Key parameters for strength control of rammed sand–cement mixtures: Influence of types of portland cement

The present research aims to quantify the influence of distinct types of Portland cement, amounts of
cement, porosity, curing time period and porosity/cement ratio in the assessment of unconfined compressive
strength (qu) of rammed sand–cement mixtures. A program of unconfined compression tests
considering distinct types of Portland cement (types I, III and IV), porosities (g), cement contents (C)
and curing time periods (t) was carried out in the present study. It was found that a ratio between porosity
and cement [(g/Civ)1.5] applies to all equations that control the strength of blends (for the curing periods
and cement types studied here). The qu values of the specimens moulded for each cement type and
curing period were also normalize (i.e. divided by the qu attained by a specimen with porosity/cement
ratio equals to 20). It was found that a single power function adapts well to the normalized values for
all the cement type and curing period studied. From a practical viewpoint, this means that carrying
out only one (1) compression test with a specimen moulded with a specific cement time and cured for
a given time period, allows the equation that controls the strength for distinct porosity and cement content
to be determined.

A practical methodology for the determination of failure envelopes of fiber-reinforced cemented sands

This study aims to estimate the MohreCoulomb failure envelope of fiber-reinforced and non-reinforced
artificially cemented sands based on splitting tensile strength (st) and unconfined compressive strength
(sc) of such materials, without the necessity of carrying out triaxial testing. Based on the concept previously
established by Consoli et al. that the st/sc relationship is unique for each specific soil, fiber and
cement agent, it is shown that the effective angle of shearing resistance of a given fiber-reinforced or
non-reinforced cemented sandy soil (f0) is dependent of the st/sc ratio of such geomaterials and that
effective cohesion intercept (c0) is a direct function of the unconfined compressive strength (sc) [or
splitting tensile strength (st)] and st/sc ratio of the fiber-reinforced/non-reinforced improved soil. Finally,
the concepts presented herein are successfully checked for glass fiber-reinforced/non-reinforced silty
sand treated with ordinary Portland cement, considering weak, moderate and strong cementation levels.

Uplift Performance of Anchor Plates Embedded in Cement-Stabilized Backfill

Aseries of pullout tests is presented in this paper and is used to identify the kinematics of failure and the uplift response of circular anchor
plates embedded in sand-cement stabilized layers at distinct normalized embedment depths (H/D), where H is the thickness of the treated layer andD
is the diameter of the anchor plates. Experimental results show that the uplift capacity of anchor plates embedded in sand backfill layers increases
considerably after mixing 3% cement with the backfill material. Distinct failure mechanisms observed for anchor plates embedded in both sand and
cement-stabilized backfills are shown to be a function of H/D. The addition of cement to the sand backfill leads to an increase in uplift capacity of 9
times for anH/D ratio of 1.0 and of 13 times for an H/D ratio of 2.0. For sand backfill withH/D51:0, the failure surface had a truncated cone shape
with a vertical inclination of 22,whereas forH/Dof 1.5 and 2.0, radial crackingwas observed, andfinal failure surfaces had inclinations of 26 and 30,
respectively. Pullout of anchor plates in cement-stabilized backfills atH/Dratios ranging from 1.0 to 2.0 exhibit two distinct characteristics: (a) a linear
elastic deformation response at small pullout displacements and (b) a later stage where radial fracturing of the stabilized backfill leads to hardening just
prior to failure. Radial cracks starting at the top of the layer near the center of the anchor plates start to propagate only at about 90% of the final uplift
failure load, irrespective of H/D. DOI: 10.1061/(ASCE)GT.1943-5606.0000785.

The strength of soil–industrial by-products–lime blends

The aim of this study is to assess the strength controlling parameters of a sandy soil (Botucatu residual soil (BRS))
treated with industrial by-products (basaltic powdered rock (PR) or coal fly ash (FA)) and lime, as well as to show
that the porosity/volumetric lime content (/Lv) plays a fundamental role in the assessment of the target strength.
The controlling parameters evaluated were addition of industrial wastes, quantity of lime, porosity and /Lv: The
unconfined compressive strength (qu) increased non-linearly with the amount of lime and decreased with porosity
for all studied mixtures. Similar equations were found relating qu to /(Lv)0:12 for BRS–lime, BRS-PR–lime and BRSFA–
lime mixtures. Tests of potential reactivity of siliceous materials with alkalis on the materials studied indicated
that the higher amount of dissolved silica in the alkaline environment of the FA, when compared with the BRS and
the PR, was responsible for increasing the number of reactions with the lime and consequently increasing the
strength for BRS (25% FA)–lime mixtures, when compared to BRS–lime and BRS (25% PR)–lime blends.

Metodologia de Dosagem para Solos Areno-Pedregulhosos Cimentados

A técnica de solo cimento se apresenta como uma ferramenta eficaz no melhoramento
de distintos solos, adequando-os às necessidades da engenharia geotécnica. O tratamento do solo se
aplica, por exemplo, na construção de bases para plataformas rodo-ferroviárias. Dessa forma, o
presente estudo visa quantificar a influência da quantidade do cimento e porosidade em relação a
resistência mecânica da mistura. Assim, ensaios de resistência à compressão simples foram
realizados com o objetivo de obter uma metodologia de dosagem de uma mistura de areiapedregulho com cimento. Para a formação da mistura artifical, foram utilizados 25% de pedregulho,
10% de areia grossa e 32,5% de areia média e fina, cimento Portland de alta resistência inicial e
água destilada. Corpos de prova cilíndricos foram moldados com 10cm de diâmetro e 20cm de
altura, com teores de 1, 2, 3, 5, 7 e 9% de cimento em relação a massa de solo seco. Ensaios de
resistência à compressão simples foram realizados após 7 dias de cura em ambiente com
temperatura e umidade controlada.