دکتر مهدی محمدرضایی

Concrete is one of the widely consumed building materials in the construction industry, Among the specifications of the concrete which have been paid attention to by the researchers are compressive strength and tensile strength. So, to attain this goal, in the recent years, using a less ratio of water to cement with superplasticizers and natural and or synthetic pozzolans and also with fibers of different materials and specifications in the concrete mixture is a normal method. In this research, the effect of the combined use of fibre microgels and steel fibres on the mechanical properties and durability of concrete has been studied in a laboratory. Fiber microgels include micro-silica (silica fume), polypropylene fibers (pp fibers) and superplasticizers. Consumable steel fibers are 5 cm long and 0.8 mm in diameter with a hooked end. The effect of microgels and steel fibers were each compared and evaluated in five ratios of fibrous microgels 0, 0.5, 1, 2, 5% and steel fibers in ratios of 0, 05, 1, 1.5, 2%. A total of 25 mixing designs were tested for compressive and flexural strength to evaluate mechanical properties. The results of compressive and bending strength tests have shown that by adding different percentages of fibers, the percentage of increase in compressive strength in most of the 7-day samples has improved more than the 28-day samples. The highest resistance growth was related to the samples containing 5% fibrous microgel and 2% steel fibers.

Granites are interesting because of their abundance in the continental crust and the presentation of valuable information from the depths of the earth and their close dependence on tectonic and geodynamic processes (Bonin, 2007). The Mishu granites are exposed over an area around 50 km2 in the northwestern Iran near the city of Tabriz (Figures 1 and Figures 2). The Mishu granites have been injected into the Neoproterozoic shales, carbonates, sandstones, and tuffs of the Kahar Formation (Asadian et al. 1994). Mafic and ultramafic rocks (gabbro, basalt, and dunite) occur at the north and northeast of the Mishu granites and seem to be the host of granites. Field observations show a magmatic injection of the Mishu granites into the mafic-ultramafic rocks. There are several outcrops of granite rocks in the northwest Iran, including Takab–Zanjan, Khoy, Soursat, and Mishu. Among these outcrops, there are no systematic geochemical and geochronological studies on the Mishu rocks. In this paper, we investigate the genetic relationship between different parts of the mass, origin of the constructive magma and the tectonic position of this intrusion with the help of the results of field studies governing different parts of the Harris intrusion mass, petrography and geochemical analysis of the main and rare elements.

A total of 150 samples were collected from Mishu granites. Polished thin sections were prepared from all the collected samples.
Based on petrographic observations, 20 samples with minimal effects of hydrothermal alteration were selected for whole-rock geochemical analysis (Table 1). These selected samples were analyzed for major and trace elements at the ACME Laboratory (in the ACME Analytical Laboratories of Vancouver, Canada). Analytical errors for major elements are assessed as <1% of the determined concentrations. Results are reported in Supplementary Table 1. Major element oxide analysis was performed by Lithium Borate Fusion and Inductively Paired Plasma Emission Spectrometer (ICP-ES). In this method, the number of oxides of the main elements is measured based on weight percentage. The measurement accuracy for the main elements in this method was 0.01 Wt.%. Also, in this method, the number of volatiles in the form of L.O.I. was measured with an accuracy of 0.01%. The induced coupled plasma mass spectrometer (ICP-MS) method was used to measure the amount of trace and rare elements. The detection threshold of these elements, depending on the element, varied from close to 0.01 ppm to 10 ppm.

Harris granite rocks are in the northwestern Iran and about 20 km west of Shabestar city. This mass is composed of alkaline feldspar granite. The most abundant texture seen in these rocks is micro-pertite and myrmicite and based on lithographic and geochemical properties, they belong to A2-type granites. The samples are meta-aluminous to per-aluminous is based on the saturation index of alumina. In general, the studied granites have higher amounts of Na2O + K2O, Fe / Mg, Ga / Al, HFSEs and lower amounts of CaO, Sr and Eu. Also, the content of REEs of the samples in the normalized graph concerning chondrite shows a negative Eu anomaly. In other words, it is likely that A-type alkaline granites after collision have been created in this area following collision events and during their placement the tensile structure is predominant. Normalized multi-element diagrams as well as high Rb indicate that the continental crust has played a significant role in the formation of the Harris granite producing magma, possibly due to the melting of the lower crust by a tonalitic-granodioritic combination. 

All lithographic and geochemical data show that Harris granite rocks are of A-type nature. Negative anomalies of Ba, Nb, Ti, Sr and Eu and enrichment in LILEs, especially Rb and Th, indicate the crustal origin of these rocks separation of feldspar during crystallization or the presence of feldspar as a residual phase in the origin and the anomaly of P and Ti to iron-titanium and apatite oxides. Enrichment in LILE and HFSE elements with negative anomalies of Nb and Ti is a characteristic of subduction-dependent. The negative anomaly of Eu in the trace element pattern can be attributed to granites, usually attributed to the mantle origin, previously due to the metamorphic activity of fluids from sediments deposited by LILE and HFSE elements (Pearce et al., 1984), or may be the nature of magmas rooted from a subcontinent meteorite mantle formed during early subduction. In addition, enrichment at Th, Rb, and depletion at Sr, Eu, Ba, Nb, and Ti indicate that the granites are rooted in crustal lavas (Zhao and Zhou., 2007).

In urban areas, based on the space constraints, one of the most important issues in the stabilization of slopes is to choose a suitable method for the design of the slope by considering technical and executive problems. Despite the proper design and execution of slopes, a variety of the natural and the artificial factors in a particular period of time may greatly affect their stability. In this study, the investigate the effect of microclimates on the stability of gables under the effect of steady state seepage, seepage analysis was performed using Seep / W software and finite element method, assuming unsaturated saturation flow and in steady state flow. Also, using Slope / W software, slope stability in different conditions including distance, diameter and angle of micropile has been investigated and the sensitivity of the results for permeability and soil resistance parameter has been investigated. The innovation of the present study is using the special parts which eliminates the common assumptions of the limit equilibrium method. Therefore, it is expected that this method will has less error in determining the reliability coefficient. According to the results, it was observed that seepage in the slope, diameter and distances of small piles have a great effect on the stability of the slope, which can be varied according to different conditions. As the distance between the micropiles increases, the slope reliability coefficient with different micropiles diameters becomes closer to the slope reliability coefficient without micropiles and somehow converges to this reliability coefficient.