Concrete Composites

This paper deals on flexural strength of RCC one way slabs using fly ash, silica fume and M-sand and steel fibre. One conventional reinforced concrete one way slab and Nine steel fibre reinforced concrete one way slabs with fly ash; silica fume and M sand are casted by changing the reinforcement ratio and thickness. The slabs are size of 1.2m x 0.4m. The slabs were tested under three point loading. The ultimate load carrying capacities of slabs are found out. The results shows that load carrying capacity of slabs are increased with increase of reinforcement percentage and thickness.

Ferrocement laminates are introduced to enhance the overall performance of pre-cracked high strength concrete beams. Eight beams of size 150mm width, 200mm depth and 1500mm overall length were cast and tested for flexure. Out of eight beams two beams were treated as control beams and the remaining beams are to damaged under overloading by applying 65% ultimate load for two beams and 75% ultimate load for another two beams and 85% ultimate load for remaining two beams and strengthened by fastening ferrocement laminates. Fastening of ferrocement laminates onto the tension surface of the pre-cracked beam was done by using epoxy resin adhesive. The strengthened beams were again tested for ultimate load carrying capacity by conducting flexural test. A comparative study was made between the control beams, the pre-cracked beams strengthened by ferrocement laminates. From the test results it could be seen that ferrocement can be used as an alternative strengthening material for the pre-cracked high strength concrete beams damaged due to overloading.

The importance of bridge vibrations induced by moving vehicles, which act as oscillators on a bridge as well as time variant forces, has long been recognized. This vibration can amplify the propagation of existing cracks resulting in further damage to the bridge. It has become one of the causes of reduction in long-term serviceability of the bridge, although major bridge failures are not usually caused directly by moving vehicles. It is also a critical factor to bridge structure fatigue and rapid deterioration since, the vehicle-induced vibration is more critical to bridges with medium to small span; it is worthwhile to investigate the possibility of applying Tuned Mass Damper (TMD) on these bridges. A TMD is a passive type control device with variety of merits in that it has permanent service time and only requires easy management and maintenance efforts and no external power supply source. In order to achieve the above objective, a general formulation of the vehicle-induced bridge vibration controlled with a TMD system is developed here in this paper, which takes into account the road surface conditions. Then, a comprehensive investigation is made to investigate the efficiency of the TMD for suppressing vibrations of bridge under moving vehicles. Such a study is helpful in evaluating the control performance before real control devices are designed in practice. These analytical results will also be useful in carrying out further studies for control strategies suppressing the vehicle-induced bridge vibration

This paper presents the seismic behavior of beam-column joints with special confinement in the joint region along with different reinforcement detailing for anchorage of beam bars, confinement in joint and additional reinforcement in beam and column. External confinement is carried out by glass fiber reinforced polymer(GFRP).The performance of the specimens are compared in terms of lateral load- versus displacement curves. The dimensions of the specimens were fixed to be 0.2m x 0.2m cross section and the height of the column was fixed as 1m and the cantilever length of the beam was fixed as 0.6m to carry out the experimental work. Five numbers of exterior beam-column joints were designed according to Bureau of Indian Standards were cast and tested under lateral loading. The specimen was designed as per IS 456:2000 and IS 13920-1993 and reinforced accordingly with that. Out of five specimens three specimens were designed with special confinement one was control specimen and the final one was control + GFRP. Results by experimental and analytical shows that special confinement specimen carries more load carrying capacity than the control specimen and almost close to control + GFRP.

The State of the art of concrete filled steel tubular columns is presented in this paper. Experimental data has been collected and compiled in a comprehensive format listing parameters involved in the study. Areas of further research are presented and results of ongoing experimental and numerical investigations are also shown.

An experimental study has been carried out on axially loaded short and slender high strength concrete columns confined with glass fiber-reinforced polymer (GFRP) sheets. A total of 10 specimens were loaded to failure in axial. The column specimens are square in shape with 150 mm length,150 mm width and 1000 mm height. Concrete compressive strength was 58 MPa. All columns were reinforced with steel and wrapped with different layers of GFRP. Results of testing was increasing the compressive strength of concrete column with GFRP wrapping, the columns wrapping with glass FRP is most effective in control column. Four layers of FRP wrapping of column was gave the highest result of compressive strength test. A modified analytical model was presented to predict the strength of FRP-confined square column.

Fatigue cracking and rutting contribute significantly to the failure of asphalt pavement. In the design of asphalt pavement, it is necessary to investigate these critical strains and design against them. In Nigeria, the only developed design method for asphalt pavement is the California Bearing Ratio (CBR) method. Most of the roads designed using the CBR method failed soon after construction by fatigue cracking and rutting deformation. This study was conducted to develop a modified Nigeria CBR procedure for low volume asphalt pavement adopting the layered elastic analysis procedure which involves selection of materials and layer thickness for specific traffic conditions such that fatigue cracking and rutting deformations are minimized. Analysis were performed for hypothetical asphalt pavement sections using the layered elastic analysis program EVERSTRESS. Regression equations were developed for predicting pavement thickness in cement-stabilized base, low-volume asphalt pavement. The result was validated by comparing calculated maximum fatigue and rutting strains developed using the modified procedure and measured strain data from the Kansa Accelerated Testing Laboratory (K-ATL). The calculated and measured fatigue and rutting strain were calibrated and compared using linear regression analysis. The calibration of calculated and measured fatigue and rutting strains resulted in R2 of 0.999 and 0.994 respectively for subgrade modulus of 31MPa, 0.997 and 0.997 respectively for subgrade modulus of 41MPa, 0.996 and 0.999 respectively for subgrade modulus of 62MPa, 0.992 and 0.995 respectively for subgrade modulus of 72MPa, 0.999 and 0.998 respectively for subgrade modulus of 93MPa, and 0.999 and 0.999 respectively for subgrade modulus of 103MPa indicating that the coefficients of determination were found to be very good.

A major part of the civil engineering infrastructure will need significant repairs. The innovative rehabilitation and strengthening methods for reinforced concrete structures, especially with composite materials, has taken a large portion of the research work in the field of repair and restoration of structural elements. Also, some of these techniques were used to strengthen columns by confinement with composite enclosure. This paper investigates the strengthening of High Strength Concrete short circular columns using Glass Fiber Reinforced Polymer [GFRP] sheets. The main variables of the work are the slenderness ratio of the columns and the number of layers of GFRP wrapping. Column specimens of three different slenderness ratios [3, 6 and 9] each wrapped with 3 and 4 layers of GFRP fabric was considered for the study. Another set of unwrapped columns serves as the reference. The diameter of the columns is 150 mm. The columns were tested under uni-axial compressive loading until failure. The test results show that the load carrying capacity as well as the ductility capacity of the columns improved with the increasing slenderness ratio and number of layers of GFRP wrapping.