Effect of Mix Proportions on Fresh and Rheological Properties of Cementitious Mixture Containing Natural Fibre: Modelling Using Factorial Design

This paper aims to discuss the influence of mix composition of cement mortar on fresh and rheological properties of cement mortar. Two different natural fibres, basalt (BA) and sisal (SL) are selected based on fresh and rheological behaviour for its usability in a cementitious mixture. The workability and rheological behaviour are evaluated by flow table test, cone penetrometer and slump test of the mixture. A full factorial design method was used to investigate the effects of four mix components: dosage of cement content (B), percentage of fly-ash (FA) by mass of cement, dosage of basalt fibre (BA) and dosage of superplasticizer (SP) along with a water/binder ratio of 0.41. A mathematical model which predicts the main effect and interactions of these components for each of the measured properties are derived using the factorial design. The proposed mixtures consist of two levels of binder content as 550 kg/m3 and 650 kg/m3, FA as 5% and 20% by mass of cement, BA as 1 kg/m3 to 3 kg/m3 and SP as 2 kg/m3 to 4 kg/m3. By reducing the number of test batches needed, the mathematical models produced with this method can expedite optimizing the mixture proportions of cement mortar to achieve desired fresh and rheological properties.

Abaqus Simulation on Basalt Fibre Reinforced Polymer Epoxy Tube Subjected to Axial Compression for Energy Absorption

In practical application, fibre reinforced polymer (FRP) technology is implemented as the outer jackets in structural elements such as column, beam and in automobile engineering as light weight components in the head liners of car, brake pads and energy. In civil engineering FRP is mainly used in the retrofitting technique against corrosion, in columns, piles and poles. The research aims to provide a recyclable, natural, low-cost energy absorption material capable of increasing the load bearing capacity of the structure by increasing the fabric layer. The study focuses on the finite element analysis (FEM) of the energy absorption characteristics of basalt fibre reinforced polymer epoxy tube (BFRPE) subjected to axial compression with varying BFRPE layers. The results also discuss the failure modes of the specimens using abaqus. Parameters such as the energy absorption, crush force efficiency (CFE) are discussed. Energy absorption is defined as the area under the load displacement and CFE is defined as the ratio of the mean load to that of the initial peak force. The test results indicate that as the number of layers increases the ultimate load and CFE of the tube also increases. Compared to flax fibre reinforced polymer the thickness of the basalt fibre is very less with better energy absorption.

Unidirectional fibre reinforced geopolymer matrix composites

<p>Geopolymers have been suggested in the literature as matrix materials for fibre reinforced composites due to a unique combination of low-temperature synthesis and high temperature stability. This study investigated several key aspects of fibre reinforced geopolymer matrix composites in order to improve the basic knowledge of these materials. It was demonstrated that geopolymer matrix composites show great potential as fire-resistant materials for near room temperature applications. In particular, basalt fibre composites were of great interest due to their comparatively low cost and good mechanical performance. Microstructural investigations indicated that basalt fibres can potentially be used in geopolymer matrices up to 600°C. However, the success of the application of geopolymer matrix composites at higher temperatures is seen as critical and depends on further development of suitable matrices. Several compositions within a sodium-metahalloysite model matrix system were evaluated in order to identify a suitable formulation for composite fabrication. An average compressive strength of ~ 79 MPa and flexural strength and modulus of ~ 10 MPa and 8.5 GPa, respectively, were achieved for the best batch of the main matrix composition. By optimising the matrix composition, the mechanical properties could be significantly improved, achieving an extremely high maximum compressive strength value of 145 MPa. Issues with reproducibility and the influence of various aspects of the fabrication process are discussed. The room temperature flexural properties of unidirectional fibre reinforced composite bars with basalt, carbon and alumina fibres were investigated. Besides the fibre type, the effects of several other parameters including fibre sizing, matrix strength, span-to-depth ratio and specimen dimensions on the flexural properties and the failure behaviour of the composites were studied. Significant improvements to the mechanical properties were achieved with all fibre types. However, the mechanical behaviour was highly influenced by the elastic modulus of the fibre. Furthermore, it was shown that the composite properties were affected by the overall sample dimensions, the testing span and the mixing time of the geopolymer binder. The alumina fibre composites achieved the highest flexural stress with a maximum value of 470 MPa and a fibre content of ~ 30 vol.-%. Basalt and carbon fibre composites showed maximum flexural strength values around 200 MPa. Although all composite types displayed considerable post-fracture strength, only the basalt composites failed in tensile mode. The applicability of the weak matrix composites (WMC) concept to describe the mechanical behaviour of geopolymer matrix composites was discussed. The fibre-matrix interactions were analysed between room temperature and 1000°C by means of electron microscopy, EDS and x-ray diffraction. All fibres were found to be chemically stable under the highly alkaline conditions of the geopolymer synthesis and showed no significant reaction with the geopolymer matrix at room temperature. The results indicate that basalt fibre composites may be used up to 600°C without significant degradation of the fibre. The heating of the carbon fibre composites to 600°C had drastic effect on the strength and integrity of the composite, in particular, when using sized carbon fibres. The alumina fibres showed good wetting and bonding behaviour but otherwise little reaction with the matrix even after heating to 1000°C.</p>