Showing papers in "Cement and Concrete Research in 2003"

TL;DR: In this article, a 28-day compressive strength of 28 MPa concrete was used as a source of aggregate for new concretes, simulating the situation prevailing in precast concrete plants.

TL;DR: In this paper, the in situ strength of concrete was determined through compression test of cores drilled out from laboratory cast beams, and the apparent porosity and pore size distribution of the same concrete were determined through mercury intrusion porosimetry, performed on small-drilled cores.

TL;DR: In this paper, various mechanisms suggested to cause autogenous shrinkage are presented The mechanisms are evaluated from the point of view of their soundness and applicability to quantitative modeling of autogeneous shrinkage.

TL;DR: In this article, a high-strength concrete is tested on a high strength concrete to establish the permeability and self-healing behavior of cracked concrete as a function of temperature between 20 and 80 °C and crack width between 0.05 and 0.20 mm.

TL;DR: In this paper, the QTM-D3 conductivity tester developed in Japan was used to investigate factors influencing thermal conductivity of concrete, mortar, and cement paste, and seven testing variables such as age, water-cement (W/C) ratio, types of admixtures, aggregate volume fraction, fine aggregate fraction, W/C ratio, temperature, and humidity condition of specimen were adopted in this test.

TL;DR: In this paper, a multistep micromechanics approach that starts at the nanolevel of the C-S-H matrix, where two types of C−S−H develop in the course of hydration, is proposed to predict the aging elasticity of ordinary portland cement.

TL;DR: In this paper, a pervious concrete pavement material used for roadway is introduced, which consists of a surface layer and a base layer, and compressive strength of the composite can reach 50 MPa and the flexural strength 6 MPa.

TL;DR: In this article, the authors investigated the durability of AAS concrete in acid environments and found that it had a high resistance in acid environment, superior to OPC concrete of similar grade.

TL;DR: In this paper, three types of hybrid composites were constructed using fiber combinations of polypropylene (PP) and carbon, carbon and steel, and steel and PP fibers at the same volume fraction (0.5%) in terms of compressive, splitting tensile, and flexural properties.

TL;DR: In this paper, the effect of limestone filler on the degree of hydration, the volume of hydrating products, and the optimal replacement of limestone filling in cement pastes at different w/cm ratios (0.25-0.50) were investigated by using a quadratic statistical model.

TL;DR: In this article, a phenomenological approach, based on semi-adiabatic calorimetry, is only associated with first-order phenomena, and the study excludes the complex physicochemical details involved in the chemistry of cement.

TL;DR: In this paper, the effect of silica fume (SF) and class C fly ash (FA) on the thermal conductivity of lightweight aggregate concrete (LWAC) was measured.

TL;DR: In this paper, the effect of technological variables on pore structure and mechanical properties of lime-based mortars was discussed, including the influence of curing time, binder-aggregate (B/Ag) ratio, aggregate attributes and porosity.

TL;DR: In this article, a relationship between the Hydraulic Index (HI) of slag at 7 and 28 days (HI7 and HI28) and the influencing properties of slags, namely, glass content, fineness and chemical composition, was investigated.

TL;DR: In this paper, the use of a new technique for the controlled combustion of Egyptian rice husk to mitigate the environmental concerns associated with its uncontrolled burning and provide a supplementary cementing material for the local construction industry was investigated.

TL;DR: In this paper, the pore structures of OPC and ground granulated blastfurnace slag (GGBS) were investigated in respect to their pore structure, chloride diffusion coefficients, internal and external chloride-binding capabilities by expression method and leaching method and the microstructure analysis on Friedel's salt.

TL;DR: In this paper, expanded polystyrene (EPS) beads were used as lightweight aggregate both in concretes and mortars containing silica fume as a supplementary cementitious material.

TL;DR: In this paper, three different matrices were used: (a) granulated blast furnace slag activated with waterglass (Na2SiO3+NaOH) with a concentration of 4% Na2O by mass of slag and cured at room temperature, (b) aluminosilicate fly ash activated with 8M NaOH and cured with 85 °C during the first 24 h and (c) 50% fly ash+50% slag activation with 8m NaOH solution at room-temperature.

TL;DR: In this article, the authors developed a mechanistic model for the mechanism of attack resulting from sodium and magnesium sulfate solutions, and the potential of these mechanistic models for use in service life prediction models has also been identified.

TL;DR: In this paper, the authors investigated the effect of water-cement ratio, aggregate size, and age on the microstructure of the interfacial transition zone (ITZ) between normal weight aggregate and the bulk cement paste.

TL;DR: In this paper, the results of an experimental investigation carried out to evaluate the mechanical properties of concrete mixtures in which fine aggregate (sand) was partially replaced with Class F fly ash by weight.

TL;DR: In this article, the effect of heat treatment parameters on the dehydroxylation/amorphization process of the kaolinite-based materials such as natural and artificial kaolin clays with different amounts of amorphous phase (metakaolin) was investigated.

TL;DR: In this article, a series of experiments using recycled aggregate of various compositions from building rubble was conducted, and the test results show that the building rubble could be transformed into useful recycled aggregate through proper processing.

TL;DR: In this article, the results of the investigation of the hydration of alkali-activated slag (AAS) by nuclear magnetic resonance spectroscopy (NMR) were presented.

TL;DR: In this paper, the physical and mechanical properties of Portland cement (PC) containing metakaolin (MK) or combination of MK and slag and the compatibility between such materials and superplasticizers were investigated.

TL;DR: In this paper, an experimental study on the autogenous shrinkage of Portland cement concrete (OPC) and concrete incorporating silica fume (SF) was conducted. And the results indicated that most of the total shrinkage in concrete specimens with very low w/c ratio and SF exposed to 65% relative humidity after an initial moist curing of 7 days did not seem to be due to the drying shrinkage but due to auto-noising shrinkage.

TL;DR: In this paper, the authors investigated which factor for a sodium silicate-based activator influences the setting time of AAS paste and found that the activator dosage, defined as the sum of the SiO 2 and Na 2 O concentrations, shows a significant trend with the AAS setting time.

TL;DR: In this article, the authors investigated the effect of mineral admixture and curing condition on the sorptivity of concrete and showed that the effect is very sensitive to the curing condition.

TL;DR: In this article, a method for estimating the electrical conductivity of cement paste pore solution at 25 °C is proposed based on the concentrations of OH−, K+ and Na+.

TL;DR: In this article, the effects of metakaolin additions on transport properties of mortars were investigated and compared to ordinary Portland cement to determine the influence of addition and replacement percentage on the transport properties.