HIGH PERFORMANCE CONCRETE: TECHNICAL RELATIONS IN ITS PRODUCTION ASSOCIATED WITH THE CONVENTIONAL CONCRETE. Engenheiro Civil

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1 HIGH PERFORMANCE CONCRETE: TECHNICAL RELATIONS IN ITS PRODUCTION ASSOCIATED WITH THE CONVENTIONAL CONCRETE Valdeir Alves da Silva Junior 1 ; Mônica Mollina Moreira 2 ; Maria da Consolação Fonseca de Albuquerque 3 ; José Afonso Rocha 4 1 Engenheiro Civil valdeiralvez@hotmail.com 2 Engenheira Civil 3 Professora Doutora, PPGEC/UNESP, Ilha Solteira, São Paulo, Brasil 4 Professor Mestre, UNIFEV, Votuporanga, São Paulo, Brasil e DoutorandoPPGEM/UNESP, Ilha Solteira, São Paulo, Brasil. ABSTRACT The ability to withstand higher demands for compression with a reduced concrete volume and consequently a greater utilization of useful construction area, as well as constructions with a longer lifetime, more durable and sustainable, has been encouraging researches and emphasizing the importance of high performance concrete (HPC). As the need for more and more the use of a material with improved rheological and bearing capabilities, the construction industry has been encouraging the research of high performance concrete. Therefore, this research aims to study the differences between technical advantages and disadvantages regarding the production of high performance concrete versus conventional concrete for in situ production. Keywords: conventional concrete, high performance concrete, compressive strength, technical control. 709

2 1 INTRODUCTION High-performance concrete (HPC) is the improvement of the usual concrete, being usually required for this concrete specific properties for a particular purpose, which the conventional concrete does not provide. Most of the times the characteristics are of a long-lasting, sustainable and rational concrete in its proportions in its production. For both conventional and high performance concrete the selection of materials, their dosage, the mixing time and the sequence of the operations in the preparation are the ones that define the properties of the concrete in the fresh and, consequently, in the hardened form. In this research, comparisons were made between conventional and high-performance concrete, related to the characteristic of greater compressive strength and its production performed in situ. It was established relations of technical advantages and disadvantages regarding the production between both concretes, in the fresh and in the hardened form. The results were obtained through consistency tests and compressive strength in the periods of 7, 14, 21 and 28 days. 2 MATERIALS AND METHODS 2.1 Constituent Materials Binder In this research, the Portland Cement - PC II-Z-32 was used and its characteristics are presented in Tables 1 and 2. Sieve residue 75 mm (%) Fineness Table 1 Physical and Mechanical Propertiesof PC II-Z-32 Specific área (m²/kg) Concrete setting time Initial set (h) Final set (h) Expandability Cold (mm) Hot (mm) Compressive strength 1 st day 3 rd day (MPa) 12, (1) Source: Santos, L. R. G. 7 th day 28 th day 710

3 Table 2 Chemical Properties Insoluble residue (%) Loss to fire (%) Mg (%) SO3(%) CO 2(%) S (%) 16,0 6,5 6,5 4,0 5 - Source: Santos, L. R. G Aggregates Table 3 Physical characteristics of the aggregates Aggregates Characteristics Medium sand Gravel 01 Single Mass (Kg/dm 3 ) 1,43 1,46 Specific Mass (Kg/dm 3 ) 2,7 2,66 Maximum Dimension (mm) - 20 Fineness Unit 2,59 6,7 Absorbance (%) 0,23 1, Mineral Additive The silica fume in powder form was used as mineral additive. Its physical and chemical characteristics are presented in Table 4. Table4 Physical and Chemical characteristics of the silica fume. Propriedades Físicas e Químicas Resultados Specific Mass(Kg/dm 3 ) SiO2 Content (%) 85 Specific Surface(m²/Kg) Moderate Dimension (mm) 0,20 Source:Tecnosil 711

4 2.1.4 Chemical Additives The superplastificizer TEC-FLOW 7000 was used as chemical additive. Itscharacteristics are presented in Table 5. Tabela 5 Superplastificizer Characteristics Description TEC-FLOW 7000 Specific Mass(g/cm³) 1,075 1,115 Solid Content (%) 40 Source: Grace Construction Products Water It was used drinking water from Votuporanga s water supply network according to NBR (ABNT). 2.2 Methods Dosing and Mixing Conventional Concrete Dosage Conventional concrete was dosed using the Absolute Volume Method in order to achieve in the 28 th day compressive strength of 25 MPa and a slump test of 75 to 100 mm. The mix is presented in Table 6. Table6 Conventional Concrete Dosage Mixture Mix for a 50 kilogram cement package Cement Sand Grave Water (L) C25 1; 2,38; 2,89; 0, For the sequence and mixing time parameters were used to obtain a homogeneous mass, in which the values are presented in Table

5 Table 7 - Conventional Concrete mixture sequence Approximate mixing time Components Seconds seconds Water 75% 25% Cement 100% - Fine aggregate - 100% Coarse aggregate 100% High Performance Concrete Dosage The high performance concrete was dosed aiming to achieve in the 28 th day compressive strength of 50 MPa and a slump test of 230 mm. The mix is presented in Table 8. Mix for a 50 Mixture kilogram cement package C50 1; 0,10; 1,6; 2,4; 0,4; 0,012 Table8 High Performance Concrete Dosage Cement Silica Sand Grave Water (L) Superplastificizer (L) ,4 For the sequence and mixing time, it was used a sequence based on bibliographies and researches, in order to obtain a homogeneous mass, in which the values are presented in Table

6 Table 9 High Performance Concrete mixing sequence Approximate mixing time Components seconds seconds seconds Water 100% - - Cement 100% - - Fine aggregate - 100% - Coarse aggregate - 100% - Silica 100% - - Superplastificizer 50% - 50% Molding andcompression test For conventional and high-performance concrete, 24 cylindrical specimens measuring 15x30cm and 10x20cm, respectively, were molded. Both were correctly molded, vibrated, demolded, followed by immersion curing, submitted to plating process and ruptured at 7, 14, 21 and 28 days. The specimens with dimensions of 15x30cm were submitted to plating process with sulfur, while those of 10x20cm were regularized by polishing their surfaces. 3 RESULTS AND DISCUSSION It was used the Slump-Test for the conventional concrete while for the high performance one was used the Slump-Flow Test. The results are shown in Table 10. Table 10 Conventional Concrete Slump Test and High Performance Concrete Slump-Flow Test Expected Slump Expected Slump-Flow (Conventional Concrete) (High Performance Concrete) Attained Specimen Slump Attained Specimen Slump-Flow (Conventional Concrete) (High Performance Concrete)

7 Compressive strength and standard deviation from the samples can be analyzed in Tables 11 and 12. Da y Specime n 01 Table11 Conventional Concrete Compressive Strength Conventional Concrete Compressive Strength(MPa) Mix Conventional Concrete (1; 2,38; 2,89; 0,54) Age of the trials - Slump 85 mm Specime n 02 Specime n 03 Specime n 04 Averag e (KN) f ck,medium(mpa ) Standard Deviatio n (MPa) 7 th 379,03 372,54 344,37 371,10 366,76 20,75 15,32 14 th 427,38 423,78 433,84 465,03 437,51 24,76 18,81 21 st 450,22 446,40 457,47 420,05 443,54 25,10 16,31 28 th 496,69 497,08 488,09 526,27 502,03 28,41 16,68 Table 12 High Performance Concrete Compressive Strength High Performance Concrete Compressive Strength (MPa) Mix - High Performance Concrete (1; 0,10; 1,6; 2,4; 0,4; 0,012) Age of the trials Slump 450 mm Standard Deviation Day Specimen 01 Specimen 02 Specimen 03 Specimen 04 Average (KN) f ck,medium (MPa) (MPa) 7 th 363,13 318,00 358,76 318,24 339,53 43,23 24,79 14 th 369,09 369,35 403,90 350,50 373,21 47,52 22,28 21 st 363,75 358,21 427,00 359,00 376,99 48,00 33,43 28 th 369,07 377,75 440,60 357,70 386,28 49,18 37,13 715

Deviation (%) In Graph 02 we have the relation between the expected fck x specimen fck for

8 Graph 1 and 2 show the relation between the expected conventional fck s x specimen standard deviation (%) Graph1 Relation between the Expected Conventional fck s x Specimen Standard Deviation (%) In Graph 02 we have the relation between the expected fck x specimen fck for both concretes (%) Graph 2 Relation between the Expected fck x Specimen fck for both concretes (%) 716

9 4 CONCLUSION The conventional concrete presented satisfactory results in the experimental mix, showing that it already has well defined dosing parameters. This enables its production with a small variation range of its physical properties, when compared to the desired parameters for already defined dosage proportions. It was possible to observe that it is necessary to have more time and energy for the high performance concrete production, and even if it did not reach the expected strength, the difference was only approximately 2%. For this reason, it s important to observe that from the information of another researches about high performance concrete it was possible to obtain characteristics very close to the one desired, already in the first mix. Even if these characteristics are not achieved, these researches provide a calculation line and show how important it is the knowledge generated about this material. It is indispensable that dosage correction be performed for the dosage proportions of the high performance concrete, since it is not possible to achieve results of all the desired satisfactory properties only with the first experimental mix. 717

10 5 REFERENCES [1] AITCIN, Pierre-Claude. Concreto de alto desempenho. São Paulo: Pini, p. Tradução de: Geraldo G. Serra. [2] ARAÚJO, Fábio Elias. et all. Influência da sequência de mistura dos materiais na betoneira na resistência do concreto de alto desempenho. Instituto Brasileiro de Concreto IBRACON, 43º Congresso Brasileiro. [3] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Aditivos químicos para concreto de cimento Portland- Requisitos. NBR Rio de Janeiro, [4] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Agregado miúdo Determinação da absorção de água. NBR NM 30. Rio de Janeiro, [5] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Agregados Determinação da massa unitária e do volume de vazios. NBR NM 45. Rio de Janeiro, [6] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Agregado miúdo Determinação da massa específica e massa específica aparente. NBR NM 52. Rio de Janeiro, [7] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Agregados para concreto- Especificação. NBR Rio de Janeiro, [8] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Água para amassamento do concreto. Parte 1: Requisitos. NBR Rio de Janeiro,

11 [9] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Câmaras úmidas e tanques para cura de corpos-de-prova de argamassa e concreto. NBR Rio de Janeiro, [10] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Cimento Portland composto. NBR Rio de Janeiro, [11] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Cimento Portland de alta resistência inicial.nbr EB-2. Rio de Janeiro, [12] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Cimento Portland Determinação da resistência à compressão. NBR Rio de Janeiro, [13] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Concreto Determinação da consistência pelo abatimento do tronco de cone. NBR NM 67. Rio de Janeiro, [14] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Concreto- Ensaio de compressão de corpos-de-prova cilíndricos. NBR Rio de Janeiro, [15] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Concreto- Procedimento para moldagem e cura de corpos-de-prova. NBR Rio de Janeiro, [16] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. Concreto de cimento Portland Preparo, controle e recebimento Procedimento. NBR Rio de Janeiro, [17] BATTAGIN, A. F. et al. Influência das condições de cura em algumas propriedades dos concretos convencionais e de alto desempenho. Instituto Brasileiro de Concreto IBRACON, 44º Congresso Brasileiro. 719

12 [18] COLLEPARDI, S. et al. Mechanisms of actions of different superplasticizers for high-performance concrete. In: INTERNATIONAL CONFERENCE ON HIGHPERFORMANCE CONCRETE, AND PERFORMANCE AND QUALITY OF CONCRETES STRUCTURES, 2nd. Proceedings, Gramado, RS, 1999, p [19] CORDEIRO, Guilherme Chagas. Concreto de alto desempenho com metacaulinita. Dissertação (mestrado). Universidade Estadual do Norte Fluminense. Campos dogoytacazes, RJ, [20] HARTMANN, Carine Toso; HELENE, Paulo Roberto do Lago. Avaliação de aditivos superplastificantes base policarboxilatos destinados a concretos de cimento Portland. Boletim técnico da Escola Politécnica da Universidade de São Paulo. São Paulo, SP, [21] MEHTA, P. Kumar; MONTEIRO, Paulo J. M. (2014) Concreto: microestrutura, propriedades e materiais. 2ª ed., São Paulo: IBRACON, 782 p. [22] MENDES, Sandro Eduardo da Silveira; BIANCHINI, Mauricio; FARIA, Vanessa de Jesus. Produção de concreto de alto desempenho do laboratório para a central dosadora de concreto IBRACON, 49º Congresso Brasileiro. [23] NEVILLE, Adam M. Propriedades do concreto. 5ª ed. 2016, Porto Alegre: Bookman, 523 p.tradução: Ruy Alberto Cremonini. [24] PICCOLI, Geraldo Moritz et at. Influência da dosagem de materiais cimentícios na resistência à compressão do concreto de alto desempenho. Instituto Brasileiro de Concreto IBRACON. [26] VIEIRA, Júlia Paulo. Interação cimento-superplastificante: Avaliação da estabilidade do comportamento. Dissertação (mestrado). Universidade Técnica de Lisboa,

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