Freeze-thaw resistance and microstructural characteristics of concretes containing pozzolans.

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When water freezes, it expands about 9 percent. As the water in moist concrete freezes it produces pressure in the pores of the concrete. If the pressure developed exceeds the tensile strength of the concrete, the cavity will dilate and rupture. The accumulative effect of successive freeze-thaw cycles and disruption of paste and aggregate can eventually cause expansion and cracking, scaling, and.

Concrete freeze–thaw resistance was determined from the damage induced during the freeze–thaw cycles based on the weight of the scaled material (European standard CEN/TS –9 EX) and the relative dynamic modulus of elasticity (RDME) (CEN/TR 15,). Whilst mass loss is the most prominent type of damage observed in concrete exposed to deicing salts, it is of minor importance in Cited by: 4.

The strength development up to 90 days and the freeze-thaw-resistance without salt is comparable with the reference concretes. The results of the freeze-thaw-resistance-tests with salt meet all. Freeze-thaw resistance and microstructural characteristics of concretes containing pozzolans (MK), fly ash (FA) and blends of FA and MK and to assess the effects of such pozzolans on freeze-thaw durability, air void system and microstructure of hardened concrete.

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Cement was partially replaced by various quantities of the pozzolanic : George Christodoulou. Freeze-Thaw Resistance and Microstructural Characteristics of Concretes Containing Pozzolans. Student thesis: Doctoral ThesisAuthor: George Christodoulou. SCC containing fly-ash, an equivalent or even higher freeze-thaw resistance has been observed.

However, concretes containing limestone powder have shown increased alteration in the freeze thaw test (Mňahončáková et al, ). The poor resistance of the latter was attributed to the presence of a family of capillary pores absent in the first.

Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air void system parameters are normally 6% +/- 1% total air and spacing factor. The ceramic waste analysed from the sanitary ware industry.

This waste is used as a coarse aggregate in the manufacture of structural concretes. The durability to freeze-thaw cycles of these concretes is better than convectional concretes. ITZ of the new aggregate/paste is more resistance than natural aggregate.

The recycled ceramic aggregate improve the quality of new concretes. The freezethaw resistance, expressed by the scaling factor (Sn), was also studied. - Additionally, the microstructural characteristics of the hardened concretes were investigated by FEG-SEM and MIP analyses. The obtained results demonstrate that the addition of % bwoc of nanoSiO-2 improves the SCC durability due to the refinement.

concrete during the freeze-thaw cycling. The effect of freeze-thaw cycling has a significant effect on cement concrete and it causes cracking and scaling and ultimately failure [1]. There are three categories of freezes: 1) dry freeze and hard dry freeze, 2) wet freeze, and 3) hard wet freeze.

Freeze-thaw rresistance of concrete depends on the. Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air void system parameters are normally: 6 ± 1 percent total air, and spacing factor less than millimeters.

However, it was observed that some concretes that did not possess these commonly. Freeze-thaw resistance and microstructural characteristics of concretes containing pozzolans.

Author: Christodoulou, George. ISNI: Awarding Body: University of Glamorgan Current Institution: University of South Wales Date of Award. Get this from a library. Properties of Portland cement concretes containing pozzolanic admixtures. [United States. Federal Highway Administration.

Materials Division.;] -- A laboratory comparison was made of the properties of a concrete containing no pozzolan with several mixtures containing pozzolans. Used were a natural pozzolan (Lassenite), two fly ashes of.

Some mixes also contain a further addition of 10 and 20 wt% of these powders to the Portland cement. Surface scaling and internal damage tests and a capillary suction test are performed on the concretes, to obtain a basic understanding of the freeze–thaw durability of the mineral powder concretes.

The day freeze–thaw resistance of hardened concrete mixtures was determined on three × mm cylinder specimens in accordance with ASTM: C standard. The concrete specimens were frozen in air from 5 ± 2 °C to −18 ± 2 °C within 3 h and they were thawed in water to 5 ± 2 °C within 1 h in a single cycle.

The pore-size distributions of the hardened concrete were measured by a mercury porosimeter.

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The test results indicated that the freezing and thawing resistance decreased with increasing chloride content in both water and seawater. The air-entrained concrete containing less than percent NaCl showed a good freezing and thawing resistance.

Mangat, P. Lambert, in Sustainability of Construction Materials (Second Edition), Freeze–thaw resistance. The freeze– thaw resistance of Portland cement concrete is related to physical characteristics such as pore structure, pore saturation, strength of the matrix, and voids provided by air entrainment.

The chemical composition of the hydration products is less significant. Li et al. studied the freeze–thaw resistance of concrete by using carbonated coarse recycled concrete aggregate (C-CRCA) to completely or partially replace natural coarse aggregate (NCA).

Under the same freeze–thaw cycle conditions, the highest relative dynamic modulus of elasticity was achieved with complete replacement; after freeze–thaw cycles, the highest residual compressive.

The rate of deterioration tends to be accelerated in concretes containing higher levels of supplementary cementitious materials including slag and limestone.

A fundamental insight into the relationship between cement composition and freeze–thaw resistance is therefore imperative for developing durable composite cement concretes.

The freeze-thaw resistance, expressed by the scaling factor (Sn), was also studied. Additionally, the microstructural characteristics of the hardened concretes were investigated by FEG-SEM and MIP analyses. The obtained results demonstrate that the addition of % bwoc of nano-SiO2 improves the SCC durability due to the refinement.

This paper discusses laboratory evaluations to assess the long-term performance of concrete containing HRM produced in North America for resistance to chloride penetration and reduction in.

Transport properties and freeze-thaw resistance of mortar mixtures containing recycled concrete and glass aggregates. European Journal of Environmental and. This study is based on determination of the freeze-thaw resistance of air-entrained and non-air-entrained normal strength concrete (NC) and high strength concrete (HSC) produced with fly ash and silica fume according to surface scaling.

The procedure allows us to measure the amount of scaling per unit surface area due to a number of well defined freezing and thawing cycles in the presence of.

concretes containing higher levels of supplementary cementitious materials (SCMs) including slag and limestone. Fundamental insight into the relationship between cement composition and freeze-thaw resistance is therefore imperative for developing durable composite cement concretes.

In this paper. The residual compressive strength of all specimens was lower than the values obtained for specimens not subjected to any freeze-thaw resistance test, except those containing GGBS.

The performance characteristics, such as basic physical properties, mechanical strengths, water resistance, harsh environment resistance, and microstructure, of.

The FRN to assess freeze and thaw resistance of non-autoclaved aerated concretes containing GGBFS and MS has been developed. The accomplishment of this research has been the comparison between compressive strength, dry density, void ratio, and water absorption capacity of NAAC mixtures and the determination of RDME, DF, weight change, moisture uptake, S d, W loss, and S res.

It is recommended that the air void system of concrete contain approximately 6 percent total air and a spacing factor less than millimeters. It was observed however in laboratory studies that some concretes exhibited good freeze-thaw resistance with an air content and spacing factor outside of the accepted thresholds.

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Freeze-thaw resistance of concrete: destruction mechanisms, concrete technology, test methods, quality control: a contribution to the BRITE/EURAM project BREU-CT Methods for development of frost resistant concretes, and for strict con­ mm and the length mm containing a centrical ribbed bar of diameter 25 mm with the.

Concretes had cement contents of 4 or 6 bags per cu yd and a slump of 2 to 3 in. Non-air-entrained and air-entrained concretes were prepared for each cement content. The air contents for the air-entrained concretes ranged from 5 to 6 percent. The max­ imum size of aggregate used was 1 in.

for the specimens tested in the laboratory and. having low and high air contents. The effects of entrainment upon freezeMthaw resistance were demonstrated. Freeze-thaw characteristics of saturated aggregates relative to physical properties such as porosity, absorption, and bulk specific gravity were studied by submerging individual particles in .However, without chemical treatment, MWNT concretes tend to have poor freeze-thaw resistance.

Among the different chemical treatments, MWNT concrete treated with sodium polyacrylate has the best compressive strength, chloride resistance, and freeze-thaw durability.This in principle reduces the freeze‐thaw durability problem to the calculation of stresses and strains.

However, development of the model to full application would require various new types of tests for calibration of the model, as well as development of a finite element code to solve the governing differential equations.