Influence of Limestone Powder and Fly Ash on the Freezing and Thawing Resistance of Roller-Compacted Concrete (original) (raw)
Related papers
The aim of this study is to evaluate the effect of high-volume fly ash on some durability characteristics of roller compacted concrete (RCC). In addition to a control mixture without fly ash, two different series of mixtures were prepared by partial replacement of either cement or aggregate with fly ash. The mixtures were designed by a maximum density method. A total of 28 mixtures having four different water/binder ratios (0.30, 0.35, 0.40 and 0.45 by mass) were prepared to determine the optimum water/binder ratio. Among these, seven mixtures containing the optimum water content were selected for further experimental study. It was observed that in the mixtures where cement was substituted with fly ash, increasing the fly ash content adversely affected the durability performance up to 90 days. However, fly ash substitution for a part of the aggregate improved the durability characteristics of the mixture as the amount of fly ash increased.
EFFECT OF FREEZING-THAWING ON SELF CONSOLIDATED CONCRETE INCLUDING FLY ASH
This paper presents the effect of freezing-thawing on self consolidated concrete that contain different percentages of fly ash (FA) and air entraining agents. Self consolidated concretes (SCC) containing four different contents of FA as a replacement of cement (0, 15, 30 and 45 by weight), and containing three different contents of air entraining agent (0, 0.15 and 0.30%) were prepared. All concrete mixtures have the same superplasticizer content as 1.3% of cementitious materials by weight. The fresh properties of the SCCs were observed through, slump flow time and diameter, air content, V-funnel flow time, L-box height ratio, setting time and segregation ratio. The hardened properties included the compressive strength, ultrasonic pulse velocity, permeability evaluation (absorption, sorptivity and rapid chloride permeability tests) and freezing-thawing tests up to 300 cycles. Following the ASTM C 666 standard test method and for this purpose, to determine the dynamic modulus of elasticity value of concrete specimens; the resonant frequency test apparatus was developed.
International Journal of Engineering and Technology, 2013
This paper presents the effect of curing conditions on freeze-thaw durability of self-consolidating concrete. In order to determine the effect of curing conditions on the durability properties of self-consolidating concrete, some specimens were cured in air and the others in water. Moist-cured (M-C) specimens were kept in water for 14 days at a temperature of 23±2°C before they were subjected to freeze-thaw cycles. Air-cured (A-C) specimens were however left in ambient laboratory conditions and were saturated in water for a day before they were subjected to the same freeze-thaw cycles. From the permeability tests, it was concluded that air cured specimens have higher permeability. Furthermore, an increase in fly ash content resulted in a reduction in the permeation properties of self-consolidating concrete. On the other hand, more variations were observed in permeability results since only two specimens were used for permeability tests. During the freezing-thawing test, it was observed that air cured specimens were not affected by freezing-thawing and did not indicate any degradation since they were not totally saturated because of the lack of the saturation period that was employed.
Durability of biomass fly ash concrete: Freezing and thawing and rapid chloride permeability tests
Fuel, 2008
Strict interpretation of ASTM C 618 excludes non-coal fly ashes, such as biomass fly ashes from addition in concrete. Biomass fly ash in this investigation includes (1) cofired fly ash from burning biomass with coal; (2) wood fly ash and (3) blended fly ash (wood fly ash mixing with coal fly ash). A set of experiments conducted on concrete from pure cement and cement with fly ash provide basic data to assess the effects of several biomass fly ashes on the performances of freezing and thawing (F-T) and rapid chloride permeability test (RCPT). The F-T tests indicate that all fly ash concrete has statistically equal or less weight loss than the pure cement concrete (control). The RCPT illustrate that all kinds of fly ash concrete have lower chloride permeability than the pure cement control concrete.
Effect of fly ash on freeze–thaw durability of concrete in marine environment
Australian Journal of Structural Engineering, 2018
Deterioration of structural concrete exposed to freeze-thaw cycles is one of the most important durability problems under subzero temperature conditions. It becomes more devastating when associated with marine environment. Supplementary cementitious material such as fly ash may be used as partial replacement of cement for making more dense, less absorptive and less permeable concrete which improve freeze-thaw durability. This paper presents a part of an experimental study on the freeze-thaw effect of concrete specimens exposed to artificial seawater simulating marine environment and plain water over 360 cycles. Three different grades of concrete M38, M33 and M28, each with four different fly ash replacement level, 20, 30, 40 and 60% were used for the experimental programme. The deteriorative effects were measured by studying weight and volume change, compressive strength, permeability characteristics and rapid chloride penetration resistance of the deteriorated test specimens. the optimum amount of cement replacement is reported to be around 30 to 40%. The study reveals that fly ash concrete has better resistance against freeze-thaw deterioration due to pozzolanic activity of fly ashes that creates more calcium silicate hydrate gel and fills pore spaces, which can effectively reduce the corrosion of the embedded steel reinforcement.
Enhancing high volume fly ash concretes using fine limestone powder
Synopsis: One of the primary approaches to producing more sustainable concretes consists of replacing 50 % or more of the portland cement in a conventional concrete with fly ash, producing a so-called high volume fly ash (HVFA) concrete. While these mixtures typically perform admirably in the long term, they sometimes suffer from early-age performance issues including binder/admixture incompatibilities, delayed setting times, low early-age strengths, and a heightened sensitivity to curing conditions. Recent investigations have indicated that the replacement of a portion of the fly ash in these concrete mixtures by a suitably fine limestone powder can mitigate these early-age problems. The current study investigates the production of concrete mixtures where either 40 % or 60 % of the portland cement is replaced by fly ash (Class C or Class F) and limestone powder, on a volumetric basis. The mixtures are characterized based on measurement of their fresh properties, heat release, setting times, strength development, rapid chloride penetrability metrics and surface resistivity. The limestone powder not only accelerates the early age reactions of the cement and fly ash, but also provides significant benefits at ages of 28 d and beyond for both mechanical and transport properties.
Properties of high performance concrete systems incorporating large amounts of high-lime fly ash
Construction and Building Materials, 1995
This research was undertaken to evaluate the engineering propenies of high-lime (ASTM Class C) fly ash concretes. An air-entrained reference concrete mixture without fly ash was proportioned to have 28-day compressive strength of 41 MPa. Additionally, concrete mixtures were also proportioned to have cement replacement with Class C fly ash in the range of O-70% by weight. For each concrete mixture, specimens were made to evaluate compressive strength, tensile strength, flexural strength, modulus of elasticity, shrinkage, abrasion resistance, air permeability, water permeability, chloride ion permeability, air-void parameters, freezing and thawing durability, and salt scaling resistance, of hardened concrete. The results of this study established that high-performance concrete incorporating Class C fly ash at 30% cement replacement can be proportioned for high-strength applications. In general, concrete mixtures up to 50% cement replacement with fly ash showed satisfactory performance with respect to strength and physical durability properties appropriate for structural applications.
2009
The aim of the present study is to investigate the effect of low-permeability concrete, made with reduced water‐to‐binder ratios (w/b) and/or supplementary cementitious materials (SCMs), on the need for air entrainment to achieve freezing‐thawing (F‐T) durability. In the present study, concrete mixes were made with different types of cement (Types I and IP), with or without fly ash replacement (15%), with different water‐to‐binder ratios (w/b =0.25, 0.35, 0.45 and 0.55), and with or without air entraining agent (AEA). All concrete mixtures were controlled to have a similar slump by using different dosages of superplasticizer. The rapid chloride permeability and F-T durability of the concrete samples were determined according to ASTM C1202 and ASTM C666A, respectively. The air void structure of the concrete was studied using the Air Void Analyzer, RapidAir, and porosity tests (ASTM C642). In addition, the general concrete properties, such as slump, air content, unit weight, and 28‐da...
Using of Limestone Filler and Fly Ash as Partial Substitution of Cement in Concrete
2018
Leilla-Luciana Vago 1 Sorin Dan 2 Maura Vioreanu3 UDK: 666.972.11 DOI: 10.14415/konferencijaGFS2018.022 Summary: In order to have a cleaner environment and to reduce emissions of CO2 people are interested in the development of new ternary cements with low fly ash content (max 30%) and high limestone filler content (max 65%). Limestone filler due to its chemical and physical effect (interaction with aluminates) could give rise to a synergetic effect when it is used with fly ash. Despite the fact that the use of fly ash as a cement replacement material increases the long term strength and durability of the concrete, on early ages the strength of fly ash concrete is low, so we have to accelerate the pozzolanic properties of fly ash. This study is investigating the strength of ternary cements (clinkerfly ash-limestone filler) CEM 1v2 (30 V 65 K 5 LL) and CEM 12v2 (30 V 35 K 35 LL) at early age containing three kinds of activators CaSO4 (sulphate), Na2SO4 (sulphate+alkali) and NaOH (alka...
Properties of High-Lime Fly Ash Concrete
Fly ash is a waste product from coal based thermal power stations. About seven million tons of fly ash is being produced annually from these thermal power stations in Turkey. Concerted efforts are needed to make the material used to a great extent.