Microstructure and bonding behavior of fiber-mortar interface in fiber-reinforced concrete

The interfacial properties between fiber and matrix play a critical role in the overall mechanical responses of composite materials. In this paper, the glass fiber-mortar interfacial microstructure in fiber reinforced concrete (FRC) is visualized and characterized using X-ray microscopy. Additionally, three types of fiber-mortar interface (glass fiber, high modulus polyvinyl alcohol (PVA) fiber, and basalt fiber) are analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The results revealed a lot of microcracks along with the glass fiber-mortar interface; moreover, the hydration product of the glass/PVA/basalt fiber-mortar interface was much lower than that of the mortar matrix. Because microcracks or lower hydration product have such a negative effect on the interfacial bonding between fiber and mortar, the objective of this paper was to provide an analysis of this problem through extensive testing of their bonding properties. Specimens made of three types of fiber were tested along with three different mortar types under tensile stress and a combined stress state to investigate the interfacial bond properties between fiber and mortar. Results show that both of the tensile and shear bond strength of the interface were not only improved by stronger mortar matrix, but also significantly affected by fiber type. Furthermore, when the interface failed by slipping along the interfacial area, the interface showed an increasing shear bond strength with the increase of compressive stress. This was not the case when failure was due to the crushing of mortar. Finally, the FRC splitting tensile strength was tested to demonstrate the bonding mechanism effects on the FRC mechanical properties

EFEK PENAMBAHAN SERAT POLYPROPYLENE TERHADAP KUAT TEKAN DAN MODULUS ELASTISITAS SELF COMPACTING MORTAR (SCM)

Pada dinding pracetak penggunaan fiber reinforced sebagai lapis kulit dinding sandwich dengan metode self-compacting mortar (SCM) akan sangat tepat digunakan karena akan lebih mudah dan cepat dalam proses produksi panel dinding pracetak. Penelitian ini bertujuan untuk mengetahui nilai kuat tekan dan modulus elastisitas pada self-compacting mortar (SCM) dengan penambahan serat polypropylene. Penambahan serat polypropylene dalam adukan self-compacting mortar (SCM) diberikan dalam 4 (empat) variasi, yaitu: 0 kg/m3; 0,5 kg/m3; 1 kg/m3; 1,5 kg/m3 serat polypropylene. Adukan mortar ditetapkan dengan perbandingan volume: 1 semen dan 5 pasir, f.a.s 0,9 dan sikamen NN 1,2 dari berat semen. Pengujian yang dilakukan pada kuat tekan dan modulus elastisitas dilakukan setelah mortar berumur 28 hari. Data untuk setiap variasi campuran serat diperoleh dari 3 (tiga) benda uji silinder berukuran 15 x 30 cm. Dari hasil penelitian didapatkan kuat tekan silinder mortar dengan penambahan serat polypropylene 0 kg/m3; 0,5 kg/m3; 1 kg/m3;dan 1,5 kg/m3 Berturut turut adalah 12,44 MPa; 10,40 MPa; 12,23 MPa; 9,48 MPa. Dan besarnya nilai modulus elastisitas dengan campuran 0 kg/m3; 0,5 kg/m3; 1 kg/m3; 1,5 kg/m3serat polypropylene. Berturut turut sebesar 9959,53MPa; 8650,95MPa; 10080,19 MPa; dan 8074,94 MPa

Experimental evaluation of new pipe sleeve with weep holes for concrete leakage prevention

Mortar is a layer with high water absorption rate over concrete due to its porous structure. The mortar layer that frequently exposed to water or moisture is more likely to contain moisture in its layer. The example of area that is mostly exposed to water is the bathroom. The water infiltrated and trapped in the mortar slab in the bathroom will eventually increase the moisture content of the mortar slab and will raise many problems such as the deterioration of the building structure surface. Therefore, this study has been carried out to produce a technology to remove the trapped water in the mortar slab and to reduce the moisture content in the mortar layer. The infiltration rate of the water into the mortar slabs installed with the conventional pipe sleeve (T1), the circular weep-holes pipe sleeve (T2), the vertical weep-holes pipe sleeve (T3) and the inclined weep-holes pipe sleeve (T4) have been measured and the results show that T4 has recorded the highest reading of 7.74 ml/min compared to other pipe sleeves. Besides that, T4 has also recorded the highest water flow rate out of the mortar with 1.31 ml/min and recorded the lowest moisture content of 10.1%. Inclined weep-holes pipe sleeve was proven able to work better than other designs. Therefore, the New Pipe Sleeve (NPS) performance with inclined weep-holes designs are studied in depth by changing the weep-holes angles to 15°, 30°, 45°, 60° and 75° and weep-holes surface area of 6%, 8% and 10%. As a result, the weep-holes angle of 60° with 10% weep-holes surface area has recorded the highest water infiltration rate and water flow rate out of the mortar with 20.898 ml/min and 3.764 ml/min, respectively, obtaining the highest reduction of the moisture content by 3.1%. The optimum performance of the pipe sleeve with inclined weep-holes design has been proposed by using Design Expert Software and the optimum performance can be achieved with the used of the weep-holes angle of 69.55° and 10% weep-holes surface area, producing water infiltration rate of 20.4513 ml/min and water flow rate out of the mortar of 3.3795 ml/min. Therefore, application of optimise design of weep-holes has promising potential method to reduce leakage and fungi problem that normally occurred in bathroom area

A segmentation-free isogeometric extended mortar contact method

This paper presents a new isogeometric mortar contact formulation based on an extended finite element interpolation to capture physical pressure discontinuities at the contact boundary. The so called two-half-pass algorithm is employed, which leads to an unbiased formulation and, when applied to the mortar setting, has the additional advantage that the mortar coupling term is no longer present in the contact forces. As a result, the computationally expensive segmentation at overlapping master-slave element boundaries, usually required in mortar methods (although often simplified with loss of accuracy), is not needed from the outset. For the numerical integration of general contact problems, the so-called refined boundary quadrature is employed, which is based on adaptive partitioning of contact elements along the contact boundary. The contact patch test shows that the proposed formulation passes the test without using either segmentation or refined boundary quadrature. Several numerical examples are presented to demonstrate the robustness and accuracy of the proposed formulation.Comment: In this version, we have removed the patch test comparison with the classical mortar method and removed corresponding statements. They will be studied in further detail in future work, so that the focus is now entirely on the new IGA mortar formulatio

Influence of Mortar Rheology on Aggregate Settlement

The influence of the rheology of fresh concrete on the settlement of aggregate is examined. Fresh concrete exhibits a yield stress that, under certain conditions, prevents the settlement of coarse aggregate, although its density is larger than that of the suspending mortar. Calculations, based on estimates of the yield stress obtained from slump tests, predict that aggregate normally used in concrete should not sink. To test this prediction, the settlement of a stone in fresh mortar is monitored. The stone does not sink in the undisturbed mortar (which has a high yield stress), but sinks when the mortar is vibrated, presumably due to a large reduction in its yield stress. This implies that during placement of concrete, the aggregate settles only while the concrete is being vibrated. A unique experimental method for measuring aggregate settlement is also introduced and demonstrated

Use of crushed clay brick waste as dune sand granular corrector in mortar manufacturing

The present study aims to investigate the possibility of using crushed clay brick waste as dune sand granular corrector in mortar manufacturing. The mixtures composition method is based on the progressive substitution of dune sand with crushed waste at different weight contents; 5, 10, 15, 20 and 25%. The effect of these recycled materials was studied in an experimental programme through several tests. The performance of these modified mortars was evaluated in terms of strength, workability, water absorption, and resistance to sulfuric acid attack. The results obtained show that the incorporation of the used waste has a significant influence on the behavior of the mortar, in the fresh state and the hardened state. Further to this, it has also been observed that its inclusion with certain percentages makes it possible to obtain performances comparable to those of the alluvial sand-based mortar, which demonstrates its effectiveness in improving the various properties of the mortar