scholarly journals Efeitos da carbonatação acelerada em compósitos do tipo Engineered Cementitious Composites

2019 ◽  
Vol 8 (3) ◽  
pp. 50-61
Author(s):  
Sabrine Eduarda Tonioli
Keyword(s):  
Strain Hardening ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites

O setor da construção civil é considerado um dos maiores emissores de CO2 (dióxido de carbono) na atmosfera, tornando-se um setor estratégico na busca pela sustentabilidade. A literatura indica que materiais à base de cimento Portland podem capturar CO2 da atmosfera, em poucas idades, através da carbonatação acelerada. Este trabalho objetiva estudar a influência da carbonatação acelerada nas propriedades mecânicas de um compósito cimentício à base de cimento Portland (ECC – Enginereed Cementitious Composites), reforçado com fibras de PVA (Acetato de Polivinila). O compósito foi hidratado sob duas condições: baixa e alta umidade relativa. Foram realizados ensaios mecânicos, de termogravimetria e de termogravimetria derivativa. Os resultados apontam que a cura úmida beneficia as propriedades mecânicas da matriz, uma vez que favorece as reações de hidratação do cimento, e que a carbonatação acelerada, contribui para o aumento de tensão de primeira fissura. Percebeu-se também que o modo de cura preliminar do compósito influenciou na formação dos produtos hidratados. Identificou-se ainda que a carbonatação não inibe as características de strain hardening do compósito cimentício, tornando possível a sua utilização sob efeito da carbonatação acelerada.

A Review on the Methods of Improving Fiber Distribution of Engineered Cementitious Composites (ECC)

2013 ◽  
Vol 683 ◽  
pp. 46-50
Author(s):  
Heng Mao Niu ◽  
Yong Ming Xing ◽  
Yan Ru Zhao
Keyword(s):  
Surface Morphology ◽  
Strain Hardening ◽  
Crack Width ◽  
Mineral Admixtures ◽  
Cementitious Composites ◽  
Fiber Distribution ◽  
Crack Bridging ◽  
Engineered Cementitious Composites ◽  
C Fiber ◽  
Matrix Components

Engineered cementitious composites(ECC) are characterized by strain hardening and tight crack width control. Good fiber distribution can maximize fiber contribution at each stage of the crack bridging process. However, poor fiber distribution can be disadvantage to fiber contribution, even influence the robustness of strain-hardening. Combined with the latest research results, this review highlights the methods of improving fiber distribution in ECC. Good fiber distribution is based on excellent matrix fluidity, which can be determined by mineral admixtures, admixture and water/binder (w/c). Fiber included surface morphology, size and content of fiber have also an effect on fiber distribution in the ECC. Additionally, slag and sand size shape of matrix components play a surprising role on fiber distribution. Based on the reviewed methods it is argued that fiber optimization and matrix components tailoring can be used to improve fiber distribution.

Effects of Processing on Fiber Distribution and Mechanical Performance of Engineered Cementitious Composites (ECC)

2013 ◽  
Vol 709 ◽  
pp. 122-126
Author(s):  
Heng Mao Niu ◽  
Yong Ming Xing ◽  
Yan Ru Zhao
Keyword(s):  
Strain Hardening ◽  
Crack Width ◽  
Mechanical Performance ◽  
Processing Technique ◽  
Cementitious Composites ◽  
Fiber Distribution ◽  
Engineered Cementitious Composites ◽  
Research Results

Engineered cementitious composites (ECC) are characterized by strain hardening and tight crack width control. Good fiber distribution can maximize fiber contribution. Processing can substantially influence fiber distribution, and consequently influence mechanical performance. Combined with the latest research results, this review summarizes the results of several studies in which the influence of processing on fiber distribution and mechanical performance was investigated. Based on the reviewed methods it is argued that the processing technique of producing ECC can improve fiber distribution.

scholarly journals Structural Performance of Polymer Fiber Reinforced Engineered Cementitious Composites Subjected to Static and Fatigue Flexural Loading

2021 ◽  
Author(s):  
Mohamed A. A. Sherir ◽  
Khandaker M. A. Hossain ◽  
Mohamed Lachemi
Keyword(s):  
Fly Ash ◽  
Strain Hardening ◽  
Fatigue Loading ◽  
Fiber Reinforced Concrete ◽  
Silica Sand ◽  
Cementitious Composites ◽  
Polymer Fiber ◽  
Fiber Reinforced ◽  
Engineered Cementitious Composites ◽  
Cracking Behavior

This paper presents the influence of silica sand, local crushed sand and different supplementary cementing materials (SCMs) to Portland cement (C) ratio (SCM/C) on the flexural fatigue performance of engineered cementitious composites (ECCs). ECC is a micromechanically-based designed high-performance polymer fiber reinforced concrete with high ductility which exhibits strain-hardening and micro-cracking behavior in tension and flexure. The relative high cost remains an obstacle for wider commercial use of ECC. The replacement of cement by SCMs, and the use of local sand aggregates can lower cost and enhance greenness of the ECC. The main variables of this study were: type and size of aggregates (local crushed or standard silica sand), type of SCMs (fly ash “FA” or slag), SCM/cement ratio of 1.2 or 2.2, three fatigue stress levels and number of fatigue cycles up to 1 million. The study showed that ECC mixtures produced with crushed sand (with high volume of fly ash and slag) exhibited strain hardening behavior (under static loading) with deformation capacities comparable with those made with silica sand. Class F-fly ash combined with crushed sand was the best choice (compared to class CI fly ash and slag) in order to enhance the ECC ductility with slag–ECC mixtures producing lowest deflection capacity. FA–ECC mixtures with silica sand developed more damage under fatigue loading due to higher deflection evolution than FA–ECC mixtures with crushed sand.

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