Bala Muhammad

Characteristics of treated effluents and their potential applications for producing concrete

Conservation and preservation of freshwater is increasingly becoming important as the global population grows. Presently, enormous volumes of freshwater are used to mix concrete. This paper reports experimental findings regarding the feasibility of using treated effluents as alternatives to freshwater in mixing concrete. Samples were obtained from three effluent sources: heavy industry, a palm-oil mill and domestic sewage. The effluents were discharge into public drain without danger to human health and natural environment. Chemical compositions and physical properties of the treated effluents were investigated. Fifteen compositional properties of each effluent were correlated with the requirements set out by the relevant standards. Concrete mixes were prepared using the effluents and freshwater to establish a base for control performance. The concrete samples were evaluated with regard to setting time, workability, compressive strength and permeability. The results show that except for some slight excesses in total solids and pH, the properties of the effluents satisfy the recommended disposal requirements. Two concrete samples performed well for all of the properties investigated. In fact, one sample was comparatively better in compressive strength than the normal concrete; a 9.4% increase was observed at the end of the curing period. Indeed, in addition to environmental conservation, the use of treated effluents as alternatives to freshwater for mixing concrete could save a large amount of freshwater, especially in arid zones.

Corrosion behaviour of dual‐phase and galvanized steels in concrete

Purpose – The purpose of this paper is to present results of an evaluation of dual‐phase and galvanized steel reinforcements in corrosive environments.Design/methodology/approach – Low carbon steels were intercritically annealed at 740°C followed by water quenching to obtain dual‐phase structures with 37 per cent volume fraction of martensite dispersed in ferrite matrix. Dual‐phase and galvanized steel rebars were embedded in concrete cubes and immersed in 5 per cent NaCl solution for up to 100 days. Corrosion rate, tensile and macro as well as microhardness tests were performed. The dual‐phase and galvanized zinc layers were observed under scanning electron microscopy (SEM).Findings – From all of the tests carried out it was found that dual‐phase steels exhibited better corrosion resistant properties and superior strength compared to galvanized steels.Originality/value – The results reported show that dual‐phase steel can be a good candidate for reinforcement in concrete especially in aggressive and corr...

Elastomeric Effect of Natural Rubber Latex on Compressive Strength of Concrete at High Temperatures

The inclusion of elastomeric substances into concrete aimed at improving performance properties may pose a serious threat, particularly at high temperatures. This paper presents experimental findings regarding the elastomeric influence of natural rubber latex on compressive strength of concrete at elevated temperatures. Normal and modified concrete specimens were prepared, heated, and subsequently tested for compressive strength. Five temperatures—ambient temperature (27°C), 150, 300, 500, and 800°C—were applied. Microstructural samples were observed through scanning electron microscopy (SEM), and the role of poly(1,4-isoprene) particles in the modified system was evaluated using thermogravimetric analysis (TGA) conducted on hardened cement paste, latex film, and cement-latex blend. Finally, compressive strength of the modified concrete was observed to depreciate at the softening point temperature of the latex films in the comatrix, eventually with more strength loss. At 800°C, the strength loss was 50.5%...

Embedded Sensor for Detecting Corrosion of Reinforcement in Concrete

Corrosion of reinforcement is a worldwide problem which causes premature degradations in reinforced concrete structures. Monitoring reinforcement corrosion in concrete can be achieved by embedding corrosion sensor within the concrete cover. In this research, capacitance-based embedded sensor was developed to monitor corrosion potential (Ecorr) and corrosion rate (Icorr) parameters of reinforcement continuously. The sensors were tied to the reinforcement and embedded in concrete slab specimens followed by immersion into NaCl solution for 70 days. During this period, corrosion parameters were weekly recorded. At the same time, half-cell corrosion testing using Portable SRI-CMIII was conducted for calibration purpose. From the research, it was observed that the patterns of Ecorr and Icorrshown by the embedded sensors were similar to that of portable SRI-CMIII device - an indication of suitability of the embedded sensor towards sensing existing corrosion activities around the embedded steel bars. Eventually, the bars were found corroded from the broken specimens to confirm the detection of corrosion activities as recorded by the sensors.