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SEASONAL VARIATION IN TURAG RIVER WATER …

KEY WORDS: River pollution, Turag river, Alkalinity, Bicarbonate, Concrete industry Filling station, Hospital and Tongi Bridge near the sample location (Source: Modified from Google Maps, 2021 ...

Effect of calcium sulfoaluminate cement on the hydration …

This trend aligns with the variation in compressive strength of cement mortar at 3 d. Download: Download high-res image (494KB) Download: Download full-size image; Fig. 5. ... Alkaline activators provide alkaline conditions for the hydrolysis of slag and the hydration of phosphogypsum slag cement. However, the alkalinity of the system needs to ...

Evaluation of alkalinity changes and carbonation of geopolymer concrete

The investigation of alkalinity changes of geopolymer concrete (GPC) in various environments is important to enhance the application of GPC in the construction field. ... The changes in pH value, carbonation depth, compressive strength variation, and electrical resistance were determined after a six-month exposure to the three-above-mentioned ...

Pore Solution Chemistry of Calcium Sulfoaluminate Cement …

Variation i n the water-cement ratio, clinker constitution, hydration time, temperature or other factors may cause the ion composition to change greatly. Thus, it would not be suitable to adopt an

EFFECT OF CEMENT ALKALINITY ON PORE SOLUTION …

DOI: 10.14359/11967 Corpus ID: 54620735; EFFECT OF CEMENT ALKALINITY ON PORE SOLUTION CHEMISTRY AND CHLORIDE-INDUCED REINFORCEMENT CORROSION @article{Dehwah2002EFFECTOC, title={EFFECT OF CEMENT ALKALINITY ON PORE SOLUTION CHEMISTRY AND CHLORIDE-INDUCED REINFORCEMENT CORROSION}, …

Variability of Portland cement

Effect of alkali content of cement on properties of high …

Higher alkali level negatively affects workability, setting and strength of HPCM. Higher alkali level increased shrinkage, permeable voids and RCP in HPCM. Even in HPCMs …

RS-AAT with distributed permeable pipes and alkaline water: …

Fig. 11 delineates the spatial variations in local alkalinity, quantified by pH values at varying depths from the exposed concrete surface. For comparison purposes, the pH values of the control group representing the cases without employing RS-AAT are also given. ... Ex situ leaching measurement of concrete alkalinity. Cement Concr. Res., 35 ...

Alkalis in Portland cement

The predominant source of alkalis in concrete is the Portland cement.As noted in Chapter 2, Portland cement contains relatively minor amounts of both sodium (Na) and potassium (K) and these are usually expressed as oxides, Na2O and K2O, in a typical chemical analysis. Since these alkalis tend to behave fairly similarly in Portland cement concrete, it is common …

Understanding the initial use stage of cement mortar lining …

At a fixed hardness, the cumulative aluminum release decreased with increasing alkalinity, however, the cumulative aluminum release from the experiment with alkalinity 150 mg/L was always slightly higher than that from the experiment with alkalinity 100 mg/L (Fig. 4d). Except for A30H5 and A5H40, the cumulative release of calcium decreased and ...

Understanding the effect of alkali content on hydration, …

In this study, we systematically investigate the sources of alkalis in Portland cement compositions and their effects on cement hydration, hardening, microstructure, and durability, aiming to provide insights into the design and development of cement and concrete.

Effect of Cement Alkalinity on Chloride Threshold and Time …

Abstract A series of reinforced G109-type concrete specimens with cement of equivalent alkalinity (EqA) either 1.08 or 0.32 was cyclically ponded with a 15-wt% sodium chloride (NaCl) solution and time-to-corrosion initiation, Ti, was determined. The specimens were subsequently dissected, the steel-concrete interface examined and characterized, and …

Effects of cement alkalinity, exposure conditions and steel-concrete …

Effects of (1) cement alkalinity (low, normal and high), (2) exposure conditions (RH and temperature), (3) rebar surface condition (as-received versus cleaned) and (4) density and distribution of ...

Durability of SFCB reinforced low-alkalinity seawater sea sand concrete …

These results underscore the potential of low-alkalinity concrete in improving the long-term durability and structural performance of SFCB-reinforced marine concrete infrastructures. ... but lower than that between the BFRP bars and alkali-activated seawater coral aggregate concrete (AACAC). This variation is due to the tighter mechanical ...

Alkali-Silica Reaction (ASR)

Reactive phases of silica are found in some sources of construction aggregates with wide regional variations. The soluble alkali ions may be present in the pore solution of the concrete (the amount being primarily dependent on cement alkalinity) and/or from external sources of salts such as seawater, or road de-icing substances.

Effect of alkalinity on phosphogypsum-base non-calcined cement

Three experimental binder mixes with variation in the composition of the main constituents (cement clinker, ground limestone and ground granulated blast furnace slag) and constant content of ...

Carbonation of cement paste: Understanding, challenges, …

In the past, a lot of research has been devoted to studying effects of carbonation on durability of reinforced concrete. In concrete, reinforcing steel is protected from active corrosion by a passive film of ferrous oxide which forms on its surface in the highly alkaline concrete pore solution [2], [3].This alkalinity, corresponding to a pH value above 12.5, is provided by …

Passivation behavior of steel in novel low-carbon binders …

In a concrete pore solution with pH > 13, steel bar is naturally passivated by forming a stable oxide layer [[5], [6], [7]].Although the minimum pH level of alkaline solution to result in a stable passivation state of steel was reported at 11.5 [8], Carsana et al. [9] demonstrated that steel in CSA concrete reached passivation at a low pH value of 10.8, yet …

A feasibility study of using low-alkalinity seawater sea sand concrete …

The significant variation in bond strength degradation with different bar geometries, concrete grades, manufacturing processes, aging processes, and so on makes the bond durability of BFRP-reinforced concrete under seawater attack unclear. ... [35] found that substituting low-alkalinity concrete for normal concrete may improve the durability of ...

Developing green and economical low-alkalinity seawater …

A study achieved a reduction in concrete alkalinity from 12.5 to 11.1 by adding 50% silica fume (Yi et al., 2022). ... The pH variation of SWSSC under pure silica fume replacement is illustrated in Fig. 2 (c). The pH value only shows a decreasing trend in the first 60 days, but ultimately no significant difference compared to the control group. ...

Why Flooring Professionals Must Test For Moisture And Alkalinity

Alkalinity is too high in the concrete due to a high moisture emission rate. Alkalinity is measured by pH from 1-14. Ideally, concrete should have a pH of 7-9 before installing a floor covering; otherwise, the high alkalinity (high pH) combined with moisture will destroy flooring adhesive bonds. ... But regional and seasonal variations mean ...

Variability of Portland cement

Discusses why cement from a particular source may vary over time, with particular emphasis on strength variability. ... Variation in raw materials and fuels are likely to result in changes in kiln conditions and consequently, to some extent at least, to changes in the cement. ... This increased alkalinity accelerates alite hydration, giving ...

Variation of alkalinity in cement paste with high volume fly …

Request PDF | Variation of alkalinity in cement paste with high volume fly ash during long-term hydration | A series of experiments were carried out to investigate the stability of alkaline ...

(PDF) Structure and Properties of Alkaline Cement and …

A new structure-based model for the durability (cracking) assessment of the alkaline cement concrete with heat of hydration and deformation properties during hardening …

(PDF) Decrease of pore solution alkalinity in concrete tested …

The alkalinity difference between cement paste cylinders and reactive concretes was about the same level at 4 weeks (Tables 6 and 7). Pore solution alkalinity in Paste-Mass was 837 mmol/l, whereas in concrete, the alkalinity dropped to 561 mmol/l (33%) for Potsdam, to 478 mmol/l (40%) for Spratt, and to 558 mmol/l (33%) for Limeridge.

Alkali Aggregate Reaction in Concrete – Types, …

Alkali aggregate reactions (AAR) occur when aggregates in concrete react with the alkali hydroxides in concrete producing a hygroscopic gel which, in the presence of moisture, absorbs water and causes expansion and cracking over …

Mitigating the deterioration of BFRP bars in seawater sea …

The high alkalinity of normal concrete can be reduced by replacing a large amount of Portland cement with silica fume or in combination with other pozzolanic materials [21], [22]. This method can consume portlandite formed by the hydration of ordinary Portland cement, enhance the alkali absorption capacity of C–S–H and lower their ...

Annual variation of source contributions to PM10 and …

High alkalinity of cement plant emissions due to hydration of clinker, the main constituent of cement, consisting mainly of alite (3CaO•SiO2) and tricalcium aluminate (3CaO•Al2O3), calcium aluminoferrite (Ca2(Al,Fe)2O5) and additives added at the later stage, may have strong health effects (Weinbruch et al., 2023 and reference therein).

COMPARISON OF EXPANSION TESTS FOR ALKALI …

quantification of alkalinity resulting from several interactions in concrete environment, variation of alkalinity due to leaching and reactions, effects of variation of humidity. ii) by extending the proposed approach by inclusion of …

Re-alkalization of Carbonated Reinforced …

Removal of carbonated concrete mechanically and replacing the same with new repair mortar involves a lot of work and also consumes time as well as money. Realkalisation helps in increasing the alkalinity of concrete i.e. pH of …