Study on moisture loss and drying shrinkage behaviour of mortar with mineral admixture based on pore structure

The moisture loss and drying shrinkage behavior of mortar with mineral admixture such as blast-furnace slag and fly ash are investigated focusing on the microstructure affected by curing temperature. The curing at high temperature greatly accelerates the hydration reaction of the mortar with mineral admixture to make pore structure denser and leads to smaller moisture loss than that of mortar without mineral admixture. The moisture loss is almost proportional to the accumulated volume of pores whose radii are larger than the radius at the liquid/vapour interface based on the Kelvin equation and BET theory of absorbed water. When the shrinkage is assumed to be induced only by the capillary tension, the estimated shrinkage shows different tendency from experimental one. It suggests that the other shrinkage driving forces that have been believed to be dominant under severe drying conditions should be taken into account even under normal drying condition (RH=60% at 20 degree)

Characterization of landfill leach ate from municipal solid wastes landfills in Sri Lanka

Open dumping of municipal solid waste (MSW) is the most common way of handling solid waste in Sri Lanka due to high cost involved with advanced technologies for landfilling, lack of technical capacity, lack of know-how to manage landfill sites, and so on. Landfill leachate generated from the MSW landfill sites must be treated before dispose into the environment as it creates many social and environmental problems. Characterization of landfill leachate is important to identify the most critical pollutants present in the leachate and thereby to introduce suitable and applicable treatment technologies such as in-situ permeable reactive barrier technologies for contaminant remediation. Therefore, the objective of this research is to characterize landfill leachate collected from several MSW landfills in Sri Lanka. The leachate samples were collected from 12 landfill sites located in Matale, Hambantota, Kataragama, Bandaragama, Kolonnawa, Gampola, Gohagoda, Wennappuwa, Rathnapura, Negombo, Galle, and Matara. For the collected samples, general water quality parameters (pH, EC, DO, ORP, and SS), organic pollutants (BOD5, COD, TOC, IC, TN, TP), typical anions and cations (Cl-, SO42-, NH4+, K+, Mg2+, Ca2+, etc), and heavy metals (Cr, Mn, Fe, Se, Pb, etc) were measured. The results showed that most of the pollutants (F-, Cl-, PO43-, NH4+, Fe, Se, Pb, BOD5, and COD) exceeded the maximum tolerance limits in Sri Lankan Standards. It was found that the BOD5/COD ratio ranged from 0.01 to 0.6 for the most samples and the highest value of 0.6 was observed in the Kolonnawa sample. Measured EC values for all samples were high and varied ranging from 4.5 to 38.3 mS/cm, indicating the biological treatment system alone would not be effective in reducing the pollutants especially for heavy metals. The results of this study will be used in developing site specific remediation technologies in landfill leachate treatment

Prohibitins Are Required for Cancer Cell Proliferation and Adhesion

Prohibitin 1 (PHB1) is a highly conserved protein that together with its homologue prohibitin 2 (PHB2) mainly localizes to the inner mitochondrial membrane. Although it was originally identified by its ability to inhibit G1/S progression in human fibroblasts, its role as tumor suppressor is debated. To determine the function of prohibitins in maintaining cell homeostasis, we generated cancer cell lines expressing prohibitin-directed shRNAs. We show that prohibitin proteins are necessary for the proliferation of cancer cells. Down-regulation of prohibitin expression drastically reduced the rate of cell division. Furthermore, mitochondrial morphology was not affected, but loss of prohibitins did lead to the degradation of the fusion protein OPA1 and, in certain cancer cell lines, to a reduced capability to exhibit anchorage-independent growth. These cancer cells also exhibited reduced adhesion to the extracellular matrix. Taken together, these observations suggest prohibitins play a crucial role in adhesion processes in the cell and thereby sustaining cancer cell propagation and survival

Determination of relevance between surface free energy and adsorption capacity of cement particles

ABSTRACT The compatibility between superplasticizer and cement was influenced by the adsorption capacity of cement particles. This study investigated the relevance between the adsorption capability and surface free energy. Adsorption capacity and surface free energy of both sulphoaluminate cement and portland cement were measured. The adsorption capacity of cement particles was measured by ultraviolet spectrophotometry. The test showed that particles of sulphoaluminate cement adsorbed more molecules of superplasticizer than portland cement particles. The weight of superplasticizer adsorbed by 2g of sulphoaluminate cement and portland cement were 0.28mg and 0.159mg respectively. Surface free energy of cement particles was calculated by contact angle and the contact angles were determined by the thin-layer wicking technique and washburn equation which is theoretical basis of thin-layer wiching technique presented by Chibowski E. The sulphoaluminate cement, portland cement's surface free energy were 51.46 mJ·m-2 and 49.36 mJ·m-2 respectively. The results showed that the higher adsorption capacity of particles was usual accompanied by higher surface free energy. The fluidity of cement paste was influenced by the adsorption capacity of cement particles because the more molecules of superplasticizer was adsorbed by cement particles there were lacking superplasticizer in the paste. The macro-behaviour of higher adsorption capacity is that the cement paste need more superplasticizer to reach the needed fluidity

Experimental investigation of innovative hybrid composite girders with GFRP and CFRP

This paper focuses on flexural behavior of innovative hybrid I-shaped girders consisting of Glass Fiber Reinforced Plastics and Carbon Fiber Reinforced Plastics. The experimental investigation revealed that the delamination at the interface of glass and carbon fibers in the compressive flange caused a sudden failure and lead to smaller loading capacity than the expected in the case of girders with smaller flange width. In the case of wider flange width, the local buckling of flange in compressive side was observed. It was experimentally found that the appropriate installation of web stiffeners is an effective way to prevent the local buckling of wide flange sections but that FRP materials cannot also exhibit their intrinsic material strength due to the delamination. In order to utilize the materials properties of FRP effectively, it is recommended that further study is conducted with a section having neutral axis towards the upper side of the section

Mechanical behavior of hybrid FRP composites with bolted joints

The behavior of an innovative hybrid Fibre Reinforced Polymer (FRP) composite with bolted joints was investigated. Coupons and full-size specimens were tested to determine the effect of applied bolt torque and the contribution of adhesive bonding on the load capacity and failure mode of the hybrid FRP with bolted joints. The results showed that at different levels of applied bolt torque (10, 15, 20 and 25 N-m), little friction resistance developed. A slight increase on the load capacity was however observed with increasing tightening torque. On the other hand, the bolting accompanied by adhesive bonding provided resistance against slipping. The full-size hybrid FRP girder with joints using bolts and epoxy exhibited the same strength and stiffness as the girder without joints while bolting alone resulted to a beam with only 65% of the stiffness of those without joints. Theoretical analyses were conducted and result showed a good agreement with the experimental results

DETECTION OF CORROSION-INDUCED DAMAGE IN REINFORCED CONCRETE BEAMS BASED ON STRUCTURAL DAMPING IDENTIFICATION

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan