Evaluation the compressive strength of the cement paste blended with supplementary cementitious materials using a piezoelectric-based sensor

2018 ◽  
Vol 171 ◽  
pp. 504-510 ◽  
Author(s):  
Ehsan Ghafari ◽  
Ying Yuan ◽  
Chen Wu ◽  
Tommy Nantung ◽  
Na Lu
Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 204
Author(s):  
Yi Han ◽  
Seokhoon Oh ◽  
Xiao-Yong Wang ◽  
Run-Sheng Lin

At present, reducing carbon emissions is an urgent problem that needs to be solved in the cement industry. This study used three mineral admixtures materials: limestone powder (0–10%), metakaolin (0–15%), and fly ash (0–30%). Binary, ternary, and quaternary pastes were prepared, and the specimens’ workability, compressive strength, ultrasonic pulse speed, surface resistivity, and the heat of hydration were studied; X-ray diffraction and attenuated total reflection Fourier transform infrared tests were conducted. In addition, the influence of supplementary cementitious materials on the compressive strength and durability of the blended paste and the sustainable development of the quaternary-blended paste was analyzed. The experimental results are summarized as follows: (1) metakaolin can reduce the workability of cement paste; (2) the addition of alternative materials can promote cement hydration and help improve long-term compressive strength; (3) surface resistivity tests show that adding alternative materials can increase the value of surface resistivity; (4) the quaternary-blended paste can greatly reduce the accumulated heat of hydration; (5) increasing the amount of supplementary cementitious materials can effectively reduce carbon emissions compared with pure cement paste. In summary, the quaternary-blended paste has great advantages in terms of durability and sustainability and has good development prospects.


2017 ◽  
Vol 1144 ◽  
pp. 121-127 ◽  
Author(s):  
Michal Hlobil

The evolution of stiffness and strength belong to the most important properties of mortars. Motivated by an increasing demand for clinker substitution by supplementary cementitious materials (SCMs), this paper presents a multiscale model for prediction of elastic stiffness and compressive strength of blended mortars. Mortars are envisioned as hierarchically organized materials with microstructural phases spanning several orders of magnitude. On the scale of hundreds of nanometers, "CSH foam" consists of amorphous calcium silicate hydrates mixed with capillary pores which on the scale of hundreds of microns acts as a contiguous matrix reinforced by unhydrated clinker, SCM grains, and by crystalline hydration products forming "cement paste". The largest scale of observation describes mortar as quartz sand aggregate inclusions embedded into a contiguous cement paste matrix. Continuum micromechanics homogenization approach is used to upscale stiffness from calcium silicate hydrates, represented by needle-shaped ellipsoids, up to the scale of mortar. Macroscopic quasi-brittle failure of mortar is associated with a concentration of strain energy density-related microscopic stresses within a critically oriented needle-shaped hydrate in "CSH foam". Successful model validation on OPC-based and blended mortars provides strong evidence that continuum micromechanics is an efficient tool for quantification of stiffness and compressive strength.


Author(s):  
Karima Arroudj ◽  
Saida Dorbani ◽  
Mohamed Nadjib Oudjit ◽  
Arezki Tagnit-Hamou

Much of the current research on concrete engineering has been focused on including siliceous additions as supplementary cementitious materials (SCMs). Silica reacts with Calcium hydroxide release during cement hydration, and produces more C-S-H. The latter contributes to increase compactness, mechanical strengths and sustainability of concrete. This paper explores the hydration characteristics of cement paste based on various natural mineral additions, that are very abundant in Algeria and present a high silica content (ground natural pozzolana “PZ” and ground dune sand “DS”). For this purpose, several analyses were carried out on modified cement pastes and mortars. TheseSCMswere introduced by replacement levels of 15, 20 and 25 by weight of cement. We first, studied the effect of these SCMs on the heat of hydration and mechanical strength of mortars at different ages. The evolution of hydration of modified paste was studied, by using Thermal analysis (TG/TDA) at different ages, to analyze the Calcium Hydroxide (CH) content of the modified pastes. It is shown that the CH content of the mixes including SCMs is lower than that of the plain cement paste, indicating that silica reacts with the cement paste through a pozzolanic reaction. Increased pozzolanic activity results in higher amounts of Calcium Silicate Hydrate in the paste, which in turn results in higher compressive strength for modified cement mortars. Due to its crystalline morphology, the ground DS particles present a partial pozzolanic effect, compared to PZ which is semi-crystalline. Modified mortars by 20% DS can be the optimal composition. It presents satisfactory results: good mechanical strength and low heat of hydration. It can lead to an economic and sustainable concrete. Ground DS is very abounded in Africa and free of any impurities and can be a good alternativeSCMsin cement industry.


2019 ◽  
Vol 26 (1) ◽  
pp. 449-464 ◽  
Author(s):  
Mifeng Gou ◽  
Longfei Zhou ◽  
Nathalene Wei Ying Then

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.


Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4248
Author(s):  
Xingxing Li ◽  
Ying Ma ◽  
Xiaodong Shen ◽  
Ya Zhong ◽  
Yuwei Li

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.


Author(s):  
Olusola Emmanuel Babalola ◽  
Paul O. Awoyera

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.


2012 ◽  
Vol 37 (3) ◽  
pp. 535-544 ◽  
Author(s):  
A. Elahi ◽  
Q. U. Z. Khan ◽  
S. A. Barbhuiya ◽  
P. A. M. Basheer ◽  
M. I. Russell

2014 ◽  
Vol 923 ◽  
pp. 42-47 ◽  
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Roman Kotiv

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.


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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