Key Engineering Materials Vol. 895

Abstract: . This investigation aims to improving mechanical properties of normal concrete such as compressive strength, tensile strength, and flexural strength by using integral waterproof admixture (IWP) and also decreasing absorption of concrete, using different mix proportions of concrete, study shows a good increment of compressive strength for all mixes by using integral waterproof and also increasing the flexural and tensile strengths. The study contains also a sulfate attack study on normal mixes and integral waterproof mixes. Different percentages of IWP used in the study containing 0.0%, 1% ,1.5% and 2% for each 100 kg cement. Concrete mixes with 2% IWP admixture and 1:1:1.5 mix proportions give the highest values of compressive, tensile, and flexural strength in the study. compressive strength improved from 33.6MPa for reference 1:1:1.5 mix to 39.8 MPa by using IWP, also less absorption concrete obtained, the absorption was lowered from 3.5% to 1.7%, also deterioration in strength due to sulfate attack was small compared with reference mixes, same to other mixes 1:2:4, 1:1.5:3 that also improved by IWP admixture and lead to increasing mechanical properties and reducing absorption and sulfate attack.

Abstract: Castellated columns are structural members that are created by breaking a rolled column along the center-line by flame after that rejoining the equivalent halves by welding such that for better structural strength against axial loading, the total column depth is increased by around 50 percent. The implementation of these institutional members will also contribute to significant economies of material value. The main objectives of this study are to study the enhancement of the load-carrying capacity of castellated columns with encasement of the columns by Reactive Powder Concrete (RPC) and lacing reinforcement, and serviceability of the confined castellated columns. The Castellated columns with RPC and Lacing Reinforcement improve compactness and local buckling (web and flange local buckling), as a result of steel section encasement. This study presents axial load test results for four specimens Castellated columns section encasement by Reactive powder concrete (RPC) with laced reinforcement. The encasement 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 o0f the web of the castellated column. The inclination angle of lacing reinforcement concerning the longitudinal axis is 45o. Four specimens with four different configurations will be prepared and tested under axial load at columns. The first group was the control group (CSC1) Unconfined castellated steel column, the second group was consists of Castellated columns (web and flange) confined with 17mm of (RPC), welded web, and 6mm laced reinforcement (CSC3). While group three (CSC4) consists of a Castellated steel column same as the sample (CSC3), but without using welding between two parts of the castellated steel column. Groups four and five consist of a Castellated steel column same as sample (CSC4) encased partially with reactive powder concrete (25.5 mm) (CSC5) and full encased flange with reactive powder concrete (34mm) mm (CSC6), respectively. The tested specimens' results show that an increase in the strength of the column competitive with increasing the encased reactive powder concrete thickness. And the best sample was sample CSC6 with (34mm) mm in experimental and ABAQUS results.

Abstract: The study aims to improve some mechanical properties like compressive strength, tensile strength, modulus of elasticity and flexural strength of polymer modified concrete (PMC). This improving for PMC done by using waste iron filling as replacement from fine aggregate. waste iron filings and chips used in this research as percentages from sand ranged from 0 % to 40 % , the compressive strength of ordinary polymer concrete increase from 32.2 MPa to 41.81 MPa by 40% replacement of sand with waste iron filings and chips, tensile strength increased also from 2.83 MPa to 4.23 MPa by 40% replacement also. Flexural strength increased from 3.7 MPa for reference mix to about 7.1 MPa for mixes with 40% replacement, modulus of elasticity increased from 21087 MPa to 25233 MPa by using maximum percentage of waste iron filings. There is a slight increment in mechanical properties of polymer modified concrete after 30% ratio of waste iron filings and chips. Also research includes mixes modified with larger dosage of super plasticizer and less water/cement ratio to improve mechanical properties of PMC.

Abstract: The aim of study is to produce durable structural concrete by using waste ceramics with specified type (white clay ceramics) as coarse aggregates in concrete. Mechanical properties were studied, the study also show good resistance to fire resistance for concrete contains ceramics as coarse aggregates compared with normal aggregates concrete, good mechanical properties such as compressive, tensile, and flexural strength. Results of study gave 17.5% increment in compressive strength by using 100% replacement of waste ceramic, flexural strength increased with 27.8% increment. Study also show less reduction in strength due to fire resistance by using waste ceramics compared to ordinary concrete, and also more durable concrete for salty water effects by using ceramic.

Abstract: This investigation aims to improve some of the mechanical properties of concrete such as compressive strength, flexural strength, and modulus of elasticity, by using different percentages of polypropylene fibers, and also studying the durability of concrete for freeze-thaw cycles. the study shows a small increment in compressive strength due to adding fibers which were 28.3% compared with increment in flexural strength which was perfect (about 191%), modulus of elasticity also increased by adding fibers. The durability of concrete against freezing-thaw cycles for all mixes was studied. Fiber-reinforced concrete shows more durability against freezing-thawing cycles and less reduction in strength compared with reference mixes without fibers,21.5% reduction in strength for optimum polypropylene fiber concrete while the reduction in strength for normal concrete was found 54.2% in this study.

Abstract: Recently, the construction industry uses the Recycled Concrete Aggregates (RCA)resulting from construction and demolition waste (CDW) to achieve sustainable requirements andeconomic benefits. In this paper, asphalt paving mixes were prepared with RCA instead of naturalaggregates for the base course in flexible road pavements and walking areas used by pedestrians andcyclists. Different asphalt mixes samples were prepared with different asphalt contents to meet therequired specifications. Additionally, several laboratory tests were carried out to assess mixturebehavior including the Marshall test. The results indicated that the mixture made with aggregates ofCDW have met all the requirements of Iraqi specifications of roads and bridges (SORB/R9). Thisinvestigation could be a useful guide for road engineers in designing asphalt mixtures from RCA.

Abstract: This paper investigates the effect of using wastes sawdust as a replacement of fine aggregate (sand) on mechanical properties naming compressive, tensile and flexural strengths of ordinary Portland concrete. The wastes sawdust was treated before incorporating it in concrete mixtures. Three different methods were used to pre-treat the sawdust including a) soaking the sawdust in distilled water at 50 oC, b) soaking the sawdust in Ca (OH)2 solution, and c) soaking the sawdust in Ca (OH)2 solution and using a set accelerator in the concrete mixture. In addition to the control mixture (having no sawdust), three more concrete mixtures were prepared to explore the effect of the three different methods of pre-treatment on the mechanical properties of concrete. Results showed that the compressive strength of the concrete incorporating wastes sawdust pre-treated with the calcium hydroxide solution (slaked lime) and having the accelerator was higher than that of the control mixture. The tensile and flexural strengths of the concrete mixture having waste sawdust pre-treated by Ca (OH)2 solution and having the accelerator were found to be very comparable to those of the control mixture. On the other hand, the compressive, tensile, and flexural strengths of the concrete mixture with sawdust pre-treated by Ca (OH)2 solution only were somehow comparable to those of concrete mixture having sawdust pre-treated by distilled water. While the compressive strength of the concrete mixtures incorporating sawdust pre-treated with either Ca (OH)2 solution or distilled water was less than that of the control mixture, both tensile and flexural strengths of the two treated concrete mixtures were approximately comparable to those of the control mixture.

Abstract: Several parameters affect the properties of Portland cement and one of these parameters is the cooling rate of the clinker. If the effectiveness of the cooling method of the clinker increases, a good enhancement in the properties of Portland cement will be found. Depending on the new cooling method suggestion by Nasr et. al. [20], the counter pattern of air clinker flow was studied using (FLUENT 6.3.26). The dimensions of the cooling room in grate cooler, the constant mass flow rate of both clinker and air, different height ratios, and different clinker porosity were considered in this numerical work. The results show that the heat transfers in the first half of the cooling room (0 < X < 0.9 m) is larger than that in the second half (0.9 < X < 1.8 m), and this leads to an increase in the temperature of outlet air so can benefits from it in the heating of furnace. When the clinker and air are flowing in the counter direction, the cooling method is more beneficial when compared with that of parallel flow because the exiting clinker has a great rate of cooler and the air exits from the grate cooler is loaded with large thermal energy. Finally, it can design the best length of gate according to the required clinker temperature at the outlet side, and this results to reduce the cost of the cooling process according to the temperature distribution results at (0 < X > 1.8m) for different porosity and H.R values.

Abstract: The Asymmetrical Castellated concavely – curved soffit Steel Beams with RPC and Lacing Reinforcement improves compactness and local buckling (web and flange local buckling), vertical shear strength at gross section (web crippling and web yielding at the fillet), and net section ( net vertical shear strength proportioned between the top and bottom tees relative to their areas (Yielding)), horizontal shear strength in web post (Yielding), web post-buckling strength, overall beam flexure strength, tee Vierendeel bending moment and lateral-torsional buckling, as a result of steel section encasement. This study presents two concentrated loads test results for seven specimens Asymmetrical Castellated concavely – curved soffit Steel Beams section encasement by Reactive powder concrete (RPC) with laced reinforcement. The encasement of the Asymmetrical Castellated concavely – curved soffit Steel Beams 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 concavely – curved soffit Steel Beams web. The inclination angle of lacing reinforcement concerning the longitudinal axis is 45. Seven specimens with seven 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: unconfined Asymmetrical Castellated Steel Beams (Reference1), second model; Asymmetrical Castellated concavely – curved soffit Steel Beams (web and flange) confined with (RPC) only, third model; Asymmetrical Castellated concavely – curved soffit Steel Beams (web and flange) confined with (RPC) and laced reinforcement, fourth model; is same as the third model but it has one web opening with increase the depth of web post by 10 %, 20%, and 30 % as a gap between top and bottom parts of Asymmetrical Castellated concavely – curved soffit Steel Beams respectively. The results that have been obtained from the experimental part and the numerical analysis results by ABAQUS demonstrated that the increase of the gap leads to an increase in the load against the deflection curve. Sample CB8 with 122 mm gap has gained the highest load against deflection when compared with either reference sample without gap and other samples with 65 mm and 105 mm gap for concavely–curved soffit Steel Beams.