This article focuses on the experimental investigation carried out on the characteristics of ferrocement thin composite elements using various reinforcement meshes in flexure. The parameters of this study include: the effect of the various kinds of reinforcement meshes (stainless steel meshes and E-fiberglass meshes); number of mesh layers and various mesh diameters with opening size as well as various kinds of mortar materials as matrix (cement grout mortar and polymer— cement grout mortar) on the first crack load; bending stiffness; ultimate flexural load; load—deflection behavior; crack characteristics; energy absorption capacity; and ductility index. The results clarify that the use of stainless steel meshes as reinforcement system in the ferrocement thin composite elements contributes significantly to the improvement of bending characteristics in terms of first crack load, bending stiffness, ultimate flexural load, energy absorption to failure, and numerous fine and well-distributed cracks with a smaller width than while using fiberglass meshes. The method outlined by ACI Building Code is used to compute ultimate moment capacities. The results obtained using this method are compared with the experimental results.

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Traditional building materials may not be appropriate in view of the urgency in dealing with flash flood victims which need for immediate replacement of destroyed housing at a reasonable cost. Thus, the solution lies in making the best use of lightweight sandwich composite technology for flash flood victims lost residence in a short time. Therefore, this research focuses on comprehensive comparisons in bending of LWF sandwich/concrete (RC) composite beams. The flexural response of the LWF/RC beams is investigated in terms of crack load, load-deflection curves, stiffness, energy absorption capacity, ductility index, ultimate flexural load-to-weight ratio, load-strain curves, crack patterns, number of cracks, average crack width, crack spacing, and the failure mode. The test results reveal the remarkable enhancement in the flexural behavior and potential application for reconstruction of flash flood victims lost residence utilizing lightweight sandwich composite technology. The method outlined by ACI Building Code is used to compute ultimate moment capacities. The results obtained using this method are compared with the experimental results.

This paper presents the simultaneous effect of alkali activator and water/slag cement ratios on composites properties by full replacement of Portland cement at different ages under steam curing condition. Twelve mortar composites divided into four different groups were prepared using municipal slag cement and alkali activator of sodium meta-silicate by varying the ratios of alkali activator/slag cement and water/slag cement. The results revealed that the addition of municipal slag cement by full replacement of Portland cement was largely worthwhile for slag mortar composites under steam curing condition. The preparation of the mortars by taking various ratios of alkali activator/slag cement and water/slag cement contributed significantly in improving the compressive strength with an acceptable drying shrinkage to slag composites. Scanning electron microscopic technique was used to analyze the microstructure of slag composites at different ages. The ACI 209 and EC 2 design equations were used to predict the compressive strength.

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In recent years, strengthening concrete structures with FRP sheets using carbon or aramid fibers has gained great interest. In this method, FRP sheets are bonded to the concrete surface, which is roughened in advance using a tool such as a disk-grinder. The bond strength between an FRP sheet and concrete influences the structural behavior of concrete elements reinforced with FRP sheet bonding. The surface roughness has a great influence on bond strength. It is necessary to introduce an evaluating method for concrete surface roughness and to grasp the relation between bond strength and the surface roughness index in order to establish reliable performance from the FRP sheets method. The present study describes the relations between bond strength and various surface roughness indexes. The surface roughness of concrete was varied by changing the treatment methods, such as, sandpaper polishing, disk-grinding, sand-blasting and chipping. The 3D profiles were measured using an optical displacement meter. Surface roughness indexes, maximum depth Dmax, superficial area St, form factor k and the bearing ratio curve were obtained based on the measurements. Bond tests on the concrete treated by above methods were carried out as well. It was found that profile depth CF derived from the bearing ratio curve has the greatest influence on bond strength among the indexes.

A new thermal radiation technique using an infrared radiometer has been developed to detect flaws of materials,such as inclusion,crack and pinhole. In the present study, several incident radiation energies like sun, lamp and gas, were injected to the test material with an artificial internal flaw. Transient radiation temperature image of the flaw on the CRT represents the existence of the internal flaw with higher radiation temperature than that of the surface without the flaw. The characteristics of various incident energy methods were compared with each other. The detecting limitation of internal flaws is determined by the surface temperature variance of the tested materials. The heat flow around the flaw was numerically analyzed by solving a heat conduction equation to verify the surface temperature behavior above the flaws.

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