Garje Rajesh Kumar

It is known that the deformation capacity is given due importance along with strength in the flexural design of reinforced concrete structures. When a structure is overloaded, adequate deformation capacity available in the structure can ensure safety and is achieved by dissipating excessive energy through plastic hinges. Compaction and curing are most important to achieve requisite strength and durability properties and this is achieved through self-curing self-compacting concretes in the present work. The parameters considered in the study include grade of concrete (Mix A, Mix B), type of curing regime (water curing and self-curing with polyethylene glycol 4000) and type of reinforced section (under-reinforced and over-reinforced beams). Beams of size 1800 mm × 200 mm × 120 mm were cast and tested for flexural strength and the moment–curvature relationships were obtained. It can be inferred from the results that there is a significant difference in the moment–curvature relationships between self-cured and wet-cured specimens. The ultimate moment values of self-cured beams are on a par with water-cured specimens. Optimum dosage of self-curing agents has significantly improved the structural behaviour of self-compacting concrete.

The role of hydrophilic (polyethylene glycol) and hydrophobic (light liquid paraffin wax) chemicals as self-curing compounds to improve the curing efficiency of self-compacting concrete (SCC) was investigated in terms of performance and microstructure. The parameters considered in the investigation were the concrete grade, dosage of self-curing compound, curing regime, temperature and duration of curing. Performance investigations included water retention tests, compressive strength test and durability studies (porosity, sorptivity, rapid chloride permeability and accelerated corrosion permeability tests). Microstructural analyses studies (X-ray diffraction analysis and scanning electron microscopy) were conducted to confirm the results obtained from the macrostructural studies. Two grades of concretes, with compressive strengths of 70 MPa and 50 MPa, were used. Based on experimentation and microstructural studies, it was concluded that the addition of optimum dosages of hydrophilic and hydrophobic chemicals arrested loss of moisture, resulting in improved water retention and progressive hydration of SCC.

Self-curing self-compacting concrete (SCC) is a modern construction material developed with the aim of improving overall quality and efficiency in construction. In this paper, the stress–strain behaviour of tie-confined self-compacting SCC is analysed and a comparison is made with SCC prepared without self-curing agents. The methodology included studying the stress–strain behaviour of two grades of self-compacting SCCs and comparing the results with normal SCC subjected to water curing and no curing. To determine the stress–strain behaviour, prism specimens were tested under axial compression. Lateral ties and longitudinal bars were used in the prisms and two grades of concrete of compressive strength were used. The results obtained will be useful for design engineers working on concrete with curing agents.

Presence of pore water in recycled aggregate-based concretes cannot escape easily due to evaporation because of the presence of old Interfacial Transition Zone, which is likely to prevent this. These pores, in which water is present, can serve as water reservoirs to replenish the water demand whenever hydrated particles require. Further, addition of self curing chemicals like polyethylene glycol and Paraffin wax can help retain the embedded moisture inside the concrete specimens. In the present study, the performance of self curing agents in natural and recycled aggregates is investigated. The parameters in the study include type of aggregate, type of curing regime, type of self curing chemicals, and dosage. Water retention, compressive strength, and sorptivity tests were carried out to determine the optimum dosage of self curing agents. It was concluded from the detailed investigation that addition of self curing chemicals benefitted recycled aggregate concretes in a better way.

Internal curing can be adopted to ensure the availability of water for the hydration of cement, mitigating the adverse effect of water loss to surroundings. The use of self-curing compounds is increasing in the context of the widespread use of self-compacting concrete (SCC) owing to its superior performance in both fresh and hardened states. This paper addresses the effect of using paraffin wax as a self-curing compound in SCC mixes. The variable parameters of the study include curing type, concrete grade (mix proportions), molecular weight and dosage of paraffin wax. Water retention, sorptivity and compressive strength tests were conducted on hardened concretes. The weight loss after 90 d was found to be less in specimens with a self-curing agent than in specimens without. The compressive strengths of the self-cured specimens closely matched those of conventional water-cured specimens. The optimum dosages of light and heavy molecular weight liquid paraffin wax were determined to be 0·1% and 1·0% by weight of cement respectively. It is this concluded that the use of self-curing compounds in SCC facilitates better hydration and thus enhancements in strength and durability properties.

Curing of concrete involves maintaining satisfactory moisture content during early stages to develop the desired properties. Properly cured concrete has improved durability and surface hardness, and is less permeable. Prevention of loss of moisture is important not only for strength development but also to prevent plastic shrinkage, for decreased permeability and to improve resistance to abrasion. Good and complete curing is not always practical for several reasons, particularly in higher grade concretes. Using self-curing agents can solve this problem. The concept of self-curing agents is to reduce water evaporation from concrete, and hence increase its water retention capacity compared to conventional curing. Several materials, including polymeric glycol and paraffin wax, can act as self-curing compounds. This study investigates the role of paraffin wax as a self-curing agent and compares this with the effect of different curing regimes simulating traditional methods of curing. The parameters include grade of concrete, type and dosage of paraffin wax, curing conditions and age of curing. Weight loss and compressive strength are determined as a performance benchmark for the investigated curing compounds. It is found that the lower dosage (0·1%) liquid paraffin wax compounds act as the best curing compounds in higher grade concretes.