Evaluation of Correlative Factors between Destructive and Non- Destructive Tests of Concrete

تتطلب عملية تقييم المنشات الجديدة والقديمة إنفاق المال للتعرف على الحالة الفعلية المنشا لاستخدامه بصورة امنة من خلال استخدام الاختبارات الغير اتلافية حيث تصبح أدوات مفضلة لمراقبة كفاءة وجودة المنشات. ان إحدى الطرق الأكثر فعالية والأقل كلفة هو استخدام سرعة نبض الموجات فوق الصوتية (UPV). ان الهدف من هذا البحث هو ايجاد علاقة رياضية بين سرعة نبض الموجات فوق الصوتية وقوة انضغاط الخرسانة. لذا يتم التقصي للمتغيرات الهامة التي لها تأثير ملحوظ على هذه العلاقة اذ تشمل هذه المتغيرات نوع طريقة الفحص UPV (المباشرة، شبه المباشرة، وغير مباشرة)، ومقاومة الانضغاط. ولتحقيق الهدف من هذه البحث لذا فقد تم إجراء دراسة تجريبية لاعداد ستة الخلطات الخراسانية المختلفة (من C20 إلى C45) التي تستخدم في صب عينات الاختبار تتكون من 6 كتل خراسانية بابعاد 40 × 40 × 100 سم ولكل واحدة 9 مكعبات بقياس 15 سم والتي تم اختبارها في عمر 7، 28، و60 يوما. من نتائج الفحوصات المختبرية التي تم الحصول عليها تمت عملية التحليل الإحصائي لمعالجة تلك النتائج باستخدام البرنامجين MathLab وMicrosoft Excel لايجاد واستخراج العلاقات والرسوم للعلاقات الرياضية المختلفة. وتبين نتائج الدراسة وجود علاقة بين سرعة نبض الموجات فوق الصوتية (UPV) لكل انواع الفحص وقوة انضغاط الكتل والمكعبات الخراسانية وهذه العلاقة تاخذ نوع العلاقة الاسية والتي تكون متوافقة مع نوع العلاقة المعطاة للمدونة 228ACI وبالنتيجة يمكن استخدام العلاقة في هذا البحث لتقييم الواقع الفعلي للمنشات. تم ملاحظة ان قيمة UPVبالطريقة المباشرة هو اعلى بنسبة 5٪ و8.7٪ مقارنة بطريقتي UPVشبه المباشر، وغير مباشرة على التوالي. وعلاوة على ذلك، فإن المسارات الصغيرة لطريقة UPV تعطي تقديرات عليا لمقاومة انضغاط الخرسانة.وأخيرا، تمت مقارنة المعادلة المشتقة في هذا البحث مع معادلة باحثين آخرين للتاكد من دقة نتائج البحث باستخدام تجارب موثوقة.The assessment of new and old structures requires spending money to recognize the actual state for safe using them and to satisfy that the using of nondestructive testing become a favored tool to be applied for the function and quality control for the structures. One of the most effective and least costly methods is using Ultrasonic Pulse Velocity (UPV) method. The target of this paper is to find a mathematical relationship between the Ultrasonic Pulse Velocity (UPV) and the compressive strength of concrete. Therefore, the important variables which have a sensible effect on this relationship shall be investigated. These parameters include the test type of UPV testing method (direct, semi direct, indirect), concrete strength. To achieve the goal of this paper, an experimental study has been conducted to preparation six different concrete mixtures (from C20 to C45) at casting the specimens which consist of 6 concrete blocks of dimension 40×40×100 cm and for each one 9 cubes are cast of size 15 cm which has been tested at ages of 7, 28, and 60 days. For the obtained results, a statistical experimental program has been carried out in order to establish a fairly accurate relation between the ultrasonic pulse velocity and the concrete compressive strength using both MathLab and Microsoft Excel programs for extracting and plotting the final relationship models. From the obtained results, the relationships between the direct UPV, semi direct UPV, and indirect UPV in the concrete blocks and cubes with the compressive strength of concrete were found. It is found that the type of an equations is exponential type which has the similar trend of  given a relationship of ACI committee 228so these results indicate that direct, semi direct, and indirect model methods can be used to assess the actual state of in-situ structures. The direct UPV is 5% and 8.7 % higher than the average semi direct and indirect UPV respectively. Moreover, the small UPV paths give higher overestimations of concrete strength. Finally, the suggested equation in this paper is compared with the other researcher's equations to indicate the accuracy using a verification study

Properties of pervious concrete made from graded and single size crushed coarse aggregate

The current search is aimed to investigate the properties of the pervious concrete cast from graded and single size coarse aggregate. A total of 18 mixes, nine mixes for each type, were designed, cast and sampled. The properties concerning compressive strength, flexural strength, density and porosity were discussed. The influence of aggregate type, water-cement ratio (w/c) and coarse aggregate to cement content ratio (CA/C) on the characteristics of pervious concrete was tested. Three w/c (0.3, 0.35 and 0.4) were used in each type of pervious concrete. For each w/c, three CA/C (3.5, 4.0 and 4.5) were employed. Besides, relationships between compressive and flexural strength, compressive strength and density, compressive strength and porosity and between density and porosity were developed and discussed. The experimental results prove that both types of pervious concrete have the usual tendency regarding the properties. At the same time, the tests of compressive strength, flexural strength and density reflect the reduced mechanical characteristics of pervious concrete in comparison to normal concrete. The density of the tested specimens decreased with increasing porosity up to 22% and 32% for graded and single size aggregate pervious concrete respectively, and then it continued approximately stable

ESTIMATION OF COMPRESSIVE STRENGHT OF THE CONCRETE CONTAINING SUPERPLASTICIZERS

The aim of this study is investigating of effect of superplasicizer (SP) type and dosage at different levels of compressive strength on the fresh concrete workability and compressive strength development with age. The experimental program included preparation of 18 concrete mixes; these mixes were divided to three groups depending on compressive strength level, in each group, three different types of superplasticizer with two different dosages (0.5 and 1.0%) for each type of SP. The results showed that the type and dosage of SP have pronounced an effect on the development in early age especially. The early compressive strength development of concrete containing PCP and AP types was almost similar and faster than that of NF type. The estimated compressive strength in the early ages by EC2 and ACI 209 equation was lower than the experimental results