Development of high durability concrete for the Arabian Gulf environment.

Concrete is probably the most widely used construction material in the world. In the Arabian Gulf region, deterioration of concrete due to the aggressive environment is recognized to be the main factor affecting their structural integrity. The durability of concrete structures can be preserved by various protection methods; however, using cement replacement materials is one of the most effective and economic methods of maintaining their stability as well as extending their service life. The aim of this project is to study four interrelated aspects, namely, (1) the effect of hot environment on the properties of fresh concrete incorporating mineral admixtures, (2), the influence of exposure environment on the engineering properties of hardened concrete, under various curing conditions, without and with mineral admixture, (3), the differences in porosity and pore structure of the same set of mixes, and, (4) the effect of outdoor exposure on the durability-related properties of concrete. To achieve the above aims, the experimental programme involved the study of five different mixes of combinations of silica fume/slag and silica fume. The effects of real exposure to the Arabian Gulf environment of these mixes subjected to four curing regimes, namely, continuous water curing, no water curing after demolding, and air drying after 3 and 7 days of initial water curing were investigated. The properties investigated include (1) consistency and setting times of cement pastes, workability and workability loss with time, (2) engineering properties such as compressive strength, dynamic modulus of elasticity, pulse velocity, shrinkage, expansion and thermal expansion, (3) microstructural properties such as porosity and pore size distribution, (4) durability-related properties such as permeability, water absorption and carbonation depth. The results show that exposure to hot environment results in rapid setting times, faster loss of slump, higher porosity, coarser pore structure and more permeable concretes. It was found that part cement replacement by silica fume and slag improves the quality of concrete mixtures, refined the pore structure and produced concretes with very low porosity and continuous pore diameter in both indoor and outdoor environment. The properties of concrete containing mineral admixture appear to be more sensitive to poor curing than the plain concrete, with the sensitivity increasing with increasing amount of slag in the mixture

A novel approach of introducing crystalline protection material and curing agent in fresh concrete for enhancing hydrophobicity

A new line of research to enhance the performance of concrete under adverse (harsh) and normal (air cured) curing conditions is presented. A crystallising hydrophobic admixture and curing agents were added to fresh concrete to improve its resistance against severe environmental conditions. A two-stage approach was pursued by adding the crystallising admixture to fresh concrete followed by curing agents, in a wax and liquid forms, in a separate application process, followed by exposing concrete to normal and adverse curing conditions. Results obtained suggests that protecting concrete with the crystallising admixture followed by applying wax based curing agent improves concrete strength and its resistance to water ingress than concrete cured with the liquid curing agent. When following the crystallising-wax treating system under adverse curing conditions, a more conserved strength was noticed compared to that produced by the crystallising-liquid system. Using the liquid curing agent in concrete with high water to cement ratio (w/c) has increased the cracks in the internal structure, while water permeability has decreased, either under normal curing conditions or adverse conditions. Following this protection-curing system in industry would resolve the problem of applying protection on wet surfaces and increase concrete’s resistance to deterioration. A microscopic study of the crystallising material was attained with a Scanning Electron Microscope (SEM) to check crystal growth with time

Helicobacter pylori infection and celiac disease in children, what is the relationship?

Background: Celiac disease (CD) is an autoimmune disease affecting the small intestine, triggered by gluten. The pathogenesis of CD has been well defined, and the increasing prevalence of this disease had led to studying several environmental risk factors that may trigger an autoimmune process in the small intestine. Infection is one of the most important factors that can trigger autoimmune processes. The researchers have studied the association between H. pylori infection and CD, the authors have reported conflicting results. Purpose: to study the association of H. pylori and celiac disease (CD) at the time of CD diagnosis in children. Patient and Methods: All patients in the study were subjected to full history taking, thorough clinical examination, and laboratory investigations including Anti-tissue transglutaminase antibodies (IgA), anti-endomysial (IgA EMA), Stool Ag for H. pylori, CLO test for H. pylori, Immunoglobulins level, Upper gastrointestinal endoscopy with multiple biopsies for histopathological examination. Results: Anti TTG Ig A and Endomysial Ab were positive in 49 patients, while one patient showed negative results. 7 patients (14%) had H.&nbsp

Bloody stool in infants with gastrointestinal manifestations of cow milk protein allergy, any significance?

Background: Cow milk protein (CMP) is the most common cause of food allergy in infants and young children. CMP allergy (CMPA) can affect more than one system, such as the skin, respiratory, or digestive systems.  Gastrointestinal tract manifestations are nonspecific. One of the most important GI manifestations of CMPA is bloody stool. Purpose: This study aims to describe how many infants with GI manifestations of CMPA presented with bloody stool as it was a very annoying symptom to the family and describe how can be managed adequately. Methods: This study included 100 patients with gastrointestinal manifestations of CMPA, their ages ranged from 8 weeks to 2 years.  52 males and 48 females. All study patients were subjected to complete history, thorough clinical examination, imaging necessary, and laboratory investigations Results: bloody diarrhea was recorded in 23 patients, and 2 of them were diagnosed with food protein-induced enterocolitis syndrome (FPIES). Occult blood was detected in 11 patients in the diarrhea group (33.33%), 17 patients in the GER group (47.2%), and was detected in 5 patients (83.33%) who presented constipation associated with massive abdominal distension.&nbsp