Economical desert sand engineered cementitious composites (DS-ECCs) using a mixture of cement, fly ash, local sand, water, low-cost PVA fibers, and chemical additives were developed, aiming for further enhancement in ductility toughness. The mechanical behavior DS-ECCs two samples (from Mu Us Tengger deserts, China) was determined uniaxial tension/compression tests three-/four-point bending tes...

Nano-TiO2 (NT) and nano-SiO2 (NS) were separately added in the cement paste to investigate the rheological property of fresh mixtures and mechanical strength in hardened state. The effects of different dosages and types of nano-particles on the properties of cement paste were studied. The results indicated that the rheological behavior of the fresh cement paste coincides with the Modified Bingh...

Calcium leaching from cementitious materials into bentonite is a key process for the long-term alteration of cement–clay interfaces engineered barrier systems. Strong chemical gradients between cement and clay drive precipitation minerals such as calcium silicate hydrate (C–S–H) calcite. To analyze mineralogical porosity evolution at interface, composite specimens consisting paste mixed with va...

The micromechanics design theory has realized random short fiber-reinforced cement composites showing pseudostrain hardening (PSH) behavior with over 5% of strain capacity under tension. Nevertheless, this existing theory currently is limited to specific constituent properties, which does not account for chemical bond and fiber rupture. This article presents a new design theory that eliminates ...

Four different composite mixtures with varying amounts of expanded vermiculite were exposed to high temperatures of 300, 600, 900 and 1100uC for 6 h. Physical and mechanical properties including unit weight, porosity, water absorption, residual compressive strength, residual splitting tensile strength and also ultrasonic pulse velocity were determined after air cooling. Microstructures were inv...

The paper proposes a combined application of composite theory and Powers’ model for microstructural development for the estimation of the diffusion coefficient as a function of the moisture content of a defect-free cementitious material. Measurements of chloride diffusion in mortar samples (440 kg/m rapid-hardening Portland cement, w/c = 0.5, maturity minimum 6 months) stored at 65% and 85% RH,...