Durability of concrete is of great significance to prolong the service life of concrete structures in corrosive environments. Aiming at the economical and environment-friendly production of concrete by comprehensive utilization of the supplementary cementitious materials made of industrial byproducts, the resistances to chloride penetration, sulfate attack, and frost of high-performance concrete were studied in this paper. Fifteen concretes were designed at different water–binder ratio with the changes of contents of fly ash (FA), silica fume (SF), ground granulated blast-furnace slag (GGBS), and admixture of sulfate corrosion-resistance (AS). The compressive strength, the total electric flux of chloride penetrability, the sulfate resistance coefficient, and the indices of freezing and thawing were measured. Results indicate that, depending on the chemical composition, fineness, and pozzolanic activity, the supplementary cementitious admixtures had different effects on the compressive strength and the durability of concrete; despite having a higher fineness and pozzolanic activity, the GGBS gave out a negative effect on concrete due to a similar chemical composition with cement; the SF and FA presented beneficial effects on concrete whether they were used singly with GGBS or jointly with GGBS; the AS improved the compressive strength and the sulfate corrosion resistance of concrete. In general, the grade of durability was positively related to the compressive strength of concrete. Except for the concretes admixed only with GGBS or with GGBS and FA, others had super durability with the compressive strength varying from 70 MPa to 113 MPa. The concretes with water to binder ratio of 0.29 and total binders of 500 kg/m³ admixed with 7% FA + 8% SF + 8% GGBS or 7% FA + 8% SF + 8% GGBS + (10~12)% AS presented the highest grades of resistances specified in China codes to chloride penetration, sulfate corrosion, and frost, while the compressive strength was about 100 MPa.

In many infrastructural engineering techniques, a common challenge is how to control the continuous damage caused by the cracks of concrete slab/decks overlay under environmental impaction or vehicle load. It drives the development of a high-flowability hybrid polypropylene and steel fiber-reinforced concrete (HPSFC), which has peculiarities for the overlay construction. In this aspect, an experimental study of HPSFC was carried out considering the factors, the volume ratio of binder paste to aggregates (P/A ratio) varied from 0.48 to 0.60, and the polypropylene (PP) fiber content changed from 0.45 to 1.35 kg/m ³ with a hybrid steel fiber at 0.8% volume fraction. The workability of fresh mixes was evaluated by the indices of slump flowability and static segregation rate with an explanation of the rheological properties, and it was verified by a pumping test. The peculiarity of HPSFC applied for slab/decks overlay was determined using the tests including the early cracking resistance, the water penetration resistance, the bond strength to existing concrete, and the impact resistance. Meanwhile, the basic mechanical properties including cubic compression strength, flexural strength, and toughness were also measured. Results indicate that the fresh mixes met the requirement of high-flowing without segregation, although the indices varied with the influence of P/A ratio and PP fiber content. The resistances to early cracking and water penetration obviously improved by increasing the PP fiber content. The bond strength to existing concrete could be improved by increasing the PP-fiber content. The impact resistance enhanced with the increase of the P/A ratio and the PP-fiber content. The compressive strength and flexural strength presented an increased tendency with the P/A ratio, while the flexural toughness reached a peak at certain values of P/A ratio and PP fiber content. Comprehensively, for the high-flowability HPSFC designed with a water-to-binder ratio of 0.36, a fly-ash content of 30%, and a sand ratio of 52%, the optimal P/A ratio is 0.54 and the PP-fiber content is 0.90 kg/m ³ .