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This article presents the results of a study dealing with the concrete resistance to repeated cycles of freezing and thawing of nonair entrained, fine lightweight aggregate (LWA) and air‐entrained concrete when tested in accordance with ASTM C 666, procedures A and B. The water‐to‐binder ratios (w/b) of the mixtures ranged from 0.25 to 0.35, and the percentage of cement replacement by silica fume were 7% on a weight basis and constant throughout study. Binder dosage was 500 kg/m3 and constant. LWA was pumice aggregate (PA) and expanded perlite aggregate (EPA). PA and EPA were replaced by 10, 20, and 30% of total volume of 1 m3 as a fine aggregate (0–2 mm fine aggregate fraction). Also one group was produced with air entraining agent by 0.1% ratio of binder dosage. The 200 freeze–thaw cycles were carried out according to ASTM C666/C666M‐15, procedure A and B. The compressive strength, ultrasonic pulse velocity, relative dynamic modulus of elasticity and dry unit weight of mixtures were investigated. Based upon the analysis of the test data, it is concluded that samples contain air‐entrained agent and 10% LWA were more durable than that of control sample. With the increasing of the LWA content the freeze–thaw resistance of samples decreased. Thus, higher content of LWA is not recommended when it is to be subjected to repeated freeze–thaw cycles. Freezing–thawing procedures were compared with each other and found that procedure A was more severe than procedure B.

The aim of this work is to experimentally investigate the effect of properties of nano-CaO in cement-based materials. Mortars and paste samples were produced by using nano-CaO in 2.5, 5, and 7.5% ratios instead of cement. The initial and final setting times and volumetric autogenous shrinkage tests of paste samples and 7, 28, and 360 days' compressive strength, the ultrasonic pulse velocity, heat of hydration, and linear autogenous shrinkage of mortar samples were determined. In addition, the micro-structures of paste samples were characterized by X-raydiffraction and SEM. As a result, the shrinkage and setting times were reduced with the increase of nano-CaO content. CaO with nano size increased the compressive strength (about 10-22%) and the heat of hydration. The compressive strength of mixture containing 7.5% nano-CaO was lower than that of 2.5 and 5% nano-CaO at 360 days of curing duration. The heat of hydration increased for all the mixtures containing nano-CaO at an early stage and very rapidly between 4 and 16 hr. K E Y W O R D S autogenous shrinkage, compressive strength, hydration heat, nano-CaO, SEM, X-ray-diffraction

This paper investigates the effects of expanded perlite aggregate (EPA) on the properties of mortar and concrete. A volume of 10, 20, and 30% EPA were used instead of 0–2 mm fine aggregate. Water/binder ratio of 0.30 was constant for all the mortar and concrete mixtures. The compressive strength, ultrasonic pulse velocity (UPV), and linear autogenous shrinkage tests were performed on both mortar and concrete mixtures. Furthermore, the heat of hydration test was only made for mortar mixtures and restrained shrinkage test was only employed to measure cracking time and strain for concrete mixtures. For both mortar and concrete mixtures, the experiments show that the compressive strength, UPV, and linear autogenous shrinkage were generally decreased with increasing the amount of EPA according to control sample, while the heat of hydration is generally increased. However, the reduction ratios in the compressive strength of mortar and concrete samples gradually decreased with increasing the curing time. In addition, the increases in the heat of hydration for EPA10, EPA20, and EPA30 were 5, 7, and 8%, compared with the control.

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