Geopolymers as an alternative to Portland cement: An overview

A comparative study on the compressive strength prediction models for High Performance Concrete containing nano silica and copper slag using regression analysis and Artificial Neural Networks

Utilisation of industrial waste materials in concrete compensates the lack of natural resources, solving the disposal problem of waste and to find alternative technique to safeguard the nature. There are a number of industrial wastes used as fully or partial replacement of coarse aggregate or fine aggregate. This review carries out a thorough assessment about industrial waste substances, which can be adequately utilised in concrete as fine aggregate substitution. This paper reviewed some of these industrial wastes like waste foundry sand, steel slag, copper slag, imperial smelting furnace slag (ISF slag), blast furnace slag, coal bottom ash, ferrochrome slag, palm oil clinker etc. Out of these materials, maximum number of experiments have been conducted using waste foundry sand and copper slag as fine aggregate replacement, but still more examinations are required for other waste materials as replacement of sand in concrete. Different physical and mechanical properties of industrial waste as well as of industrial waste concrete, in which natural sand is substituted have been reviewed and comparisons are made between them. Deflection and leaching study review are carried out additionally and compared. It can be observed that the concrete where sand is replaced by copper slag, imperial smelting furnace slag, class F fly ash exhibits improved strength and durability properties, but it’s slump increases as the rate of replacement increases in the case of copper slag and the slump decreases in the case of class F fly ash. There is a less research work reported on ferrochrome slag and palm oil clinker used as sand substitution, so it is felt that further detailed investigations are required.

Sustainable use of industrial-waste as partial replacement of fine aggregate for preparation of concrete – A review

Sustainable use of copper slag in self compacting concrete containing supplementary cementitious materials

This study investigates the effects of steel fiber and silica fume on the mechanical and fracture properties of ultra-high performance geopolymer concrete (UHPGC). Four volume fractions of steel fiber (0%, 1%, 2% and 3%) and four contents of silica fume by the mass of total binders (5%, 10%, 20% and 30%) were used. The mechanical and fracture properties evaluated include the compressive, splitting tensile and ultimate flexural strengths, modulus of elasticity, flexural behavior, fracture energy and stress intensity factor. In addition, the correlations among the compressive and splitting tensile strengths, and compressive strength and elastic modulus were studied. The results indicated the increase of steel fiber dosage resulted in the decrease of the workability, but the continuous improvement of mechanical and fracture performance of UHPGC. The empirical equations for predicting elastic modulus of conventional ultra-high performance concrete overestimated the elastic modulus of UHPGC, however some prediction formulas for the splitting tensile strength of PC-based concretes could be applied for UHPGC. Silica fume had a complicated influence on workability and hardened properties of UHPGC, which is strongly dependent on its amount. The inclusion of 10% silica fume induced the increase of the flowability, but the sharp degradation of the mechanical performance, while the specimens with 20% and 30% silica fume possessed the superior mechanical characteristic to that with 5% silica fume. The steel fiber dosage could be decreased without sacrificing the mechanical and fracture performance of UHPGC, via the increase of silica fume content.

Mechanical and fracture properties of ultra-high performance geopolymer concrete: Effects of steel fiber and silica fume

Studies on ultra high performance concrete incorporating copper slag as fine aggregate

This paper presents the development of ambient temperature cured ultra-high-performance geopolymer concrete (UHPGPC). Ultra-high-performance concrete (UHPC) mixtures were developed by completely eliminating Portland cement and activating industrial by-product materials such as ground granulated blastfurnace slag and silica fume. Local standard sand (maximum size 2 mm), quartz sand (600 μm) and 0·16 mm diameter steel fibres of 13 and 6 mm length were used. Fresh properties (density and flowability) and mechanical properties (compressive strength) of the UHPGPC produced under ambient temperature curing conditions were evaluated. Four mixtures with fibres and one mix without fibre addition were studied as the UHPGPC mixtures. The highest average compressive strengths obtained were 175 MPa for UHPGPC with steel fibres (1% 6 mm and 2% 13 mm) and 124 MPa for UHPGPC without fibres. Prismatic specimens (100 × 100 × 500 mm) were cast to determine the flexural strength, which was found to be 10·3–13·5 MPa and 9·1 M...

Development of ultra-high-performance geopolymer concrete

In this study, the fine and coarse aggregates were completely replaced by fly ash aggregates in fly ash concrete. A mix design was done for M20 grade of concrete by IS method. Ordinary Portland cement of 43 grade was selected and fly ash aggregates were prepared by mixing fly ash with cement and water. The properties of fly ash fine aggregates and fly ash coarse aggregates were studied. The aggregate crushing value and aggregate impact value of fly ash coarse aggregates were also studied. The cement and fly ash proportions of 10:90, 12.5:87.5, 15:85, 17.5:82.5, 20:80 and 22.5:77.5 were tried with a suitable water cement ratio 0.3 to get the fly ash aggregates. The concrete cubes, cylinders and beams were cast with the fly ash aggregates obtained from the above six cement fly ash proportions. Then the compressive strength, split tensile strength and flexural strength were tested and compared with control concrete. This paper briefly presents the compressive strength development of fly ash aggregate concrete at different ages. The split tensile strength and flexural strength of all the concrete mixes were also investigated at different days of curing.

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Study on Utilization of Fly Ash Aggregates in Concrete

Risk is the outcome of an event which may be predicted on the basis of statistical probability. Construction projects have inherent risks associated with it. The main aim of this paper is to identify the critical risk factors and to propose a model to find the probability of cost deviation in medium sized construction projects. A total of 46 risk factors were shortlisted based on pilot study and experts' opinion. A questionnaire survey was conducted among 223 various construction professionals each representing one project i.e. from 223 different projects. Based on factor analysis, 46 risk factors which influence the cost deviation in construction projects were classified under nine key risk groups viz. project scope and evaluation risk, work environment risk, documentation and legal framework risk, construction and operational risk, resource productivity risk, knowledge sharing risk, site supervision risk, financial viability risk and lean construction risk. Logistic regression analysis was also carried out to develop a model to find the probability of cost deviation in construction projects. It is concluded that the risk groups such as project scope and evaluation risk, site supervision risk, knowledge sharing risk and lean construction risk are having higher influence in the cost deviation in medium sized construction projects. By setting the effective baseline of the project like estimation of original project cost and detailed project report, cost deviations in medium size construction projects can be eliminated. Detailed recommendations are also provided.

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Effect of critical risk factors causing cost deviation in medium sized construction projects

Delays in a construction project can be regarded as a failure. This paper aims to investigate the causes of delay in Indian construction projects undertaken by private, government and nongovernmental organizations. In view of this 45 causes of delay were identified and developed the questionnaire for the quantitative confirmation of the most causes of delay. Consequently the questionnaire was distributed to construction professionals like Managers, Engineers and others. Subsequently the collected data was analyzed using statistical tool and the factors were measured and ranked under each group by importance index for various construction professionals. The results suggest that delays are mainly due to shortage of labours, shortage of construction materials and extra works (rework and change orders). The resources like manpower and materials are having highest contribution of about 24% compared to other sources. However this paper presents recommendations for a better project management techniques & procedures which can be adopted during conceptual & detailed planning phases of the project in order to minimize the construction delay.

C. Umarani

Papers

Studies on ultra high performance concrete incorporating copper slag as fine aggregate

Development of ultra-high-performance geopolymer concrete

Study on Utilization of Fly Ash Aggregates in Concrete

Effect of critical risk factors causing cost deviation in medium sized construction projects

Causes of Delay in Indian Construction Industry