Key Engineering Materials Vol. 895

Abstract: This paper aims to investigate the relationship between the Superpave rutting parameter of asphalt (G﹡/sin δ) by conducting Dynamic Shear Rheometer (DSR) tests with the rut depth values obtained by the wheel track device. The twenty asphalt mixtures have been prepared with twenty types of unmodified asphalts and Polymer-Modified Binders (PMBs). SBS was used to produce PMBs. The twenty base and modified asphalts have been used to prepare asphalt paving mixtures required to conduct wheel track tests. The predicted model of asphalt mixtures rut depth related to asphalt rutting parameter (G﹡/sin δ) values has been founded. Besides, the minimum limits of (G﹡/sin δ) of aged asphalt have been gotten as 3.25 kPa for Iraqi asphalt cement.

Abstract: The objective of this paper is to calculate the influential properties of concrete. These are the dynamic properties of sustainable concrete in the situation in which metal waste can found within its components. Growing the rate of pollution in the world, a fast decrease of the original resource, the requirement for utilization more areas of natural land, and increase the price of the newly available area are the reasons that make the researchers give great attention to the new concrete (green concrete) and destruction of unwanted material in the green mix. The concept of reuse aimed at sustainable structures was implemented within the current paper through consuming metal waste of cans and bottle caps in concrete. The waste materials were consumed in two modes; at 1^st mode, it was applied in the role of fibres and mixed using 15% by weight of cement. On the 2^nd mode, it was applied as coarse aggregate with 25% replaced by volume. The procedure includes testing 4 concrete mixes. The estimated properties were the flexural and compressive strengths, besides modulus of elasticity. Adding bottle caps (waste materials fibres) in concrete led to enhancement in strengths. The use of walls of cans (waste materials fibres) in concrete reduced the strengths. While in the case of compacted bottle caps plus pull-tab of cans (waste materials aggregate), concrete mechanical properties a little below the reference mix. The dynamic properties of concrete contain these types of waste under impact load were determined. As known, the dynamic properties are so helpful in the strategy that deals with civil constructions put in danger of impact loads like runways, gas explosion, etc. CEB-FIP (2010) code provides wide-ranging formulas to predict the strain change of concrete. The dynamic properties are determined by this code with consideration strain level between (10^-2-10⁰). In this range, dynamic loads in the civil constructions at the level of quasi-static strain were predicted.

Abstract: A Collapsing soil usually causes problems, this kind of soil has a substantial strength while it is dry, but it loses its strength while inundating and be subjected to extreme settlement. It is impossible to predict in advance the reactions of soils subjected to inundating (i.e. landslide otherwise an important soil settlement). The reduction in irreversible volumes of collapsing soil happens quickly as well as suddenly, once the reduction starts there will be no measurement to be executed which could halt such difficulty. As a result of the soak and leach that are resulting from the dissolute and clean out of gypsum, the collapsing potentials increase during the time. There are many studies in this field that indicated the possibility of modifying this soil by using nanomaterials. In this study, the nanomaterial used is nanocarbon and the soil is gypseous soil taken from Al-Najaf city in Iraq. This work studies the effect of adding nanomaterials on the gypseous soil and investigates its behavior before and after adding nanomaterial. The results showed that adding the nanocarbon affects the collapse potential which decreases by a percent meanwhile the soil cohesion decreased partly when the nanocarbon is added with 0.8% but the friction angle increased about 19%. The best proportion of using of the nanocarbon ranges between 0.8-1.2%.

Abstract: In this study, polymer composites were manufactured with epoxy-based resin and wastes as a mineral additive. The wastes including a high content of silica (Silica fume, glass and fly ash) powder were used as fillers for an epoxy adhesive to improve its wear resistance properties. They were supplemented to mixes in various ratios via substituting the resin from 0 to 20% by weight. Tests of wear rate and hardness were conducted upon all-polymer composites at all fillers ratios. Results indicated that the epoxy hardness increased with increasing the filler addition. Consequently, the addition of wastes that include silica raised the wear resistance of polymer composites; nevertheless, it caused the composites harder materials. The wear rate decreased with increasing the silica fume, glass, and fly ash addition. In the case of fly ash addition, the minimum wear rate was at 15%, and after this percentage, the wear rate increased. However, in the case of glass addition, the minimum wear rate was at 10%, and after this percentage, the wear rate increased.

Abstract: This investigation aims to use corn cover as natural fibers in concrete mixes to improve some mechanical properties like compressive strength, tensile strength, and flexural strength. using any type of fiber in concrete, in general, can improve the tensile and flexural strength of concrete. Concrete is weak in tension, so using fibers such as natural fibers like trunk fibers or industrial fibers such as steel fibers can improve tensile, the flexural strength of concrete and that may be decreasing the use of steel reinforcement in concrete, and also fibers can improve toughness and ductility of concrete because of its work inside the concrete that can reduce the propagation of cracks under loading. This study shows slight improvement on compressive strength by using fibers, but high increments in flexural strength, the optimum ratio of corn cover fibers was 2.5% by weight of cement which gives the highest values in compressive strength and flexural strength. compressive strength increased from (31.2 to 35.9) MPa (about 15% increment), increment for flexural strength was 70.6% for the optimum fibers content and the failure by using corn fibers was a ductile failure compared with plain concrete that gives sudden failure under flexure load, also tensile strength increased by using fibers, more fibers content beyond or more than 2.5% give lower values for the mechanical properties.

Abstract: The research aims to decrease the effect of air pollution due to CO2 pollution that liberates during the manufacturing of cement and that can be done by using less cement content in concrete without decreasing the strength of concrete. also reducing cement in concrete leads to less cost of construction and easy work in casting and finishing in concrete works due to using super-plasticizer that makes mixes with high workability and not needs any compaction in construction .the study show higher values of compressive and flexural strength of concrete with low cement content obtained by using CF super-plasticizer admixture .250 kg/1 cubic meter concrete with CF admixture gave more improvement in compressive strength compared with 350 cement content, also 400 cement content gave more results in compressive and flexural strength compared with ordinary concrete with 550 cement content.

Abstract: To manufacture high-strength and high-performance concrete, the incorporation of silica fume with concrete was becoming popular nowadays. When utilizing various amounts of cement substitute products, the design becomes even more complicated. The latest research has been dedicated to researching the applicability of cement substitute products for cement kiln dust (CKD) and silica fume (SF). In permeability and compressive strength terms, the effect of these components on the efficacy of the concrete would be studied. Also, the materials proposed might limit greenhouse gas emissions, which will mitigate climate change on other causes of global pollution. Casting a standard concrete cube (100 percent OPC) equivalent to (150 gm) would initiate the experiment, which was utilized later for comparative purposes. The industrial waste materials (SF and CKD) was be applied as cement substitution proportions (10 percent, 20 percent, and 30 percent) of the dry cement weight at varying percentages of each component (5 percent, 10 percent, and 15 percent). Eventually, after 7, 14, 28 days, the compressive strength shift would be calculated. The permeability of the latest concrete will be checked after (7, 14, and 28) days of healing utilizing ultrasonic pulse velocity (UPV) technology. The experimental findings indicate that with a specimen comprising 20 percent of (SF and CKD) relative to (100 percent OPC) specimen, there is an improvement in compressive intensity and pulse velocity values in various curing times and specimens of various (SF and CKD) specimen M3 have a decrease in pulse velocity value after 7 curing days.

Abstract: Reinforced concrete foundation, rigid pavements, and other structural members with attachment with ground or salty water like piers or retaining walls and others, subjected to chloride and sulfate salts attacks and that leads to damaging the structures or at least reduce durability, some concrete admixtures like waterproofing admixtures or polymers reduce permeability and increase mechanical properties and also durability. This research aims to improve the quality of concrete and reducing corrosion of steel reinforcement by using integral waterproofing admixture, styrene-butadiene rubber (SBR) and polypropylene fibers. mechanical properties such as compressive, flexural strength highly improved in this study. The reduction of weight of steel reinforcement by subjecting reinforced concrete specimens to chloride water (6% concentration) was 2.61 % for ordinary reinforced concrete and by using waterproof –polymer concrete with poly fibers, the reduction was less and its value was 0.93% and that was for 6 months’ exposure, and for 1-year exposure, the reduction in steel reinforcement weight was 4.72% for ordinary concrete and 1.4% for waterproof concrete.

Abstract: The main objectives of this study are to study the enhancement of the load-carrying capacity of Asymmetrical castellated beams with encasement the beams by Reactive Powder Concrete (RPC) and lacing reinforcement, the effect of the gap between top and bottom parts of Asymmetrical castellated steel beam at web post, and serviceability of the confined Asymmetrical castellated steel. This study presents two concentrated loads test results for four specimens Asymmetrical castellated beams section encasement by Reactive powder concrete (RPC) with laced reinforcement. The encasement of the Asymmetrical castellated steel beam consists of, flanges unstiffened element height was filled with RPC for each side and laced reinforced which are used inclined continuous reinforcement of two layers on each side of the Asymmetrical castellated steel beam web. The inclination angle of lacing reinforcement concerning the longitudinal axis is 45. Four specimens with four different configurations will be prepared and tested under two concentrated loads at the mid-third of the beam span. The tested specimen's properties are the First model; unconfined, Asymmetrical castellated steel beam (Reference), while the second, third, and fourth models consist of Asymmetrical Castellated steel beam (web and flange) confined with (RPC) with 19.1, 38.2, and 57.3 mm gap, respectively, between the two beams sections (the upper and lower one). The results of the experimental tests show that the use of RPC enhanced the properties of the castellated beams in all selected conditions despite creating a gap between the castellated beams.