Clinkering-free cementation by fly ash carbonation Article in Journal of CO2 Utilization · January 2018 ... Clinkering-free cementation by ﬂy ash carbonation Zhenhua Weia, Bu Wanga, ... Concrete ABSTRACT The production of ordinary portland cement (OPC) is a CO
levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-ﬂy ash cement with 14.3% of calcareous ﬂy ash. The thin sections analysis conﬁrmed the values of the carbonation depth obtained from the phenolphthalein test.
chemical properties of fly ash are largely influenced by the chemical content of the coal burned (i.e., anthracite, bituminous, and lignite). Fly ash makes concrete denser, and hence less permeable, mainly by reduced water cement ratio and improved microstructure of concrete. At the same time, fly ash
The paper presents an investigation on the influence of the fineness of fly ash on the carbonation and electrical conductivity of concrete. Fly ash collected from three thermal power stations in India (with a Blaine's fineness of 200, 255, and 305 m 2 / kg, respectively) were used for this study.
In this study, effect of fly ash, silica fume and blast furnace slag to the permeation of concrete was investigated. The differences in the absorption, capillary sorption, and ultrasound transmission speed of concrete with and without mineral additives have been studied.
Carbonation in hardened pastes of fly ash cements, stored in a CO 2 atmosphere and exposed to different relative humidities, has been investigated in order to study its effects upon different properties of cement pastes. Thermogravimetry (TG), x-ray diffractometry, SEM, and mercury porosimetry (MIP) have been used to characterize the carbonation phenomenon.
An investigation has been carried out into the effects of cement replacement by fly ash on the carbonation rte of concrete. The research was mainly devoted to portland blast-furnace slag cement because this cement has a major market share in the Netherlands.
: Based on the mechanism of concrete carbonation, the effects of content of fly ash in the binder, the water to binder ratios, compound activator, and long-term curing on the carbonation depth of fly ash high-performance concrete are investigated.
The increased risk of carbonation in fly ash concrete is generally a concern when high levels of fly ash are used in low grade, poorly-cured concrete, with low cover depths over the steel. The increased susceptibility of fly ash concrete to carbonate can be compensated for by
Fly ash concrete made with 50% replacement ratio showed lower or comparable carbonation than that of control Normal Portland Cement concrete for both curing conditions. J. Khunthongkeaw et al., (2006)., arrived at a result, that the carbonation depth of concrete and mortar specimens measured until
permeability of concrete. Fly ash concretes showed similar carbonation less and had chloride ion penetration compared to the similar grade control concrete. In as general, incorporation of fly ash as partial replacement of cement improved the durability properties of concrete at early age when tio wasw/b ra adjusted to achieve
Several recent studies showed very low permeability of concrete made with fly ash and superplasticizer (HRWR) (2-10) as compared to no-fly ash concrete. Rodway and Fedirko (6) investigated permeability of concrete incorporating Class C fly ash for 68% cement replacement.
occurring during the C-S-H carbonation should be investigated. Furthermore, it is also known that the carbonation of materials made of fly ash (FA) can lead to a coarser microstructure and a possible increase in porosity. Nevertheless, since the reasons for such behaviour are still not well understood,
Besides, the fly ash has a major influence on concretes with higher RCA replacement levels and water binder ratio. The carbonation of concretes with RCA and fly ash have a holistic effect, when 30% of replacement of cement by fly ash the carbonation over time was quite similar to the reference concrete.
The effects of carbonation age, fly ash content in the binder and the water to binder ratios on the carbonation depth of fly ash concrete is investigated and the micromechanical properties of the hardened paste and the inter facial transition zone is analyzed with the micro-hardness method.
effects of carbonation. The potential for plastic shrinkage cracking is also reduced. 3.Architectural form finishes and textures are improved with fly ash. The small, spherical fly ash particles aid in concrete mobility and pattern transfer. 4.Surface treatments easily adhere to fly ash concrete mixes and last longer because of the reduction of ...
fly ash with CFBC contains a lot of unreacted CaO, it cannot be used as a raw material for concrete admixtures and its usages are limited. To reuse such material, we stabilized unreacted CaO by carbonation and investigated the carbonation rate.
An Investigation Of Steel Fiber Reinforced Concrete With Fly Ash 3 | Page 2. Compressive strength test The compressive strength of concrete is one of most important properties of concrete in most structural applications.
The improved model for hydration of PC and activity of blended cement is proposed and used in this carbonation model. This carbonation model can be used for concrete made of silica fume, fly ash and slag with various chemical composition and particle size distribution.
significantly smaller compared to the specimens without fly ash. This reveals the differences in the characteristics according to the structure and carbonation of concrete in the specimens mixed with fly ash .
For concrete with 50% fly ash it may be necessary to increase the design strength (e.g. by 4 Mpa) or extent the period of moist curing (e.g. from 1 to 3 days) to meet the same requirements. These estimates assume conditions where carbonation-induced corrosion is the predominant form of deterioration.
An investigation has been carried out on the effects of cement replacement by fly ash on the carbonation rate of concrete. The research was mainly devoted to portland blast furnace slag cement because this cement has a major market share in the Netherlands.
utilization of fly ash in concrete began (for example, USBR 1948) follow-ing the pioneering research conducted at the University of California, Berkeley (Davis 1937).The last 50 years has seen the use of fly ash in concrete grow dramatically with close to 15 million tons used in con-crete, concrete products and grouts in the U.S. in 2005 (ACAA ...
Findings of a 5-year laboratory investigation on the effect of curing on the durability of fly ash concrete are summarized. Three series of con crete mixes were cast such that concretes within a given series were of similar strength grade (nominally 25, 35, or 45 MPa) but varied in fly ash replacement level (0 to 50 percent).
Abstract: The effects of carbonation age, fly ash content in the binder and the water to binder ratios on the carbonation depth of fly ash concrete is investigated and the micromechanical properties of the hardened paste and the inter facial transition zone is analyzed with the micro-hardness method.
In order to study the carbonation resistance of fly ash concrete under multi-factor coupling conditions and provide a suggestion for the design and analysis of actual projects, an experimental investigation was conducted on the effects of the compressive and tensile stress, the high exposure temperature, and the fly ash content, on the carbonation resistance of fly ash concrete.
concrete has been investigated with the use of admixtures such as fly ash, silica fume and super plasticizer. The durability of cubes with and without admixtures, and corrosion resistance of cylinders with and without admixtures have been conducted. Index Terms—Durability, Fly ash, Poles, Prestressed
Presented herein is a numerical model to predict the carbonation depth of Portland cement (PC) and blended cement concrete under a wide range of environmental conditions. The improved model for hydration of PC and activity of blended cement is proposed and used in this carbonation model. This carbonation model can be used for concrete made of silica fume, fly ash and slag with various …
2.5.1 Carbonation of fly ash concretes 13 2.5.2 Carbonation of GGBS concretes 13 2.6 Chloride ingress and chloride induced corrosion 14 2.7 Relation between chloride ingress and carbonation 15 2.8 Accelerated carbonation 15 2.9 Concrete standards in Sweden and Europe 16 2.9.1 The k-value concept for fly ash and GGBS 17
Three mixtures of concrete were designed, which are fly ash concrete with 30% substitution ratio, fly ash, and ground granulated slag concrete with each of 20% substitution ratio, and ordinary Portland cement concrete. Class I low calcium fly ash and S105 …
Concrete containing fly ash, if not cured sufficiently, may have a higher degree of carbonation. Good quality fly ash concrete can show the same trend of carbonation as concrete made without fly ash [Malhotra & Ramezanianpour 1994]. 2.3 Accelerated carbonation The use of accelerated carbonation of concrete to
initiation of carbonation-induced corrosion may be shortened by -360% when the fly ash cement replacement is increased from 20% to 50%. The initiation time may be shortened by ;:35 when cement replacement is increased from 20% fly ash to 20% fly ash plus 8% silica fume. 17 KeyWardr Reinforcing Steel, Corrosion. Carbonation, Concrete,