Characterisation and pore structure analysis of mortar incorporating valorised rice husk ash

Physical, chemical, and mineralogical characterisation of as-received rice husk ash (RHA) samples sourced from four rice-growing regions (North, South, East, and West) of India is presented. Valorised RHA was obtained through controlled combustion at two temperature ranges (600–700◦ C and 650–700◦ C) of husks from the North in an industry set up. Valorisation efficacy has been tested through comparative characterisation of the valorised RHAs with the as-received RHAs from the four regions. Blending of 15% valorised RHA (in the beneficiated state) by weight of cement had no adverse effect on compressive strength even though water–binder ratio of the blended mortar had to be increased by 14% to achieve flow of the control cement mortar. Compared with the control cement mortar, porosity of the mortar blended with the beneficiated RHA measured using mercury intrusion porosimetry (MIP) increased by up to 10% primarily due to an increase in the number of large mesopores (0.01–0.05 μm)

Mechanical and physical properties of concrete containing FGD waste

The paper is part of a wide ranging research project on the optimum use of waste from the dry and semi dry flue gas desulphurisation (FGD) processes in concrete. It examines the influence of a typical simulated desulphurised waste (SDW) on the physical and mechanical and physical properties of concrete. SDW was chosen due to the wider variability in the composition of actual FGD waste. Two binder systems were investigated (i) cement and SDW (C-SDW) and (ii) cement, slag and SDW (C-SSDW). The SDW content ranged from 0-70% and the slag from 0-90% as partial replacement of the cement. The properties examined included compressive and flexural strength, water absorption, shrinkage and expansion. The results showed that replacing cement with SDW beyond 20% systematically reduce strength. An increase in SDW reduces shrinkage. The presence of small amounts of slag allows the use of high proportions of SDW. The use of desulphurised waste in concrete applications is possible as adequate strength can be achieved

Influence of curing on pore properties and strength of alkali activated mortars

The paper investigates the effect of wet/dry, wet and dry curing on the pore properties and strength of an alkali activated cementitious (AACM) mortar. The pore characteristics were determined from the cumulative and differential pore volume curves obtained by mercury intrusion porosimetry. AACM mortars possess a bimodal pore size distribution while the control PC mortar is unimodal. AACM mortars have a lower porosity, higher capillary pore volume, lower gel pore volume and lower critical and threshold pore diameters than the PC mortar which indicate greater durability potential of AACMs. Wet/dry curing is optimum for AACM mortars while wet curing is optimum for the PC mortar. Shrinkage and retarding admixtures improve the strength and pore structure of the AACMs

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Effect of initial curing on chloride diffusion in concrete repair materials.

This paper presents the results of an experimental investigation on the effect of initial curing on chloride diffusion in three generic repair materials and a concrete mix of similar grade. Two field conditions of initial curing were simulated as follows: (1) exposure to a chloride environment after 24 h of casting to simulate repair situations, for example in the tidal zone of marine structures where repairs cannot be protected from tidal exposure for long periods; and (2) 28 days of curing at 20 degrees C, 55% relative humidity to simulate field conditions where the repair patches art: exposed to the ambient environment without any prolonged protected curing. For comparison purposes identical specimens were cured in water at 20 degrees C for 28 days before exposure to the chloride environment. Chloride concentration profiles in the materials were determined after 28, 90, and 180 days of exposure. Regression analysis of the experimental data was carried out applying Fick's second law of diffusion to determine the diffusion coefficients (D-C) and chloride concentration on the surface (C-0) Based on the results obtained, an analytical expression for the long-term prediction of chloride concentration in repair materials is given. The results show a high rate of chloride diffusion in the cementitious repair materials containing polymer latex additives relative to plain concrete. The effect of inadequate initial curing on chloride penetration (e.g., exposure to chlorides after 24 h of casting or 28-day air curing) is mole pronounced in concrete mixes than in generic repair materials. (C) 1999 Elsevier Science Ltd. All rights reserved