Fiber-Reinforced Cement Composites: Mechanical Properties and Structural Implications 2019

The purpose of this work was to study the microstructure and the mechanical properties of the fiber-reinforced cement composites that used the nucleating-agent activated coal-fired power plant bottom ash as a raw material in the mixture for producing the composites. The raw materials for producing the fiber reinforced cement composites were the ordinary Portland cement (OPC), natural gypsum, cellulose fiber, and bottom ash. The bottom ash was chemically treated by the nucleating agent, a chemical that was prepared by the precipitation process from the aqueous solutions of sodium silicate (Na2SiO3) and calcium nitrate (Ca (NO3)2). To prepare the samples, the mixture consisting of 34.75 wt% OPC, 34.75 wt% bottom ash, 25 wt% natural gypsum, and 5.5 wt% cellulose fiber was mixed with the nucleating agent at the amount of 0 to 4.5 % of OPC weight in the mixture, and water to form the slurry. Then, the samples were produced by filter pressing process and cured in the autoclave for 16 hrs at 180 °C, and 10 bars. The mechanical properties of the samples including modulus of rupture (MOR), modulus of elasticity (MOE), and toughness were characterized by the universal testing machine (UTM). The microstructures of the samples were observed by scanning electron microscope (SEM). The results showed that the utilization of nucleating agent affect the microstructure of the sample leading to the improvement in the mechanical properties of samples.

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Effect of Expansive Admixtures on the Shrinkage and Mechanical Properties of High-Performance Fiber-Reinforced Cement Composites

The Scientific World JOURNAL ◽

10.1155/2013/418734 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 4

Author(s):

Won-Chang Choi ◽

Hyun-Do Yun

Keyword(s):

Mechanical Properties ◽

High Performance ◽

Shrinkage Strain ◽

Cement Composites ◽

Fiber Reinforced ◽

Calcium Sulfoaluminate ◽

High Performance Fiber ◽

Reinforced Cement ◽

Shrinkage Compensation ◽

Direct Tensile

High-performance fiber-reinforced cement composites (HPFRCCs) are characterized by strain-hardening and multiple cracking during the inelastic deformation process, but they also develop high shrinkage strain. This study investigates the effects of replacing Portland cement with calcium sulfoaluminate-based expansive admixtures (CSA EXAs) to compensate for the shrinkage and associated mechanical behavior of HPFRCCs. Two types of CSA EXA (CSA-K and CSA-J), each with a different chemical composition, are used in this study. Various replacement ratios (0%, 8%, 10%, 12%, and 14% by weight of cement) of CSA EXA are considered for the design of HPFRCC mixtures reinforced with 1.5% polyethylene (PE) fibers by volume. Mechanical properties, such as shrinkage compensation, compressive strength, flexural strength, and direct tensile strength, of the HPFRCC mixtures are examined. Also, crack width and development are investigated to determine the effects of the EXAs on the performance of the HPFRCC mixtures, and a performance index is used to quantify the performance of mixture. The results indicate that replacements of 10% CSA-K (Type 1) and 8% CSA-J (Type 2) considerably enhance the mechanical properties and reduce shrinkage of HPFRCCs.

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