Objective: This study evaluated compressive strength and setting time of some types of calcium silicate-based materials modified with chicken eggshell powder (CESP). Material And Methods: The samples were classified into eight major categories, including Group 1 (non-modified glass ionomer cement (GIC) as a control group), Group 2 (1 wt.% eggshell incorporated GIC powder), Group 3 (3 wt.% eggshell incorporated GIC powder), Group 4 (5 wt.% eggshell incorporated GIC powder), Group 5 (non-modified biodentine (BD) as a control group), Group 6 (1 wt.% eggshell incorporated (BD) powder) Group 7 (3 wt.% eggshell incorporated (BD) powder) and Group 8 (5 wt.% eggshell incorporated (BD) powder). Results: (group 2), (group 6) exhibited the highest statistically significant compressive strength means values, while (group 4), (group 8) exhibited the lowest statistically significant setting time means values, Conclusion : Addition of CESP to GIC and BD can increase compressive strength and decrease setting time of materials.

文章研究了圆端形椭圆钢管混凝土(round-ended elliptical concrete-filled steel tubular,RECFST)构件的受弯性能.基于有限元方法和圆端形椭圆钢管约束核心混凝土本构关系模型的等效计算方法,建立了纯弯作用下RECFST构件的数值分析模型,考虑了材料非线性、圆端形椭圆截面特征及复杂界面接触等问题;通过分析钢材强度、混凝土强度、径厚比及长短轴比等诸多参数在长、短轴方向上对RECFST构件抗弯承载力的影响规律,揭示了其破坏模式,提出了RECFST构件的抗弯承载力简化计算公式.研究表明,钢材强度越大,径厚比越小,RECFST构件的极限弯矩越大.研究结果可为圆端形椭圆钢管混凝土结构设计和应用提供参考.

Efficient structures obtained through Topology Optimization are quite complex and hence difficult to manufacture, especially when the scale of the structures is large, as is the case with Architectural and Civil Engineering Structures, and when the material is brittle, such as concrete. Fabric Formwork is one of the methods to fabricate such shapes, but there are limitations to the maneuverability of the fabric which reflects in constraints to the range of shapes that can be manufactured. This Problem, however can be solved by the external manuplation of the fabric, which can be achieved by Pin-Beds.

In the recent years the consumption of concrete is keep on increasing by the construction industry throughout the world and facing shortage in natural resources due to abundant usage.The scarcity as well as rising cost of raw materials, the concrete technologists are hunt for some alternative materials to manufacture the concrete.In this study an attempt has been made to utilize the waste products in production in concrete.The paper presents the feasibility of utilization of stone waste and industrial by-product such as fly ash for construction work.Here the artificial manufactured light-weight aggregate by pelletization process using industrial by-product such as fly ash and utilization of stone waste such as Cuddapah stone.The industrial by product such as fly ash is a promising material to produce light weight aggregate.This led to the wide spread research on using viable waste materials from industrial by-products.Along with light weight aggregate, Cuddapah stone waste is utilized in this project.In this experimental study various combinations of artificial aggregates were used to produce concrete mixes.The results concluded that the higher compressive strength values were obtained from Cuddapah stone incorporated designed concrete mixes of 50% and 100% replacement of natural coarse aggregate.Whereas the fly ash, sintered fly ash with replacement of fine and coarse aggregate have lesser weight than the normal concrete but they provide lesser strength.The UPV for normal and Cuddapah stone includes great quality higher than the cold bonding fly ash admixture containing medium quality.Keywords -Fly ash aggregate, Cuddapah stone,

The present experimental program was planned to investigate the effect of type of mineral admixture, pre-load and the presence of confining reinforcement on the spalling behaviour of heated high performance concrete (HPC). Reinforced concrete cylindrical short columns were cast and exposed to four different target temperatures. A compressive preload equal to 25% of the ultimate load capacity of column was maintained on the specimens during heating and cooling. The test results mainly focus on the influence of above said variables on spalling behaviour of reinforced HPC columns. Interesting observations have been made in the paper on the subject matter of the workshop.

This paper presents results of an experimental study undertaken to optimize the residual compressive strength of heated high performance concrete using the Taguchi off-line method and the utility concept. The design of experiments (DoEs) was first carried out by Taguchi method using a standard L9(34) orthogonal array (OA) of four factors with three material parameter levels. The factors considered in the context of high performance concrete were cement content, fly ash content, super-plasticizer content and fine aggregate content. The cube specimens were cast and heated up to 200°C, 400°C, 600°C and 800°C target temperatures. They were subsequently tested under axial compressive loads in cooled conditions. Based on the results, the material parameter responses were analyzed by utility concept to reduce the multi-characteristic response and to obtain single setting of optimized parameters in order to maximize the post-fire residual compressive strength of concrete. The results indicate that the best level of control factors paid their own contribution for compressive strength at various elevated temperatures. The cement content was found to be the most influencing parameter followed by fine aggregate content and fly ash dosage. The role of chemical admixture dosage was observed to be relatively less marked on the residual compressive strength of high performance concrete. The confirmation tests corroborated the theoretical optimum test conditions.

This paper presents results of an experimental study undertaken to optimize the residual compressive strength of heated concrete with respect to various mix design parameters using the Taguchi method. The design of experiments (DoE) was carried out by standard L9 (34) orthogonal array (OA) of four factors with three material parameter levels. The factors considered were water-cement ratio, cement content, super-plasticizer dosage and fine aggregate content. The specimens were heated up to 200°C, 400°C, 600°C and 800°C target temperatures and were subsequently tested under axial compressive loads in cooled condition. Based on the results, the material parameter responses of optimum performance characteristics were analyzed by statistical analysis of signal to noise ratio (S/N) and analysis of variance (ANOVA) techniques to maximize the post-fire residual compressive strength of concrete. The results indicate that the best level of control factors paid their own contribution of compressive strength at various elevated temperatures. The confirmation tests corroborated the theoretical optimum test conditions.