Properties of mortars with fly ash as fine aggregate

Coal power plants produce million tons waste fly ash worldwide that cause environmental problem and threaten people health. Moreover, its depoting costs are high and need extensively large depot areas. Recycling is a strategy to consume waste content left from several industries. Although fly ash has been used in cement and concrete technology. In concrete technology it has been used as supplementary cementitious material or replacement material with a portion of cement until now. But, it has not been considered as fine aggregate. In this study, the effect of fly ash as fine aggregate in mortars is investigated. Flow ability, unit weight, ultrasound pulse velocity, compressive and flexural strengths, modulus of elasticity, stress-strain behavior and free drying and restrained shrinkage tests were conducted on mortars produced. It was observed that the usage of fly ash as fine aggregate presents a new approach to consume high amount of fly ash without causing significant changes on properties of mortars when it was used at the ratio of 60-70%. © 2015 Elsevier Ltd. All rights reserved

Prediction of restrained shrinkage crack widths of slag mortar composites by Takagi and Sugeno ANFIS models

Shrinkage is an important parameter affecting crack development of mortars and concrete. With the occurrence of shrinkage cracks, the concrete starts to be exposed to the corrosion which significantly decreases the durability of concrete or mortars. In this study, the results of free shrinkage tests determining the length changes and ring test determination of the restrained drying shrinkage cracks are used for predicting the crack widths of granulated blast furnace slag fine aggregate mortars using adaptive-network-based fuzzy inference system (ANFIS). Subsequently, replacement ratios, drying time and free shrinkage length changes are used as inputs and crack width as output in order to predict the shrinkage cracking of these mortar types. The experimental test and the prediction results from the ANFIS model are compared with each other. It is clear that ANFIS can be employed directly in the prediction or discussion of the drying shrinkage cracks

Effect of metallic aggregate and cement content on abrasion resistance behavior of concrete

Many concrete structures are required to have sufficient abrasion resistance, such as dams, canals, roads and floors. The abrasion resistance of concrete may be defined as its ability to resist being worn away by rubbing. Compressive strength and aggregate type are also important factors affecting the abrasive behaviour of concrete. However, very little information on the properties of haematite containing concrete has been reported. The authors report on the abrasion resistance of concrete with four different cement contents (300, 350, 400 and 450 kg m 23 ) and with haematite as a metallic aggregate with replacement ratios of 15, 30, 45 and 60% under 5, 10 and 15 kg loads. The water/cement ratio was kept constant at 0?40 to evaluate the effects of haematite and cement content. Slump tests were conducted to evaluate the workability of fresh concretes. For hardened concrete samples, mechanical tests such as compressive strength, splitting tensile strength, unit weight and wear resistance were performed. Along with the physical and mechanical properties of concretes, haematite was studied as a mineral. Increasing both cement and haematite content has substantial effects on the strength of the concrete. Polarising microscopy views of the interfaces show that haematite aggregates exhibit greatly improved bond strength. Wear loss of concrete decreases with increasing concentration of haematite, while it increases with increasing cement content. An equation representing wear as a function of cement content, compressive strength and also applied load provides virtually perfect agreement with the experimental results

Characteristics of isolation mortars produced with expanded vermiculite and waste expanded polystyrene

Mortar is one of the most important component of cement based composites. Aggregates have also a significant effect on properties of mortars. Generally natural and crushed fine aggregates are used in mortar production for different applications and aims, one of which is energy conservation in buildings and facilities. Vermiculite and waste polystyrene as aggregates in mortar presents an opportunity to reduce the unit weight and the thermal conductivity coefficient that is important for thermal isolation. Five vermiculite+polystyrene/cement ratios, 3, 4, 5, 6 and 7, by volume were used to produce mortars. In each ratio, 100% vermiculite and 100% polystyrene by volume were studied in addition to their combination at 25%, 50% and 75%. Totally, 25 mortars with 4 × 4 × 16 cm were fabricated to investigate physical, mechanical and thermal properties. It was observed that the usage of vermiculite and polystyrene in mortar makes possible the production of mortars with unit weight between 393 and 946 kg/m3 due to very high porosity up to 67.2%. This is also very important in terms of thermal conductivity which decreases up to 0.09 W/mK. Compressive strength presents a variation between 0.57 and 5.89 MPa. Mortars with vermiculite and polystyrene can be used as a good insulation material where needed. © 2019 Elsevier Lt