Al-Qadisiyah Journal for Engineering Sciences

Abstract This study investigates the properties of 3D printed concrete mixtures, focusing on rheological characteristics, compressive strength, anisotropy, and printing path effects. Two mixtures were compared: M-1 (90% cement, 10% metakaolin) and M-2 (85% cement, 10% metakaolin, 5% silica fume). M-2 demonstrated superior performance in flowability, shape retention, and buildability, allowing for 164% more printed layers than M-1. Compressive strength tests revealed that 3D printed specimens consistently exhibited lower strength compared to cast specimens due to layering effects and anisotropy. M-2 showed higher compressive strength in both cast and printed cubes. Significant anisotropy was observed in mechanical properties, with compressive strength highest in the X direction and lowest in the Y direction. Flexural strength and elastic modulus also varied depending on loading direction. Among printing patterns, the zigzag pattern with 90-degree rotation between layers (P1) exhibited the highest compressive strength, while circular patterns (P2) showed the lowest. These findings emphasize the importance of optimizing mix design, printing parameters, and loading direction considerations for 3D printed concrete structures.

Abstract Cement is the most important component in cementitious grout production,andtt accounts for 7% of global greenhouse gas emissions. Reducing the amount of cement used in infrastructure and buildings is a desirable way to lower the total carbon footprint associated with grout production. relatedly, developments in manufacturing and transportation lead to the production of cars in large numbers, which in turn leads to an increase in the production of byproduct waste like waste tires, which are thrown away directly without recycling. Thus, this study aims to develop a novel sustainable grout by recycling paper sludge ash waste (PSA) and waste steel fiber (WSF) as partial cement replacements. This will help reduce grout production costs, minimize environmental pollution during cement production, and enhance landfill and waste management. The Grout mixtures used in this paper were prepared using ordinary Portland cement (OPC), WSF extracted from vehicle tires, PSA, and water. Different proportions of WSF(0, 1, 2, 3%) and PSA(5, 10%) were used in the weight of cement in designing sustainable grout. The mechanical properties of the sustainable grout were evaluated by examining extensive tests including flow tables, compressive strength, and flexural strength. The results showed that partially replacing the cement with 3% WSF and 1% WSP with 5% PSA resulted in a significant improvement in workability ,as well as a clear increase in compressive and flexural strength at an early age compared to the reference mixture.

Abstract Reactive Powder Concrete (RPC) is one of the new and most important concrete manufacturing advancements. A significant number of researchers have studied the mechanical properties of such type of concrete and the effect of different parameters on it. Some of these researchers presented questions to predict the properties of reactive powder concrete depends on its components and the method of curing. This research presents an experimental investigation on the mechanical properties of RPC such as compressive strength, splitting tensile strength and flexural strength. The findings were compared to the previous studies’ experimental work and formulated equations.

Abstract Know a day’s utilization of local accessible materials is an important stage for sustainable, economic building material on the earth surface. Within them Brick is one of the commonly used construction material around Jimma town due to the availability of clay soil. But brick produced by small micros un-skill enterprises rather than by traditional method, its quantity was small and its quality was unsatisfactory, because it can easily break and it has high water absorbing conduct. The purpose of investigation was be to improving the properties of clay soil properties by using Literate soil for in the manufacturing of bricks for masonry units. In order to achieve this researches include, non-probability sampling techniques was be used to collect samples in Jimma area, then collected of samples prepared for different laboratory test and by partially replacing literate soil by 5%, 10%, 15% and 20% on a clay soil in order to get optimum property by different mix ration for different laboratories. Test results indicated that shows that the lightweight bricks could be made from this study without any deterioration in the quality of bricks. Additionally, the compressive strength of the blocks optimum at 15% lateritic soil replace in clay soil contents. The optimum firing temperature furnace at a duration burning of brick was at 1000°C. It’s shown that bricks prepared of clay-laterite earth capable for high resisting capacity rather than for beauty.

Abstract This study presents an experimental investigation for push-out tests in order to evaluate the performance of continuous perfobond connectors. A total of five specimens composed of light-weight concrete-filled steel tubes (square and circle sections) with two reinforced blocks were tested. The measured parameters are the compressive strength of the concrete blocks and the type of the section. The specimens were tested under a concentric load applied on the steel tube filled with lightweight concrete; the corresponding slip value was measured   using two LVDTs. The experimental results showed that the ultimate shear strength and stiffness of the square steel tube filled with concrete were higher than that of circular samples. The ultimate shear strength and stiffness increased with an increase of concrete compressive strength, while the corresponding slips    showed decreasing in their values with increase of the compressive strength of the concrete.

Abstract Polyvinyl alcohol (PVA) has undergone intensive research work that has led to confidence in its utilization in various applications. Nevertheless, its utilization as a construction material in the concrete industry still needs to be fully addressed. In this paper, an experimental study was dedicated to investigate the influence of PVA on the fresh and hardened properties of concrete. Three different strength grades, represented by water to cement ratios (w/c), of 0.4, 0.5 and 0.6, with four different PVA dosages of 1, 2, 3 and 4%, by mass of cement, were employed in the preparation of the concrete mixes. Concerning the fresh properties, results showed that there was a significant contribution of PVA to the workability in all produced mixes, irrespective of w/c ratio. In addition, the initial and final setting time of cement pastes modified with 2% PVA were longer than that of the control paste. In term of the hardened properties, results demonstrated that the compressive (fcu) and splitting tensile (fst) strengths of concrete are dominated by amounts of PVA in the mix and w/c ratios. With the high and moderate w/c ratios, they increased when up to 2% PVA was used, and thereafter decreased. However, with the low w/c, PVA did not provide any improvement in the strength, but instead, it decreased the strength when more than 2% was added. The findings revealed also that increasing PVA content resulted in a significant reduction in total water absorption (TWA) of concrete specimens. The larger the PVA contents the lower is the TWA of the specimens

Abstract In this work the concrete free falling effect on segregation was investigated. Sixteen free falling specimens were tested by the non-destructive ultrasonic test for four types of concrete. In addition, twelve cube specimens were tested to check the accuracy of the ultrasonic test adopted in this study. Four types of aggregates (rounded gravel, crushed gravel, 10mm maximum size crushed gravel and porcelain aggregate) were used to study their effect on segregation of free falling concrete from different height. The test results show that no significant effect for the free falling on the compressive strength of concrete for the four types of aggregate and the results of the non-destructive ultrasonic test were of good agreement with those of compression machine test.

Abstract The included search casting twenty one concrete mixes, that proportion are (1:1.5:3), (1:2:4) and (1:3:6). Nine of them with out using plasticizer with three (w/c) (0.50, 0.57, 0.60) as showing at table (6).And twelve mixes contained a proportion of additive mixture of metal Gelenium No.(5) with four ratios of Gelenium as shown at table (5) and every mix has (w/c) (0.45:0.53:0.60).
- Soft conceret of non container plastizer tested by workablity (slump test). The mex (1:1.5:3) gave best result (60mm) , least mix (1:2:4) gave (40mm), least mix(1:3:6) gave (25mm) according to reference mixture.
- Soft conceret with Gelenium ratio plastizer gave best slump for Nine mixs with three (w/c) ratio (40%, 45%, 50%) And Gelenium (3%) , the best result for mix(1:1.5:3) equal (98mm),least mix (1:2:4) gave slump (85mm) , And mix (1:3:6) gave (74mm) compare with reference mixture
- Compressive strength for twelve cupics with optimum Gelenium ratio. The mix (1:1.5:3) with (2%) gave (14Mpa) at early age. And (38Mpa) at finish age, least mix (1:2:4) gave (10Mpa) at early age And (28Mpa) at finish age , And mix (1:3:6) gave (6Mpa) at early age , and (20Mpa) at finish age as shown at figure(8).
- Depend on ratio of mix , percentage(w/c) and zoom of plasticizer .these factors gave best result at mix(1:1.5:3) according to standard specification.

Abstract The objective of this research is to study the effect of Percentage on apparent porosity and compressive strength of ceramic filters. In this research, using ceramic raw materials to produced the filters. Filters made from the raw materials (Sand, Kaolin, and Calcium Carbonate), which obtained from Um Urdhuma and Al- Deuechla in the west of Iraq. Sand was the basic material used to make filters. Selective some of sand particle size (150µm, 125µm, 100µm, 75µm, 50µm), In addition to the binder material that consisted (65% Kaolin + 35% Calcium Carbonate), in different weight percentage (60% Binder + 40% Sand, 50% Binder + 50% Sand, 40% Binder + 60% Sand) ), and used the semidry compaction to forming the laboratory samples The samples dried in (110 ºC) for (24 hours), and fired or sintered at 1200ºC for soaking time (1hour),then we extracted compressive strength and apparent porosity. The experimental result led to the relationships between (rate of sand, particle size of sand) and apparent porosity and compressive strength of ceramic filter. . Increased the rate of sand increased apparent porosity, but it decreased compressive strength. ). Increased particle size of sand decreased apparent porosity, but it increased compressive strength. The rustles show the maximum apparent porosity (41.328%) at the maximum weight percentage of sand (60%)), and minimum particle size of sand (50µm).The highest compressive strength( 11.831MPa) at lowest weight percentage of sand (40%), and maximum particle size of sand (150µm) .

Abstract In this experimental work, four different curing methods were applied namely including water, air, water heated-air and water heated –water. The results showed that the highest compressive strengths are attributed to the air cured under room temperature after 20hrs curing in heated water at each age. To verify the effect of insoluble residue on the compressive strength of Portland cement, fine particles sand passing from sieve no. 200 and washing in hydrochloric acid were used as an insoluble residue. The Portland cement was replaced by insoluble residue which varied between (0 -7.0) % by weight. The results showed that the higher percentage of insoluble residue to 8.13% in cement mortar gives the lower the compressive strength by 12% of the control mortar compressive strength at 1 day .Although of this reduction of strength, it was found that the compressive strength was still higher than the limits given by ASTM ,BS and Iraqi standards.

Abstract Fiber-reinforced self compacting concrete (FRSCC) is a type of concrete mix that can mitigate two opposing weaknesses: poor workability in fiber reinforced concrete and cracking resistance in plain SCC concrete. This research investigates the influence of curing conditions and effect of steel fiber on shrinkage and mechanical properties of self compacting concrete. Test results showed that water cured specimens always give the highest values followed by this cured as in dry condition irrespective of type and age of concrete and test methods. For flexural, splitting tensile strength and modulus of elasticity tests, the SCC concrete with steel fiber reinforced gives the highest values than plain SCC for all curing conditions. Steel fibers in the early stage, didn’t show any improvement in shrinkage.

Abstract The main objective of this investigation is to study the effect of oil (kerosene, gas oil and crude oil) on the compressive and tensile strengths of high performance concrete and to compare the behavior with that of normal strength concrete. Four exposure periods were used for each specimen and for each liquid, 30, 60, 90 and 120 days after 28 days water curing. To provide a basis for comparison, reference specimens were cast and exposed to water for a respective time of test. The test results showed that the loss in mechanical properties (compressive and splitting tensile strengths) resulting from exposure to oil was relatively smaller for high performance concrete (HPC) compared with normal strength concrete (NSC). The difference was about 10 percent. Furthermore, the reduction in compressive and splitting tensile strengths of NSC and HPC increased with decrease in viscosity of oil in the entire period of exposure.