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Marc-andré Bérubé - One of the best experts on this subject based on the ideXlab platform.
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use of the accelerated mortar bar test to evaluate the effectiveness of lino3 against alkali silica reaction part 2 comparison with results from the Concrete Prism test
Journal of Astm International, 2008Co-Authors: C Tremblay, Marc-andré Bérubé, Kevin J Folliard, Benoit Fournier, M D A Thomas, P C NkinamubanziAbstract:For the time being, the Concrete Prism test (CPT) CSA A23.2-14A or ASTM C1293 remains the most reliable test method to evaluate the effectiveness of lithium nitrate against alkali-silica reaction (ASR) in Concrete; however, the extended testing period of two years has often limited its acceptance by practitioners. In its actual form, the popular accelerated mortar bar test (AMBT) CSA A23.2-25A or ASTM C1260 cannot be used to predict this effectiveness, thus it needs to be modified accordingly. Part I of this study looked at the influence of a number of parameters on the effectiveness of lithium to control expansion of mortar bars incorporating a variety of reactive aggregates from Canada and the United States. The second part of this study (Part II) compares the results obtained in modified versions of the AMBT with those from the CPT performed on the same aggregates, with the objective of proposing the best accelerated test procedure for determining the minimum amount of lithium nitrate necessary to counteract ASR expansion in Concrete. The results obtained in this study have shown that the effectiveness of lithium nitrate greatly varies from one reactive aggregate to another while not being correlated with the degree of reactivity or the petrographic nature of the reactive aggregates to counteract. A safe method of predicting the effective [Li]/[Na+K] to used in Concrete is proposed which uses two AMBTs, one of which involves adding lithium to both the mortar bar and the soak solution. It allows the prediction of an effective [Li]/[Na+K] for aggregates that respond relatively well to lithium. The method allows the identification of aggregates that respond particularly badly to the lithium, for which the Concrete Prism test is recommended for evaluating the minimum lithium dosage to use for ASR control.
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evaluation of the expansion attained to date by Concrete affected by alkali silica reaction part i experimental study
Canadian Journal of Civil Engineering, 2004Co-Authors: Nizar Smaoui, Marc-andré Bérubé, Benoit Fournier, Benoit Bissonnette, Benoit DurandAbstract:The expansion to date of the Concrete from a structure affected by alkali–silica reaction (ASR) is a crucial parameter in the evaluation of the structural integrity of the structure. Three methods have been used to evaluate this expansion: (i) the "stiffness damage test" (SDT), (ii) the "damage rating index" (DRI), and (iii) surface cracking. Concrete cylinders were made using several types of coarse and fine reactive aggregates and subjected to the Canadian Standards Association (CSA) Concrete Prism test CSA A23.2-14A (or American Society for Testing and Materials (ASTM) test method C1293), i.e., at 38 °C and >95% relative humidity (RH). At various expansion levels, the specimens were subjected to SDT and DRI tests. Very good relationships were obtained between the expansion due to ASR and the SDT. The correlation between the ASR expansion and the DRI was not as good but still of interest. Width measurements of surface cracks were also performed on a number of blocks made with different reactive aggregat...
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alkali mass balance during the accelerated Concrete Prism test for alkali aggregate reactivity
Cement and Concrete Research, 2003Co-Authors: Marc-andré Bérubé, Patrice Rivard, J P Ollivier, Gerard BallivyAbstract:The alkali mass balance was calculated in Concrete specimens submitted to the storage conditions of the Canadian standard CSA A23.2-14A Concrete Prism test for expansion because of alkali-aggregate reaction (AAR). The alkali concentration of both the Concrete pore solution expressed under high pressure and the water below specimens in storage pails (bottom water) was measured. Measurements were conducted over a 1-year period that corresponds to the length of the above test. Two reactive aggregates were testes [Potsdam sandstone (PO) and Spratt limestone (SP)]. Each aggregate was incorporated in two Concrete mixtures (mass Concrete and structural Concrete), for a total of four batches. Significant alkali leaching occurred at 38 degrees centigrade while performing tests in high moisture storage conditions even though Prisms were covered with plastic sleeves. After 52 weeks, the alkali loss ranged from 12% to 25% of the original Na(2)O(e) content of the Concrete, depending on the mixture proportioning and the aggregate type. After estimation of the proportion of alkalis fixed in cement hydrates, it appears that about 23% to 39% of the original alkalis released by the cement are quickly sorbed on aggregate surfaces or have rapidly migrated inside aggregate particles, which may have been incorporated with time in the AAR product. After 52 weeks at 38 degrees centigrade, the pore solution alkalinity expressed from mass Concrete made with PO was 250 mmol/l, whereas the alkalinity was 270 mmol/l in mass Concrete incorporating SP. Since Prisms of both mixtures were still expanding at 1 year, these alkalinity values are above the thresholds required for sustaining AAR in these Concrete mixtures.
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long term effectiveness of supplementary cementing materials against alkali silica reaction
Cement and Concrete Research, 2001Co-Authors: Josée Duchesne, Marc-andré BérubéAbstract:Abstract The long-term effectiveness of six supplementary cementing materials (SCM) were tested according to the CSA-A23.2-14A Concrete Prism Method in the presence of two very alkali–silica reactive aggregates from Canada. Three fly ashes, two silica fumes, and one ground granulated blast furnace slag (GGBFS) were selected based on their elemental composition in order to represent a wide range of composition. The performance of SCMs in suppressing expansion due to alkali–silica reaction was compared with that obtained by a low-alkali cement. Pore solution composition of the mixtures was also determined. Results show that expansion curves flatten out after 2 years of curing. This phenomenon was due to alkali leaching from the Concrete Prisms and alkali binding by the alkali aggregate reaction products in the presence of the very reactive aggregates used, which was supported by very low alkali ion concentrations measured on Concrete samples at the end of the experiment. A 2-year expansion limit is then suggested when using the CAN/CSA-A23.2-14A method to evaluate mixtures containing SCM. The proportion of SCM and total alkali content of the Concrete are very significant factors controlling Concrete expansion.
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The effectiveness of supplementary cementing materials in suppressing expansion due to ASR: Another look at the reaction mechanisms part 1: Concrete expansion and portlandite depletion
Cement and Concrete Research, 1994Co-Authors: Josée Duchesne, Marc-andré BérubéAbstract:Abstract Portlandite content (TGA) of cement pastes made with two condensed silica fumes, three pulverized fly ashes and one ground granulated blast furnace slag was measured up during a 1 year time period. Results were compared to expansions obtained for a 2 year time period in the CAN/CSA A23.2-14A Concrete Prism Method for Concrete specimens made with two very alkali-silica reactive aggregates and tested at the same conditions and water/cement/SCM. No correlation was obtained between reduction in Concrete expansion and the portlandite depletion which appears to be only a consequence of pozzolanic reaction.
Michael D A Thomas - One of the best experts on this subject based on the ideXlab platform.
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alkali silica reaction asr performance testing influence of specimen pre treatment exposure conditions and Prism size on Concrete porosity moisture state and transport properties
Cement and Concrete Research, 2013Co-Authors: Jan Lindgard, Michael D A Thomas, Bard Pedersen, E J Sellevold, Harald Justnes, Terje F RonningAbstract:Abstract Whether or not Concrete Prism tests (CPTs) developed for assessment of alkali–silica reactivity of aggregates might be suitable for general ASR performance testing of Concrete has been evaluated. This paper presents the background for the choice of test procedures and results on how variations in specimen pre-treatment, ASR exposure conditions and Prism size influence Concrete porosity, moisture state and transport properties. Results from measurements of alkali leaching and Prism expansions during the ASR exposure are presented in a separate paper, together with discussion of consequences for ASR test procedures. For ordinary Portland cements and with water-to-cementitious-materials ratio (w/cm) 0.45 and higher it was found that the internal moisture state is sufficiently high in all the assessed procedures to produce ASR expansion. However, for less permeable Concretes lack of internal moisture and lower rate of diffusion can significantly reduce the rate and extent of ASR expansion during laboratory performance testing.
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the current state of the accelerated Concrete Prism test
Cement and Concrete Research, 2010Co-Authors: Jason H Ideker, Michael D A Thomas, Bradley East, Kevin J Folliard, Benoit FournierAbstract:Abstract Expansions due to alkali–silica reaction (ASR) in the accelerated Concrete Prism test (ACPT–60 °C) show a significant reduction at 13 weeks compared to 52 week testing in the standard Concrete Prism test (CPT–38 °C). Previous work indicated that increased leaching, higher mass loss and a reduction in the pH were observed when temperature was increased from 38 to 60 °C. After further investigation the authors have revealed that non-reactive fine aggregate from certain sources combined with the same reactive coarse aggregate exhibited further reduction in expansion in the ACPT. Expansion data for a wide range of reactive coarse aggregates in 38 and 60 °C testing regimes is shown. Data investigating the Spratt reactive coarse aggregate combined with seven different non-reactive sands will be shown to demonstrate the dramatic effect of the non-reactive sand. Selected pore solution analyses will be given to further elucidate this issue.
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test methods for evaluating preventive measures for controlling expansion due to alkali silica reaction in Concrete
Cement and Concrete Research, 2006Co-Authors: Michael D A Thomas, Jason H Ideker, Kevin J Folliard, Benoit Fournier, Medhat H ShehataAbstract:Abstract This paper provides a critical evaluation of the various methods available for testing the efficacy of measures for preventing expansion due to alkali–silica reaction (ASR) in Concrete containing deleteriously reactive aggregate. The ideal test method should be rapid, reliable and capable of determining the influence of aggregate reactivity, alkali availability and exposure conditions. None of the currently available or commonly used methods meet all of these criteria. The shortcomings of the different test methods are discussed and suggestions are made for modifying the Concrete Prism test and accelerated mortar bar test to make these tests more acceptable.
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use of ternary blends containing silica fume and fly ash to suppress expansion due to alkali silica reaction in Concrete
Cement and Concrete Research, 2002Co-Authors: Medhat H Shehata, Michael D A ThomasAbstract:Abstract This paper investigates the effects of cementitious systems containing Portland cement (PC), silica fume (SF) and fly ash (FA) on the expansion due to alkali–silica reaction (ASR). Concrete Prisms were prepared and tested in accordance with the Canadian Standards Association (CSA A23.2-14A). Paste samples were cast using the same or similar cementitious materials and proportions that were used in the Concrete Prism test. Pore solution chemistry and portlandite content of the paste samples are reported. It was found that practical levels of SF with low-, moderate- or high-calcium FA are effective in maintaining the expansion below 0.04% after 2 years. Pore solution chemistry shows that while pastes containing SF yield pore solutions of increasing alkalinity at ages beyond 28 days, pastes containing ternary blends maintain the low alkalinity of the pore solution throughout the testing period (3 years).
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The effect of metakaolin on alkali–silica reaction in Concrete
Cement and Concrete Research, 2000Co-Authors: Terrence Ramlochan, Michael D A Thomas, Karen Ann GruberAbstract:This article reports on a study to evaluate the efficacy of high-reactivity metakaolin (HRM) in controlling expansion due to alkali–silica reaction (ASR). The expansion of Concretes and mortars containing 0–20% HRM as a partial replacement for OPC was studied. Concrete Prisms were prepared according to the CAN/CSA A23.2-14A Concrete Prism method with two alkali–silica reactive aggregates: a siliceous limestone (Spratt) and a greywacke-argillite gravel (Sudbury). The amount of HRM required to control the expansion to
Josée Duchesne - One of the best experts on this subject based on the ideXlab platform.
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long term effectiveness of supplementary cementing materials against alkali silica reaction
Cement and Concrete Research, 2001Co-Authors: Josée Duchesne, Marc-andré BérubéAbstract:Abstract The long-term effectiveness of six supplementary cementing materials (SCM) were tested according to the CSA-A23.2-14A Concrete Prism Method in the presence of two very alkali–silica reactive aggregates from Canada. Three fly ashes, two silica fumes, and one ground granulated blast furnace slag (GGBFS) were selected based on their elemental composition in order to represent a wide range of composition. The performance of SCMs in suppressing expansion due to alkali–silica reaction was compared with that obtained by a low-alkali cement. Pore solution composition of the mixtures was also determined. Results show that expansion curves flatten out after 2 years of curing. This phenomenon was due to alkali leaching from the Concrete Prisms and alkali binding by the alkali aggregate reaction products in the presence of the very reactive aggregates used, which was supported by very low alkali ion concentrations measured on Concrete samples at the end of the experiment. A 2-year expansion limit is then suggested when using the CAN/CSA-A23.2-14A method to evaluate mixtures containing SCM. The proportion of SCM and total alkali content of the Concrete are very significant factors controlling Concrete expansion.
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The effectiveness of supplementary cementing materials in suppressing expansion due to ASR: Another look at the reaction mechanisms part 1: Concrete expansion and portlandite depletion
Cement and Concrete Research, 1994Co-Authors: Josée Duchesne, Marc-andré BérubéAbstract:Abstract Portlandite content (TGA) of cement pastes made with two condensed silica fumes, three pulverized fly ashes and one ground granulated blast furnace slag was measured up during a 1 year time period. Results were compared to expansions obtained for a 2 year time period in the CAN/CSA A23.2-14A Concrete Prism Method for Concrete specimens made with two very alkali-silica reactive aggregates and tested at the same conditions and water/cement/SCM. No correlation was obtained between reduction in Concrete expansion and the portlandite depletion which appears to be only a consequence of pozzolanic reaction.
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the effectiveness of supplementary cementing materials in suppressing expansion due to asr another look at the reaction mechanisms part 2 pore solution chemistry
Cement and Concrete Research, 1994Co-Authors: Josée Duchesne, Marc-andré BérubéAbstract:Abstract Pore solution chemistry (high pressure extraction method) of cement pastes made with two condensed silica fumes, three pulverized fly ashes and one ground granulated blast furnace slag was measured after 7, 28, 84, 182, 364 and 545 days of curing (38°C and 100% R.H.). Results were compared to expansions obtained for a 2 year time period in the CAN/CSA A23.2-14A Concrete Prism Method for Concrete specimens made with two very alkali-silica reactive aggregates and tested at the same conditions and water/cement/SCM. A long-term threshold in alkali hydroxide concentration was observed around 0.65N, below which no significant expansion occurred in corresponding Concretes. The lower the SCM alkali content and the Concrete alkali content as well, and the higher the SCM content, the easier this limit is satisfied.
Medhat H Shehata - One of the best experts on this subject based on the ideXlab platform.
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the capacity of ternary blends containing slag and high calcium fly ash to mitigate alkali silica reaction
Cement & Concrete Composites, 2014Co-Authors: Seyon Kandasamy, Medhat H ShehataAbstract:Abstract The efficiency of ternary blends containing high-calcium fly ash and slag in mitigating alkali-silica reaction (ASR) was evaluated. The Concrete Prism expansions showed that the ternary blends did not offer significant advantage over binary blends of portland cement and either of the individual material at the same total SCM content. The ability of a particular blend to mitigate ASR was related to its capacity to retain alkalis in its hydration products, as evaluated by an alkali leaching test. For the slag and fly ash used in this study, the capacity to retain alkalis increased with the ability of the blend to consume Ca(OH)2 during its pozzolanic reaction. For the blends investigated here, the alkali leaching test was more realistic than the accelerated mortar bar test in predicting the 2-year expansion of Concrete Prisms. The adopted alkali leaching test is proposed to be used as a tool to compare the efficacy of different cementing blends to mitigate ASR.
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test methods for evaluating preventive measures for controlling expansion due to alkali silica reaction in Concrete
Cement and Concrete Research, 2006Co-Authors: Michael D A Thomas, Jason H Ideker, Kevin J Folliard, Benoit Fournier, Medhat H ShehataAbstract:Abstract This paper provides a critical evaluation of the various methods available for testing the efficacy of measures for preventing expansion due to alkali–silica reaction (ASR) in Concrete containing deleteriously reactive aggregate. The ideal test method should be rapid, reliable and capable of determining the influence of aggregate reactivity, alkali availability and exposure conditions. None of the currently available or commonly used methods meet all of these criteria. The shortcomings of the different test methods are discussed and suggestions are made for modifying the Concrete Prism test and accelerated mortar bar test to make these tests more acceptable.
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use of ternary blends containing silica fume and fly ash to suppress expansion due to alkali silica reaction in Concrete
Cement and Concrete Research, 2002Co-Authors: Medhat H Shehata, Michael D A ThomasAbstract:Abstract This paper investigates the effects of cementitious systems containing Portland cement (PC), silica fume (SF) and fly ash (FA) on the expansion due to alkali–silica reaction (ASR). Concrete Prisms were prepared and tested in accordance with the Canadian Standards Association (CSA A23.2-14A). Paste samples were cast using the same or similar cementitious materials and proportions that were used in the Concrete Prism test. Pore solution chemistry and portlandite content of the paste samples are reported. It was found that practical levels of SF with low-, moderate- or high-calcium FA are effective in maintaining the expansion below 0.04% after 2 years. Pore solution chemistry shows that while pastes containing SF yield pore solutions of increasing alkalinity at ages beyond 28 days, pastes containing ternary blends maintain the low alkalinity of the pore solution throughout the testing period (3 years).
Benoit Fournier - One of the best experts on this subject based on the ideXlab platform.
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assessment of the potential reactivity of granitic rocks petrography and expansion tests
Cement and Concrete Research, 2016Co-Authors: Violeta Ramos, Benoit Fournier, Isabel Fernandes, Antonio Santos Silva, D Soares, Sara Leal, Fernando NoronhaAbstract:Abstract Granite is one of the most commonly employed materials in the production of aggregates for Concrete, and represents 40% of the total volume of aggregates produced in Portugal. This type of rock is traditionally considered as slowly/late reactive or even non-reactive to alkalis. However, a number of cases of damaged Concrete structures in Portugal, due to alkali–silica reaction, have been related to granitic aggregates. A research program has been developed in order to define the best test method for evaluating the potential alkali-reactivity of granitic rocks. The present study involved thirteen granites collected from different quarries. The tests carried out included: petrographic examination of the aggregate, as well as mortar and Concrete expansion tests. It was concluded that the content of microcrystalline quartz correlates better with the results of Concrete Prism expansion tests than with the mortar-bar expansion test.
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the current state of the accelerated Concrete Prism test
Cement and Concrete Research, 2010Co-Authors: Jason H Ideker, Michael D A Thomas, Bradley East, Kevin J Folliard, Benoit FournierAbstract:Abstract Expansions due to alkali–silica reaction (ASR) in the accelerated Concrete Prism test (ACPT–60 °C) show a significant reduction at 13 weeks compared to 52 week testing in the standard Concrete Prism test (CPT–38 °C). Previous work indicated that increased leaching, higher mass loss and a reduction in the pH were observed when temperature was increased from 38 to 60 °C. After further investigation the authors have revealed that non-reactive fine aggregate from certain sources combined with the same reactive coarse aggregate exhibited further reduction in expansion in the ACPT. Expansion data for a wide range of reactive coarse aggregates in 38 and 60 °C testing regimes is shown. Data investigating the Spratt reactive coarse aggregate combined with seven different non-reactive sands will be shown to demonstrate the dramatic effect of the non-reactive sand. Selected pore solution analyses will be given to further elucidate this issue.
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use of the accelerated mortar bar test to evaluate the effectiveness of lino3 against alkali silica reaction part 2 comparison with results from the Concrete Prism test
Journal of Astm International, 2008Co-Authors: C Tremblay, Marc-andré Bérubé, Kevin J Folliard, Benoit Fournier, M D A Thomas, P C NkinamubanziAbstract:For the time being, the Concrete Prism test (CPT) CSA A23.2-14A or ASTM C1293 remains the most reliable test method to evaluate the effectiveness of lithium nitrate against alkali-silica reaction (ASR) in Concrete; however, the extended testing period of two years has often limited its acceptance by practitioners. In its actual form, the popular accelerated mortar bar test (AMBT) CSA A23.2-25A or ASTM C1260 cannot be used to predict this effectiveness, thus it needs to be modified accordingly. Part I of this study looked at the influence of a number of parameters on the effectiveness of lithium to control expansion of mortar bars incorporating a variety of reactive aggregates from Canada and the United States. The second part of this study (Part II) compares the results obtained in modified versions of the AMBT with those from the CPT performed on the same aggregates, with the objective of proposing the best accelerated test procedure for determining the minimum amount of lithium nitrate necessary to counteract ASR expansion in Concrete. The results obtained in this study have shown that the effectiveness of lithium nitrate greatly varies from one reactive aggregate to another while not being correlated with the degree of reactivity or the petrographic nature of the reactive aggregates to counteract. A safe method of predicting the effective [Li]/[Na+K] to used in Concrete is proposed which uses two AMBTs, one of which involves adding lithium to both the mortar bar and the soak solution. It allows the prediction of an effective [Li]/[Na+K] for aggregates that respond relatively well to lithium. The method allows the identification of aggregates that respond particularly badly to the lithium, for which the Concrete Prism test is recommended for evaluating the minimum lithium dosage to use for ASR control.
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test methods for evaluating preventive measures for controlling expansion due to alkali silica reaction in Concrete
Cement and Concrete Research, 2006Co-Authors: Michael D A Thomas, Jason H Ideker, Kevin J Folliard, Benoit Fournier, Medhat H ShehataAbstract:Abstract This paper provides a critical evaluation of the various methods available for testing the efficacy of measures for preventing expansion due to alkali–silica reaction (ASR) in Concrete containing deleteriously reactive aggregate. The ideal test method should be rapid, reliable and capable of determining the influence of aggregate reactivity, alkali availability and exposure conditions. None of the currently available or commonly used methods meet all of these criteria. The shortcomings of the different test methods are discussed and suggestions are made for modifying the Concrete Prism test and accelerated mortar bar test to make these tests more acceptable.
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evaluation of the expansion attained to date by Concrete affected by alkali silica reaction part i experimental study
Canadian Journal of Civil Engineering, 2004Co-Authors: Nizar Smaoui, Marc-andré Bérubé, Benoit Fournier, Benoit Bissonnette, Benoit DurandAbstract:The expansion to date of the Concrete from a structure affected by alkali–silica reaction (ASR) is a crucial parameter in the evaluation of the structural integrity of the structure. Three methods have been used to evaluate this expansion: (i) the "stiffness damage test" (SDT), (ii) the "damage rating index" (DRI), and (iii) surface cracking. Concrete cylinders were made using several types of coarse and fine reactive aggregates and subjected to the Canadian Standards Association (CSA) Concrete Prism test CSA A23.2-14A (or American Society for Testing and Materials (ASTM) test method C1293), i.e., at 38 °C and >95% relative humidity (RH). At various expansion levels, the specimens were subjected to SDT and DRI tests. Very good relationships were obtained between the expansion due to ASR and the SDT. The correlation between the ASR expansion and the DRI was not as good but still of interest. Width measurements of surface cracks were also performed on a number of blocks made with different reactive aggregat...