Influence of Polypropylene and Steel Fibers on the Performance and Crack Repair of Self-Compacting Concrete

The research reported in this paper aims to evaluate the epoxy injection technique used to strengthen fiber-reinforced self-compacting concrete (FRSCC) with high strength. This method is carried out on ruptured concrete specimens to assess the efficiency of the epoxy resin adhesive injection retrofitting technique for strength and stiffness. Five FRSCC mixes were designed and placed using different types (steel and polypropylene) and contents (0%, 0.25%, and 0.45% by volume) of fibers. The fresh and mechanical properties in addition to the microstructure of produced mixes were evaluated to assess the impact of fibers on the behavior of FRSCC. Results showed that the workability of FRSCC is reduced by increasing steel or polypropylene fiber content; however, the rheological characteristics of placed mixes satisfied the European Guidelines for Self-Compacting Concrete recommendation for fresh concrete. Also, splitting tensile, flexural, and shear strengths were enhanced by increasing fiber content. The simultaneous application of epoxy injection in FRSCC for repairing damaged concrete beams was shown to be highly effective.

Analysis of the physcial properties of particleboard from a mixture of cocoa pod peel powder and styrofoam

<p><strong><em>Abstract</em></strong><strong></strong></p><p><strong><em>Abstract. This study aims to determine the effect of optimal physical properties and microstructure on particleboard samples. The percentage variations of cocoa pod peel powder mixture, styrofoam with epoxy resin adhesive were sample A (69:0:30), sample B (68:2:30), sample C (67:3:30), and sample D (66:4:30). 6:30). The materials were compressed were a hot press and a conditioning time of 14 days. sThe most optimum particleboard sample was found in sample B with values of density, moisture content, and thickness expansion, respectively 0,80 g/cm</em></strong><strong><em>²</em></strong><strong><em>, 7,74%, and 9,32%, and met the standards of SNI 03-2105- 2006. The surface shape of the particle board morphology in sample B shows the composition of the material with the adhesive binding optimally so that there are very few empty spaces or cavities.</em></strong><strong></strong></p><h1 align="center"><em> </em></h1><p><strong><em>Keywords:</em></strong><em> cocoa pod husk powder, styrofoam, particle board, epoxy resin.</em></p>

Effect of Injecting Epoxy Resin Adhesive into Cement Mortar on Tile Adhesion Performance

Large porcelain tiles have attracted increased demand owing to their cost-effectiveness and superior esthetics. Here, an epoxy resin adhesive was injected into cement mortar, which was then applied to tiles. The adhesion performance of the tiles was subsequently evaluated in terms of the permeability and drying shrinkage under various curing conditions. The epoxy resin adhesive not only penetrated the tile–mortar and mortar–concrete interfaces, but also directly penetrated the mortar, thus enhancing the mechanical adhesion at each interface. In addition to the mechanical adhesion between the tiles and mortar, the epoxy resin adhesive prevents the degradation of adhesion due to shear stress by minimizing the moisture evaporation and shrinkage of the mortar. Evaluation of the adhesion characteristics under water and freeze–thaw curing conditions revealed the vulnerability of the epoxy resin to moisture; however, adequate adhesion performance was observed when the epoxy resin was air-cured prior to being exposed to harsh environments. Moreover, the injection method did not prolong the construction period, but could potentially reduce it during actual application. Nevertheless, further research on the adhesion performance of tiles with injected epoxy resin adhesive is required to evaluate the long-term durability.

Interface Debonding Detection of Precast Segmental Concrete Beams (PSCBs) Using Piezoceramic Transducer-Based Active Sensing Approach

An active sensing approach using piezoceramic induced stress wave is proposed to provide monitoring and early warning for the development of interface debonding damage of precast segmental concrete beams (PSCBs). Three concrete specimens with toothed interfaces were fabricated and bonded with high-strength epoxy resin adhesive to form PSCBs. Smart aggregates (SAs) embedded in concrete specimens are used as actuators and sensors. The PSCBs are subjected to periodic loading with hydraulic jack to test the different degrees of debonding damage. The experimental results of time-domain and frequency-domain analysis clearly show that the amplitude of the signal received by the piezoceramic sensor is reduced when debonding crack occurs. The energy analysis and damage index based on wavelet packet can be used to determine the existence and severity of interface debonding damage in PSCBs. The experimental research validates the feasibility of monitoring the interface debonding damage in PSCBs using SA transducers based on active sensing technique.