scholarly journals Influence of quartz powder and silica fume on the performance of Portland cement

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ludmila Rodrigues Costa Tavares ◽  
Joaquim Francisco Tavares Junior ◽  
Leonardo Martins Costa ◽  
Augusto Cesar da Silva Bezerra ◽  
Paulo Roberto Cetlin ◽  
...  
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Electrical Resistance ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Heat Of Hydration ◽  
Supplementary Cementitious Materials ◽  
Cementitious Composites ◽  
Quartz Powder ◽  
Hydration Properties

AbstractSupplementary cementitious materials interact chemically and physically with cement, influencing the formation of hydrate compounds. Many authors have analyzed the filler and pozzolanic effect. However, few studies have explored the influence of these effects on hydration, properties in the fresh and hardened states, and durability parameters of cementitious composites separately. This study investigates the influence of the replacement of 20% of Portland cement for silica fume (SF) or a 20-µm medium diameter quartz powder (QP) on the properties of cementitious composites from the first hours of hydration to a few months of curing. The results indicate that SF is pozzolanic and that QP has no pozzolanic activity. The use of SF and QP reduces the released energy at early times to the control paste, indicating that these materials reduce the heat of hydration. The microstructure with fewer pores of SF compounds indicates that the pozzolanic reaction reduced pore size and binding capability, resulting in equivalent mechanical properties, reduced permeability and increased electrical resistance of the composites. SF and QP increase the carbonation depth of the composites. SF and QP composites are efficient in the inhibition of the alkali-aggregate reaction. The results indicate that, unlike the filler effect, the occurrence of pozzolanic reaction strongly influences electrical resistance, reducing the risk of corrosion of the reinforcement inserted in the concrete.

Use of Algerian Natural Mineral Deposit as Supplementary Cementitious Materials

2018 ◽  
Vol 34 ◽  
pp. 48-58 ◽  
Author(s):  
Karima Arroudj ◽  
Saida Dorbani ◽  
Mohamed Nadjib Oudjit ◽  
Arezki Tagnit-Hamou
Keyword(s):  
Mechanical Strength ◽  
Calcium Hydroxide ◽  
Cement Paste ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Heat Of Hydration ◽  
Cement Industry ◽  
Supplementary Cementitious Materials ◽  
Natural Mineral ◽  
Different Ages

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.

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.

Minimising the risk of thermally induced cracking in mass concrete structures through suitable materials selection and processing

MRS Advances ◽  
2018 ◽  
Vol 3 (34-35) ◽  
pp. 2051-2061
Author(s):  
Yunus Ballim
Keyword(s):  
Portland Cement ◽  
Concrete Structures ◽  
Cementitious Materials ◽  
Heat Of Hydration ◽  
Supplementary Cementitious Materials ◽  
Mass Concrete ◽  
Concrete Element ◽  
Near Surface ◽  
Temperature Development ◽  
Different Types

ABSTRACTThe hydration of cement is an exothermic reaction which generates around 300 kJ/kg of cement hydrated. In mass concrete structures such as dams and large foundations, this heat of hydration causes a significant rise in temperature in the internal sections of the concrete. If thermal gradients between the internal sections and the near-surface zone of the concrete element are sufficiently large, the thermal stress can cause cracking of the concrete. This cracking may cause functional or structural problems in the operation of the structure. In order to minimise the potential for such cracking, it is necessary to minimise the rate and amount of heat that is evolved, particularly during the early period of the hydration process. This can be achieved by design engineers and concrete technologists through judicious selection and processing of concrete-making materials. This paper presents the observations and results obtained over a number of years from adiabatic testing of concretes, computational modelling of temperature development in large concrete structures and direct temperature measurements in actual structures, with a view to understanding the effects of concrete-making materials on temperature development in concrete. The paper considers the effects of different types of rock aggregates, different types of Portland cement, fineness of grinding of the cement, the addition of supplementary cementitious materials and variations in the concrete starting temperature on temperature development in a large concrete element over time. The results indicate that using a coarser ground cement, adding significant amounts of supplementary cementitious materials and cooling the concrete mixture before placing has a more significant effect in reducing the risk of cracking than varying the aggregate type of the Portland cement type.

scholarly journals The properties of slag-silica fume ternary blended mortar with quarry dust

2020 ◽  
Vol 14 (1) ◽  
pp. 6443-6451 ◽  
Author(s):  
Chow Wee Kang ◽  
Cheah Chee Ban ◽  
Oo Chuan Wei ◽  
Part Wei Ken ◽  
Leow Khang Heng
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Drying Shrinkage ◽  
High Strength ◽  
Total Porosity ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Fine Aggregate ◽  
Granulated Blast Furnace Slag ◽  
Quarry Dust

High carbon emissions of manufactured Portland cement in the concrete industry have incurred several interests in reducing the use of Portland cement by partially replacing it with supplementary cementitious materials. Most of which, are by-products from other manufacturing industries. Hence, the main purpose of this study is to investigate the effects of different combinations of ternary blended mortars incorporating supplementary cementitious materials such as Ground Granulated Blast Furnace Slag (GGBS) and Densified Silica Fume (DSF). In this study, mortars were prepared with 100% quarry dust and GGBS was replaced with DSF at 2% step increments up to 16% at a w/b ratio of 0.24. At the same time OPC content was fixed at 50%. The compressive and flexural strength, drying shrinkage, and porosity of mortars were all tested. The results indicated that the increasing DSF content increases; GGBS reduces the superplasticizer dosage for the desired workability of the mortar. The utilization GGBS and DSF has improved the performances ternary blended mortar incorporating quarry dust as a fine aggregate in terms of mechanical strength, drying shrinkage and total porosity tested. The high strength ternary blended mortar incorporating GGBS and DSF exhibited optimum mechanical and durability performance at the OPC:GGBS:DSF ratio of 50:38:12.

Development of an Alternative Cementitious Materials Based on Calcium Carbide Residue and Silica Fume

2021 ◽  
Vol 904 ◽  
pp. 435-440
Author(s):  
Thunthanut Inyai ◽  
Phongthorn Julphunthong ◽  
Panuwat Joyklad
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Silica Fume ◽  
Ordinary Portland Cement ◽  
Raw Materials ◽  
Calcium Carbide ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Engineering Properties ◽  
Calcium Carbide Residue

The present study evaluated the engineering properties and microstructure of an alternative binder composed of calcium carbide residue and silica fume. The cementitious mechanisms of this alternative binder based on the pozzolanic reaction in raw materials. The ratio of calcium carbide residue and silica fume was decided based on the chemical composition of raw materials and their chemical reaction. The calcium carbide residue-silica fume mortar was prepared and tested for its compressive strength at several curing periods, with results then compared to conventional mortar made with ordinary Portland cement. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the microstructure of hardened mortars. The test results suggest that the compressive strength of calcium carbide residue-silica fume mortar continuously developed throughout the curing period. The relative compressive strength of calcium carbide residue-silica fume mortar reached 72.78% of the ordinary Portland cement mortar strength at 28 days curing age.

Evaluation of strength of concrete on different initial exposure condition

2020 ◽  
Vol 13 ◽  
Author(s):  
Sri Ram Krishna Mishra ◽  
Pradeep Kumar Ghosh ◽  
Manoj Kulshreshtha
Keyword(s):  
Portland Cement ◽  
High Strength ◽  
Cementitious Materials ◽  
General Purpose ◽  
Supplementary Cementitious Materials ◽  
Exposure Condition ◽  
Portland Cement Concrete ◽  
Initial Exposure ◽  
Skilled Manpower ◽  
Standard Practices

Background: The previous studies have focused curing effect of mainly on high strength concrete, where strict supervision is maintained. This study is based upon general purpose concreting work for commercial and residential construction in absence of skilled manpower and supervision. Objective: The objective of this study is to establish a thumb rule to provide 7 days initial curing for maintaining quality for unsupervised concreting irrelevant to type of cement and grading. Methods: In this study concrete samples made with locally available commercial cements were cured for various initial exposure. Results: The results shows that concrete cured after a gap of 4 days from the time of de-moulding have given lowest strength as compared to concrete cured in standard practices i.e. where proper curing protocol had been followed. Conclusion: Initial curing is most important aspect of gaining desired strength. The findings after this study shows that curing affects the strength of concrete in variable grading. Initial curing has great importance for concrete with all types of Portland cement. Concrete with supplementary cementitious materials gives lowest strength initially but results higher strength after 28 days as compared to Portland cement.

scholarly journals Special Issue: Supplementary Cementitious Materials in Concrete, Part I

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2291
Author(s):  
Alessandro P. Fantilli ◽  
Daria Jóźwiak-Niedźwiedzka
Keyword(s):  
Environmental Impact ◽  
Portland Cement ◽  
Building Materials ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Special Issue ◽  
Cement Production ◽  
Concrete Part

The environmental impact of the Portland cement production and the large use of cement-based building materials is a growing problem [...]

scholarly journals A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3467
Author(s):  
Ankit Kothari ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Carbon Dioxide ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cementitious Materials ◽  
Cold Climate ◽  
Supplementary Cementitious Materials ◽  
Short Exposure ◽  
Chemical Admixtures ◽  
Composite Cements ◽  
Alkali Activated

Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

Research Progress on the Hydration of Portland Cement with Calcined Clay and Limestone

2021 ◽  
Vol 1036 ◽  
pp. 240-246
Author(s):  
Jin Tang ◽  
Su Hua Ma ◽  
Wei Feng Li ◽  
Hui Yang ◽  
Xiao Dong Shen
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Research Progress ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Early Hydration ◽  
Calcined Clay ◽  
Dense Microstructure

The use of calcined clay and limestone as supplementary cementitious materials, can have a certain influence on the hydration of Portland cement. This paper reviewed the influence of limestone and calcined clay and the mixture of limestone and calcined clay on the hydration of cement. Both limestone and calcined clay accelerate the hydration reaction in the early hydration age and enhance the properties of cement. Limestone reacts with C3A to form carboaluminate, which indirectly stabilized the presence of ettringite, while calcined clay consumed portlandite to form C-(A)-S-H gel, additional hydration products promote the densification of pore structure and increase the mechanical properties. The synergistic effect of calcined clay and limestone stabilize the existence of ettringite and stimulate the further formation of carboaluminate, as well as the C-(A)-S-H gel, contributed to a dense microstructure.

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