Effect of Steel Fiber on Concrete’s Compressive Strength

The general goal of this research is to investigate whether steel fiber has a significant “positive” or “negative” influence on concrete compressive strength, as well as the optimal steel fiber ratio that delivers best result. Manually, cement, fine aggregates, coarse aggregates, steel fibers, and water were mixed together properly. A slump test was carried on the mixed concrete. After determining the workability, the mixed concrete was poured into cubes dimension 150 mm × 150 mm × 150 mm and left for 24 hours. After 24 hours, the samples were removed from the mold and placed in a water tank to cure for 7 to 28 days. The cube was tested for compressive and flexural strength in a universal testing machine after the samples had cured for the required 7 - 28 days. This study focuses on how to obtain high strength concrete using with steel fiber in the Conventional mix ratio to enhance concrete strength. Concrete reinforcement using steel fibers alters the characteristics of the concrete, allowing it to withstand fracture and hence improve its mechanical qualities. This study reports on an experimental study that reveals the effect of steel fiber on concrete compressive strength and the optimal steel fiber ratio that produces the best results. Steel fiber reinforcing improved the compressive strength of concrete. The average compressive strength of normal M25 concrete with 0% steel fibers and curing ages of 7 and 28 days was determined to be 22.97 N/mm2 and 25.78 N/mm2, respectively. The steel fibers are then added in various concentrations, such as 1%, 2%, and 3%, with aspect ratios of 70. The compressive strength of concrete with 1%, 2%, and 3% steel fiber with an aspect ratio of 70 was examined at 7 days and found to be 23.96, 24.80, and 26.14 N/mm2 correspondingly.

Simulation of Temperature Effects on Concrete Residual Strength of the Slab-Column Connections

Finite element simulations were conducted to explore the effects of high temperatures on the loading capacity of slab-column connection for the concrete flat-plate structures by the finite element analysis software ABAQUS.The structure used for the simulation is a slab which thickness is 150 mm with a 300 mm square column in the middle of slab,the column height is 450mm.The size of this slab is the same as experiments conducted by previous paper[1].Based on the results of simulation,the punching capacity of this structure not experienced high temperature can be predicted with very good accuracy.But the result from simulations underestimated the loading capacity of the structure after it has been cooled by around 10%.This phenomenon is a little bit conflicts with the known experimental results,however,it can be adjusted by modify the material parameters built-in the software.This article is focus on how to best simulate the concrete behavior for both linear and nonlinear part under the room temperature and cooling after experience a very high temperature.