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This research investigates the means to improve the compressive strength of mortar mixtures through using novel mixtures. These mixtures include magnetic water (MW) and fly ash (FA). MW was obtained by circulating tap water (TW) through a magnetic field. The magnetization duration was represented by the number of cycles, the content of FA was replaced with cement, and the super plasticizer percentage (SP) and the curing age were used and evaluated experimentally for producing the mortar mixtures. Mortar flow, crushing compressive strength, and ultrasonic pulse velocity (UPV) tests were applied to evaluate the performances of mixing characteristics. The results demonstrate that the MW-treated mortar mixtures show higher compression strength results than those prepared by TW. The compressive strength was increased up to 60% with 150 cycles, a dose of 0.5% of SP and no FA content at the age of 56 days. The dose of SP can be cut down by a maximum of 40% to 50% in cementitious mortar. the workability was enhanced by a percentage of 70%.

This study is planned to investigate the properties of Portland cement mixtures containing silica fume and mixed with saturated lime water. The conducted Portland cement mixes included three groups; cement pastes, cement mortars and cement concrete mixes. The main parameters were; type of mixing solution (water or lime-water) as well as the percentage of Portland cement replaced by silica fume. Consistency level, times of initial and final settings, compressive strength development, existence and intensity of CH crystals with age, pozzolanic activity as well as efficiency of the investigated matrices to delay the corrosion of embedded steel bars were the investigated properties. Test results show that using lime-water in mixing enhances consistency degree compared to the corresponding control mixes. Furthermore, it delays both initial and final setting times compared with traditional water due to the common ion effect principles. Moreover, combined use of limewater and silica fume enhances the pozzolanic reaction that was identified by the strength development at both early and later ages. The existence of CH crystals for higher percentages of silica fume (up to 30%) for further reaction at later ages was observed by XRD results. Moreover, combined use of silica fume and lime-water ensures a high alkaline media around steel bars from the moment of ingredients mixing as long as later ages despite of pozzolanic reaction that was identified from results of chloride attack.

This study is directed to evaluate the ability of using cone penetration test as a simple method to investigate the consistency level of fresh concrete. A cone of 30°apex angle attached with different load values was used. Eighteen concrete mixes divided into three groups were conducted. Three types of coarse aggregate were tried. Crushed dolomite, round gravel, and crushed basalt all of 20 mm maximum grain size were investigated. For each type of coarse aggregate, six levels of concrete consistency calibrated by standard slump test were tried. For the investigated mixes and at a specified consistency level, the displaced volume values were directly proportional to the applied load. The inclination of this relation is termed as the displaced volume rate (D.V). The results of cone penetration were analyzed and compared to the corresponding slump test values. The displaced volume per unit mass, bearing strength, as well as shear yield strength were the evaluated properties. The results introduce the cone penetration test as a simple instrument that could be adopted either at a laboratory or at site to evaluate fresh concrete workability. Moreover, it is being more sensitive compared to the well known slump test. It can simply and clearly distinguish between stiff mixes as well as floppy ones. Very useful numerical limits for the evaluated properties controlling the workability levels of very low, low, medium, high and very high were proposed. ª 2014 Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center.

The experimental program was undertaken to investigate the performance of different geopolymer bricks (GB) made with different amounts of industrial waste materials by Taguchi method. Taguchi approach (with L16 orthogonal array) was used to design the experimental plan to reduce the number of experiments as well as to analysis the results. Recycled concrete aggregates (RCA), marble powder (MP) and limestone powder (LP) were considered as the main variables (control factors) to develop the sustainable geopolymeric concrete designated for building bricks. Four responses where density, mechanical properties (compressive and flexural strengths) at 28 days age and the percentage of water absorption were conducted. The test results revealed that combining an eminently RAC, MP and LP can produce GB with 28 days compressive strength of about 36-58 MPa with ambient temperature. The RCA was the most influential factors on the performance of GB due to its performance contribution. Furthermore, the GB containing RCA is suitable for environment friendly construction and is comparable to a normal GB made with natural aggregate.

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