Development of Statistical Model, Mixture Design, Fresh and Hardened Properties of Furnace Slag - Lightweight Self Consolidating Concrete (FS-LWSCC)

A response surface method was carried out to model the influence of key mixtureparameters on properties affecting the performance of Expended Furnace Slag - LightweightSelf Consolidating Concrete (FS-LWSCC). Three key parameters that have significantinfluence on mixture characteristics of LWSCC were selected to derive mathematical modelfor evaluating the concrete fresh and hardened properties. Experimental levels of the variables(maximum and minimum) water/binder ratio (0.30 to 0.40), HRWRA (SP) (0.3 to1.2% bytotal content of binder), and total binder content (410 to 550kg/m3) were used for the designof Furnace Slag-LWSCC mixtures. A total of 18 mixtures were designed and produced. Theresponses of the derived statistical model were slump flow, V-funnel flow time, J-Ring flow,J-Ring height difference, L- box, filling capacity, bleeding, air content, initial and final settingtime, sieve segregation test, fresh unit weight, 28 days air dry unit weight, 28 days oven dryunit weight, and 7 and 28 days compressive strengths. It was seen that the proposed mixdesign model is a useful tool to understand the interactions between mixture parametersaffecting important characteristics of Expanded Furnace Slag - LWSCC. This understandingmight be simplified the mix design process and the required testing, as the model identifiesthe relative significance of each parameter, therefore providing important informationrequired to optimize the mix design. Consequently, minimize the effort needed to optimizeLWSCC mixtures ensuring balance between parameters affecting fresh and hardenedproperties

Optimizing a Test Method to Evaluate Resistance of Pervious Concrete to Cycles of Freezing and Thawing in the Presence of Different Deicing Salts

The lack of a standard test method for evaluating the resistance of pervious concrete to cycles of freezing and thawing in the presence of deicing salts is the motive behind this study. Different sample size and geometry, cycle duration, and level of submersion in brine solutions were investigated to achieve an optimized test method. The optimized test method was able to produce different levels of damage when different types of deicing salts were used. The optimized duration of one cycle was found to be 24 h with twelve hours of freezing at −18 °C and twelve hours of thawing at +21 °C, with the bottom 10 mm of the sample submerged in the brine solution. Cylinder samples with a diameter of 100 mm and height of 150 mm were used and found to produce similar results to 150 mm-cubes. Based on the obtained results a mass loss of 3%–5% is proposed as a failure criterion of cylindrical samples. For the materials and within the cycles of freezing/thawing investigated here, the deicers that caused the most damage were NaCl, CaCl 2 and urea, followed by MgCl 2 , potassium acetate, sodium acetate and calcium-magnesium acetate. More testing is needed to validate the effects of different deicers under long term exposures and different temperature ranges

Effect of kaolin waste content on the properties of normal-weight concretes

This paper presents the mechanical, transport and drying shrinkage properties of normal-weight kaoline waste (MW) incorporated concretes. Six different concrete mixtures that have a constant water-binder ratio (w/b) of 0.40 and a binder (Portland cement + kaoline waste) content of 400 kg/m(3) were designed with various MW replacement contents (0%, 5%, 10%, 15%, 20% and 25% of Portland cement by weight). Workability, unit weight, compressive and tensile strengths, water absorption, porosity, sorptivity, rapid chloride permeability and drying shrinkage tests were performed on fresh and hardened concretes. Test results were analysed by considering the KW content and it was concluded that use of MW worsened the workability and decreased unit weight irrespective of KW content. MW incorporation affected the compressive strength positively, especially at the 10% and 15% replacement levels beyond 28 days. Replacement of MW up to 15% exhibited virtually identical porosity and water absorption values with the control concrete. Sorptivity values of KW concrete mixtures (at 5% and 10% kaolin waste replacement) were equal or somewhat lower than that of the control mixture. Chloride ion penetration resistance of concretes improved drastically with the increase of MW content. (C) 2015 Elsevier Ltd. All rights reserved