The physicochemical properties of Portland cement blended with precipitated calcium carbonate with different morphologies as a supplementary cementitious material

2022 ◽  
pp. 130309
Author(s):  
Lewis J. McDonald ◽  
M. Ara Carballo-Meilan ◽  
Ricardo Chacartegui ◽  
Waheed Afzal
2019 ◽  
Vol 4 ◽  
pp. 89-102 ◽  
Author(s):  
Alice T Bakera ◽  
Mark G Alexander

Numerous research efforts on metakaolin as a supplementary cementitious material (SCM) have been undertaken in the past 20 years. This material, while relatively expensive mainly due to low production volumes worldwide, nevertheless has a significantly lower production cost than Portland cement. However, industry remains tentative in considering metakaolin in concrete. This paper takes the view that industry should consider investing in the production and application of metakaolin in appropriate concrete projects, particularly in aggressive environments where plain Portland cement may be inadequate, and where other SCMs may not readily be available. The main contribution of the paper is a global review of recent studies on the use of metakaolin in different types of concrete. This international experience is then compared with results from a study on the durability performance of metakaolin concrete using local materials in the Western Cape province of South Africa, as a means of concrete performance improvement. The study investigates concrete durability properties: penetrability (sorptivity, permeability, conductivity and diffusion), mitigation of Alkali-Silica Reaction (ASR), and carbonation resistance. The concretes were prepared with three water-binder ratios (0.4, 0.5 and 0.6), and with metakaolin replacement levels of 0% (control), 10%, 15% and 20%. Performance results show that, with increasing metakaolin content, the transport properties of concrete are considerably improved, ASR expansion due to a highly reactive local aggregate decreases to non-deleterious levels, while no detrimental effect on carbonation is observed. Thus, metakaolin could serve as a valuable SCM to enhance the durability performance of concrete in local aggressive environments.


Author(s):  
K. D. C. Silva ◽  
G. C. Silva ◽  
J. F. Natalli ◽  
J. C. Mendes ◽  
G. J. B. Silva ◽  
...  

2021 ◽  
Author(s):  
Carlos Hernando Aramburo Varela ◽  
Luiz Felipe de Pinho ◽  
César Pedrajas Nieto-Márquez ◽  
Rafael Talero Morales

The thermal activation of clays to produce highly reactive artificial pozzolans on a large scale is one of the most important technologies developed on an industrial scale to reduce CO2 emissions in cement manufacture. This technical document deals with the scientific basis for the thermal activation of clays to produce an extraordinarily high quality supplementary cementitious material (SCM) based on the contents of its hydraulic factors, reactive silica (SiO2r–) and reactive alumina (Al2O3r–). The production process and the optimization of its use in the new cements offers better performance, features and durability. Furthermore, its mixture with Portland cement is much more appropriate when carried out in a blending station after both components, activated clay and Portland cement, are ground separately and not jointly in a single mill.


Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 554 ◽  
Author(s):  
Lewis McDonald ◽  
Fredrik Glasser ◽  
Mohammed Imbabi

The production of Portland cement accounts for approximately 7% of global anthropogenic CO2 emissions. Carbon CAPture and CONversion (CAPCON) technology under development by the authors allows for new methods to be developed to offset these emissions. Carbon-negative Precipitated Calcium Carbonate (PCC), produced from CO2 emissions, can be used as a means of offsetting the carbon footprint of cement production while potentially providing benefits to cement hydration, workability, durability and strength. In this paper, we present preliminary test results obtained for the mechanical and chemical properties of a new class of PCC blended Portland cements. These initial findings have shown that these cements behave differently from commonly used Portland cement and Portland limestone cement, which have been well documented to improve workability and the rate of hydration. The strength of blended Portland cements incorporating carbon-negative PCC Admixture (PCC-A) has been found to exceed that of the reference baseline—Ordinary Portland Cement (OPC). The reduction of the cement clinker factor, when using carbon-negative PCC-A, and the observed increase in compressive strength and the associated reduction in member size can reduce the carbon footprint of blended Portland cements by more than 25%.


2014 ◽  
Vol 982 ◽  
pp. 114-118 ◽  
Author(s):  
Martin Keppert ◽  
Kirill Polozhiy

Fly ashes collected in Air Pollution Control lines of Municipal Solid Waste Incinerators (MSWI) differ highly from fly ashes generated during coal burning what complicates their utilization in building materials production. Nevertheless after a treatment such ashes can have properties relatively comparable with coal fly ashes and thus can be used as Supplementary Cementitious Material (SCM). The water extracted MSWI fly ash was used as partial Portland cement replacement in mortars. The mortars strength evolution in time was monitored; behavior typical for pozzolans – slower increase of strength – was observed. Influence of thermal load on strength of mortars was studied as well. It can be concluded that water extracted MSWI fly ash can be used as 10 % Portland cement substitute without loss of mechanical properties.


TAPPI Journal ◽  
2011 ◽  
Vol 10 (7) ◽  
pp. 29-34
Author(s):  
TEEMU PUHAKKA ◽  
ISKO KAJANTO ◽  
NINA PYKÄLÄINEN

Cracking at the fold is a quality defect sometimes observed in coated paper and board. Although tensile and compressive stresses occur during folding, test methods to measure the compressive strength of a coating have not been available. Our objective was to develop a method to measure the compressive strength of a coating layer and to investigate how different mineral coatings behave under compression. We used the short-span compressive strength test (SCT) to measure the in-plane compressive strength of a free coating layer. Unsupported free coating films were prepared for the measurements. Results indicate that the SCT method was suitable for measuring the in-plane compressive strength of a coating layer. Coating color formulations containing different kaolin and calcium carbonate minerals were used to study the effect of pigment particles’ shape on the compressive and tensile strengths of coatings. Latices having two different glass transition temperatures were used. Results showed that pigment particle shape influenced the strength of a coating layer. Platy clay gave better strength than spherical or needle-shaped carbonate pigments. Compressive and tensile strength decreased as a function of the amount of calcium carbonate in the coating color, particularly with precipitated calcium carbonate. We also assessed the influence of styrene-butadiene binder on the compressive strength of the coating layer, which increased with the binder level. The compressive strength of the coating layer was about three times the tensile strength.


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