scholarly journals Eco-efficient concrete, optimized by Alfred’s particle packing model, with partial replacement of Portland cement by stone powder

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Heloisa Fuganti Campos ◽  
André Lucas Bellon ◽  
Eduardo Reis de Lara e Silva ◽  
Maurício Villatore Junior
Keyword(s):  
Compressive Strength ◽  
Co2 Emissions ◽  
Cementitious Materials ◽  
Particle Packing ◽  
Partial Replacement ◽  
Cement Particle ◽  
Distribution Factor ◽  
Packing Model ◽  
The Matrix ◽  
Hardened State

Abstract The partial replacement of clinker by complementary cementitious materials can significantly contribute to the reduction of carbon emissions in the production of concrete. Another alternative to reduce these emissions is to increase the efficiency of the concrete, achieving higher compressive strength with lower consumption of cement. Particle packing models are efficient tools to optimize the composition of the matrix and contribute to the production of more eco-efficient concretes. In this context, the objective of the present study is evaluating the production of concretes with partial replacement of cement by stone powder, optimized by Alfred’s particle packing model, seeking to reduce cement consumption and CO2 emissions per MPa of compressive strength. The replacement content of cement by stone powder was 20% by mass (equivalent to 22.4% by volume). Concretes were produced with different distribution factor (q) - 0.37; 0.21; 0.45 - to verify the influence of fines on the flow between particles and on the efficiency of the produced concrete. The analyses were carried out in terms of properties in the fresh state, hardened state, and sustainability parameters (cement consumptions and CO2 emissions). The application of the proposed method resulted in a higher compressive strength than the expected for the water/cement ratio used (0.5). The most efficient concrete reached the compressive strength of 68 MPa with 240 kg/m3 of cement, which represents 3.5 kg of cement/m3/MPa and 3.1 kg of CO2/m3/MPa, a value below the references found in the literature for conventional concretes. Therefore, the proposed method allows to produce more eco-efficient concrete, contributing to the use of waste and reducing CO2 emissions.

scholarly journals Influence of Partial Replacement of Micro-Silica by Fly-Ash on Strength Properties of Reactive Powder Concrete

2020 ◽  
Vol 9 (3) ◽  
pp. 2932-2937
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Reactive Powder Concrete ◽  
Experimental Investigations ◽  
Reactive Powder ◽  
Micro Silica

Reactive powder concrete (RPC) is the ultra-high strength concrete made by cementitious materials like silica fumes, cement etc. The coarse aggregates are completely replaced by quartz sand. Steel fibers which are optional are added to enhance the ductility. Market survey has shown that micro-silica is not so easily available and relatively costly. Therefore an attempt is made to experimentally investigate the reduction of micro-silica content by replacing it with fly-ash and mechanical properties of modified RPC are investigated. Experimental investigations show that compressive strength decreases gradually with addition of the fly ash. With 10 per cent replacement of micro silica, the flexural and tensile strength showed 40 and 46 per cent increase in the respective strength, though the decrease in the compressive strength was observed to be about 20 per cent. For further percentage of replacement, there was substantial drop in compressive, flexural as well as tensile strength. The experimental results thereby indicates that utilisation of fly-ash as a partial replacement to micro silica up to 10 per cent in RPC is feasible and shows quite acceptable mechanical performance with the advantage of utilisation of fly-ash in replacement of micro-silica.

On Effects of Fly Ash as a Partial Replacement of Cement on Concrete Strength

2012 ◽  
Vol 204-208 ◽  
pp. 3970-3973
Author(s):  
Reagan J. Case ◽  
Kai Duan ◽  
Thuraichamy G. Suntharavadivel
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Concrete Strength ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Replacement Ratio ◽  
Interface Reactions ◽  
Compressive Strength Of Concrete ◽  
Interface Bonding Strength ◽  
Large Research

As a part of a large research program aiming at the cementitious materials containing recycled materials at Central Queensland University – Australia, the current paper presents the preliminary results of a study on the effects of fly ash, which is used to replace cement in concrete, on the concrete compressive strength. For this purpose, systematic experiments have been carried out to investigate the influences of fly ash ratio and age. The compressive strength of concrete specimens with replacement ratios of 15%, 30% and 45%, and aged 7 and 28 days are measured and are compared with those of the concrete specimens without fly ash at the same ages. The results demonstrate that the strength of fly ash containing concrete improves more slowly but more strongly with aging, than their fly ash free counterparts, and an optimum fly ash replacement ratio exists where the maximum compressive strength of fly ash containing concrete can be achieved, and the maximum strength for the specimens aged 28 days and above is higher that of fly ash free concrete. Furthermore, the observation strength behaviours are analysed and discussed in terms of the influences of fly ash on interface reactions and interface bonding strength.

scholarly journals Effect of Fibre Hybridisation on Mechanical Properties of Cementitious Composites

2019 ◽  
Vol 9 (2) ◽  
pp. 1573-1579
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Cementitious Materials ◽  
Strength Test ◽  
Supplementary Cementitious Materials ◽  
Modulus Of Rupture ◽  
Low Velocity Impact ◽  
Split Tensile Strength ◽  
Steel Fibres ◽  
The Matrix

Conventional cement based composites have constituent materials such as Portland cement, supplementary cementitious materials, fine sand, super-plasticizer and water. To achieve high performance, these composites needs high cement content in it which will cause high cost of production. Addition of supplementary cementitious materials as partial substitutes for cement will help in reducing the cost. In this study, a pre-characterized mix proportion of cementitious composite, in which 30% of cement was substituted with lime powder. To enhance the ductility of the composite, the matrix is reinforced with 2% (by volume of composite) of crimped steel fibres. Further, hybridisation of metallic and non-metallic fibres is done in this study to bring the self-weight of the mix down and to reduce the chances of degradation due to the corrosion of fibres. Fibre hybridisation was done by replacing 25%, 50%, 75% and 100% by volume of steel fibres with poly propylene (PP) fibres. The characterisation of the fibre reinforced composites was done by assessing their workability by conducting flow test, compressive strength test, split tensile strength test, flexure test and low velocity impact test. It was observed that, the mix with 100% of steel fibres replaced with PP fibres exhibited better workability. It was also observed that, compressive strength, split tensile strength, modulus of rupture and impact resistance were maximum for the mix reinforced with steel fibre alone and the strengths got reduced gradually due to hybridisation of fibres. Based on the requirement of strength, a combination of steel and PP fibres can be used for reinforcing the matrix, which will help in improving ductility, reducing self-weight. By this, the matrix can be made more resistant to corrosion and can be used in structures especially in the marine environment.

scholarly journals Recycled PET Sand for Cementitious Mortar

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 273
Author(s):  
Angélica Faria Campanhão ◽  
Markssuel Teixeira Marvila ◽  
Afonso R. G. de Azevedo ◽  
Tulane Rodrigues da Silva ◽  
Roman Fediuk ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mineral Resource ◽  
Sustainable Development ◽  
Compressive Strength ◽  
Quartz Sand ◽  
Mineral Resources ◽  
Cementitious Materials ◽  
Recycled Pet ◽  
Fresh State ◽  
Hardened State

Cementitious materials cause a great impact on the environment due to the calcination of clinker and the extraction of non-renewable mineral resources. In this work, the replacement of quartz sand from the river by PET sand was evaluated at levels of 10%, 20%, and 30%. Tests were performed in the fresh state through consistency, air retention, density, and incorporated air and in the hardened state for compressive strength, flexural strength, density, capillarity, and water absorption. The results show that PET sand is viable in contents of up to 10%, improving the mechanical properties of the mortar and without compromising its workability and incorporated air properties. Above that level, the loss of properties is very excessive, mainly of workability and incorporated air. The incorporated air of the 30% composition, for example, reaches 24%, an excessive value that impacts the properties of the hardened state, making it impossible to use the material at levels greater than 20%. It is concluded that the use of recycled PET sand is a possibility that contributes to sustainable development, as it reduces the extraction of quartz sand from the river, a non-renewable mineral resource.

scholarly journals Workability and mechanical properties of ultrafine cement based grout for structural rehabilitation: A parametric study on the partial replacement with SCMs

2018 ◽  
Vol 199 ◽  
pp. 07006
Author(s):  
Md Shamsuddoha ◽  
Götz Hüsken ◽  
Wolfram Schmidt ◽  
Hans-Carsten Kühne ◽  
Matthias Baeßler
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Hardened Cement ◽  
Binder Ratio ◽  
Strengthening Technique ◽  
Ultrafine Cement

Grouting is a universal repair and strengthening technique, which is constantly used for structural remediation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. Having an extremely small particle size of only few microns, ultrafine cements are ideal for grouting applications due to their superior permeability and compressive strength properties of the hardened cement paste compared to that of the less-expensive, but coarser ordinary Portland cements. Supplementary cementitious materials (SCMs) are often used to replace ultrafine cement in order to modify certain properties and to reduce costs. The aim of this experimental study is to investigate the effect of three supplementary materials: microsilica (MS), fly ash (FA), and metakaolin (MK) on the workability, and mechanical properties of an ultrafine cement based grout with a constant water-binder ratio and constant superplasticizer content. Maximum percentages of replacement with ultrafine cement were 6% by volume of cement for MS and 16% for FA, and MK. In general, results suggest that the workability is improved by addition of FA, whereas is reduced, when modified with MS and MK. The compressive strength of grout after cement replacement remains comparable to that of pure cement grout. However, there is a tendency of the MS to positively affect the compressive strength opposite to FA, whereas flexural strength is positively affected by FA. Based on the results, it is evident that grouts with Hägerman cone flow more than 500 mm and compressive strength of more than 90 MPa after 28 days can be produced.

scholarly journals Evaluation of compressive strength of concrete with metakaolin using different levelling techniques

2021 ◽  
Vol 10 (3) ◽  
pp. e31510313341
Author(s):  
Ayrton Wagner dos Santos Gomes de Sá ◽  
Yane Coutinho ◽  
Renan Gustavo Pacheco Soares ◽  
Fernanda Cavalcanti Ferreira ◽  
Arnaldo Manoel Pereira Carneiro
Keyword(s):  
Compressive Strength ◽  
High Strength ◽  
Strength Test ◽  
Mix Design ◽  
Partial Replacement ◽  
Initial Strength ◽  
Compressive Strength Test ◽  
Mineral Additions ◽  
Hardened State ◽  
Compressive Strength Of Concrete

The partial replacement of cement by mineral additions such as metakaolin has been widely applied in the production of high-strength and durable concretes due to the pozzolanic action, allowing a reduction in the consumption of cement. Tests are performed to determine the mechanical properties of these materials, such as compressive strength, for which there are different levelling techniques of specimens, such as sulphur and neoprene, indicated for different resistance classes. The present study aimed to characterize the behaviour, in the hardened state, of concrete produced with high initial strength Portland cement (CPV-ARI) and metakaolin and evaluate the different levelling methods. Three groups of samples dosed by the IPT-EPUSP method, with mix designs of 1:3, 1:5, and 1:6, and replacements of 8 and 10% of cement by metakaolin, were subjected to compressive strength test, at the ages of 28 days, with levelling by neoprene, and 90 days, with levelling by sulphur. It was observed an increase in strength with addition of metakaolin at both ages. Comparing the results in the two ages, it was verified an increase in strength for the mix designs 1:5 and 1:6 and a reduction for the mix design 1:3. Such fact can be explained by the high strengths achieved by this mix design. As the levelling method used was sulphur, it is confirmed the imprecision of results for strengths above 50 MPa with this technique.

Chemical attack on concrete containing a high volume of crumb rubber as a partial replacement to fine aggregate in engineered cementitious composite (ECC)

2021 ◽  
Author(s):  
Wesam Salah Alaloul ◽  
Muhammad Ali Musarat ◽  
Sani Haruna ◽  
Bassam Tayeh ◽  
Muhammad Nurzahin Bin Norizan
Keyword(s):  
Compressive Strength ◽  
High Volume ◽  
Crumb Rubber ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Cementitious Composite ◽  
Conventional Concrete ◽  
Engineered Cementitious Composite ◽  
Chemical Attack

This research has been conducted where the focus is on the chemical attack towards the Engineered Cementitious Composite (ECC) containing a high volume of the crumb rubber in terms of durability, behaviour, and comparison with conventional concrete. Two variables have been considered in developing rubberized ECC mixtures, i.e. the amount of crumb rubber as a replacement to fine aggregate by volume of 0-30% and PVA fibres by volume of 0-2% to cementitious materials. The resistance properties of ECC incorporating crumb rubber were investigated for 13 different variable combinations developed by Response Surface Methodology (RSM). The experimental results revealed that the presence of crumb rubber in the ECC matrix enhanced the resistance of the ECC in both acidic and sulphate environments. It was also revealed that by incorporating 15% of crumb rubber, the loss of compressive strength significantly reduced from 38% to 15%

Mechanical Properties of Self-Healing System in Cementitious Material with Microcapsule

2018 ◽  
Vol 913 ◽  
pp. 1090-1096 ◽  
Author(s):  
Peng Liang ◽  
Qian Jin Mao ◽  
Zi Ming Wang ◽  
Su Ping Cui
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Strength Loss ◽  
Cementitious Materials ◽  
Self Healing ◽  
Healing System ◽  
The Matrix

In this paper, several urea–formaldehyde/epoxy microcapsules with different particle sizes were synthesized by in-situ polymerization. The chemical structure and compressive rupture load of microcapsule were characterized. The effect of microcapsule dosage, particle size and preload pressure on compressive strength of cementitious materials was studied. The result shows: when the particle size of microcapsule is 2 mm~2.5 mm, the rupture load of microcapsule is highest, more than 3N; When the microcapsule dosage is less than 2.5%, the strength loss of the matrix is relatively small; With the increase of the particle size of the capsule, the strength of the matrix decrease greatly; When the dosage of microcapsule is 2.5%, the particle size is 1.5 mm and the preload pressure is 30%~45%fmax, the compressive strength of the self-healing specimen is 8% higher than that of the non-preloaded specimens, which shows a certain self-healing performance.

scholarly journals Utilization of Corn Cobs Ash as Cementitious and Binary Cementitious Materials in Concrete and Cement-based Composites: A Review

2021 ◽  
pp. 26-42
Keyword(s):  
Compressive Strength ◽  
Energy Savings ◽  
Low Cost ◽  
Cementitious Materials ◽  
Pulse Velocity ◽  
Partial Replacement ◽  
Hardened Concrete ◽  
Biomass Ash ◽  
Operational Conditions ◽  
Corn Cobs

This paper reviews the utilization of corn cobs ash (CCA) as pozzolanic, cementitious, and binary cementitious materials in concrete. CCA is the grey-to-brown, inorganic or heterogeneous residual material derived from the high- temperature incineration or combustion of corn cobs (CC). Despite the typical problematic nature of biomass ash, the chemical composition of CCA renders it a potential pozzolanic material. Therefore, numerous studies have critically examined the process technologies and operational conditions for CCA production and its application as a partial replacement for cement in concrete. Other studies have extensively characterized the physicochemical, morphological, microstructure, and thermal properties of CCA through various analytical techniques. Potential pozzolanic materials must meet the condition: SiO2 + Al2O3 + Fe2O3 ≥ 70%, according to ASTM C618, to which CCA complies satisfactorily. Hence, the use of CCA as a replacement for cement has been investigated over the years. Findings indicate that the partial replacement of cement with CCA decreases compressive strength, thermal conductivity, ultrasonic pulse velocity, and density of the hardened concrete at normal temperatures. Nevertheless, the thermal treatment (calcination) of CCA and extended curing enhances compressive strength owing to higher silica content and extended surface area. Besides, the partial replacement of cement with CCA enhances the insulation properties of mortar, which improves thermal comfort, costs and energy savings in buildings. Hence, the partial replacement of cement with CCA provides an environmentally friendly, low cost, and sustainable approach for valorizing CC residues whilst addressing CO2 emissions in construction.

scholarly journals Assessing, Understanding and Unlocking Supplementary Cementitious Materials

2016 ◽  
Vol 1 ◽  
pp. 50 ◽  
Author(s):  
Ruben Snellings
Keyword(s):  
Co2 Emissions ◽  
Cementitious Materials ◽  
Cement Industry ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
New Materials ◽  
Cement Production ◽  
Blended Cements ◽  
International Commitments ◽  
Roll Out

The partial replacement of Portland clinker by supplementary cementitious materials (SCM) is one of the most popular and effective measures to reduce both costs and CO2 emissions related to cement production. An estimated 800 Mt/y of blast furnace slags, fly ashes and other materials are currently being used as SCM, but still the cement industry accounts for 5-8% of global CO2 emissions. If no further actions are taken, by the year 2050 this share might even rise beyond 25%. There is thus a clear challenge as to how emissions will be kept at bay and sustainability targets set by international commitments and policy documents will be met.Part of the solution will be a further roll-out of blended cements in which SCMs constitute the main part of the binder to which activators such as Portland cement are added. Since supply concerns are being raised for conventional high-quality SCMs it is clear that new materials and beneficiation technologies will need to step in to achieve further progress. This paper presents opportunities and challenges for new SCMs and demonstrates how advances towards more powerful and reliable characterisation techniques help to better understand and exploit SCM reactivity.

Sign in / Sign up

Export Citation Format

Share Document