Evaluation of Self-Compacting Concrete Strength with Non-Destructive Tests for Concrete Structures

Abstract

Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated concrete (NVC), namely higher cement paste dosage and smaller volume of coarse aggregates. In addition, the maximum size of coarse aggregates is also reduced in SCC to prevent blocking effect. Such specificities are likely to affect the results of non-destructive tests when compared to those obtained in NVC with similar compressive strength and materials. This study evaluates the applicability of some non-destructive tests to estimate the compressive strength of SCC. Selected tests included the ultrasonic pulse velocity test (PUNDIT), the surface hardness test (Schmidt rebound hammer type N), the pull-out test (Lok-test), and the concrete maturity test (COMA-meter). Seven sets of SCC specimens were produced in the laboratory from a single mixture and subjected to standard curing. The tests were applied at different ages, namely: 1, 2, 3, 7, 14, 28, and 94 days. The concrete compressive strength ranged from 45 MPa (at 24 h) to 97 MPa (at 94 days). Correlations were established between the non-destructive test results and the concrete compressive strength. A test variability analysis was performed and the 95% confidence limits for the obtained correlations were computed. The obtained results for SCC showed good correlations between the concrete compressive strength and the non-destructive tests results, although some differences exist when compared to the correlations obtained for NVC.

Models for compressive strength estimation through non-destructive testing of highly self-compacting concrete containing recycled concrete aggregate and slag-based binder

“…SCC is characterized by a large content of fines and water [48] and therefore a large proportion of cement paste [32] to achieve proper flowability. The accuracy of non-destructive testing in this particular material, has been demonstrated in some studies [30,47]. Their main conclusion was that the pre-established ratios between compressive strength and the indirect measures, suitable for conventional concretes, were not applicable.…”

“…Very early [18] and more recent studies [30] have shown that an increase in the hardened density of concrete facilitates the propagation of ultrasonic pulses. In this study, the necessary reduction of the coarse aggregate content to obtain an SF3 slump-flow class resulted in a lower number of discontinuities within the concrete matrix, which affected this relationship [8].…”

“…The global model represented in Eqs. 10 and 11 was tested with data obtained from existing research works that studied both indirect measures in SF2 class SCC [30,47,[71][72][73]. The comparison between the observed values of the referenced studies and those calculated by the model is shown in Fig.…”

“…Some new trends in this field include their successful use at evaluating the compressive strength of concrete at early ages [20,21], to study the spatial variability of concrete strength [22,23], especially in beams [24], and high-precision detection of micro-cracking within the damaged concrete [2,25], especially with UPV analysis [26]. In addition, there is also a field of research regarding their applicability in concretes made with alternative materials [27,28], and in nonconventional concretes, such as high performance fiberreinforced concrete [29] and Self-Compacting Concrete (SCC) [30].…”

Special Issue on “Architectural Structure”

“…These aspects are important to fulfill many architectural requirements. In [9], the applicability of non-destructive tests to estimate the compressive strength of self-compacting concrete was studied and useful correlations were presented for practice. Additionally, the performance of structural members in existing structures may have to be evaluated in light of current codes of practice.…”