Review on investigation of corrosion behavior of reinforced concrete with supplementary cementitious materials

Cement concrete is the most widely used material for various constructions. Properly designed and prepared concrete results in good strength and durability. Sometime these mixes are found to be inadequate, hence variety of admixtures are used along with cement. A certain percentage of cement will be replaced separately with metakaolin and silica fumes. Hence the flexural strength test of concrete and evaluation of corrosion behavior of the reinforcement can be performed. The study of flexural property of concrete will be conducted at 7 or 28 days characteristic strength with different replacement level of cement (i.e.0%, 5%, 10%, 15%, 20%). Corrosion behavior of reinforcement will be evaluated based on half-cell potential. Concrete samples will be cured in either fresh water of 4% NaCl saline water for 7 or 28 days of curing period. We assumed that the addition of silica fumes and metakaolin will improve the flexural strength characteristics of concrete and corrosion resistivity of reinforcement. Keywords: Flexural strength, corrosion, metakaolin, silica fumes.

Flexural Property of Composite Biomaterials Used in the Oral Cavity

Composite materials are widely used in the dental field in clinics as biomaterials. For example, it has been used as a biomaterial to repair caries and restore masticatory function, and as a cement to adhere the restoration to the tooth substrate. In order to demonstrate its function, dental biomaterials are measured their mechanical strength. From such basic research, we explained the potential of dental biomaterials, especially flexural strength and modulus of elasticity. Mechanical properties of dental biomaterials similar to those of the tooth, thermal stimulation, and aesthetic elements in the oral cavity. In this part, we will introduce the commercialized products of composites suitable for the characteristics and tooth quality, and provide the reader with the characteristics from the flexural characteristics of the composite materials used in clinical dentistry. In clinical performance, it might be advisable to delay polishing when composite biomaterials are used for luting materials, filling materials and core build-up materials since improved the flexural strength and the flexural modulus of elasticity were displayed after 1-day storage. And it is thought that flexural strength or characteristics is a significant important mechanical property of oral biomaterials.

Study on cement based composite board of wire mesh and straw fibers in severe cold area of Northeast China

There is a large amount of residual straw fibers resources in Northeast China. Rice straw fibers was chosen to make steel-wire-net mortar roof-board composed of straw fibers in different sizes. Cold-drawn and low-carbon steel-wire-nets, whose diameter was 3mm and whose size of mesh opening was 60mm×60mm ,were set on both upper and lower sides. Vertical tied cold-drawn low-carbon wires were set between the upper and lower cold-drawn and low-carbon steel-wire-lath for spot welding. The distance between two vertical tied steel wires was 120mm. After the mortar was squirted on the steel-wire-nets, outbound alkali resistance fiber glass mesh and thin floated finish make the alkali resistance fiber glass mesh and thin plastering mortar and horizontal wire mesh mortar and compressed straw fibers slab straw fibersboard work together. The deformation characteristics that studies roof-board composed of straw fibers boards; the fracture distribution and the feature of crack developing that studies the boards; the strain distribution and its change law were summarized, the loading mechanism of roof-board composed of straw fibers boards had been studied; by observing the failure form and destruction feature of test specimen, the factors affecting the flexural property of roof-board composed of straw fibers boards had been studied, preparation points of roof-board composed of straw fibers boards had been put forward. The advantages of grass steel-wire-net thin plastering roof-board composed of straw fibers boards reside in cheap materials, moderate carrying capacity and it was easy to be applied.

Synthesis of a 9,10-dihydro-9-oxo-10phosphaphenanthrene-10-oxide-based reactive flame-retardant curing agent

This paper aims to prepare a new curing agent, reactive flame retardant (DTF), through one-pot synthesis of 9,10-Dihydro-9-oxo-10-phosphaphenanthrene-10-oxide (DOPO), formaldehyde and triacetonediamine for Epoxy resin (EP). This new DTF was successful prepared through Fourier-transform infrared, 1H NMR, and 31P NMR spectroscopy. The flame-retardant epoxy thermoset was prepared using the 4′4-diaminodiphenylmethane (DDM) as a co-curing agent. The analysis results using the differential scanning calorimetry (DSC) showed that DTF can cure EP and improve the carbon residue yield of epoxy thermoset after burning. It observed that if the content of phosphorus was 1.0 wt%, the limiting oxygen index (LOI) of EP/DDM/DPT-4 was 30.4%, and UL94 reached the V-0 rating. The highest tensile property of the epoxy thermoset reached 98.56 MPa (P content = 0.5%), whereas the highest flexural property reached 137.28 MPa (P content = 0.75%), and the highest impact property reached 24.1 KJ · m–2 (P content = 0.5%).