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The paper investigates the influence of bacteria on the strength and durability properties of normal and Ground Granulated Blast Furnace Slag (GGBS) concrete. Cement was replaced with 40% of GGBS by weight. Different cell concentrations of bacteria were used in making the concrete mixes. Tests were performed for compressive, split tensile, Rapid Chloride Penetration Test (RCPT) and sulphate attack (Suthar and Parikh, 2016). Compressive strength and split tensile strength of GGBS bacterial concrete were higher with reduction in chloride penetration and increase in strength after sulphate attack was observed with a concentration 105 cells/mL of bacteria (Sudarshan and Tejas, 2016). Pseudomonas putida improves the strength and durability of concrete through self-healing effect. [ABSTRACT FROM AUTHOR]

The utilization of industrial and agricultural waste produced by industrial process has been the focus of waste reduction research for economical, environmental and technical reasons. This is because over 300 million tons of industrial waste is being produced per annum by agricultural and industrial processes in India. The problem from continuous technological and industrial development is the disposal of waste material. With the increase in demand for construction materials, there is a strong need to utilize alternative materials for sustainable development. Advancements in technology not only help in improving human comforts but also harm the environment. The use of china clay industrial waste aggregate in construction industry has become popular and safe now. At present, construction industry is in need of finding a cost-effective material to enhance the strength of concrete. In this paper, the effect of china clay waste and the chemical admixture (superflo) on concrete has been investigated. Natural aggregate was replaced with china clay industrial waste in different percentages, namely, 10, 20, 30, 40 and 50. A comparison was made between the specimens of partially replaced fine aggregate and the same set of specimens admixed with superflo. The effect on mechanical properties and durability properties was reported. [ABSTRACT FROM AUTHOR]

The paper presents experimental studies conducted on two grades of High Performance Concrete (HPC) mixes of M50 and M60 using mineral and chemical admixtures in various proportions. The main purpose of this investigation is to develop confidence among user agencies in India to use mineral and chemical admixtures in a desirable proportion in most of the construction works. Overall, the paper highlights the usage of admixtures to achieve high strength concrete mixes and from the experimental investigation, it is clear that mineral admixtures contribute effectively a lot not only for achieving durability but also high strength. [ABSTRACT FROM AUTHOR]

The paper presents experimental studies conducted on two grades of High Performance Concrete (HPC) mixes of M70 and M80 using mineral and chemical admixtures in various proportions. The main purpose of this investigation is to develop confidence among user agencies in India to use mineral and chemical admixtures in a desirable proportion in most of the construction works. Overall, the paper highlights the usage of admixtures to achieve high strength concrete mixes, and from the experimental investigation, it is clear that mineral admixtures contribute effectively a lot not only for achieving durability, but also high strength. [ABSTRACT FROM AUTHOR]

Concrete structure exposed to marine environments is very susceptible to chloride ion ingress into the concrete, which in turn corrodes the steel reinforcing. The loss, in terms of repair of damaged structures and reduction in design life of structures, is very high. Therefore, this paper presents the laboratory investigations conducted to study the chloride permeability characteristics of admixed concrete specifically with Fly Ash (FA). The influence of various parameters such as water/cement (w/c) ratio, age of concrete and percentage of mineral admixture were undertaken. Rapid Chloride Permeability Test (RCPT) was used to study the chloride permeability characteristics of concrete. RCPT adopts a voltage of 60 V to measure the resistivity of concrete. This is the inherent disadvantage of RCPT. Because of this higher voltage, the specimen gets heated up, increasing the chances for encouraging chloride permeability. Hence, in the present work, experimental investigations for various voltages were performed. The outcome of this paper is to suggest an optimized percentage of FA suitable for concrete in an aggressive environment and to develop correlation between various parameters, which are responsible for chloride permeability. [ABSTRACT FROM AUTHOR]

Ordinary cement concrete has very low tensile strength which leads to the failure of concrete. It has been found that different types of fibers added in specific percentage to concrete improves the mechanical properties, durability and serviceability of the structure. It is now established that one of the important properties of Steel Fiber Reinforced Concrete (SFRC) is its superior resistance to cracking and crack propagation. In this paper, the effect of fibers on the strength of concrete for M40 grade has been studied by varying the percentage of fibers in concrete. The fiber content was varied by 0.25%, 0.50%, 0.75% and 1% by volume of concrete. Cubes of size 150 mm x 150 mm x 150 mm were used to conduct the compressive strength before and after corrosion test. All the specimens were cured for a period of 3, 7 and 28 days before testing. A considerable reduction in corrosion potential was noticed. The results indicate that the strength degradation was marginal in the case of SFRC before and after accelerated corrosion test. The slump cone test results revealed that workability gets reduced with the increase in fiber content. [ABSTRACT FROM AUTHOR]

Initially, in India, the construction industry and the engineers did not take advantage of research and scientific developments in concrete construction to its fullest extent due to the lack of education and training facilities in concrete technology. Due to the lack of knowledge and skill of supervisors and construction contractors, there is a wrong notion that the greater the quantity of cement in concrete, the better will be the quality and strength of concrete. This paper reports the results of an investigation carried out to understand the effect of chloride and sulphate attack on concrete. It was observed that several million tons of waste glass are generated annually worldwide due to the rapid growth of population, improvement in the standard of living, industrialization and urbanization. Hence utilization of waste glass has become a critical issue worldwide. Concrete produced by replacing cement with waste Glass Powder (GP) in different proportions was studied. It was found that the strength properties were affected when concrete was subjected to attack, and higher resistance to attack was obtained when 20% cement was replaced with waste glass. [ABSTRACT FROM AUTHOR]

Long-term performance of structures has become vital to the economies of all nations. Concrete has been the major instrument for providing stable and reliable infrastructure. Deterioration, long-term poor performance and inadequate resistance to hostile environment coupled with greater demands for more sophisticated architectural form led to the accelerated research into the microstructure of cements and concretes and more elaborate codes and standards. As a result, innovation of supplementary materials and composites has been developed. In other side, India has an enormous growth in the steel and copper industries yielding many by-products. If the by-products, such as copper slag and Ground Granulated Blast Furnace Slag (GGBS) are not disposed of properly, they may cause environmental hazards to the surrounding area. Considering the long-term performance and stability of structures, it is planned to replace some percentage of fine aggregate with copper slag and some percentage of cement with GGBS to develop High Performance Concrete (HPC). The paper presents an experimental investigation to assess the durability parameters of HPC with the industrial wastes. Durability parameters such as water absorption and chloride penetration were studied. [ABSTRACT FROM AUTHOR]

External environment plays a major role in affecting the performance of concrete structures. Pozzolanic materials, such as fly ash, up to 50% replacement of cement, provide excellent durability properties. This paper presents the study of durability characteristics of Indian fly ash mixes with locally available ingredients. Durability study was conducted by subjecting cubes 150 × 150 × 150 mm to 1% sulphuric acid, 1% hydrochloric acid and seawater curing. The results of the investigations show that on exposure to sulphuric acid, loss of compressive strength is severe, when compared to hydrochloric acid and seawater curing. Low volume fly ash concrete, up to 30% replacement by fly ash, showed better resistance to aggressive exposure, when compared to high volume fly ash concrete. [ABSTRACT FROM AUTHOR]

The paper presents the effects of using different pozzolanic materials as a partial cement replacement material in mortar mixes. This work is based on an experimental study of mortar made with 43 grade Ordinary Portland Cement (OPC) and 12% of OPC partially replaced by different cement replacement materials such as Fly Ash (FA), Rice Husk Ash (RHA) and silica fumes in mortar mixes. The mechanical properties of control cement mortar, FA mortar, RHA mortar and silica fumes mortar were tested to determine the effect of these materials on mortar properties. Mortar specimens were cured in water for 28 days, through which compression strength was tested at ages 3, 7 and 28 days, while tensile strength and flexural strength were determined at age 28 days. Then the rest of the specimens were immersed in fresh water and solutions of 10% sodium sulfate (Na2SO4) and 10% magnesium sulfate (MgSO4) for a period of 3 months. Through this period, the specimens were tested for compressive strength at 1, 2 and 3 months to investigate their durability. The obtained results show that the compressive strength, tensile strength, flexural strength and also durability of the mortar containing FA and RHA and silica fume were better than that of the control cement mortar and the silica fume was the best pozzolan used in this research. It was also found that magnesium sulfate has a more severe effect on the durability when compared with sodium sulfate [ABSTRACT FROM AUTHOR]

Concrete is extensively used in construction world, hence researchers and scientists are always studying to develop an alternative environment-friendly material, and one such alternative material used is rubber. At places where high strength concrete is not required, concrete with rubber aggregates can be used because of their ability to absorb high plastic energy. This study is carried out on rubberized concrete by replacing the fine aggregate with crumb rubber to study the properties and microstructure of the concrete thoroughly. The mix design used for the study was M25. The replacements of fine aggregate varied from 0-10 with 2% increment. Cubes, cylinders and beams were casted for each percentage to study the mechanical properties, durability properties and mineralogical composition of the concrete. Various destructive tests like compression strength test, split tensile strength, flexural strength and modulus of elasticity were carried out along with nondestructive tests like Ultrasonic Pulse Velocity (UPV) test and rebound hammer test to study the mechanical properties of the concrete. To check the durability properties of concrete, water absorption test and sorptivity test were carried out. The concrete from the destructive test was sent for further study of the mineralogical composition of rubberized concrete. [ABSTRACT FROM AUTHOR]

Concrete is one of the most widely used construction materials in the world, mainly due to its favorable features such as durability, versatility, satisfactory compressive strength, cost-effectiveness and availability. Globally, the concrete industry consumes large quantities of natural resources, which are becoming insufficient to meet the increasing demands. At the same time, many old buildings have reached the end of their service life and are being demolished, resulting in waste concrete; some concrete waste is used as backfill material, with much being sent to landfills. Recycling concrete by using it as new aggregate in concrete could reduce concrete waste and conserve natural sources of aggregate. In the last two decades, a variety of recycling methods for Construction and Demolition Wastes (CDW) were explored and developed. It is known as Recycled Aggregate (RA). BS EN Standards (BS 8500-1 Concrete, 2006; and BS 8500-2 Concrete, 2006) recommends that recycled concrete be used in secondary structural members of relatively low grades, e.g., curbs, paving blocks and ground bearing floor slabs. [ABSTRACT FROM AUTHOR]