Introduction To Alkali-aggregate Reaction In Concrete

Poole, A. B.

doi:10.4324/9780203036631.ch1

Cited by 37 publications

(88 citation statements)

References 3 publications

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“…In comparing this rim sequence with those described by Bisque (1959), Bisque & Lemish (1958, 1960, Lemish et al(1958), Poole (1981), and Poole & Sotiropoulos (1978, 1980, it is veiy likely that the daric dolomite rim corresponds to the darker inner aggr^ate rim observed by Lemish et al(1958) and to zone A in Poole's (1981) observations. The lightcolored paste reaction rim seems to correspond to the hght outer paste rim in Lemish et al's (1958) rim sequence, and to zone B of Poole's (1981) rim sequence. Zone C described by Poole (1981) is missing fixxn the ccmcretes studied in the present research.…”

Section: Rim Development Sequencesupporting

confidence: 59%

“…alkali -carbonate, alkali -siUca, and alkah -silicate reactions (Gillott, 1975;Poole, 1992; Rogers, 1993 (Poole & Sotiropoulos, 1978, 1980Poole, 1981).…”

Section: Aggregate -Paste Reaction As a Potential Cause Of Concrete Dmentioning

confidence: 99%

“…Reactions between clay-rich carbonate aggregate (in Iowa) and cement paste have been reported to result in reaction rims with increased silica coocentiatirais at the outer mar^ns of the aggregate (Bisque & Lemish, 1958). Concretes containing certain types of dolomite aggregate have undergone reactions that result in dolomite aggregate rims with elevated calcium and reduced magnesium (Poole & Sotiropoulos, 1978, 1980Poole, 1981).…”

Section: Aggregate -Paste Reaction As a Potential Cause Of Concrete Dmentioning

confidence: 99%

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The role of magnesium in concrete deterioration

Gan¹

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1996Signature was redacted for privacy.Signature was redacted for privacy.Signature was redacted for privacy.Signature was redacted for privacy Signature was redacted for privacy.Signature was redacted for privacy.Signature was redacted for privacy. NOMENCLATUREIn tbis dissertadoQ, ibe tenn concrete refers to tbe mixture of Portland cement paste, coarse aggregate and fine aggregate; Paste or cement paste will be used to indicate the Portland cement hydration product, as distinguished from the fine and coarse aggregates which occur within the paste; Aggregate, coarse aggregate or dolomite aggregate will be used for the coarse dolomite aggregate used in the concretes;Interface refers to the coarse dolomite aggregate -cement paste interface. GENERAL INTRODUCTION Deterioration of Iowa ConcretesPremature failures of concrete in highways are due predominantly to deterioration of joints and cracks. This deterioration is generally referred to as D-cracking, which was defined as "cracking in a slab surface in a pattern that appears first in an orientation parallel to transverse and longitudinal joints and cracks, continues around comers, and may progress into the central area of the slab" by Girard et al. (1982), and as "a form of PCC deterioration associated primarily with the use of coarse aggregates in the concrete that disint^rate when they become saturated and are subjected to repetitive cycles of freezing and thawing" Sdiwaitz (1987 Since 1978, research at the Iowa DOT has focused on the pore system of limestones used as coarse aggregate in PCC concrete and its relationship to fi"eeze/thaw failure (Marks & Dubberice, 1982; Dubberke, 1983 Aggregate -Paste Reaction as a Potential Cause of Concrete DeteriorationOne potential factor is the chemical reactions between the cement paste and aggregate particles, \^ch is called "alkali -aggregate reaction". Three types of alkali -aggregate reaction have been recognized:alkali -carbonate, alkali -siUca, and alkah -silicate reactions (Gillott, 1975;Poole, 1992; Rogers, 1993 (Poole & Sotiropoulos, 1978, 1980Poole, 1981). The Role of Magnesium, Calcium and Sodium in Concrete DeteriorationAnother potential factor is the deicers applied to reduced hazards of winter snow and ice. Studies show that sodium and calcium chloride deicers produce corrosion of aggregate (Dubberke & Marks, 1985) and ccnaete (Boies & Bcwtz, 1965;Neville, 1969; Sayward, 1984) show that the addition of magnesium chloride into sodiinn chloride solution appears to enhance the durability of certain types of concrete. OBJECTIVES OF RESEARCHThe main objective of the current research is to investigate the role of magnesium, vdiich m^ be introduced into die paste, either fixxn dedolonitizaticm of coarse dolomite aggregate, or from surface-applied magnesium deicets, in the detenOTad^i of Iowa highway concrete. The second objective is to investigate the effects of deicer salt ^licaticxis csi Iowa hi^w^ concretes to determine if magnesium deicers might be less damaging than rock salt, NaCl.These objectives were ...

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Section: Rim Development Sequencesupporting

confidence: 59%

“…alkali -carbonate, alkali -siUca, and alkah -silicate reactions (Gillott, 1975;Poole, 1992; Rogers, 1993 (Poole & Sotiropoulos, 1978, 1980Poole, 1981).…”

Section: Aggregate -Paste Reaction As a Potential Cause Of Concrete Dmentioning

confidence: 99%

Section: Aggregate -Paste Reaction As a Potential Cause Of Concrete Dmentioning

confidence: 99%

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The role of magnesium in concrete deterioration

Gan¹

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“…According to Poole [6], the deterioration may occur within days, after years or even decades, until the cement alkali completely reacts with the aggregate. With an estimated average time from 5 to 12 years to develop.…”

Section: Alkali-aggregate Mechanismmentioning

confidence: 99%

Analysis of concrete structures deteriorated by alkali-aggregate reaction: case study

Costa

Torres²,

Neves³

2016

J Build Rehabil

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This research aims to analyze the alkali-aggregate reaction with the case study of a waterfront structure pier, a reinforced concrete structure located in a marine environment in Brazil. In the present work is done a literature review on the subject of alkali-aggregate reaction, focusing on Brazilian standards, addressing the chemical mechanism, risk analysis and prevention of this pathological phenomenon. That said, petrographic analyses are also carried out for the characterization of the aggregates used in the structures of mooring dolphins of that pier. The results obtained in laboratory tests reveal the presence of characteristic minerals of the alkali-aggregate reaction in Dolphin C. However, the alkali-aggregate reaction has, as one of its features, the heterogeneous distribution along the affected structures, reason why it is very difficult to establish their degree of development and evolution stage. Therefore, it is not possible to define if the expansive process evidenced in Dolphin C will still be occurring over the years.

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“…Ce phénomène d'ionisation est à l'origine d'un mouvement des ions à travers la solution interstitielle. La seconde réaction consiste à couper des ponts siloxanes (Si-O-Si) entraînant la formation de sites négativement chargés ou protonés [3][4][5][6]. Suite à l'attaque de la silice du granulat, à pH très basique, il y a création de sites négativement chargés à la surface, tandis que simultanément des silicates passent en solution.…”

Section: Introductionunclassified

Nouvelle approche pour le suivi de la réactivité de phases SiO₂soumises à la Réaction Alcali Silice (RAS)

Jabkhiro

Hamoudi

Khouchaf

et al. 2012

MATEC Web of Conferences

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Résumé. Nous avons suivi-au moyen de la microscopie électronique à balayage environnementale (MEBE) la diffraction X et la spectroscopie d'absorption des rayons X sous rayonnement synchrotron (XANES)-la réactivité de certaines phases SiO 2 lors du processus de la Réaction Alcali Silice (RAS). Cette réactivité est étroitement liée à la structure locale autour des atomes de silicium ainsi qu'à la présence d'impuretés comme le fer. Dans le cas du silex brut, la raie blanche du seuil K du fer ressemble davantage à celle de Fe 3 O 4 ce qui permet de déduire la présence d'un mélange de Fe 2 +/Fe 3+ dans le silex de départ. Après réaction, l'allure du spectre d'absorption des rayons X au seuil K du fer du silex est conservée avec un léger déplacement de la raie blanche vers les hautes énergies. Cette augmentation montre une prédominance de la valence Fe 3+ au détriment de la valence Fe 2+ . Les résultats montrent que le fer participe à la stabilisation de la structure des phases formées. Cette étude peut être étendue à d'autres éléments traces présents dans la structure du silex de départ.Abstract. In this study the reactivity of some SiO 2 phases under Alkali Silica Reaction (RAS) process is followed, using the environmental scanning electron microscopy (ESEM) X-ray diffraction and absorption spectroscopy X-ray synchrotron radiation (XANES). This reactivity is closely related to the local structure around the silicon atoms and the presence of impurities such as iron. In the case of flint raw skate white iron K line is more like that of Fe 3 O 4 which allows to deduce the presence of a mixture of Fe 2+ / Fe 3+ in the flint to start. After reaction, the shape of the spectrum of X-ray absorption K edge of iron in the flint is retained with a slight displacement of the white stripe to high energies. This increase shows a predominance of the valence Fe 3+ at the expense of Fe 2+ valence. The results show that iron is involved in stabilizing the structure of phases formed. This study can be extended to other trace elements present in the structure of the flint to start.

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Introduction To Alkali-aggregate Reaction In Concrete

Cited by 37 publications

References 3 publications

The role of magnesium in concrete deterioration

The role of magnesium in concrete deterioration

Analysis of concrete structures deteriorated by alkali-aggregate reaction: case study

Nouvelle approche pour le suivi de la réactivité de phases SiO₂soumises à la Réaction Alcali Silice (RAS)

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Introduction To Alkali-aggregate Reaction In Concrete

Cited by 37 publications

References 3 publications

The role of magnesium in concrete deterioration

The role of magnesium in concrete deterioration

Analysis of concrete structures deteriorated by alkali-aggregate reaction: case study

Nouvelle approche pour le suivi de la réactivité de phases SiO2soumises à la Réaction Alcali Silice (RAS)

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Nouvelle approche pour le suivi de la réactivité de phases SiO₂soumises à la Réaction Alcali Silice (RAS)