With the increase in strength, concrete explodes spontaneously at failure creating a serious safety hazard. Researchers are actively looking for methods to arrest the cracks in concrete and design a higher strength concrete that fails in a more ductile fashion. Fiber-reinforced concrete has emerged as one of the solutions to this problem. This paper presents findings from the experimental investigation conducted to compare the fracture behavior of plain and fiberreinforced high strength concrete of varying compressive strength. Six different concrete mixes were prepared with w/b ratios of 0.47, 0.36, and 0.20 resulting in average compressive strength of 36, 52, and 92 MPa. Each mix consists of two variations, first without fiber and second with 1% of steel fiber by volume. The mixes were tested for their strength and fracture Behavior using various standard codes and recommendations. From the Load-deflection and Load-CMOD (Crack Mouth Opening Displacement) curves obtained from the study, Fracture parameters like Fracture energy, Stress intensity factor, energy release rate, and Characteristic length is evaluated and compared for plain and Steel fiber reinforced concrete. It was found that adding steel fiber significantly improves the fracture properties of the concrete of different compressive strengths. By adding 1% of steel fiber in the high-strength concrete, the average fracture energy increased by 850%, 770%, and 450% respectively for the concrete with compressive strength of 36, 52, and 92 MPa. Other parameters also show a very significant improvement suggesting fiber reinforcement as a suitable choice to prevent brittle failure and increase the fracture performance of high strength concrete.

High strength concrete is being widely used in construction nowadays and therefore, it is important to develop the design parameters for effective use and considerations. The Indian Standard has the equation for prediction of modulus of elasticity (MOE) but it is valid for normal strength concrete only. The modulus of elasticity is considered as a function of compressive strength of concrete and therefore, all the parameters that have influence on the properties of concrete should necessarily have its effects on the value of the modulus of elasticity. MOE depends on the properties of the aggregates, cement paste and their interactions at the interfacial transition zone. There are numbers of equations to evaluate the modulus of elasticity by various International codes and literatures. This paper aims in developing an empirical equation to evaluate the modulus of elasticity for both normal and high strength concrete considering the indigenous aggregates and materials. The analysis considers test results of modulus of elasticity with a wide range of compressive strength of concrete with a total of about 100 test results. Based on the experimental results for granite and calc‐granulite aggregate an empirical equation is proposed for the prediction of MOE and is compared with the empirical equations available in the different International standards. Also the effect of basalt aggregate on modulus of elasticity as compared to granite aggregate is studied.

The current study is aimed to evaluate and critically analyze the properties of Light Weight Geopolymer Fly Ash Sand (LWGFAS). LWGFAS has been prepared by geopolymerisation of the fly ash. Liquid solution of 4M NaOH, and Na2SiO3/NaOH=2 was used as an activator and post set heat treatment of 1 hour at 100 o C was applied for preparation of LWGFAS. The LWGFAS sample was analyzed for different physical and chemical parameters along with studies on mineralogy and alkali silica reactivity. The molar concentration of activator solution and duration of post set heat treatment plays vital role on the physical and mechanical properties (particularly specific gravity, bulk density and water absorption) of the Geopolymer fly ash sand. The specific gravity and water absorption of LWGFAS were 1.57 and 17.85% respectively. Experimental concrete mixes made with LWGFAS as a replacement of natural sand were evaluated for compressive strength and different durability properties of concrete. The study indicates that LWGFAS can be suitable for a wide range of applications in making concrete ranging from light weight in nature to normal weight concrete based on the physical and chemical characteristics of Geopolymer Fly Ash Sand.

There is rapid growth of Portland Pozzolana Cement (PPC) production over the last few years. The use of PPC has been included by Indian and international standards/specifications in the past. But in India, the use of PPC for prestressed concrete (PSC) is generally not recommended in different specifications due to apprehension of late strength development and a lack of data on other critical properties of PSC like creep, shrinkage, and fatigue. The critical properties affecting PSC structures such as strength, modulus of elasticity, drying shrinkage, and creep as studied in the past by NCB are at par in case of available PPC when compared with ordinary portland cement (OPC). The present study is carried out to evaluate the flexural and fatigue behavior of PSC beams made with OPC and PPC. The study was conducted on M40 grade concrete using two locally available Indian cements, i.e. OPC and PPC. The test results of flexural strength test conducted on PSC beams indicate that flexural behavior for both OPC and PPC made PSC beams are similar. Based on fatigue studies, it is seen that the fatigue effects are also similar in case of both OPC and PPC made concrete. During flexure testing without fatigue, it was observed that the first cracking load is slightly lower in case of PPC but ultimate load is almost equal in PPC and OPC. Fatigue test results of PSC beams are similar for both OPC and PPC made concrete.

Hydraulic structures like spillways, glacis, etc. undergoes abrasion-erosion due to impact & cavitation losses due to the flowing water action. To overcome the deterioration of the concrete in such structures, addition of fibers to the concrete can be viable solution as it is known to increase the structural integrity of the concrete. A comparative study of various engineering characteristics using high strength concrete by incorporating steel fibers and micro polypropylene fibers has been carried out. Water/binder ratio of 0.23 has been kept constant for the study. Dosage for steel fibers are kept as 1, 1.25 and 1.5% by volume while for polypropylene fibers were kept as 1, 2 & 3 kg/m3. Engineering properties such compressive strength, flexural strength, toughness, energy absorption, splitting tensile strength, drying shrinkage, abrasion resistance, and water and air permeability of high performance concrete with & without fibers in its fresh & hardened state are investigated in this paper. Based on the study, the steel fibers with 1.5% dosage are found to be more effective in countering the abrasive and repetitive loading which can be more effective in the repairs of spillways and glacis of concrete dams.