Advanced Materials Research Vols. 887-888

Abstract: For the problems such as layering and splitting of traditional sandwich structure composite, a resin matrix composite with lattice and interface reinforced structure has been designed, The composite material has high specific strength and stiffness. On this basis, a road pavement developed by this composite material used in engineer urgent was designed. The connection between the pavements was designed for quick assembling, which could make the pavement assemble operation was simple, fast and reliable. Experiments and engineer application indicate that the composite pavement has characters of low cost, simple maintenance, corrosion resistant and reusable, which has a great application prospect.

Abstract: In this paper, the mechanical properties and permeability of the concrete with steel slag coarse aggregates were investigated by comparing with the concrete with crushed limestone coarse aggregates. Results show that the concrete with steel slag aggregates shows similar strength with the concrete with crushed limestone aggregates at the age of 28 days, but it shows a little higher strength especially splitting tensile strength at the age of 90 days. Steel slag coarse aggregates tend to have limited influence on the elastic modulus and permeability of concrete. The results at different water to cement ratios are similar.

Abstract: Artificial sintered aggregate produced by self-firing is one of the few building materials, which can be produced with only fly ash. If the character of the fly ash is optimal, no other additions are needed. However, not every fly ash has optimal composition. Quality of fly ash then influences composition of the mix, technological parameters and quality of produced aggregate. Parameters influence the process of self-firing, strength of granules during the phases of drying process, ignition and burning under given underpressure on an agglomerating bed. This often influences correct setting of proportion of combustion material and reduces quality of aggregate. The paper evaluates fly ash produced in the Czech Republic by both high temperature and fluidized bed combustions. Their granulometry, specific surface, bulk weight, structure, chemical composition and behavior at higher temperatures up to the melting point are evaluated.

Abstract: In order to investigate the influence of surface modification on concrete comprehensive properties, special electrodeposition process is applied to modify the surface of steel fiber. Then the modified fiber and the non-modified fiber are added into concrete for comparisive test and analysis. The results illustrate that the bond strength between the modified fiber and concrete increases about 50% when competing with the non-modified group. Besides, the crack area of non-modified fiber group declines 46% and the toughening effect rises approximately 30%.

Abstract: In order to research the changes of concrete properties in freeze-thaw environment, five concrete samples with water-cement ratio respectively equal to 0.60, 0.65, 0.70, 0.75 and 0.80 were tested in freeze-thaw environment according to GB/T50082-2009 concrete rapid freeze-thaw cycles test method. Five samples were carried out 0, 25, 50, 75, 100 times faster freeze-thaw cycles test. With the increasing number of freeze-thaw cycles, the concrete relative dynamic modulus of elasticity loss rises, the compressive strength drops, and the carbonation depth increases. The greater the water-cement ratio of concrete specimens with freeze-thaw cycles, the greater the degree of damage increases.

Abstract: The paper discusses strength-time relation of unfired bricks reinforced with and without natural fibers. Untreated and treated coconut fibers with three different lengths (1 cm, 2.5 cm and 4 cm) were prepared for soil lime bricks reinforcements. The effects of 4% uniform 2.5 cm fiber reinforcement was compared to the effects of 4% non-uniform fiber reinforcement, which constitutes a fiber mix between 1/3 part each of 1 cm, 2.5 cm and 4 cm fiber length. Absorption of brick was also evaluated. Experimental investigations reveal that for all type of bricks, up to 90 days compressive strengths decrease a little but bending strengths rapidly decrease with time. The results show that unfired bricks added with uniform treated fiber resulted in better strength performances compared to those added with uniform untreated, non-uniform untreated and non-uniform treated fibers, and also to those without fibers.

Abstract: Laminated veneer lumber is taken as an object of study, and use LVL specimens of different sizes for compression test and tensile test. The goal of the experiment is to investigate the size effect on compressive strength and tensile strength as well as the influence of the secondary glued laminated face, which appears in the secondary molding processes. The results show that both compressive strength and tensile strength have the size effect apparently and the existence of the secondary glued laminated face lower the compressive strength of LVL specimens. Afterwards, the relationship between compressive strength and volume along with tensile strength and area are obtained by the test results.

Abstract: The main objective was to determine the effect of additions of cactus mucilage (colloquially called cactus slime which on drying produces weddellite and whewellite crystals, calcium oxalates) and/or volcanic ash in masonry mortars made with lime, on the properties as mechanical resistance to compression, tension and bending, and the physical properties such as porosity which,leachates and capillary absorption. The Fagerlünd method was used, on lime mortar specimens according to ASTM standards. Four mortar mixtures were debeloped: with additions and without them, like sample witness. The lime is slaked handcrafted and comes from Piedras de Lumbre Quarry Stone, Zitacuaro, Michoacan, Mexico; the volcanic ash is a mud from Acambaro, Guanajuato, Mexico and the fine aggregate, sand, proceeds from Joyitas Quarry stone in Morelia, Michoacan, Mexico. A correlation of the mechanical properties of the four mortar mixes versus its degree of porosity was made. Porosity and absorption were affected by the mucilage and/or ashes addition increasing the mechanical strength; however this was not the aim of the research, since it is not intended that the mortars were rigid, it was intended that they were capable of absorbing deformations of the natural stone masonry. The addition of mucilage and/or ash, did reduce the percentage of total porosity, the cactus mucilage when dried formed crystals of whewellite and wheddellite which filled in the pores of the mortar matrix, and the ash, mud, as it is an igneous extrusive stone, in crypto crystallite form, it presented puzolan activity forming new minerals filling the matrix pores.

Abstract: Effect of material mix proportion on strength of cement asphalt concrete (CAC) was studied based on 7d cleavage strength. Results indicate that the cleavage strength of CAC increase sharply with the increase of the cement content (0-6%), and the optimum content of added water and emulsified asphalt were 2% and 6% respectively while the cement content was 5%.

Abstract: The C60 self-compacting concrete (SCC) mixed artificial silica fume (ASF) and silica fume (SF) respectively were evaluated systematically through the items, such as compressive strength, slump loss, air content, and setting time, by which effect principles and mechanisms of ASF on compressive strength and workability of self-compacting concrete were obtained. The results indicate that ASF improves performances of fresh SCC better than SF, and it is a kind of high activity mineral mixture with high-early-strength.