INFLUENCE OF HIGH TEMPRATURE HISTORY ON MECHANICAL PROPERTIES OF CEMENTITIOUS MATERIALS WITH LOW WATER-TO-BINDER RATIO

Full utilization of mechanical properties of glass fiber fabric-reinforced cement composites is very limited due to a low bond strength between fibers and the binder matrix. An experimental setup was developed and evaluated to correlate the mortar penetration depth with several key parameters. The studied parameters included fresh mortar properties, compressive and flexural strengths of mortar, the fabric/mortar bond strength, fabric pullout strength, and a single-lap shear strength. Results showed that an average penetration of mortar did not exceed 100 µm even at a higher water-to-binder ratio. The maximum particle size of the used fillers should be below an average spacing of single glass fibers, which in this case was less than 20 µm to avoid the sieving effect, preventing effective penetration. The pullout strength was strongly affected by the penetration depth, while the single-lap shear strength was also additionally affected by the mechanical properties of the mortar.

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The role of shrinkage reducing admixtures and supplementary cementitious materials in volume stability and strength development

MATEC Web of Conferences ◽

10.1051/matecconf/201928902005 ◽

2019 ◽

Vol 289 ◽

pp. 02005

Author(s):

Ioanna Papayianni ◽

Fotini Kesikidou ◽

Philip Henes Alt

Keyword(s):

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Strength Development ◽

Capillary Absorption ◽

Volume Stability ◽

Cement Mortars ◽

Shrinkage Reducing Admixture ◽

Binder Ratio ◽

Shrinkage Reducing Admixtures ◽

Water To Binder Ratio

Shrinkage is one of the main reasons for mortar and concrete failures like curling, crack formation and de-bonding. It is a complex phenomenon due to many factors involved, such as the type and amount of cement, water to binder ratio, binder to aggregates ratio and the type and granulometry of the aggregates, relative humidity, air temperature and the temperature of concrete. To reduce this phenomenon, Shrinkage Reducing Admixtures (SRAs) have been studied over the last 30 years. On the other hand, investigation in the field of Supplementary Cementitious Materials (SCMs) has indicated that their use in concrete may improve its volume stability depending on their percentage and the type of the material. In this paper, the addition of a Shrinkage Reducing Admixture and Supplementary Cementitious Materials like ladle furnace slag, calcareous fly ash and limestone filler, were investigated. Their influence, separately and in combination, in volume stability and strength development of cement mortars was identified. Capillary absorption and open porosity were also determined.

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Microscopic Analysis and Study of High-Performance Seawater All-Coral Concrete

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.815.216 ◽

2019 ◽

Vol 815 ◽

pp. 216-222

Author(s):

Chao Chen ◽

Jin Ming Liu ◽

Yang Yang ◽

Zhi Guo Guo

Keyword(s):

Mechanical Properties ◽

Natural Environment ◽

High Performance ◽

Work Performance ◽

Room Temperature ◽

Microscopic Analysis ◽

Internal Curing ◽

Mix Design ◽

Binder Ratio ◽

Water To Binder Ratio

The ocean islands are far from inland and the concrete sandstone aggregates are scarce. In this paper, high-performance seawater all-coral concrete was developed by seawater mixing and room temperature maintenance design, and by optimizing the water-to-binder ratio, regulating internal curing, changing auxiliary cementing materials and blending ratio, incorporating expansion agent, adjusting fiber blending, etc. Combined with the consideration of work performance and mechanical properties, the concrete self-shrinkage is adjusted to further optimize the mix design. The mechanical properties of the optimized high-performance seawater all-coral concrete were studied, and the relevant durability tests were carried out according to the natural environment characteristics of the island. This is of great significance to the construction of island projects, repair and construction, and construction of protective projects [1].

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Workability and mechanical properties of ultrafine cement based grout for structural rehabilitation: A parametric study on the partial replacement with SCMs

MATEC Web of Conferences ◽

10.1051/matecconf/201819907006 ◽

2018 ◽

Vol 199 ◽

pp. 07006

Author(s):

Md Shamsuddoha ◽

Götz Hüsken ◽

Wolfram Schmidt ◽

Hans-Carsten Kühne ◽

Matthias Baeßler

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Cementitious Materials ◽

Strength Properties ◽

Supplementary Cementitious Materials ◽

Partial Replacement ◽

Hardened Cement ◽

Binder Ratio ◽

Strengthening Technique ◽

Ultrafine Cement

Grouting is a universal repair and strengthening technique, which is constantly used for structural remediation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. Having an extremely small particle size of only few microns, ultrafine cements are ideal for grouting applications due to their superior permeability and compressive strength properties of the hardened cement paste compared to that of the less-expensive, but coarser ordinary Portland cements. Supplementary cementitious materials (SCMs) are often used to replace ultrafine cement in order to modify certain properties and to reduce costs. The aim of this experimental study is to investigate the effect of three supplementary materials: microsilica (MS), fly ash (FA), and metakaolin (MK) on the workability, and mechanical properties of an ultrafine cement based grout with a constant water-binder ratio and constant superplasticizer content. Maximum percentages of replacement with ultrafine cement were 6% by volume of cement for MS and 16% for FA, and MK. In general, results suggest that the workability is improved by addition of FA, whereas is reduced, when modified with MS and MK. The compressive strength of grout after cement replacement remains comparable to that of pure cement grout. However, there is a tendency of the MS to positively affect the compressive strength opposite to FA, whereas flexural strength is positively affected by FA. Based on the results, it is evident that grouts with Hägerman cone flow more than 500 mm and compressive strength of more than 90 MPa after 28 days can be produced.

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The Influence of Partial Substitution of Raw Materials with Heavy Ash on the Main Properties of Portland Cements

Revista de Chimie ◽

10.37358/rc.18.4.6216 ◽

2018 ◽

Vol 69 (4) ◽

pp. 860-863 ◽

Cited By ~ 2

Author(s):

Carmen Oproiu ◽

Georgeta Voicu ◽

Adrian Ionut Nicoara ◽

Alina Ioana Badanoiu

Keyword(s):

Raw Materials ◽

Bottom Ash ◽

Cementitious Materials ◽

Cement Industry ◽

Raw Material ◽

Supplementary Cementitious Materials ◽

Partial Substitution ◽

X Ray Diffraction ◽

Binder Ratio ◽

Water To Binder Ratio

The use of wastes in cement industry have impact both from economic and environmental point of views. Wastes can be used in clinker manufacture (to substitute raw materials or as alternative fuel) as well as supplementary cementitious materials in cement. This paper presents results regarding the use of heavy ash (bottom ash) as component of raw mix used for the clinker manufacture. Two types of cements were obtained by the milling of clinker produced with/without heavy ash (HA) as component of raw mix and gypsum (2%). The compressive strengths of these cements was assessed on plastic mortars (water:binder = 1:2 ratio and binder:aggregate = 1:3 ratio), cast in prismatic moulds (14x14x160 mm3), hardened different periods of time comprised between 1 to 28 days. The hydration and hardening processes which occur in the cementitious systems with/without waste content were assessed on pastes with water to binder ratio of 0.5, hardened for 1 up to 90 days. X-ray diffraction (XRD) and complex thermal analysis (DTA-TG) were used for pastes� characterization. The composition of clinker was assessed by XRD and microstructure by scanning electron microscopy (SEM). The results obtained in the framework of this research do not show any important difference between the clinkers� characteristics produced with alternative raw material (heavy ash) as compared with the ones produced with natural raw materials. Also, the properties of cements produced of these clinkers are similar.

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Durability of Normal and Lightweight Aggregate Mortars with Different Supplementary Cementitious Materials

WSEAS TRANSACTIONS ON ENVIRONMENT AND DEVELOPMENT ◽

10.37394/232015.2021.17.28 ◽

2021 ◽

Vol 17 ◽

pp. 271-281

Author(s):

Efstratios Badogiannis ◽

Eirhnh Makrinou ◽

Marianna Fount

Keyword(s):

Blast Furnace ◽

Blast Furnace Slag ◽

Lightweight Aggregate ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Granulated Blast Furnace Slag ◽

Binder Ratio ◽

Pumice Sand ◽

Water To Binder Ratio ◽

Furnace Slag

A study on the durability parameters of normal and lightweight aggregate mortars, incorporated different supplementary cementitious materials (SCM) is presented. Mortars were prepared using limestone or pumice as aggregates and Metakaolin, Fly ash, Granulated Blast Furnace Slag and Silica Fume, as SCM, that they replaced cement, at 10 % by mass. Ten different mortars, having same water to binder ratio and aggregate to cement volumetric ratio, they were compared mainly in terms of durability. The use of pumice sand was proved to be effective not only to the density of the mortars as it was expected, but also in durability, fulfilling at the same time minimum strength requirements. The addition of the different SCM further enhanced the durability of the mortars, where Metakaolin was found to be the most effective one, especially against chloride’s ingress.

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Effect of the Key Mixture Parameters on Shrinkage of Reactive Powder Concrete

The Scientific World JOURNAL ◽

10.1155/2014/426921 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Shamsad Ahmad ◽

Ahmed Zubair ◽

Mohammed Maslehuddin

Keyword(s):

Empirical Equation ◽

Cementitious Materials ◽

Reactive Powder Concrete ◽

Test Results ◽

Total Period ◽

Concrete Mixtures ◽

Binder Ratio ◽

Reactive Powder ◽

Water To Binder Ratio ◽

Different Levels

Reactive powder concrete (RPC) mixtures are reported to have excellent mechanical and durability characteristics. However, such concrete mixtures having high amount of cementitious materials may have high early shrinkage causing cracking of concrete. In the present work, an attempt has been made to study the simultaneous effects of three key mixture parameters on shrinkage of the RPC mixtures. Considering three different levels of the three key mixture factors, a total of 27 mixtures of RPC were prepared according to 33factorial experiment design. The specimens belonging to all 27 mixtures were monitored for shrinkage at different ages over a total period of 90 days. The test results were plotted to observe the variation of shrinkage with time and to see the effects of the key mixture factors. The experimental data pertaining to 90-day shrinkage were used to conduct analysis of variance to identify significance of each factor and to obtain an empirical equation correlating the shrinkage of RPC with the three key mixture factors. The rate of development of shrinkage at early ages was higher. The water to binder ratio was found to be the most prominent factor followed by cement content with the least effect of silica fume content.

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