Evaluation of synergic methods for corrosion protection of reinforced steel

Purpose This study aims to evaluate the effect of pH on the reinforced concrete steel protection for rebars coated with paint formulations containing talc and free from it. As the presence of talc in paints can offer high pH which cordially affects the protection behavior of the coated rebars. Additionally, this study includes evaluating the durability of concrete mixes in presence of some replacements of ordinary cement such as meta-kaolin (MK) and ground granulated blast furnace slag (GGBFS). Design/methodology/approach Two paint formulations were prepared containing the same ingredients except that (P1) is free from talc and (P2) contains talc. The anticorrosive behavior of painted steel in the blended concrete mixes containing MK and GGBFS was studied by using different electrochemical techniques in chloride solution. The concrete durability was evaluated by the means of compressive and bond strength beside chloride permeability. Different concrete mixes containing mineral groups or pozzolanic materials were prepared by replacing (10, and 30%) GGBFS and (5, 10 and 15%) MK as binary from cement CEM I with (w/b) 0.45 with superplasticizer ratio (SP) 2% of the binder Findings It was found that the presence of talc, in spite of its ability to offer high pH, has affected positively the corrosion behavior of reinforced concrete steel by forming a complex with concrete even if it is present in paint formulation and not free in the medium. Originality/value The results revealed that concrete blended with (30% GGBFS and 10% MK) with coated rebars with P2 containing talc showed the highest corrosion protection performance in addition to modified permeability and compression resistance.

Study Using Different Fibres in Fibre Reinforced Concrete

The most widely used man-made materials in the construction industry are concrete. It is a combination of cemeteries, water, compounds and various types of admixtures to a certain extent. New concrete has plastic properties, which means that before casting it it behaves like plastic but over time, it becomes harder as rock. These hardening structures occur due to the chemical reaction between water and cement, it hardens over a long period of time. From the last century onward, the strength of the RCC structures was largely based on the round steel bars, which were readily available in the market. Over time, these items have also changed in appearance, structure, and power. For example, Pozzolana cement is used in place of conventional cement and TMT bars are applied in place of stainless steel. Energy testing methods are based on Indian standards. Test equipment provides complete results after examination of cubes, cylinders and beams, which are inserted and stored in water for treatment for 28 days continuously. Concrete structures, either in the 1970s or later made of high-strength steel-reinforced steel, have replaced concrete structures and structures with various additives in cement and admixtures with their acceleration or deceleration capacity. Now, instead of steel bars, steel fibers, polypropylene, natural polymers etc. are used. The reasons for the demands are many, but as a building engineer, we have to think hard and architecture by using building materials. In anticipation of long-term sustainability, we need to be able to meet needs.

COMPARATIVE STUDY OF THE REINFORCED STEEL BARS OBTAINED FROM A FAILED RESIDENTIAL BUILDING AND THE SHELVES

Nigeria is a developing nation, the need to build structures is on high rise. The rate of structure failure and building collapse is also on the rise. This paper presents a comparative study on Mechanical Properties of Reinforced steel bars obtained from the shelves, and that obtained from the failed structure of a residential building which is then compared to International standard NO-432 . Steels are main reinforcing materials for most structural buildings, but when the integrity is compromised, it leads to devastating consequences. The quality of concrete and steel reinforcement must be such that has appropriate yield strength so that the structure can sustain the require load within the required time interval. The Ultimate Tensile Strength and percentage elongation of the steel bars obtained from the two sources were investigated. One of the sources was a reinforcing bar used in Millennium Estate, Mary Land, Lagos State, Nigeria. The steel bar samples of sizes 10mm and 16mm diameter were subjected to mechanical testing using a universal testing machine. The percentage elongation met with the standards while the 16mm samples are below the standards for both the failed structure and shelves.

Flexural Strength Estimation for Hollow Cross-Section Simply Supported UHPC Beams

The hollow structural elements occupy a great deal of researchers’ interest due to the possibility of losing their weights and maintaining or developing their resistances especially when increasing both compressive and tensile strength of modern materials. The flexural strength based on the forces balance and stain compatibility was derived. Nine beams of Ultra High Performance concrete (UHPC) and conventional reinforced steel bars were casted. Several parameters were taken which are the thickness of the concrete top flange, thickness of the concrete bottom flange, depth of the longitudinal hollow and the ratio of the longitudinal reinforcing steel. By comp aring the practical and theoretical results, the proposed flexural strength provided a safety factor of one-fifth against the experimental collected data. The ultimate flexural force developed up 260 % when increasing the reinforced steel area 4.6 times and 230 % comparing with the solid beam. Many aspect ratios were also mentioned that keep the strength in developing.