Effects of Polyvinyl Alcohol fibers in engineered cementitious composite concrete

The present work majorly focused on the effect of Polyvinyl Alcohol fibers (PVA) in engineered cementitious composite concrete. However, PVA fibers are used as added to the ECC concrete with propotion of 0% to 2% of weight to cementitious materials. All the concrete samples are prepared with mix proportion of 1 cement: 1.1 silica fume: 0.36 ratio of sand/binder: 0.30 ratio of water/binder: 0.01 water reducer. whereas compressive, flexural, split tensile, water absorption and rapid chloride permeability tests are evaluated in order find out the performance of ECC with addition of PVA fibers. Thus, the results, ECC concrete has better mechanical and durability performance than conventional concrete and also its high early strength. From this study concludes that upto 1.5% of PVA fibers can be used in the ECC concrete, which has 60.12MPa and 18% of strength increment than the reference mix.

Bio-Engineered Concrete: A Critical Review on The Next Generation of Durable Concrete

Concrete is a prerequisite material for infrastructural development, which is required to be sufficiently strong and durable. It consists of fine, coarse, and aggregate particles bonded with a fluid cement that hardens over time. However, micro cracks development in concrete is a significant threat to its durability. To overcome this issue, several treatments and maintenance methods are adopted after construction, to ensure the durability of the structure. These include the use of bio-engineered concrete, which involved the biochemical reaction of non-reacted limestone and a calcium-based nutrient with the help of bacteria. These bio-cultures (bacteria) act as spores, which have the ability to survive up to 200 years, as they are also found to start the mineralization process and the filling of cracks or pores when in contact with moisture. Previous research proved that bio-engineered concrete is a self-healing technology, which developed the mechanical strength properties of the composite materials. The mechanism and healing process of the concrete is also natural and eco-friendly. Therefore, this study aims to critically analyze bio-engineered concrete and its future potentials in the Structural Engineering field, through the use of literature review. The data analysis was conducted in order to provide gradual and informative ideas on the historical background, present situation, and main mechanism process of the materials. According to the literature review, bio-engineered concrete has a promising outcome in the case of strength increment and crack healing. However, the only disadvantage was its less application in the practical fields. The results concluded that bio-engineered concrete is a new method for ensuring sustainable infrastructural development. And also, it indicated that more practical outcome-based analysis with extensive application in various aspects should be conducted, in order to assess the overall durability.

Influence of Plant Roots On Slope Stabilization: A Geotechnical Investigation

Direct shear tests conducted on soil samples reveal that soils with plant roots show an increase in cohesive factor but increase in frictional angle is insignificant. Displacement and shear strength graphs, however, indicate that soil with plant roots can withstand more shear stresses. Among the three plant species selected for the present study, Chimonobambusa sp. has the highest shear strength increment, ∆C = 5.0 KN/m2 followed by Cymbopogon sp., and Pseudosasa japonica with 4.5KN/m2 and 1.0KN/m2 shear strength increments respectively. An increase in shear strength is also observed in the reinforced soils with increase in number of roots of these plant species. Cymbopogon sp. has higher root density near the surface but decreases with increasing depth and absent at 320mm depth, Pseudosasa japonica has the lowest root density but penetrates deeper up to 530mm while Chimonobambusa sp. penetrates deepest at 700mm with lateral branches extending up to 650mm. Cymbopogon sp., and Pseudosasa japonica may be useful as a bioengineering tool to mitigate soil erosion while Chimonobambusa sp. to mitigate both erosion and shallow landslides.

Composition rules of Ni-base single crystal superalloys and its influence on creep properties via a cluster formula approach

The present work investigated the composition evolution of the TMS series of Ni-base single crystal (SC) superalloys in light of the cluster formula approach systematically. The cluster formula of SC superalloys could be expressed with $${[}\overline{{{\text{Al}}}} {-} \overline{{{\text{Ni}}}} 12{](}\overline{{{\text{Al}}}} {, }\overline{{{\text{Cr}}}} {)}m$$ [ Al ¯ - Ni ¯ 12 ] ( Al ¯ , Cr ¯ ) m , in which all the alloying elements were classified into three groups, Al series ($$\overline{{{\text{Al}}}}$$ Al ¯ ), Cr series ($$\overline{{{\text{Cr}}}}$$ Cr ¯ ), and Ni series ($$\overline{{{\text{Ni}}}}$$ Ni ¯ ). It was found that the total atom number (Z) of the cluster formula units for TMS series of superalloys varies from Z ~ 17 to Z ~ 15.5, and then to Z ~ 16 with the alloy development from the 1st to the 6th generation, in which the superalloys with prominent creep resistance possess an ideal cluster formula of $${[}\overline{{{\text{Al}}}} {-} \overline{{{\text{Ni}}}} 12{](}\overline{{{\text{Al}}}} 1.5\overline{{{\text{Cr}}}} 1.5{)}$$ [ Al ¯ - Ni ¯ 12 ] ( Al ¯ 1.5 Cr ¯ 1.5 ) with Z = 16. Similar tendency of composition evolution also appears in the PWA and CMSX series of SC superalloys. Typical TMS series of superalloys with prominent creep properties generally exhibit a moderate lattice misfit of γ/γ′ which could render alloys with appropriate particle size of cuboidal γ′ precipitates to acquire a maximum strength increment by precipitation strengthening mechanism. More importantly, the relationship between the lattice misfit (δ) of γ/γ′ and the creep rupture lifetime (tr) of superalloys was then established, showing a linear correlation in the form of lgtr–lg|δ|3/2 at both conditions of 900 °C/392 MPa and 1100 °C/137 MPa. Combined with the lattice misfit, the cluster formula approach would provide a new way to modify or optimize the compositions of Ni-base superalloys for further improvement of creep property.

Behavior and properties of tin slag polyester polymer concrete confined with FRP composites under compression

Polymer concrete (PC) has acquired niche in construction industry due to superior mechanical properties, recyclability and adoption of variety of aggregates. This workpresents compressive behavior and properties of one such novel PC i.e. tin slag/polyester polymer concrete. Comparable siliceous content of tin slag was considered promising to provide better mechanical strength as in natural aggregates. Cylindrical short column specimens were fabricated to be tested under quasi-isostatic loading rate of 1 mm/min. Three different aggregate sizes in gap-graded configuration were tested to assess influence on mechanical properties. In addition, specimens were confined with GFRP and CFRP to determine and compare mechanical behavior with Portland Cement Concrete (PCC). Coarsest size (4+2 mm) aggregate offered the highest strength of 37.71 MPa for unconfined sample. This performance of coarsest size persisted in confined condition with compressive strength increment of 69.68 MPa (84.7%) and 98.36 MPa (160.8%) for one and two layers GFRP; 86 MPa (128.05%) and 125.07 MPa (231.66)% for one and two-layer CFRP, respectively. It was concluded that both increment in aggregate size and number of layers improved the compressive strength.

Interference Behaviour in Steel Concrete Composite Construction

The objective of this study is to obtain the most effective utilization of steel and concrete by the method of composite construction through obtaining proper interaction between steel and concrete. Composite construction has various advantages compared to normal method of non composite construction. It provides greater stiffness and provides good strength against bending. By providing proper interaction we can obtain a more economical section and sections with good structural properties It is also a fast track construction practice. Both theoretical and software analysis of normal composite section and a section with profiled steel sheeting have been presented. After analysis it is found that shear connectors and profiled steel sheeting are advantageous in strength increment, reducing deflection and other factors.

Influence of Zn and Sn on the Precipitation Behavior of New Al–Mg–Si Alloys

In this study, we demonstrate how Zn and Sn influence hardening behavior and cluster formation during pre-aging and paint bake treatment in Al–Mg–Si alloys via hardness tests, tensile tests, and atom probe tomography. Compared to the standard alloy, the Sn-modified variant shows reduced cluster size and yield strength in the pre-aged condition. During the paint bake cycle, the clusters start to grow very fast and the alloy exhibits the highest strength increment. This behavior is attributed to the high vacancy binding energy of Sn. Adding Zn increases the formation kinetics and the size of Mg–Si co-clusters, generating higher yield strength values for both the pre-aged and paint baked conditions. Simultaneous addition of Zn and Sn creates a synergistic effect and produces an alloy that exhibits moderate strength (and good formability) in the pre-aged condition and accelerated hardening behavior during the paint bake cycle.

Comparison of Different FE Modeling for In-Plane Shear Strengthening of Brittle Masonry with FRCM

Few design oriented models on strengthening of unreinforced masonry (URM) panels under in-plane actions with composite systems are currently available (among them, the pioneers researches [1, 2] and the guidelines [3, 4] for FRPs). Usually, the in-plane shear capacity of a strengthened panel is evaluated as the sum of two terms: the contribution of URM masonry and that of the composite strengthening system (usually only the fibers are considered, also in the case of inorganic matrix, as illustrated in [5, 6, 7], neglecting the shear contribution of the matrix). Mostly, the models proposed to compute the strength increment of the URM can be seen as extensions of provisions for steel-reinforced masonry, where the reinforcement is modeled by the truss analogy [8] and an effective ultimate strain is introduced to account for premature failure of fibers in shear applications. However, the development of the ideal truss in a masonry wall is strongly conditioned by a proper anchorage of fibers and availability of a fiber grid, which is not always ensured. Several failure modes can be expected for strengthened masonry, like diagonal splitting cracking, sliding of a portion over the other, so that the contribution of the composite can be engaged in different ways. The aim of this study is to compare different modeling strategies in the numerical field accounting for matrix as a continuum or as a stiffening of individual fibers, and to provide novel FEM analyses revealing the different role of fiber orientations and matrix properties.