Comparative study on the using of PEG and PAM as curing agents for self-curing concrete

There are many factors, which may affect on concrete quality. One of those is concrete curing. Self-curing concrete is the solution. It may produce by using chemical curing agents. The concept of those agents is to reduce the water evaporation from concrete. This research aims to study the effect of chemical curing agents on the behavior of self-curing concrete. Two different chemical curing agents were used to study the main mechanical properties of concrete. The main variables are; the type of curing agent (Polyethylene glycol "PEG400"–Poly Acrylamide "PAM") and its dosages. The results obtained in terms of compressive, tensile and flexure strength values. Test results showed that the self-curing concrete cured by each agent performed better in hardened properties compared to none cured concrete. Also, curing using the both agents together perform better than using each one individually

Economical reactive powder concrete cast using available materials in North Sinai, Egypt

In this research reactive powder concrete (RPC) was prepared using sand from North Sinai. The mechanical properties of locally cast RPC were investigated and evaluated by studying the effects of using different cement and silica fume contents and new steel fibers’ aspect ratios as reinforcement for RPC. Specimens’ preparation, curing regimes and testing procedures to evaluate the compressive strength, the modulus of elasticity, the indirect tensile strength and the flexural strength were discussed. A compressive strength of 154.5MPa, indirect tensile strength of 11.98MPa, modulus of elasticity of 45.1GPa and flexural strength of 30.26MPa have been achieved for reinforced RPC contains 800 kg/m3 cement content and silica fume content 30% of cement weight. The test results showed some improvements by increasing cement and silica fume contentsas well as adding steel fibers on the compressive strength, modulus of elasticity and indirect tensile strength

Economical Reactive Powder Concrete Cast Using Available Materials in North Sinai, Egypt

In this research reactive powder concrete (RPC) was prepared using sand from North Sinai. The mechanical properties of locally cast RPC were investigated and evaluated by studying the effects of using different cement and silica fume contents and new steel fibers’ aspect ratios as reinforcement for RPC. Specimens’ preparation, curing regimes and testing procedures to evaluate the compressive strength, the modulus of elasticity, the indirect tensile strength and the flexural strength were discussed. A compressive strength of 154.5MPa, indirect tensile strength of 11.98MPa, modulus of elasticity of 45.1GPa and flexural strength of 30.26MPa have been achieved for reinforced RPC contains 800 kg/m3 cement content and silica fume content 30% of cement weight. The test results showed some improvements by increasing cement and silica fume contentsas well as adding steel fibers on the compressive strength, modulus of elasticity and indirect tensile strength

Repairing and strengthening of elliptical paraboloid reinforced concrete shells with openings

This investigation is carried out to evaluate the repair and strengthening the techniques of elliptical paraboloid reinforced concrete shells with openings. An experimental program of several different techniques in repair and strengthening is executed. The materials, which are considered for strengthening, are; Glass fiber reinforced polymers GFRP at different position of the shell bottom surface, steel strip and external tie. They loaded by four concentrated loads affected on the corners of the opening. The initial and failure loads as well as the crack propagation for the tested shells at different loading stages, defl ections and failure load for repaired and shells are recorded. A non-linear computer program based on finite element techniques is used to study the behavior of these types of shells. Geometric and materials nonlinearities are considered in the analysis. The efficiency and accuracy of computer program are verifi ed by comparing the program results with those obtained experimentally for the control shell with opening and strengthened shells