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Cement

About: Cement is a research topic. Over the lifetime, 68440 publications have been published within this topic receiving 829356 citations.


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Journal ArticleDOI
TL;DR: In this paper, the effect of various types of superplasticizers on portland cement component minerals was investigated and the value of the adsorption isotherm was calculated from the amount of the super plasticizer adsorbed on a cement component mineral in an equilibrated solution.

425 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the rheological properties of clay-modified cement-based materials with nanoparticles, specifically nanoclays, calcium carbonate nanoparticles and nanosilica.
Abstract: This is a summary paper on the work being done at the Center for Advanced Cement-Based Materials at Northwestern University on the modification of cement-based materials with nanoparticles, specifically nanoclays, calcium carbonate nanoparticles, and nanosilica. The rheological properties of clay-modified cement-based materials are investigated to understand the influence of nanoclays on thixotropy. The influence of the method of dispersion of calcium carbonate nanoparticles on rate of hydration, setting, and compressive strength are evaluated. And an in-depth study on the mechanisms underlying the influence of nanosilica on the compressive strength gain of fly ash–cement systems is discussed. The motivation behind these studies is that with proper processing techniques and fundamental understanding of the mechanisms underlying the effect of the nanoparticles, they can be used to enhance the fresh-state and hardened properties of cement-based materials for various applications. Nanoclays can increase the green strength of self-consolidating concrete for reduced formwork pressure and slipform paving. Calcium carbonate nanoparticles and nanosilica can offset the negative effects of fly ash on early-age properties to facilitate the development of a more environmentally friendly, high-volume fly ash concrete.

422 citations

Journal ArticleDOI
TL;DR: The use of fly ash in concrete dates back to the late 20th century and its advantages and disadvantages had been widely researched as mentioned in this paper, however, the level of replacement is still limited to a maximum of 35% of cement by mass.

417 citations

Journal ArticleDOI
TL;DR: In this article, the compressive strength for concrete mixtures was calculated in MPa per kg of Portland cement and the results showed that the pozzolanic and physical effects have increased as the mineral addition increased in the mixture.
Abstract: Pozzolans play an important role when added to Portland cement because they usually increase the mechanical strength and durability of concrete structures. The most important effects in the cementitious paste microstructure are changes in pore structure produced by the reduction in the grain size caused by the pozzolanic reactions pozzolanic effect (PE) and the obstruction of pores and voids by the action of the finer grains (physical or filler effect). Few published investigations quantify these two effects. Twelve concrete mixtures were tested in this study: one with Portland cement (control), nine mixtures with 12.5%, 25% and 50% of replacement of cement by fly ash, rice husk ash and limestone filler; two with (12.5+12.5)% and (25+25)% of fly ash and rice husk ash. All the mixtures were prepared with water/binder ratios of 0.35, 0.50, and 0.65. The compressive strength for the samples was calculated in MPa per kg of cement. The remaining contents of calcium hydroxide and combined water were also tested. The results show that the pozzolanic and physical effects have increased as the mineral addition increased in the mixture, being higher after 91 days than after 28 days. When the results for the same strength values are compared (35 and 65 MPa), it was observed that the filler effect (FE) increased more than the pozzolanic effect. The PE was stronger in the binary and ternary mixtures prepared with rice husk ash in proportions of 25% or higher.

417 citations

Journal ArticleDOI
TL;DR: In this paper, a modified Andreasen & Andersen particle packing model is used to achieve a densely compacted cementitious matrix, and the results show that the influence of FA, ground granulated blast-furnace slag (GGBS) and limestone powder (LP) on the early hydration kinetics of UHPC is very similar during the initial five days, while the hydration rate of the blends with GGBS is mostly accelerated afterwards.
Abstract: This paper addresses the development of an eco-friendly Ultra-High Performance Concrete (UHPC) with efficient cement and mineral admixtures uses are investigated. The modified Andreasen & Andersen particle packing model is utilized to achieve a densely compacted cementitious matrix. Fly ash (FA), ground granulated blast-furnace slag (GGBS) and limestone powder (LP) are used to replace cement, and their effects on the properties of the designed UHPC are analyzed. The results show that the influence of FA, GGBS or LP on the early hydration kinetics of the UHPC is very similar during the initial five days, while the hydration rate of the blends with GGBS is mostly accelerated afterwards. Moreover, the mechanical properties of the mixture with GGBS are superior, compared to that with FA or LP at both 28 and 91 days. Due to the very low water amount and relatively large superplasticizer dosage in UHPC, the pozzolanic reaction of FA is significantly retarded. Additionally, the calculations of the embedded CO2 emission demonstrate that the cement and mineral admixtures are efficiently used in the developed UHPC, which reduce its environmental impact compared to other UHPCs found in the literature.

408 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20248
20234,852
20228,607
20213,442
20203,929
20194,260