Microstructural study of sulfate attack on ordinary and limestone Portland cements at ambient temperature

Irassar, Edgardo F.; Bonavetti, Viviana L.; González, María Cristina García

doi:10.1016/s0008-8846(02)00914-6

Cited by 192 publications

(86 citation statements)

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“…Earlier, when the OPC-based cementitious materials were employed widely as geothermal well-casing cement, which serves in supporting mechanically the metal casing-pipe and in protecting it against corrosion, one serious drawback was their limited resistance to the hot acidic environment created by the combination of concentrated dihydrogen sulfide (H 2 S) and carbon dioxide (CO 2 ) in geothermal wells. As well documented [5,6], the capacity of OPCs to withstand acid was very poor, and they suffered from severe acid erosion. To deal with this problem, acid-resistant cements had to be developed.…”

Section: Introductionmentioning

confidence: 86%

Self-degradable Cementitious Sealing Materials

Sugama¹

2010

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A self-degradable alkali-activated cementitious material consisting of a sodium silicate activator, slag, Class C fly ash, and sodium carboxymethyl cellulose (CMC) additive was formulated as one dry mix component, and we evaluated its potential in laboratory for use as a temporary sealing material for Enhanced Geothermal System (EGS) wells. The self-degradation of alkali-activated cementitious material (AACM) occurred, when AACM heated at temperatures of ≥ 200°C came in contact with water. We interpreted the mechanism of this water-initiated self-degradation as resulting from the in-situ exothermic reactions between the reactants yielded from the dissolution of the nonreacted or partially reacted sodium silicate activator and the thermal degradation of the CMC. The magnitude of self-degradation depended on the CMC content; its effective content in promoting degradation was ≥ 0.7 %. In contrast, no self-degradation was

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Section: Introductionmentioning

confidence: 86%

Self-degradable Cementitious Sealing Materials

Sugama¹

2010

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“…e ACI committee (2001) reported several types of chemical attacks such as acid attacks, alkali attacks, chloride ingress, carbonation, and sulfate attacks [1]. All of these chemical attacks deteriorate the overall properties of cementitious materials [2][3][4]. e extensive acid medium makes concrete susceptible to acid attacks.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Physicochemical and Mechanical Properties of Mortar Subjected to Acid Corrosion

Huo

2018

Advances in Materials Science and Engineering

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e 28 days cured cement mortar samples were soaked in HCl (pH � 1 and 2) and H 2 O (pH � 7) solutions for 90 days. By monitoring the ion concentration of H + and Ca 2+ and measuring the changes in weight loss, longitudinal wave velocity, and uniaxial compressive strength values of the corroded mortar, the physicochemical and mechanical properties of the mortar specimens were studied. Experimental results indicate that the process of the mortar sample subjected to HCL erosion has apparent stage characteristics. In the initial stage of corrosion, the chemical reaction increased the porosity of the specimen, which leads to the decrease of longitudinal wave velocity of the samples. At the same time, the corrosion solution continuously penetrates into the mortar pore system, which leads to the increase of the mass, and it is considered that the diffusion process plays a leading role during this period. Moreover, the colloidal compounds generated by the chemical reaction can not only fill the pore space but also block the continuous reaction, which led to the increase of the longitudinal wave velocity of the specimen. With the prolonging of corrosion time and infiltration path, the pH value and the concentration of Ca 2+ tend to be stable, the diffusion action is weakened, and the chemical reaction is continuous, which led to the decrease of the mass and wave velocity gradually. It is considered that the chemical reaction plays a leading role in this process. Based on the induction and analysis of the test results, a generalized porosity model regarding the increase of the porosity and the decrease of effective bearing area of the mortar sample was proposed. e relation between the uniaxial compressive strength and the corrosion time of the corroded mortar is deduced, and the unknown parameters are determined based on the regression analysis of the test data.

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“…Because of the results and the conclusions obtained by these authors (26), achieved in base of the following cementitious materials: 1 SRPC, 1 OPC and its 2 POZC with FA+NP (BC1 and BC2) and 1 POZC with NP (BC3), which have been submitted to the both ASTM C 452 (1) and C 1012 (27) methods, these final statements might be debatable only when calcareous fine aggregate instead of the siliceous and graduated one of the ASTM C 778-92a type (28) would have been used, which is mandatory for these two methods. Since the calcareous aggregate, both fine and coarse and their respective filler, facilitates and increases the sulphate attack to concrete, even when the applied cement is SRPC (26,(30)(31)(32), by means of both direct way (33) (in its double aspect: sulphatic hydration stimulation of the C 3 A present in OPC, in this case, by the mixing water that moistens the surface of their particles during initial mixing, and additional calcium tri-mono-and/or hemi-carboaluminate hydrated formation from C 3 A origin of OPC), and indirect way (33), but this time, with no pozzolanic activity, logically (preferential formation of calcium mono-carboaluminate hydrated instead of AFm phase which is transformed ett-vlf (o de origen el C 4 AF del mismo CPO en las mismas circunstancias), debe de ser lógicamente más bien independiente que inter-dependiente o combinada (16)(17)(18).…”

Section: Introductionmentioning

confidence: 99%

“…Puesto que los resultados y conclusiones que obtuvieron de haber ensayado 1 CPO y sus 2 PUZC con FA (BC1 y BC2), 1 PUZC con NP (BC3) y 1 CPRS con dicho método (1) y el método ASTM C 1012 (27), son además muy discutibles, al haber utilizado una arena caliza local en sustitución de la arena silícea graduada tipo ASTM C 778-92a (28), la cual es obligatorio utilizar para ambos métodos de ensayo. Puesto que, como es sabido, el árido calizo, fino y grueso, facilita a la par que aumenta el ataque de los sulfatos al hormigón, y el filler calizo también lo facilita como el propio (26,(30)(31)(32). Tanto por vía directa (33), en su doble vertiente: estimulación de la hidratación selenitosa, en este caso, del C 3 A del CPO, por el agua de amasado que los humedeció inicialmente, y formación adicional con dicho C 3 A de tri-, mono-y/o hemi-carboaluminato de calcio hidratado, como por vía indirecta, pero esta vez, sin actividad puzolánica alguna de por medio, lógicamente (formación preferente de mono-carboaluminato de calcio hidratado en detrimento de Fase AFm que se transforma en ett-lf in ett-lf (33), resulting finally in greater expansion, as logical as well; in addition, it may also be a precursor to thaumasite formation at advanced ages (34), but also not forgetting the non-direct sulphatic hydration stimulation (33) (26) state as a conclusion that "This test method procedure, ASTM C 452-68, may not be an appropriate tool for determination of sulphate resistance of blended cements, since sulfate exposure occurs before the pozzolanic effect", since whether this affirmation was supposedly true, it had also been applicable for the ASTM C 1012 method.…”

Section: Introductionunclassified

Comportamiento de los cementos Pórtland con puzolanas silícicas frente al ataque del yeso, determinado mediante el Método ASTM C 452-68

Talero¹

2013

Mater. construcc.

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For this study, ASTM C 452-68 testing was conducted for two years on 54 POZC-silica fume (SF) or diatomites (D and N) (=Z pozzolans), were tested for 2 years, by ASTM C 452-68 method, having determined to their specimens their Vcl(=ΔL(%)/day) . The results have borne out that the pozzolanic reactions from SiO 2 r-of these Z pozzolans, in a sulfatic environment, had prevailed sooner (with D and N) or later (with SF) over the sulfatic hydration of their POZC, reaching completion in the first 28 days. Therefore, after positive result is obtained in the Frattini test, as well as in other equivalent tests standardized, the ASTM C 452-68 test can be validly used to differentiate 28-day POZC-Z pozzolan or with any other from natural or artificial origin, which may or may not give rise to the development of low, moderate or high SR. The only requisite would be to establish suitable standard physical-chemical requirements and specifications.. Keywords: gypsum attack; portland cements; silica fume; diatomites. RESUMENPara este trabajo se ensayaron durante 2 años 54 PUZC, que contenían humo de sílice (SF) y diatomeas (D y N) (= puzolanas Z), mediante el método ASTM C 452-68, habiéndosele determinado a sus probetas su Vcl(=ΔL(%)/día). Los resultados obtenidos han confirmado que las reacciones puzolánicas de origen la SiO 2 r-de estas puzolanas Z, en un medio sulfático, han prevalecido más, con D y N, o menos, con SF, pronto, sobre la hidratación sulfática de sus PUZC, habiendo alcanzado su fin en los primeros 28 días. Luego, habiendo sido positivo el ensayo de Frattini, así como los ensayos normalizados equivalentes, el ensayo ASTM C 452-68 puede usarse también para diferenciar a 28 días, los PUZC preparados con puzolana Z o con cualquier otra puzolana natural o artificial, la cual podría o no, promover el desarrollo de baja, moderada o elevada RS. Únicamente, sería necesario establecer requerimientos y especificaciones químico-físicas apropiadas.

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Microstructural study of sulfate attack on ordinary and limestone Portland cements at ambient temperature

Cited by 192 publications

References 28 publications

Self-degradable Cementitious Sealing Materials

Self-degradable Cementitious Sealing Materials

Experimental Study on Physicochemical and Mechanical Properties of Mortar Subjected to Acid Corrosion

Comportamiento de los cementos Pórtland con puzolanas silícicas frente al ataque del yeso, determinado mediante el Método ASTM C 452-68

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