Assessing concrete strength by means of small diameter cores

Estimation of concrete strength may be gained from compression tests conducted on cores having a diameter considerably smaller than the recommended one of 100 mm. This paper examines the results of tests applied on the 69 and 46 mm diameter cores. A total number of 2982 cores was tested. The effects of both specimen and aggregate sizes for different length-to-diameter (l/d) ratios on the compressive strength of smaller diameter cores were analysed. The core strengths were compared to those of standard cylinder and cubes. Test results showed that maximum size and type of aggregate significantly affect the strengths of small diameter cores. As the maximum aggregate size increased the strength of core decreased. The strengths of cores removed from crushed aggregate-bearing concrete were somewhat higher than those of ones drilled from natural aggregate-containing concrete. Test results also revealed that the l/d ratio of the specimen is more effective for small diameter cores. The age of concrete was found to be an important factor in the interpretation of the results, the older the concrete the higher the core strength. The coefficient of variation of strength values were noticed to be somewhat higher for 46 mm diameter cores and cores drilled from natural aggregate-containing concrete mixtures. It was indicated that core strength was affected by both specimen and aggregate sizes. Therefore, it was proposed that the size of specimen and aggregate, type of aggregate, age of the specimen should be taken into consideration for the interpretation of the results used to convert the strengths of cores to those of standard cylinders or cubes. © 2006 Elsevier Ltd. All rights reserved.Firat University Scientific Research Projects Management Unit: 04 02 01, 03 02 23The authors would like to acknowledge the financial and technical supports supplied by Scientific Research Projects Commission of Anadolu University, Turkey (Projects 03 02 23 and 04 02 01). -

An experimental study on the evaluation of concrete test results

The compressive strength test applied to standard samples is one of the most important tests indicating the quality of concrete in structures. The results of the standard tests are compared with the values used in design calculations to check for specification compliance and quality assurance. Although the standard tests are well accepted by the construction industry, they may not represent the in-situ strength of concrete due to the differences between the degree of compaction and curing conditions of concrete and those of standard samples. The quality of concrete can be assessed by means of minor-destructive methods. Pull-out test is an example of minor-destructive tests. The test causes only minimal destruction to the structure and the hole is repaired easily after testing. In the present study, the results from pull-out tests, and maturity method were extensively analysed for the assessment of concrete strength. © RILEM 2013

Assessment of serum paraoxonase and arylesterase activity in patients with endometrial cancer.

Purpose of investigation: Serum paraoxonase (PON 1) is one of the most important enzymatic antioxidants that hydrolyzes lipid peroxidation, an indicator of carcinogenic activity. The aim of this study was to compare the serum levels of paraoxonase and arylesterase activity in patients with endometrial cancer to those of healthy controls. Methods: Serum paraoxonase and arylesterase activities, total free sulphydryl (-SH) groups and lipid hydroperoxide (LOOH) levels were measured in patients with endometrial cancer (n = 20) and controls (n = 23). Results: Serum paraoxonase, arylesterase activities and total -SH group levels were significantly lower in patients compared to controls (p &lt; 0.05, p &lt; 0.05 and p &lt; 0.001; respectively), while LOOH levels were significantly higher (p &lt; 0.001). Among patients, serum paraoxonase and arylesterase activities were inversely correlated with LOOH levels (r = -0.680, p &lt; 0.05; r = -0.708, p &lt; 0.001; respectively), while these were positively correlated with the total -SH group (r = 0.526, p &lt; 0.05; r = 0.508, p &lt; 0.05; respectively). Conclusion: Reduced serum PON 1 activity might contribute to an impaired antioxidant defense system which plays a critical role in carcinogenesis in patients with endometrial cancer.</p

The circular economy of agro and post‐consumer residues as raw materials for sustainable ceramics

The circular economy in the area of waste management implies their re‐use as a raw material in different production cycles. Both the qualitative and quantitative characteristics of the residues from the agro sector and those of the products of the ceramics sector make possible to think of a feasible application. This review will illustrate some examples of recycling of residues deriving from animal and vegetable sectors (and two post consume products, spent coffee grounds, and packaging glass cullet), studied by the authors, falling within the concept of urban and agricultural sustainable development. Not only the most traditional products such as glass‐ceramics, glazes, bricks, but also the most innovative lightweight aggregates for plant structures or in and out soil cultivation, as well as additives such as deflocculants for ceramic suspensions, which will be illustrated from the design/production, characterization, and comparison with commercial products

Biocompatible Electroactive Tetra(aniline)-Conjugated Peptide Nanofibers for Neural Differentiation

Peripheral nerve injuries cause devastating problems for the quality of patients’ lives, and regeneration following damage to the peripheral nervous system is limited depending on the degree of the damage. Use of nanobiomaterials can provide therapeutic approaches for the treatment of peripheral nerve injuries. Electroactive biomaterials, in particular, can provide a promising cure for the regeneration of nerve defects. Here, a supramolecular electroactive nanosystem with tetra­(aniline) (TA)-containing peptide nanofibers was developed and utilized for nerve regeneration. Self-assembled TA-conjugated peptide nanofibers demonstrated electroactive behavior. The electroactive self-assembled peptide nanofibers formed a well-defined three-dimensional nanofiber network mimicking the extracellular matrix of the neuronal cells. Neurite outgrowth was improved on the electroactive TA nanofiber gels. The neural differentiation of PC-12 cells was more advanced on electroactive peptide nanofiber gels, and these biomaterials are promising for further use in therapeutic neural regeneration applications