Effects of dry particle coating with nano- and microparticles on early compressive strength of portland cement pastes

2021 ◽  
Vol 12 (4) ◽  
pp. 125
Author(s):  
Hediye Yorulmaz ◽  
Sümeyye Özuzun ◽  
Burak Uzal ◽  
Serhan İlkentapar ◽  
Uğur Durak ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
High Speed ◽  
Early Period ◽  
Cement Pastes ◽  
High Tendency ◽  
Nano Sio2 ◽  
Particle Coating ◽  
Additive Particles ◽  
Dry Particle Coating

It is known that nano-and microparticles have been very popular in recent years since their advantages. However, due to the very small size of such materials, they have very high tendency to agglomeration particularly for nanoparticles. Therefore, it is critical that they are properly distributed in the system to which they are added. This paper investigated the effects of dry particle coating with nano-and microparticles to solve the agglomeration problem. For a clear evaluation, paste samples were preferred to detemine the compressive strength. Nano-SiO2 and nano-CaCO3, micro-CaCO3 and micro-SiO2, also known as silica fume, were selected as particulate additives. It was studied by the addition of various percentages (0.3, 0.7, 1, 2, 3 and 5%) of nano-and microparticles in cementitious systems, replacing cement by weight with and without dry particle coating. Dry particle coating was made by using a high-speed paddle mixer. Portland cement and additive particles were mixed at 1500 rpm for 30 seconds in high-speed powder mixer designed for this purpose. The 3-day compressive strength of the cement-based samples to which particles were added at the specified rates was determined and the effect of the dry particle coating on the early strength was investigated. According to the results, it was observed that the production of paste with the dry particle coating technique gave higher compressive strength compared to the production of paste directly in early period. Especially with dry particle coating, compressive strength increased more than 100% in paste samples containing 0.3% nano-SiO2 compared to direct addition without coating.

scholarly journals Hydration study of mechanically activated mixtures of Portland cement and fly ash

2007 ◽  
Vol 72 (6) ◽  
pp. 591-604 ◽  
Author(s):  
Gordana Stefanovic ◽  
Ljubica Cojbasic ◽  
Zivko Sekulic ◽  
Srdjan Matijasevic
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Mechanical Activation ◽  
Early Period ◽  
Negative Effects ◽  
Early Hydration ◽  
Cement Pastes ◽  
Dta And Tg ◽  
Low Activity

Fly ash (FA) can be used in cement mixtures with certain limitations. The problem of the mentioned mixtures lies in the insufficient activity of the particles of FA in the reactions which are important for the establishment of the mechanical characteristics of cement. This is particularly true for the hydration reactions. As a result of this, cement pastes formed by mixing ash and clinker have worse characteristics compared to those of pure Portland cement (PC), especially in the early period of setting. As is well known, FA can be a good solution for the neutralization of the negative effects generated due to the creation of free Ca(OH)2 during the hydration of PC, provided that the problems with the low activity of FAare overcome. For the experiments in this study, a mixture of Portland cement and fly ash was used, the content of ash in the mixture being 30 % and 50 %. Mechanical activation was performed in a vibrating ring mill. The goal of this study was to demonstrate, through experimental results, that during the mechanical activation of a PC and FA mixture, the components in the mixture which mostly affect the direction, rate and range of hydration reactions occurring in the mixture had been activated. The values of the compressive strength of the activated and non-activated mixtures and the changes of their specific surface area proved that during the grinding process, the mixture PC+FA had been mechanically activated. The highest increase of compressive strength was achieved in the early period of setting, which indicates an improvement in the early hydration of the mixture. XRD, DTA and TG analyses showed that the alite (C3S) and belite (C2S) from the PC and a part of the fly ash were activated. .

scholarly journals Physical Properties of Concrete Containing Graphene Oxide Nanosheets

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1707 ◽  
Author(s):  
Yu-You Wu ◽  
Longxin Que ◽  
Zhaoyang Cui ◽  
Paul Lambert
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Graphene Oxide ◽  
Flexural Strength ◽  
Portland Cement ◽  
Physical Properties ◽  
Ordinary Portland Cement ◽  
Construction Materials ◽  
Split Tensile Strength ◽  
Cement Pastes

Concrete made from ordinary Portland cement is one of the most widely used construction materials due to its excellent compressive strength. However, concrete lacks ductility resulting in low tensile strength and flexural strength, and poor resistance to crack formation. Studies have demonstrated that the addition of graphene oxide (GO) nanosheet can effectively enhance the compressive and flexural properties of ordinary Portland cement paste, confirming GO nanosheet as an excellent candidate for using as nano-reinforcement in cement-based composites. To date, the majority of studies have focused on cement pastes and mortars. Only limited investigations into concretes incorporating GO nanosheets have been reported. This paper presents an experimental investigation on the slump and physical properties of concrete reinforced with GO nanosheets at additions from 0.00% to 0.08% by weight of cement and a water–cement ratio of 0.5. The study demonstrates that the addition of GO nanosheets improves the compressive strength, flexural strength, and split tensile strength of concrete, whereas the slump of concrete decreases with increasing GO nanosheet content. The results also demonstrate that 0.03% by weight of cement is the optimum value of GO nanosheet dosage for improving the split tensile strength of concrete.

The use of calcium sulfo-aluminate cement as an alternative to Portland Cement for the recycling of municipal solid waste incineration bottom ash in mortar

2020 ◽  
Vol 38 (8) ◽  
pp. 868-875
Author(s):  
Marc Antoun ◽  
Frédéric Becquart ◽  
Najib Gerges ◽  
Georges Aouad
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Bottom Ash ◽  
Waste Incineration ◽  
Cementitious Materials ◽  
Hydrogen Gas ◽  
Municipal Solid Waste Incineration ◽  
Cement Pastes

Municipal solid waste incineration generates large quantities of bottom ash that should be recycled. Current use of municipal solid waste incineration bottom ash (MSWI-BA) in cementitious materials is mostly in Ordinary Portland Cement (OPC). This paper considers using MSWI-BA as sand substitution in Calcium Sulfoaluminate Cement (CSA) as an alternative to OPC. A comparison between OPC and CSA mortars containing 0–2 mm MSWI-BA is conducted. The MSWI-BA used was treated to remove the ferrous and non-ferrous metals in order to obtain a better mineral fraction. Different percentages (0%, 25%, 50%, 75%, and 100%) of standard sand were substituted by MSWI-BA based on equivalent volume. Experimental results showed that the compressive strength and porosity of the CSA mortars were superior to OPC after substitution at 1, 7, 28, and 90 days. The compressive strength of OPC mortars with 25% substitution decreased by 40% compared to 11% for CSA mortars at 90 days. This is due to the difference in pH between the two cement pastes as OPC in contact with the MSWI-BA leads to a reaction with the aluminum content which releases hydrogen gas, increases the porosity, and decreases the compressive strength.

Performance of Cement Systems with Nano-SiO2 Particles Produced Using Sol-gel Method

2010 ◽  
Vol 1276 ◽  
Author(s):  
Konstantin Sobolev ◽  
Ismael Flores ◽  
Leticia M. Torres ◽  
Enrique L. Cuellar ◽  
Pedro L. Valdez ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Composite Materials ◽  
Portland Cement ◽  
High Speed ◽  
Essential Role ◽  
Sol Gel ◽  
Strength Development ◽  
Cement Mortars ◽  
Effective Dispersion ◽  
Dispersion Of Nanoparticles

AbstractThe reported research examines the effect of 5–70 nm SiO2 nanoparticles on the mechani-cal properties of nanocement materials. The strength development of portland cement with nano-SiO2 and superplasticizing admixture is investigated. Experimental results demonstrate an in-crease in the compressive strength of mortars with SiO2nanoparticles. The distribution of nano-SiO2 particles within the cement paste plays an essential role and governs the overall perfor-mance of these products. Therefore, the addition of a superplasticizer is proposed to facilitate the distribution of nano-SiO2 particles. The application of effective superplasticizer and high-speed dispergation are found to be very effective dispersion techniques that improve the strength of su-perplasticized portland cement mortars, reaching up to 63.9 MPa and 95.9 MPa after aging dur-ing 1 and 28 days, respectively. These values compare favorably with the observed compressive strengths of reference portland cement mortars of 53.3 MPa and 86.1 MPa. It is concluded that the effective dispersion of nanoparticles is essential to obtain the composite materials with im-proved performance.

Hardened Portland cement pastes of low porosity V. Compressive strength

1972 ◽  
Vol 2 (6) ◽  
pp. 731-743 ◽  
Author(s):  
Marvin Yudenfreund ◽  
Kaissar M. Hanna ◽  
Jan Skalny ◽  
Ivan Older ◽  
Stephen Brunauer
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Cement Pastes ◽  
Low Porosity

Influence of nano-SiO2 on the Portland cement pastes

2012 ◽  
Vol 43 (6) ◽  
pp. 2706-2710 ◽  
Author(s):  
M. Stefanidou ◽  
I. Papayianni
Keyword(s):  
Portland Cement ◽  
Cement Pastes ◽  
Nano Sio2

Relationship between Compressive Strength and Young's Modulus of Cement Paste with Recycled Concrete Powder

2016 ◽  
Vol 722 ◽  
pp. 254-259 ◽  
Author(s):  
Jaroslav Topič ◽  
Jan Trejbal ◽  
Tomáš Plachý ◽  
Zdeněk Prošek
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Speed ◽  
Reference Sample ◽  
Milled Powder ◽  
Recycled Concrete ◽  
Cement Pastes ◽  
Cement Replacement ◽  
Cement Based Materials

This article deals with utilization of recycled concrete in form of high-speed milled powder into cement based materials. Recycled concrete powder in that form is used as microfiller and cement replacement. This article contains results of mechanical properties of the cement pastes with different amount of recycled concrete powder. The mechanical properties as the compressive strength, flexural strength, dynamic Young's and share moduli are observed during 409 days. According to results can be assumed that recycled concrete powder can be used as microfiller and cement replacement under 30 wt. % of total amount. Especially the results of compressive strength are comparable with reference sample. But there are some abnormalities in long term development of the strength that need to be explained.

OPTIMAL CRITERIA OF ALGERIAN BLENDED CEMENT USING LIMESTONE FINES/ALŽYRIETIŠKAS MIŠRUSIS CEMENTAS SU MALTU KALKAKMENIU

2008 ◽  
Vol 14 (4) ◽  
pp. 269-275 ◽  
Author(s):  
Z’hor Guemmadi ◽  
Musa Resheidat ◽  
Hacéne Houari ◽  
Belkacem Toumi
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Blended Cement ◽  
Total Porosity ◽  
Hardened Cement ◽  
Compact Structure ◽  
Limestone Filler ◽  
Cement Pastes ◽  
Limestone Fines ◽  
Hardened Cement Pastes

The effect of substitution of Portland cement by limestone up to 40% as well as its fineness on the physico‐mechanical properties of fresh and hardened cement pastes is studied. The binder was prepared by substitution of cement by limestone filler. Fillers were chosen of various particle sizes and with percentages from 5 to 40. Test results revealed that the replacement of Portland cement by the finest filler of limestone slightly decreases the consistency and the setting times (initial and final). The total porosity decreases and accordingly the compressive strength is improved with the content and fines of limestone. Although limestone has a little accelerating effect on the hydration process of Portland cement, but acts only as a filler reducing the porosity due to its compact structure, in which the compressive strength of the hardened cement paste is enhanced. The XRD and DTA analyses of samples cured up to 28 days showed that this amelioration is due to formation of new hydrated compounds. It is concluded that an addition of finely ground limestone filler only up to 15% gives a better strength. Santrauka Tirtos šviežios ir sukietėjusios cementinės tešlos, kurioje iki 40 % cemento pakeista įvairaus smulkumo maltu kalkakmeniu, savybės. Rišiklis buvo paruoštas dalį cemento pakeitus maltu kalkakmenio užpildu. Užpildo dalelės buvo įvairaus dydžio, o jų kiekis buvo keičiamas nuo 5 % iki 40 %. Tyrimai parodė, kad priedas leidžia sumažinti vandens kiekį, reikalingą tos pačios konsistencijos mišiniui gauti, taip pat cemento rišimosi pradžiai ir pabaigai paankstinti. Sumažėja cementinio akmens suminis poringumas ir atitinkamai padidėja stipris gniuždant cementinio akmens, kuriame yra kalkakmenio priedų. Nors kalkakmenio priedas nedaug pagreitina portlandcemenčio hidratacijos procesą, tačiau veikia kaip užpildas, sutankinantis struktūrą, dėl to labai padidėja sukietėjusio cementinio akmens stipris gniuždant. Bandinių, išlaikytų 28 dienas, rentgenostruktūrinė ir diferencinė terminė analizė parodė, kad pagerėjimas yra dėl susidariusių naujadarų. Apibendrinant galima teigti, kad 15 % malto kalkakmenio priedas turi didžiausią įtaką stiprumo rezultatams.

Sign in / Sign up

Export Citation Format

Share Document