scholarly journals Static Hardness Testing of Cement Mortars Containing Different Types of Recycled Construction Waste Powders

Solids ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 331-340
Author(s):  
Zoltán Gyurkó ◽  
Rita Nemes
Keyword(s):  
Compressive Strength ◽  
Indentation Test ◽  
Hardness Test ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Test Results ◽  
Depth Sensing ◽  
Static Hardness ◽  
Cement Mortars ◽  
Aerated Concrete

The present paper deals with the hardness of cement mortars prepared with recycled materials that are potential supplementary cementitious materials (SCM). Two potential SCMs (aerated concrete powder (ACP) and concrete powder) were investigated and compared with a reference (neat cement) sample and a sample containing metakaolin (MK). The long-term performance of the mortars was studied up to the age of one year. Based on the compressive strength tests at different ages, neither concrete powder nor ACP significantly decreases the compressive strength at a 10% substitution ratio. The samples were studied with two types of static hardness tests: the Brinell hardness test and the depth sensing indentation test at two different load levels. The hardness test results indicated that the standard deviation of the results is lower at a higher load level. In the case of metakaolin and concrete powder, the change in the compressive strength was observable in the hardness test results. However, in case of the ACP, the compressive strength decreased, while the hardness increased, which can be traced back to the filler effect of aerated concrete powder. Finally, using the DSI test, the hardness results were analyzed on an energy basis. The analysis highlighted that the change in the hardness is connected to the elastic indentation energy, while it is independent from the dissipated (plastic) indentation energy.

Durability of Sustainable Self-Consolidating Concrete

2018 ◽  
Vol 765 ◽  
pp. 285-289
Author(s):  
Osama Ahmed Mohamed ◽  
Waddah Al Hawat ◽  
Omar Fawwaz Najm
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Cementitious Materials ◽  
Chloride Penetration ◽  
Supplementary Cementitious Materials ◽  
Test Results ◽  
Self Consolidating Concrete ◽  
Human Footprint ◽  
Granulated Blast Furnace Slag

Supplementary cementitious materials such as fly ash, silica fume and ground granulated blast furnace slag (GGBS) have been used widely to partially replace cement in producing self-consolidating concrete (SCC). The production of cement is associated with emission of significant amounts of CO2 and increases the human footprint on the environment. Fly ash, silica fume, and GGBS are recycled industrial by-products that also impart favorable fresh and hardened properties on concrete. This study aims to assess the effect of the amounts of fly ash and silica fume on strength and chloride penetration resistance of concrete. Rapid Chloride Penetration Test (RCPT) was used to assess the ability of SCC to resist ingress of chlorides into concrete. SCC mixes with different dosages of fly ash and silica fume were developed and tested at different curing ages. Test results showed that replacing 20% of cement with fly ash produced the highest compressive strength of 67.96 MPa among all fly ash-cement binary mixes. Results also showed that replacing15% of cement with silica fume produced the highest compressive strength of 95.3 MPa among fly ash-cement binary mixes. Using fly ash and silica fume consistently increased the concrete resistance to chloride penetration at the early ages. Silica fume at all dosages results in low or very low levels of chloride penetration at all curing ages of concrete.

scholarly journals Evaluation of external sulfate attack (Na2SO4 and MgSO4): Portland cement mortars containing siliceous supplementary cementitious materials

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Diego Jesus de Souza ◽  
Marcelo Henrique Farias de Medeiros ◽  
Juarez Hoppe Filho
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Sulfate Attack ◽  
Supplementary Cementitious Materials ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Sulfate Ions ◽  
Cement Mortars ◽  
Physical And Chemical

ABSTRACT: Sulfate attack is a term used to describe a series of chemical reactions between sulfate ions and hydrated compounds of the hardened cement paste. The present study aims to evaluate the physical (linear expansion, flexural and compressive strength) and mineralogical properties (X-ray diffraction) of three different mortar compositions (Portland Cement CPV-ARI containing silica fume and rice husk ash, in both cases with 10% replacement of the cement by weight) against sodium and magnesium sulfate attack (concentration of SO42- equal to 0.7 molar). The data collected indicate that the replacing the cement by the two siliceous supplementary cementitious materials (SCMs) generate similar results, both SCMs were able to mitigate the effects of the sodium sulfate attack in both physical and chemical characteristics, however, both materials increase the deterioration (i.e. compressive strength) when exposed to MgSO4 solution.

scholarly journals Non-autoclaved aerated concrete made of modified binding composition containing supplementary cementitious materials

2014 ◽  
Vol 13 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Oksana Poznyak ◽  
Andryy Melnyk
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Supplementary Cementitious Materials ◽  
Polypropylene Fibers ◽  
Supplementary Cementitious Material ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
The Impact ◽  
Salt Waste

In this paper the impact of carbonate-containing and sulfate components, zeolite, polypropylene fibers on the properties of modified binding composition and non-autoclaved aerated concrete based on them is investigated. The aerated concrete based on the modified binding composition containing a supplementary cementitious material, that of carbonate-containing salt waste, reinforced with polypropylene fibers is characterized by the compressive strength of 2.7 MPa with the density of 650 kg/m3. The thickness of partitions between pores is 0.16 – 0.21 mm, and the number of pores with the size 0.2-1.0 mm is 76.4%.

scholarly journals Effects of Bacillus subtilis biocementation on the mechanical properties of mortars

2019 ◽  
Vol 12 (1) ◽  
pp. 31-38 ◽  
Author(s):  
N. SCHWANTES-CEZARIO ◽  
M. F. PORTO ◽  
G. F. B. SANDOVAL ◽  
G. F. N. NOGUEIRA ◽  
A. F. COUTO ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Calcium Carbonate ◽  
Cementitious Materials ◽  
Mechanical Analysis ◽  
Sem Analysis ◽  
Subtilis Strain ◽  
Cement Mortars ◽  
Water To Cement Ratio ◽  
Mixing Water

Abstract This study aims to evaluate the influence of B. subtilis AP91 spores addition on the mechanical properties of mortars. B. subtilis strain AP91, isolated from rice leaves of the needle variety, which has an early cycle of production, was used at the concentration of 105 spores/mL in mortars with cement-to-sand ratio of 1:3 (by weight) and water-to-cement ratio (w/c) of 0.63. These spores were added in two different ways: in the mixing water and by immersion in a solution containing bacterial spores. Scanning Electron Microscope (SEM) analysis showed crystals with calcium peaks on the EDS, which possibly indicates the presence of bioprecipitated calcium carbonate. The results obtained in the mechanical analysis showed that the bioprecipitation of CaCO3 by B. subtilis strain AP91 was satisfactory, particularly when the spores were added in the mixing water, increasing the compressive strength up to 31%. Thus, it was concluded that the addition of B. subtilis AP91 spores in the mixing water of cement mortars induced biocementation, which increased the compressive strength. This bioprecipitation of calcium carbonate may very well have other advantageous consequences, such as the closure of pores and cracks in cementitious materials that could improve durability properties, although more research is still needed on this matter.

scholarly journals The role of shrinkage reducing admixtures and supplementary cementitious materials in volume stability and strength development

2019 ◽  
Vol 289 ◽  
pp. 02005
Author(s):  
Ioanna Papayianni ◽  
Fotini Kesikidou ◽  
Philip Henes Alt
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Capillary Absorption ◽  
Volume Stability ◽  
Cement Mortars ◽  
Shrinkage Reducing Admixture ◽  
Binder Ratio ◽  
Shrinkage Reducing Admixtures ◽  
Water To Binder Ratio

Shrinkage is one of the main reasons for mortar and concrete failures like curling, crack formation and de-bonding. It is a complex phenomenon due to many factors involved, such as the type and amount of cement, water to binder ratio, binder to aggregates ratio and the type and granulometry of the aggregates, relative humidity, air temperature and the temperature of concrete. To reduce this phenomenon, Shrinkage Reducing Admixtures (SRAs) have been studied over the last 30 years. On the other hand, investigation in the field of Supplementary Cementitious Materials (SCMs) has indicated that their use in concrete may improve its volume stability depending on their percentage and the type of the material. In this paper, the addition of a Shrinkage Reducing Admixture and Supplementary Cementitious Materials like ladle furnace slag, calcareous fly ash and limestone filler, were investigated. Their influence, separately and in combination, in volume stability and strength development of cement mortars was identified. Capillary absorption and open porosity were also determined.

scholarly journals Utilization of tailings in cement and concrete: A review

2019 ◽  
Vol 26 (1) ◽  
pp. 449-464 ◽  
Author(s):  
Mifeng Gou ◽  
Longfei Zhou ◽  
Nathalene Wei Ying Then
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Solid Wastes ◽  
Supplementary Cementitious Materials ◽  
Cement Clinker ◽  
Fine Aggregate ◽  
Granulated Blast Furnace Slag ◽  
Fine Aggregates ◽  
Compressive Strength Of Concrete ◽  
Cement And Concrete

AbstractOne of the advantages of cement and the cement concrete industry in sustainability is the ability to utilize large amounts of industrial solid wastes such as fly ash and ground granulated blast furnace slag. Tailings are solid wastes of the ore beneficiation process in the extractive industry and are available in huge amounts in some countries. This paper reviews the potential utilization of tailings as a replacement for fine aggregates, as supplementary cementitious materials (SCMs) in mortar or concrete, and in the production of cement clinker. It was shown in previous research that while tailings had been used as a replacement for both fine aggregate and cement, the workability of mortar or concrete reduced. Also, at a constant water to cement ratio, the compressive strength of concrete increased with the tailings as fine aggregate. However, the compressive strength of concrete decreased as the replacement content of the tailings as SCMs increased, even whentailings were ground into smaller particles. Not much research has been dedicated to the durability of concrete with tailings, but it is beneficial for heavy metals in tailings to stabilize/solidify in concrete. The clinker can be produced by using the tailings, even if the tailings have a low SiO2 content. As a result, the utilization of tailings in cement and concrete will be good for the environment both in the solid waste processing and virgin materials using in the construction industry.

scholarly journals Study of Hydration and Microstructure of Mortar Containing Coral Sand Powder Blended with SCMs

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4248
Author(s):  
Xingxing Li ◽  
Ying Ma ◽  
Xiaodong Shen ◽  
Ya Zhong ◽  
Yuwei Li
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Silica Fume ◽  
Dilution Effect ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Limestone Powder ◽  
Chemical Effect ◽  
Granulated Blast Furnace Slag ◽  
Coral Sand

The utilization of coral waste is an economical way of using concrete in coastal and offshore constructions. Coral waste with more than 96% CaCO3 can be ground to fines and combined with supplementary cementitious materials (SCMs) such as fly ash, silica fume, granulated blast furnace slag in replacing Portland cement to promote the properties of cement concrete. The effects of coral sand powder (CSP) compared to limestone powder (LSP) blended with SCMs on hydration and microstructure of mortar were investigated. The result shows CSP has higher activity than LSP when participating in the chemical reaction. The chemical effect among CSP, SCMs, and ordinary Portland cement (OPC) results in the appearance of the third hydration peak, facilitating the production of carboaluminate. CSP-SCMs mortar has smaller interconnected pores on account of the porous character of CSP as well as the filler and chemical effect. The dilution effect of CSP leads to the reduction of compressive strength of OPC-CSP and OPC-CSP-SCMs mortars. The synergic effects of CSP with slag and silica fume facilitate the development of compressive strength and lead to a compacted isolation and transfer zone (ITZ) in mortar.

Suitability of Cordia millenii Ash Blended Cement in Concrete Production

2016 ◽  
Vol 22 ◽  
pp. 59-67 ◽  
Author(s):  
Olusola Emmanuel Babalola ◽  
Paul O. Awoyera
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Blended Cement ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Supplementary Cementitious Materials ◽  
Sieve Analysis ◽  
Concrete Production ◽  
Alternative Materials ◽  
Concrete Control

Supplementary cementitious materials are most needed to enhance a sustainable development in poor communities. It is pertinent to investigate the suitability of such alternative materials for construction. The present study evaluates the strength characteristics of concrete made with varied proportion of Cordia millenii ash blended with Portland cement. Chemical composition of Cordia millenii and the setting time when blended with cement was determined. Other laboratory tests performed on Cordia millenii blended cement include: sieve analysis and specific gravity. Five replacement percentages of Cordia millenii (5%, 10%, 15%, and 20%) were blended with cement in concrete. Control specimens were also produced with only cement. Tests to determine the workability, air entrained, bulk density and compressive strength properties of the concrete were also conducted. Results obtained revealed that optimum Cordia millenii mix is 10%, which yielded the highest density and compressive strength in the concrete.

Modified Plasters for Restoration and Finishing Works

2014 ◽  
Vol 923 ◽  
pp. 42-47 ◽  
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Roman Kotiv
Keyword(s):  
Compressive Strength ◽  
Chemical Composition ◽  
Cementitious Materials ◽  
Quality Parameters ◽  
Supplementary Cementitious Materials ◽  
Cement Matrix ◽  
Hydration Products ◽  
High Quality ◽  
Physico Chemical ◽  
White Portland Cement

The paper is devoted to the research and development of modified plasters for restoration and finishing works based on decorative multicomponent cements containing white Portland cement and supplementary cementitious materials (silica fume, metakaolin and fine ground limestone). This cements are similar to Roman cement by their chemical composition. The use of optimal granulometry of decorative multicomponent cements provide directed formation of microstructure of the cement matrix with the formation of stable hydration products. Compositions of modified plasters by the criterions of workability and compressive strength were designed. Physico-chemical modification of plaster by complex air-entraining admixture allows to obtain high-quality modified plasters with improved quality parameters.

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.

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