Assessment of the Influence of the Type of Filler Materials on the Properties of Cement Grouts

Cement grouts have many purposes in various civil engineering applications such as precast construction, soil stabilization and structural rehabilitation. Using filler materials as a component in cement grouts has been increasingly implemented. The incorporation of such fillers not only does improve the fresh and hardened properties of grouts but also contributes to the decarbonization of grouts by reducing the amount of Portland cement, thereby lowering the carbon footprint of grouting materials. This study aims at assessing the influence of various filler materials on the properties of cement grouts. Three different fillers were used in this study: commercial limestone, commercial pure dolomite, dolomitic quarry dust. These fillers were assessed in terms of their effect on the spread, flowability, cohesion and compressive strength at 3, 7 and 28 days. The results show that fresh properties of the grout were dependent on the type of fillers. Dolomitic quarry dust improved the workability and flowability more than the commercial limestone and dolomite did. The compressive strengths of cement grouts did not change significantly with the incorporation of the fillers. However, cement grout samples including quarry dust exhibited slightly higher 28-d compressive strength than other samples although the same mix had lower 1-d compressive strength than other mixes. This study highlights the benefits of utilizing quarry dust in cement-based binders without compromising the performance.

Production, characterization and mechanical properties of Solid form geopolymeric binder- via mechanochemical route using class-F fly ash.

Here, we developed Solid form geopolymeric binder, the reaction between aluminosilicate material and dry chemicals i.e. fly ash with sodium hydroxide and sodium metasilicate by ball milling for 6 hrs. to make in solid form.. Mechanochemical ball milling of raw material causes a solid-state reaction between raw materials and form solid form geopolymeric precursor which requires the addition of water to make Solid form geopolymeric binder. This geopolymer has been characterized by different characterizing techniques, such as XRD, FTIR, FESEM, and EDAX, and evaluated for compressive, flexure, and split tensile strength. In our results, we had achieved a compressive strength of 55.4 MPa, flexure strength of 5.38 MPa, and split tensile strength of 3.9 MPa after 28 days of testing. Solid form geopolymers have overcome the handling and hazards difficulties, which is associated with the conventional route. So now it is possible to use Solid form geopolymeric binder as general building construction and in-situ application for construction industry, which were limited to precast construction work by conventional geopolymer route.

Discussion on Applicability and Requirements for the Installation of Fastenings Using Robot Systems in the Construction Industry

Since robotics is becoming increasingly widespread in the construction industry, more phases and working steps should be investigated for their applicability to automation. Ideally, only few robot systems would be needed and thus be multifunctional.Current robot systems are used almost exclusively in precast construction. At the construction site, only prototypes are in use, and only individual parts of the building shell construction and assembly can be handled.This paper examines to what extent robots can be applied for the installation of fastenings and which boundary conditions exist or need to be addressed. Automated construction, and more precise installation of fastenings, has been partially implemented, which has been shown to increase productivity as well as installation quality, and therefore the components’ structural safety. This knowledge must now be extended to robots. The present work is based on an overview of current research and development and includes a discussion on the current research at the University Duisburg-Essen on a cable robot for brickwork construction. It further demonstrates that fastenings pose an important additional application, especially to ensure the changeover to other building materials. These can be built-in parts, but also brickwork connections or prefabricated parts.It can be assumed that robots will become increasingly important in the construction industry for reasons that include high quality, safety, speed and economic aspects.This is an extended paper of the Creative Construction Conference in Budapest on “Examination of Advanced Fastening Systems for the use of Robots in the Construction Industry” (Spyridis et al., 2019).

Seismic Design of Precast Component Beam-Column Joints using Headed Anchors

Precast construction system ensures high degree of quality, safety, and accelerated construction practice in R.C structures. It is well established in non-seismic conditions where gravity loads are predominated. But it is hesitated to implement during seismic conditions by the effect of lateral loads. Most of structural failures in precast framed structures are associated with beam-column joints as the integrated joint system experience high shear, and moments by cyclic action of seismic loads. In this context, researchers found that the joint distortions in precast system is well associated with its location of beam-column sub-assemblage. In beam-column joints the connections are attributed to locate in D-regions (D:Discrete) and B-regions (B:Beam) where the force transfer mechanism follows by strut - tie method (STM) or flexure beam theory(FBT) respectively. This paper analyzed the seismic performance of “Component Based Precast Joints”[CBPJ] located in D& B regions. To meet the convergence requirements, the connection systems are detailed by mechanical couplers and headed anchors. Five numerical models of exterior beam-column joints representing two models (BM1,BM2) of B-region and three models (DM1,DM2,DM3) of D-region are developed and verified their seismic performance with monolithic joint system by non-linear finite element analysis using ABAQUS software .The results indicated that the use of headed anchors in precast joints are effectively contributed to seismic requirements of shear, ductility, stiffness and energy dissipation. Also the precast joints located in D & B regions resembling good performance of joint sustainability during moderate seismic conditions as monolithic system.