Cyclic behavior of steel ring filled with compressive plastic or concrete, installed in concentric bracing system

peer reviewedThe present study intended to evaluate the dynamic behaviour of steel ring filled with compressive plastic (S.R.P.) or high-performance fibre-reinforced cementitious composites (S.R.C.) situated at the intersection of the braces. High-performance fibre-reinforced cementitious composites and plastic materials, associated with steel ring connection, seem to be helpful to dissipate the energy through braces better. Therefore, in this paper, the behaviour of S.R.C. and S.R.P. connections was analyzed under cyclic loading. Results showed a steady and relatively wide hysteresis curve for both connections, where the tensile ductility factors of S.R.P. and S.R.C. connections were found to be equal to 2.77 and 13.66, respectively. However, in general, the plastic ring, being operated efficiently to delay appearing the inelastic zone in the S.R.P. connection, was proved to outperform the HPFRCC material in the S.R.C. connection. In addition, numerical results revealed that maximum tensile and compressive loads of S.R.P. connection made with ST52 steel ring were found to be 14% and 10.7%, respectively, higher than those of S.R.P. connection made with ST37 steel ring

Effects of simultaneous utilization of natural zeolite and magnetic water on engineering properties of self-compacting concrete

A study was performed to assess the effects of magnetic water with different percentages of natural zeolite (NZ) on self-compacting concrete (SCC) mixes. Over the past decades, a limited number of studies were conducted by researches on the effects of magnetic water on SCC mixes. In addition, it seems that pozzolanic materials such as NZ can affect performance of magnetic water in SCC mixes. Following this, the present study was aimed to survey engineering properties of self-compacting concrete (SCC) containing magnetic water and NZ. To achieve this goal, slump flow, T50, V-funnel, L-box and visual stability index (VSI) were employed to evaluate the rheological properties of concrete mixes. Furthermore, hardened properties were investigated by means of compressive strength, splitting tensile strength, modulus of elasticity and water absorption tests. The concrete test results demonstrated that 20% NZ inclusion and magnetic water in SCC with the water–binder (W/B) ratio of 0.37 led to an optimum mix design and also this mixture could contribute to an increase in compressive strength, splitting tensile strength and modulus of elasticity up to 25%, 8% and 9%, respectively

An investigation on the fresh and hardened properties of self-compacting concrete incorporating magnetic water with various pozzolanic materials

The main objective of this study was to assess engineering properties of self-compacting concrete (SCC) incorporating magnetic water and silica fume, metakaolin, rice husk ash and fly ash (10% and 20% by weight of cement). The fresh properties were investigated by means of slump flow, T50, V-funnel, L-box and visual stability index(VSI). At hardened state, compressive strength was evaluated at the ages of 7 and 28 days and mixes were cast to assess the 28-day splitting tensile strength development and also durability characteristics of concrete were tested for water absorption test at the age of 28 days. Results indicate that magnetic water and pozzolanic materials in SCC can improve the self-compatibility criteria in terms of flowability and viscosity. Furthermore, SCC mixture containing magnetic water and 20% of silica fume can be considered as an optimum mix design at the age of 28 days where compressive strength and splitting tensile strength increased up to 49% and 41%, respectively and the value of water absorption decreased up to 55%. Moreover, magnetic water can reduce the amount of high range water reducer (HRWR), required for SCC, up to 45%

In-situ strength estimation of polypropylene fibre reinforced recycled aggregate concrete using Schmidt rebound hammer and point load test

peer reviewedAn appropriate amount of polypropylene fibre (PF) content is generally able to compensate for the low compressive strength of the recycled aggregate concrete. This mechanical strength is required to reliably estimate at the building site using partially and non-destructive testing methods. Therefore, in the present study, the compressive strength of concrete with PF at 0.1% by volume and different replacement levels of recycled coarse aggregate (RCA) was assessed using point load test (PLT) and Schmidt rebound hammer. According to the results, the sensitivity of the core specimens to the concentrated point load and the short size of PF in the failure zone of the PLT caused to appear a difference among the enhancement trends of PLI values by increasing the age. In addition, a two-variable equation between the rebound number and point load index (PLI) reliably predicted either strength of coarse natural concrete or recycled aggregate concrete or PRAC