lightweight aggregate are employed when making the bulk of lightweight concrete. The objective of the current study is to develop lightweight concrete by replacement of pumice stone for natural aggregate for M25 grade, with pumice stone ranging proportion from 0-27.5% at 5% intervals.

Seismic Evaluation of RC Building with Vertical Setbacks as per IS1893 (Part 1):2016

Earthquake forces are the least predictable and most devastating form of forces. These forces are not only responsible for loss of economy, property and material but possess a huge threat to lives of people as well. In past several years, severe damages to buildings and causalities have been witnessed due to these disastrous forces there by challenging the designing and construction authorities. Many buildings are designed with vertical setbacks due to architectural, functional or economic reasons wherein fewer stories in a building are wider than rest of the building. Such setbacks in buildings cause sudden jump in seismic forces at the level of discontinuity due to change in stiffness, mass and strength distribution along height. This might lead to torsion in the building under seismic forces. Structures incorporating vertical irregularities need to be studied for their behavioural aspects, identifying the weak links which might trigger the collapse. In the present study, effect of vertical geometric irregularities in a building is studied with respect to a regular building using equivalent static method and response spectrum method as per IS1893 (Part 1): 2016. The results obtained are compared in terms of displacements, storey drift, base shear, forces, modal time period, modal mass participation factor and % increase in structural members along with concrete quantity.

Dynamic Analysis of Block-Type Machine Foundation Using Barkan’s Model for Various Soil Parameters

Machine foundation involves both the static loads and the dynamic loads caused by working of the machine. The machine weighs several tons and is required to restrict amplitudes to only a few microns. Inadequately constructed foundations may result in failures exceeding many times the cost of the capital investment required for properly designed foundations. This necessitated a deeper scientific investigation of dynamic loading and analysis. Method proposed by Barkan (recommended by IS: 2974-1982) for design of machine foundations under harmonic load, still remains the most popular method for vibration analysis of block foundations in Indian industry. Finite Element (FE) is very commonly accepted analysis tool for solution of engineering problems. Effective Pre and Post-processing capabilities make modeling and result interpretation simple. The current paper aims to do the parametric study of dynamic analysis of block foundation using Barkan’s method. For the same, three different machines of 150 rpm, 250 rpm and 450 rpm are taken into account and six different soil types: (a) Medium, Stiff and Hard Clay and (b) Loose, Medium and Dense Sand are considered. Foundation sizes are optimized according to soil cases and each case is analysed using conventional method and FEM model using STAAD Pro. for 0.8, 1 and 1.2 times the soil parameters to cover the confidence range. This study is further extended for the comparison of concrete quantity consumed. The results grossly show that as the clay varies from medium to hard, and sand from loose to dense, the foundation size required, decreases. It was seen that, with the increase in stiffness of soil, natural frequency of machine foundation soil system increases and amplitude of foundation reduces. Also, FEM method of analysis indicates safer amplitude of foundation compared to classical method of analysis, inferring to conventional method being conservative.

CO2 reduction in tunnel construction from a material technology point of view

AbstractTunnelling and underground construction is a material‐intensive undertaking that involves the use of large quantities of concrete. Analyses of the life‐cycle assessment of a new tunnel show that the carbon footprint is largely determined by cement and concrete consumption. Optimising the quantity used, composition and properties of this construction material is thus crucial to reducing ‘'grey'' emissions – CO2 emissions arising from the construction phase. While strength and durability requirements along with exposure classes are clearly set out in directives and tender specifications, CO2 emissions per cubic metre of concrete are not currently considered a relevant criterion when it comes to project design, award and implementation. And this, despite the fact that the current state of knowledge and research shows that substantially lower‐carbon concretes could be used than is generally the case today. A paradigm shift is required to achieve the goal of carbon neutrality in the construction industry.This paper shows how CO2 emissions per cubic metre of concrete can be declared and reduced in tunnel construction, and how concrete recipes can be formulated using climate‐friendly materials, while maintaining the required strengths and durability properties. Using the design approaches outlined here, it is possible to increase clinker efficiency and reduce CO2 intensity without adversely affecting the structure and its functionality.

Using terrestrial laser scanning technology to assess the quality of prefabricated concrete modules

The main objective of this study was external facade deviation analyses applied to prefabricated off-site concrete modules. This article is decomposed into three main parts: the first part is dedicated to the introduction and to the research background. The second part explains and details the construction project, the off-site factory, the modules as well as the use of a terrestrial laser scanner. A Framework and a data acquisition layout are also exposed. The third part elaborates, in addition to the discussion and study limitations, the main key results which were obtained. The bulging effect on the bottom half of the modules can be explained by the fact that, the greater the quantity of concrete is poured, the more the inside pressure of the formwork increases, exposing the mould’s structure to additional deformations.

Analysis and Comparative Study of Conventional Slab With Voided Slab

Abstract— As the infrastructure is developing there is need for some changes in the construction field, as one cannot rely on the same method for a long time as it can have different consequences. The main consequence is the shortage of material and manpower. Also, money matters a lot in construction department along with it the machines, equipment and technology in some region is not at a level, which we want. Hence in order to satisfy these results Bubble deck slab is one of the most effective slab techniques to replace conventional slab in terms of money and materials. In this study a hollow shell is made by recycled plastic and is kept in the slab and comparison is to be done between voided slab and conventional slab regarding further points such as stresses at the centre and end of the slab, steel and concrete quantity is to be calculated and cost analysis is also done of both slabs by software such as Ansys or ETABS and cost analysis is done is done by hand. After that comparison of both void slab and conventional slab is shown. Keywords— Reuse of plastic, Use of plastic in construction sector, Environmental friendly, Void slab