Compressive Strength Prediction of Porous Concrete Using Nondestructive Tests

Abstract

This research focused on a prediction of compressive strength in porous concrete based on the ratio of air-entrained agents in the concrete slab using nondestructive testing methods such as the Impact Echo (IE) method, Spectral Analysis of Surface Wave (SASW) method and Free-Free Resonance (FFR) test. The method that best predicts the strength of the concrete slab can be derived from a relationship between compressive strengths and stress wave velocities. Concrete slab specimens of varying air content, were formed with a mix ratio of air-entrained agent of 0%, 0.15%, 0.3%, 0.7% and 1.5% by weight. These slabs were tested and analyzed to measure the stress wave velocities in order to develop a correlation with compressive strengths. The plot between the stress waves and compressive strengths showed a stiff slope up to an air ratio of 4% with a less steep slope beyond this point. In the process of predicting the compressive strength of concrete slab specimens, the prediction of compressive strength based on the compression wave velocity caused an average error of 4.9% in the compression wave velocity, and the prediction of compressive strength based on the surface wave velocity caused an average error of 2.2% in the surface wave velocity.