This study was conducted to investigate the impact of hot and dry environments under different curing conditions on the properties of high‐strength concrete. The concrete samples were prepared at a room temperature of 20°C and cured under different curing conditions. Some specimens underwent standard curing from 24 h after casting until the day of testing. Some specimens underwent steam curing in a dry oven at 30°C and 50°C after casting until the day of testing. Other specimens were cured for 3, 7, 21, and 28 days in water and then placed in a dry oven at 30°C and 50°C and tested at the age of 28 days, except for the specimens that were cured for 28 days, which were tested at the age of 31 days, to study the effect of curing period on the strength of concrete exposed to dry and hot environments after moist curing. The effects of hot and dry environments on high‐strength concrete with different water/binder ratios (0.30, 0.35, and 0.40), using (30%) fly ash for all mixes, and (0%, 5%, and 10%) silica fume with the binder (450, 480, and 520 kg), respectively, were separately investigated, and the effects of curing under different conditions were evaluated by measuring the compressive strength, flexural strength, microhardness, and chloride diffusion and by assessing the concretes’ microstructure. The relationships between these properties were presented. A good agreement was noted between the concrete compressive strength and concrete properties at different temperatures, curing periods, and curing methods.

In this paper, the microstructure, mechanical properties, and preparation of geopolymer were investigated. The effects of the proportion of slag and fly ash, the modulus of water glass, and the water–binder ratio on the microstructure, mechanical properties, and preparation of geopolymer were analyzed. The research content of this paper is as follows: Taking the 7-day and 28-day compressive strength and flexural strength of the geopolymer specimens as the evaluation criteria, considering the proportion of slag and fly ash, the modulus of water glass, and the water–binder ratio, the three factors and five levels are respectively considered for a total of 25 sets of orthogonal experiments. Through the range analysis and variance analysis, the influence of each factor on the mechanical properties was analyzed, and the best mix ratio was obtained. Using scanning electron microscope and X-ray diffraction analysis and other testing methods, the mechanical properties, microstructure, and phase composition of geopolymers under the influence of various factors were studied and analyzed.

A comprehensive program of experiments consisting of compression, uniaxial compression, direct shear, flexural as well as splitting tensile and air permeability tests were performed to analyse the effect of the level of fibre dosage and the water–cement ratio on the physical properties of hybrid fibre-reinforced concrete (HFRC). Two types of fibres were studied in terms of their effect on the properties of HFRC. The results indicated that the mechanical properties of concrete were significantly improved by increasing the fibre content. However, increasing the percentage fibre content past a certain peak performance limit (0.9% glass fibre (GF) and 0.45% polypropylene fibre (PPF)) led to a decrease in strength compared to reference mixes. Additionally, the incorporation of hybrid fibres yielded an increase in air permeability in the tested specimens. The results showed that the strength-related properties of HFRC were superior to the properties of single fibre-reinforced concrete.

Headed studs have been widely used as shear connectors in steel-concrete composite beams for a long time. Studies on the influence of the different shear properties of headed studs on the flexural behavior of the composite beams have been inconclusive. In this research, we studied the shear performance influence of headed studs by conducting static push-out tests on seven designed push-out specimens. The flexural behavior of a steel-concrete composite beam connected by studs was discussed in detail by conducting a two-point symmetric monotonic static loading test. Based on the actual situation of the composite beam test, a finite element numerical model was established and validated, in which the elastic connections units were used to simulate the studs, and the force–slip data obtained from the push-out tests were used as the constitutive model of the studs. The effects of the stud diameter, stud height, the number of studs arranged, and concrete strength on the flexural behavior of the composite beams were analyzed and compared. The results showed that the number of studs arranged had a significant influence on the flexural behavior of the composite beams, followed by the strength of the concrete. The specifications of the studs had little effect on the flexural behavior of the composite beams within the study scope using the modeling method in this paper.

In order to study the influence law of each parameter on the performance of the alkali-activated composite gelling system, the influence degree was sorted, and the most important parameter affecting each performance was found. The solution of liquid water glass and solid sodium hydroxide was used as the alkaline activator, and the mixing ratio was designed by the orthogonal test method. The effects of four parameters of fly ash content, water glass modulus, water glass solid content, and water–solid ratio on the working performance and mechanical properties of alkali-activated slag–fly ash composite cementation system were discussed. The gelling system was studied by microscopic experiments such as SEM and FTIR. The results show that the solid content of water glass has the greatest influence on the fluidity of the composite cementitious system, and the content of fly ash is the primary factor affecting the setting time of the material. The flexural and compressive strengths at the age of 7 d and 28 d were most affected by the content of fly ash, and the solid content of water glass had the greatest influence on the flexural and compressive strengths at the age of 2 d. From the perspective of microscopic morphology, in the high-strength samples, the fly ash particles and the remaining outer shell are embedded in the gel to form a dense whole. When the amount of silica in the composite gelling system is too high, it will cause the phenomenon of low macroscopic mechanical properties.

In this paper, fly ash is mixed into self-flowing cement mortar by the method of equal mass substitution of cement, and the redispersible latex powder is mixed into cement mortar according to the percentage of cementitious material mass, so as to study the influence on the properties and mechanical properties of cement mortar. The test results show that the incorporation of fly ash prolongs the setting time of cement mortar and reduces the flexural strength, compressive strength, and drying shrinkage. With the increase in the content of redispersible latex powder, the setting time of cement mortar increases gradually, the compressive strength and compressive fracture resistance then decrease gradually, and the flexibility and crack resistance of the cement mortar specimen are improved. The flexural strength of the cement mortar specimen first increased and then decreased, and the drying shrinkage first decreased and then increased, indicating that the mixing amount of redispersible latex powder is not the more the better, but that there is a reasonable range to achieve the best comprehensive performance of cement mortar.